Test # 4 Chapters 9,10,12 boyd

What is a cytochrome oxidase? a) A lysosomal enzyme used for cell metabolism b) A ribosomal enzyme used for cell metabolism c) An ER enzyme used for cell metabolism d) A mitochondrial enzyme used for cell metabolism

A mitochondrial enzyme used for cell metabolism Explanation: Cytochrome oxidase is a mitochondrial enzyme used for cell metabolism.

Trpv1 is activated by..... (2)

Above 43 Celcious and capsaicin

In layer IVCα, the neurons.....

Are insensitive to the wavelength of light In layer IVCα, the neurons are insensitive to the wavelength of light.

itsch, temp, and pain is carries by what type of primary afferent axon?

C (0.5-2 m/sec)

(see full question) Which layer of the striate cortex is next to the white matter?

Correct response: VI Explanation: Cell layer number VI is next to the white matter.

Use it or lose it (____)

"it" = the area in this brain dedicated to processing this

dorsal stream detects what...

"what": object recognition

dorsal stream beyond the striate cortex detects what...

"where": orientation and motor reaction of objects in space

Spinothalamic Pathway (Ascending Pain Pathway)

(also goes through VP but a larger part; more widespread disribution-- projects to a wider area of cortex thn touch)

What is the order of retinal cells that light will hit from first to last? a) Photoreceptor - ganglion cell - bipolar cell b) Ganglion cell - photoreceptor - bipolar cell c) Photoreceptor - bipolar cell - ganglion cell d) Ganglion cell - bipolar cell - photoreceptor

Ganglion cell - bipolar cell - photoreceptor Correct Explanation: Light would reach the ganglion cells, than the bipolar cells, and the photoreceptors the last since the photoreceptors are located at the way back of the retina.

Put into order from first to last to which structure light would pass in the retina: ganglion cell layer, outerplexiform layer, pigmented epithelium, inner nuclear layer a) Pigmented epithelium, inner nuclear layer, outerplexiform layer, ganglion cell layer b) Ganglion cell layer, inner nuclear layer, outerplexiform layer, pigmented epithelium c) Outerplexiform layer, inner nuclear layer, ganglion cell layer, pigmented epithelium d) Inner nuclear layer, outerplexiform layer, ganglion cell layer, pigmented epithelium

Ganglion cell layer, inner nuclear layer, outerplexiform layer, pigmented epithelium Correct Explanation: The order from first to last would be the ganglion cell layer, inner nuclear layer, outerplexiform layer, and the pigmented epithelium.

What is the most direct pathway for information flow in the retina? a) cone photoreceptor- ganglion cell- bipolar cell b) rod photoreceptor- bipolar cell- ganglion cell c) rod photoreceptor- ganglion cell- bipolar cell d) cone photoreceptor- bipolar cell- ganglion cell

cone photoreceptor- bipolar cell- ganglion cell Correct Explanation: The most direct pathway for information flow in the retina is a cone photoreceptor- bipolar cell- ganglion cell. The result of this pathway would be an action potential.

gangion cells receive their information from....

cones(either red, blue, or green cones)

light is the _____ for a g protein coupled receptor in rhodopsin

agonist

Neglect syndromes (the man who mistook his wife for a hat) Areas 5 and 7

part of body or world ignored

how do biplorar cells determine on-type or off-type

particular type of glutamate receptor (ionotoropic or G protein coupled)

3,4,5, and 6

parvocellular layers (smaller; axons from P-type cells synspse here) shape info, some color

Which pathway, magnocellular or parvocellular, provides a greater percentage of the input to the striate cortex?

parvocellular pathway provides the greatest percentage of input to the striate cortex. This pathway contains neurons with sustained responses, small receptive fields, and fewer direction selective neurons.

substance P is a __________ neurotransmitter

peptide

substance P is a _____ neurotransmitter

peptide (takes a long time to produce)

mechano receptors first resten in what animal?

rat

transection of left optic nerve

temporal view of left side will be gone. Nasal remains, as well as right side (T and L)

transection of optic chiasm

temporal views or both sides will be lost! (nasal view for both remains)

you'll feel _______ before pain

texture (A delta slower than Aß)

Thermoreceptor TRP Channels

6 diff types which fire at different temperature ranges

how many transmembrane proteins for rhodopsin?

7

What happens to the activity in the striate cortex when the retina is stimulated by a point of light? a) A broad distribution with a dip at the corresponding retinotopic location b) A narrow distribution with a peak at the corresponding retinotopic location c) A narrow distribution with a dip at the corresponding retinotopic location d) A broad distribution with a peak at the corresponding retinotopic location

A broad distribution with a peak at the corresponding retinotopic location Correct Explanation: If the retina is stimulated by a point of light, the activity in the striate cortex would be a broad distribution with a peak at the corresponding retinotopic location due to the overlap of receptive fields between retinal cells and cells in the target structure

Broadman 3b = .....

S1

Which of the following statements about scotopic vision is incorrect?

Scotopic vision occurs in the dark. Hence, rods will be mainly used. Rods are mainly found in the peripheral retina, and color is not perceived in the dark.

In the retina, what gives the most optimal responses from ganglion cells? a) All of the above b) Bright lines c) Complex shapes d) Spots of light

Spots of light Explanation: In the retina, spots of light give the most optimal response from ganglion cells.

The size of the pupil and eye movement are controlled by the projection of the retinal ganglion cells to the midbrain tectum called the _____. a) Hypothalamus b) Inferior colliculus c) Thalamus d) Superior colliculus

Superior Colliculous

orient eyes and move head to keep world focused on fovea, where most of cones are (1:1 with bipolar cells), and connection to vestibular system

Superious collicious (NOT INFERIOR bc thats for hearing, NOT visual system)

all 3 pathways converge where? (Blob Pathway, Parvo-interblob Pathway, Magnocellular Pathway)

The blob neurons! (no strict segregation)

What is the order of retinal cells that are located from innermost to outermost part of the retina? a) Ganglion cell - bipolar cell - photoreceptor b) Ganglion cell - photoreceptor - bipolar cell c) Photoreceptor - ganglion cell - bipolar cell d) Photoreceptor - bipolar cell - ganglion cell

The cell layers are named in reference to the middle of the eyeball. Hence, the ganglion cells make up the innermost layer, while the photoreceptors make up the outermost layer

In a R+G- cell, what must be done to create the strongest excitatory response? a) Bathe the receptive field center and surround with red light b) Bathe the receptive field center with red light c) Bathe the receptive field center with green light d) Bathe the receptive field center and surround with green light

To create the strongest excitatory response, one must bathe the receptive field center with red light. R+G- cell is excited by red in the receptive field center and inhibited by green in the surround. Bathing the receptive field center and surround with red light would cause a weaker excitatory response due to the partial absorption of red wavelengths of light in the green OFF surround.

Touch vs. Pain

Touch: Special structures for input (corpuscles) Fat myelinated Aβ fibers, fast Fibers connect deep in dorsal horn of spinal cord Crossover in medulla Pain: Free nerve endings Slow lightly myelinated Aδ and unmyelinated C fibers Fibers run in zone of Lissauer to substantia gelatinosa Immediate crossover

What would happen if diffuse blue light covers both the receptive field center and surround of a B+Y- cell? You selected: Activation of the receptive field center and partial activation of the surround, leading to a weaker excitatory response

A strong excitatory response Explanation: Blue light is not easily absorbed by the "red" and "green" photoreceptors in the receptive field surround. Hence, the receptive field center will have an excitatory response, and the yellow OFF surround will not be activated.

You are recording from a cell in the cortex which responds best to color differences. What kind of cell is it? A)A blob cell B)An interblob cell C)An M-type ganglion cell D)A P-type ganglion cell

A)A blob cell (the "color" channel)

a pain cell can detect only heat or chemical or all types of pain?

All nociceptors respond to all pain-- no specific corpusles but many tpes of receptosrs in all nerves(oxygen deprivation, some chemicals, temperature extremes, mechanical stress)

Which of the following are true about ipRGCs? a) All of the above b) Receive input from rods and cones c) Act as a photoreceptor d) Depolarize to light

All of the above Explanation: An ipRGC is a photoreceptor that receives input from rods and cones. It also depolarizes to light, and uses melanopsin as a photopigment.

Cytochrome oxidase-rich blobs receive direct LGN input from which cellular layers? a) All of the above b) Parvocellular layer c) Magnocellular layer d) Koniocellular layer

All of the above Explanation: The blobs receive direct LGN input from the koniocellular, magnocellular, and parvocellular layers.

How can dark adaptation be explained? a) All of the above b) Dilation of pupils c) Adjustment of the functional circuitry of the retina d) Regeneration of unbleached rhodopsin

All of the above Explanation: To explain dark adaptation, dilation of the pupils is important for this controls the amount of light entering the eye. Regeneration of unbleached rhodopsin and an adjustment of the function circuitry of the retina to allow more information from rods to ganglion cells play an important role as well.

Choose a CORRECT statement on photoreceptors. a) There are three types of cones, each of which contains a different photopigment sensitive to different wavelengths of light b) Only the cones, not the rods, are responsible for our ability to see color c) All of the above are correct d) All rod phororeceptors contain the same photopigments

All of the above are correct Explanation: Though all rod photoreceptors contain the same photopigments, there are three types of cones, each containing a different photopigment. In addition, only the cones are responsible for our ability to see color. (

Primary visual cortex names

Area 17 (from Broadman), V1, Striate Cortex

Posterior Parietal Cortex is areas...?

Areas 5 and 7 (Large receptive fields)

Cutting the right optic tract would causes loss of vision only in the left eye? A) True B) False

B) False (tract is after crossover, affects entire left visual feild; info from both eyes)

What is a way to synthesize more cGMP in the cone cells? a) Go to the dark b) Block the flow of calcium and sodium ions into the membrane c) Allow the maximum flow of calcium and sodium ions into the membrane d) Open the cGMP-gated channels

Block the flow of calcium and sodium ions into the membrane Explanation: In the dark, calcium enters the cone and has an inhibitory effect on the enzyme that synthesizes cGMP. Hence to synthesize more cGMP, one would have to block this flow of calcium and sodium ions into the membrane to allow guanylyl cyclase to synthesize cGMP.

At intermediate light levels (indoor lighting or outdoor traffic lighting at night), or mesopic conditions, which photoreceptors contribute to vision? a) Neither rod nor cone cells b) Only cone cells c) Only rod cells d) Both rod and cone cells

Both rod and cone cells contribute to vision during mesopic conditions.

The eye is designed to best detect? A)Absolute light intensity B)Colors C)Differences in light intensity D) Darkness

C)Differences in light intensity

If you injected radioactive amino acids into the cell body of a neuron in layer 5 of the right LGN, you would expect to find label in which layer of striate cortex? A)Layer IVCbeta of the left hemisphere B)Layer IVCalpha of the left hemisphere C)Layer IVCbeta of the right hemisphere D)Layer IVCalpha of the right hemisphere

C)Layer IVCbeta of the right hemisphere (1,2,3 M, 4-6 P) (1,2 project to ;3,4,5,6 project to IVCbeta)

what is importnant for light adaptation

Ca+ (which inhibits the inhibition of cGMP, to keep the channel open) glutemate (?)

S1 columns is columated bassed off of

Cells with similar characteristics in vertical columns (i.e. Slow vs fast adapting)

The ability of the eye to adapt to changes in light level relies on?

Changes in calcium concentration in the cones Explanation: Changes in calcium concentration in the cones determine the ability of the eye to adapt to changes in light level

Ventral streal is is an extension of the _________ pathway?

Coniocellular/parvo interblob (Shape analysis)

Which eye structure has the largest refractive power? a) Pupil b) Cornea c) Aqueous humor d) Lens

Cornea Explanation: The cornea has the largest refractive power because light from the air reaches the cornea, which is made of mostly of water, first. There is less refraction in the lens because other eye structures such as the aqueuous humor and vitreous humor is made up of water like the lens.

An OFF-center ganglion cell...

Correct response: Will fire more action potentials if a dark spot covers its receptive field center Explanation: An OFF-center ganglion cell will fire more action potentials if a dark spot covers its receptive field center.

On a moonless night, one can see a dim star best with the : A) Fovea B)Macula C)Central retina D)Peripheral retina

D)Peripheral retina is best for DIM LIGHT BC MANY RODS INTO EACH GANGLION CELL ((A) Fovea B)Macula C)Central retina all 1:1 wiring, detail)

How do OFF bipolar cells respond to glutamate? a) Repolarization b) Hyperpolarization c) Hypopolarization d) Depolarization

Depolarization Explanation: OFF bipolar cells respond to glutamate by depolarization from an influx of sodium ions.

What does light cause ipRGCs to do? a) Nothing, no retinal ganglion cells respond directly to light b) Depolarize c) Hyperpolarize d) Repolarize

Depolarize Correct Explanation: Light causes rods and cones to hyperpolarize. Light causes ipRGCs to depolarize.

In the dark, the membrane potential of the rod outer segment is ____. a) Hyperpolarized b) Depolarized c) Always 0mV d) Unpredictable

Depolarized Explanation: In the rod outer segment, the membrane potential is depolarized in the dark.

Area of skin innervated by both dorsal roots of single spinal segment

Dermatomes

Parallel processing is when... a) Different visual attributes are processed simultaneously using distinct pathways b) The same visual attribute is processed simultaneously using the same pathways c) Different visual attributes are processed at different times using distinct pathways d) The same visual attribute is processed at different times using distinct pathways

Different visual attributes are processed simultaneously using distinct pathways Explanation: Parallel processing plays an important role in the visual system. For example, our eyes provide two parallel streams of information simultaneously to create depth through the central nervous system.

Lateral Inhibition is done by.....(2)?

Dorsal column nuclei (brain stem) and thalamic nuclei (with Cortex influence... says "pay attention to this")

Which of the following statements regarding cone cells is incorrect? a) Each cone cell is reactive only to a single color range of wavelength b) Each type of cone is activated by a broad range of different wavelengths of light c) Different colors can be perceived by a single cone cell d) Each opsin has photopigments that are uniquely activated by different spectral sensitivities

Each cone cell is reactive only to a single color range of wavelength Explanation: Each cone cell can be reactive to a broad range of different wavelengths of light.

what do all Mechanoreceptors have in common?

Each has unmyelinated axon branches with mechanosensitive ion channels (Na+ and Ca+ in; K+ out)

To create the most optimal response of neurons outside layer IVC of the striate cortex, what stimulus must be given? a) Elongated bar of light moving across the receptive field b) Light covering the receptive field center and surround c) A spot of light in the receptive field center. d) Light covering the receptive field surround

Elongated bar of light moving across the receptive field Correct Explanation: Many neurons out layer IVC of the striate cortex respond best to an elongated bar of light moving across their receptive fields. These neurons exhibit orientation selectivity, however.

What purpose is served by the encapsulations around some sensory nerve endings in the skin?

Encapsulations around Pacinian corpuscles provide a mechanism that makes the Pacinian corpuscles rapidly adapting, which is a property that makes them sensitive to vibrating high-frequency stimuli.If the encapsulations are stripped away, as done by Loewenstein and colleagues in the 1960s, the naked nerve terminals become less sensitive to vibrating stimuli and more sensitive to steady pressure.wa

In the outside layer IVC, the neurons

Exhibit new receptive field characteristics In the outside layer IVC, the neurons exhibit new receptive field characteristics.

The ________ has receptive fields that are selectively responsive to more complex shapes, object motion, and even faces. a) Striate cortex b) Extrastriate cortex c) Retinal ganglion cell d) Photoreceptor

Extrastriate cortex Correct Explanation: The extrastriate cortex has receptive fields that are selectively responsive to more complex shapes, object motion, and faces.

small receptive fields means...

FINE DETAIL

Layers 1 and 2 or your right LGN are destroyed. You would have problems seeing: A)Colors in your left visual field B)Fast-moving stimuli in you right visual field C)Fine details of objects in your right visual field D)Fast-moving stimuli in your left visual field

Fast-moving stimuli in your left visual field

What is the main role of the cornea in vision?

Focusing an image onto the retina Explanation: The main purpose of the cornea is to focus an image onto the retina through refraction.

What is the main role of the cornea in vision? a) Amplifying an image b) Making an image clear c) Focusing an image onto the retina d) Reflecting an image

Focusing an image onto the retina Explanation: The main purpose of the cornea is to focus an image onto the retina through refraction.

Layer IVCΒ would mainly project to which layer in the striate cortex? a) III b) IVB c) IVA d) II

III Explanation: Layer IVCΒ would mainly project to cells in layer III of the striate cortex.

The pattern of radial connections maintains the retinotopic organization established in which layer? a) II b) I c) IV d) III

IV Correct Explanation: The pattern of radial connection maintain the retinotopic organization established in layer IV. Layer IV is separated into different parts and tiers.

Parvocellular LGN neurons project to which layer in the visual cortex? a) IVCα b) IVA c) IVB d) IVCΒ

IVCΒ Explanation: Parvocellular LGN neurons project to layer IVCΒ in the visual cortex.

Magnocellular to...

IVCα

Which of these layers of the striate cortex does NOT contain binocular neurons? a) IVCα b) IVA c) III d) II

IVCα Explanation: The layer IVCα of the striate cortex is monocular. All the other layers mentioned above are superficial to IVC; they are mostly binocular.

what characterizes IVCα ?

IVCα insensitive to wavelength, (Magnocellular)

Parvocellular.....

IVCβ

Calcium in the cones has what effect on the enzyme that synthesizes cGMP? a) Excitatory b) Partial effect c) Inhibitory d) No effect

Inhibitory Correct Explanation: In the dark, calcium enters the cone and has an inhibitory effect on the enzyme that synthesizes cGMP.

What type of receptor do OFF bipolar cells have? a) Ionotropic glutamate receptor b) G-protein-coupled receptor c) Tyrosine-kinase receptor d) Ion channel-linked receptor

Ionotropic glutamate receptor Explanation: OFF bipolar cells have ionotropic glutamate receptors. These glutamate-gated channels, through an influx of sodium ions, help control the depolarizing of the excitatory postsynaptic potential.

Which is a FALSE statement about area MT? a) Has large receptive fields that respond to stimulus movement in a narrow range of directions b) Cells are direction selective c) Is sensitive to an object's structure much more than its motion d) Responds to types of motion

Is sensitive to an object's structure much more than its motion Correct Explanation: Area MT responds mainly to motion. It has large receptive fields that respond to stimulus movement in a narrow range of directions, and its cells are direction selective

Large, myelinated Aβ axons conveying information about a touch to the skin enter the dorsal horn and branch. One branch synapses on second-order sensory neurons. What happens to the other branch?

It ascends straight to the brain. Explanation: This ascending input is responsible for perception, enabling us to form complex judgments about the stimuli touching the skin.

Large, myelinated Aβ axons conveying information about a touch to the skin enter the dorsal horn and branch. One branch synapses on second-order sensory neurons. What happens to the other branch? a) It synapses with interneurons in the intermediate zone. b) It ascends straight to the brain. c) It crosses over to the other side of the spinal cord and synapses with second-order sensory neurons there. d) It synapses with motor neurons in the ventral horn.

It ascends straight to the brain. Explanation: This ascending input is responsible for perception, enabling us to form complex judgments about the stimuli touching the skin.

In relation to structure and function, what makes rods more sensitive to light than cones? a) Many membranous disks b) Short, tapered outer segment c) Lower photopigment concentration d) All of the above

Many membranous disks Correct Explanation: Rods are more sensitive to light than cones due to having many membranous segments and a high photopigment concentration.

What do iPRGCs (intrinsically photosensitive retinal ganglion cells) use as a photopigment? a) Phycobilins b) Chlorophyll c) Melanopsin d) Carotenoids

Melanopsin Correct Explanation: ipRGCs use melanopsin as a photopigment to transduce light.

Based on their mechanism of activation, the neurons in the layers of the LGN are considered to be

Monocular Explanation: Since the neurons of the layers of the LGN are activated by only one eye, they are considered to be monocular. It does not depend on light levels.

Based on their mechanism of activation, the neurons in the layers of the LGN are considered to be a) Monocular in the dark b) Binocular c) Binocular in the dark d) Monocular

Monocular Explanation: Since the neurons of the layers of the LGN are activated by only one eye, they are considered to be monocular. It does not depend on light levels.

How can a discrete point of light activate many cells in the target structure? a) Increase in the frequency of action potentials b) Greater sensitivity of cells in the target structure c) Overlap of receptive fields d) None of the above

Overlap of receptive fields Explanation: A discrete point of light can activate many more cells in the target structure because of the overlap of receptive fields.

To distinguish small words in a book, what ganglion cells would most likely be involved? a) P cells b) M cells c) None of the above d) nonM-nonP cells

P cells Correct Explanation: P cells have small receptive fields that help distinguish fine detail.

Which ganglion cells are responsible for the processing of colors?

P cells and nonM-nonP cells are specialized for the separate processing of red-green and blue-yellow information.

Parvo-interblob Pathway

P type ganglion cells to parvo of LGN to IVCβ to layer II and III interblob regions Binocular, simple, and complex Orientation selective Analysis of fine object shape Small receptive feilds Shape analysis

Pathway: analysis of object shape

P-type retinal ganglion cells that project to parvocellular LGN neurons(3-6), which in turn project to layer IVC in striate cortex.

What breaks down cGMP normally present in the cytoplasm of rods?

PDE (phosphodiesterase) Explanation: PDE (phosphodiesterase) breaks down cGMP present in the cytoplasm of rods. PDE is activated by transducin.

Shape analysis is performed by ...?

Parvo-interblob Pathway

The projection to layer III of the striate cortex is a result of which input from the LGN? a) Parvocellular LGN b) Both of the above c) None of the above d) Magnocellular LGN

Parvocellular LGN Explanation: Layer IVCΒ receives parvocellular LGN input; as a result it projects to layer III of the striate cortex.

collecting all the input from 100s of rods

Peripheral retina more sensitive to light because rods for low light, more photoreceptors per ganglion cell

The outer segments of photoreceptors are embedded in ____. a) Inner plexiform layer b) Sclera c) Pigmented epithelium d) Outer plexiform layer

Pigmented epithelium Explanation: The outer segments of photoreceptors are embedded in the pigmented epithelium. Reference: Chapter 9, The Laminar Organization of the Retina

____ is the condition when a hardening of the lens accompanies the aging process and is thought to be explained by the fact that while new lens cells are generated throughout life, none are lost. a) Hyperopia b) Myopia c) Presbyopia d) Astigmatism

Presbyopia Correct Explanation: In presbyopia, a hardening of the lens occurs within the aging process. This disorder may occur due to the fact that new cells are generated throughout life, while none are lost. The lens becomes less elastic, making it harder to accommodate and change the shape of the lens

The right optic tract receives signals from _____. a. the nasal retina of the left eye b. the nasal retina of the right eye c. the temporal retina of the left eye d. the temporal retina of the right eye

a. the nasal retina of the left eye d. the temporal retina of the right eye Correct response: a, d Explanation: As shown in Figure 10.3, the right optic tract receives signals from the nasal retina of the left eye and the temporal retina of the right eye.

binocular perception occurs when?

after layer 4B and then 3 . segregated till LAYER 4 (shown in Ocular dominance columns)!!

transection of left optic tract

all of RIGHT side of vision will be lost (all of left side remains)

Retinal ganglion cells (RGC)

are affec

posterior parietal cortex (areas 5 & 7) respond to ....

association. integrated with visual. (Elaborate stimulus preferences interpretation of spatial relationships, body image, coordinated body movements)

In the striate cortex, what does layer I mostly consist of? a) input fibers b) output fibers c) axons and dendrites d) neurons

axons and dendrites Correct Explanation: Layer I, which is just under the pia mater, is mostly made up of axons and dendrites of cells in other layers.

pathway order of retinal processing

axons->

Nissl stain of the cortex leaves a deposit of dye where in the neuron? a) Dendrites b) Soma c) Nucleus d) Axon

b) Soma

Choose CORRECT statements about photopic conditions. a. occurs in nighttime lighting b. occurs in daytime lighting c. primarily rods contribute to vision d. primarily cones contribute to vision a) b, d b) b, c c) a, c d) a, d

b, d Explanation: In photopic conditions, or in daytime lighting, cones mainly contribute to vision

asterioagnosia

inability to recognize objects by touch

The periaqueductal gray decreases pain through via efferent projections to the ________ nuclei of the ________. a) raphe; thalamus b) intralaminar; thalamus c) ventral posterior; thalamus d) raphe; medulla oblongata

raphe; medulla oblongata Explanation: The PAG can influence the raphe nuclei of the medulla, which in turn can modulate the flow of nociceptive information through the dorsal horns of the spinal cord.

opponent colors

red vs. green blue vs. yellow (comes from red +green)

photoreceptor cell is more depolarized in the dark

releases a lot of neurotransmitter

Virtuous solution attached to what? (not aqueous, its a gel)

retina

central visual system pathway

retina to lateral geniculate nucleus (LGN) of thalamus to primary visual cortex

Conscious visual perception pathway

retina to lateral geniculate nucleus (LGN) of thalamus to primary visual cortex (area 17- Broadman terminology, V1, striate cortex)

what photopigment is used

rhophodopsin (in rods)

retina has the most_____

rods (peripheral vision)

receptive fields of LGN cells same as or different from the Retinal ganglion cells?

same as (no color involved)

transgential cells have_____ orientation selectivity

shifted (? what does that mean)

Pupillary light reflex

shine a light in 1 eye and both pupils contract

preferred stimulus of off-type bipolar cells

sign consevative cells; preferred stimulus of bipolar cells: OFF (in the dark) ionotropic (transmitter- gated channel)

preferred stimulus of on-type bipolar cells

sign inverting (do the oposite; glutemae inhibits the cells) do opposite of photoreceptos who send the signals

complex cells recieve information from ....

simple cells

Area 2 of the postcentral gyrus processes information related mainly to a) texture. b) temperature. c) taste. d) size.

size

Merkel's disks are ________ adapting and have _______ receptive fields.

slowly adapting and have small receptive fields.

P-types have ____ receptive feilds

small

mesotopic zone

some are still able to work at this light (rods and cones working)

second order neurons are found where?

spinal cord and brain

layer 4c has the most of what cells?

stellate cells (golgi type II, local circuit) PROJECTS TO V5

Capsaicin stimulates ________ release

substance P

The magnocellular pathway contains neurons with ___________ responses, _________ receptive fields, and the __________ percentage of direction-sensitive neurons.

transient (responses), large (receptive fields), and the highest (percentage of direction-sensitive neurons).

TRP stands for a) treatment regarding pain. b) touch/respond/pain. c) transient receptor potential. d) total reticular polarity.

transient receptor potential. Correct Explanation: Different TRP channels contribute to many different types of sensory transduction in organisms from yeast to humans. TRPV1 channels in nociceptor membranes are activated by elevations in temperature greater than 43ºC.

the surrounds and centers of the ganglion cells overlap, T or F?

true (that complicates it a lot)

Dorsal Column-Medial Lemniscal Pathway

used for touch and vibration: Dorsal root ganglion>dorsal column>crossover at medulla>Ventral Posterior (VP) nucleus of thalamus>Primary Somatosensory Cortex (S1)

How can lens change shape?

via ciliary muscles

Somatosensory integrated with other systems, especially ______________

visual (think clenching fist of a phantom limb and the reflection of their real hand)

visual field crossover, not eyeball crossover

visual field crossover (both eyeballs carry info from its visual feild and some of the other, up till the optic chiasm)

duplex retina means..

we have rods and cones

is there overlap between dermatomes?

yes (One to one relationship between spinal segments and dermatomes)

is retinotrppy preserved after layer 4?

yes (it would retain similar properties, respond to the same thing)

are there columns of cells which respond to specific frequencies, like in the auditory system?

yes, cells communicate to other cells that are in the same orientation

Aß cell bodies are found where???

in the dorsal root ganglions

inner plexiformlayer means...

towards the middle of the eye

G protien is called...

transducin

_______________ depolarizes nociceptors

Histamine

visual system for animals vs humans

human visual system is superious to that of cats, birds, amphibias

Hyperalgesia is due to....

-Increased intensity, reduced threshhold, spontaneous -Primary-area -Secondary-surrounding area -Peripheral and CNS mechanisms -Bradykinin, substance P (made by nociceptors), prostaglandins can make nociceptors more sensitive -Cross-talk between touch and pain pathways in spinal cord (shutting the gate for rubbing a stubbed toe)

retinotopy

-Neighboring retinal cells inform neighboring target cells in the LGN and striate cortex -Distorted, not exact representation, central field over represented, or magnified (more ganglion cells near fovea) -Point of light can activate many cells, overlap, peak of distribution -No little pictures, just PRECISE firing patterns

Simple cell receptive fields

-V1 neurons receiving a converging input from three or more LGN cells with receptor fields that are aligned along and axis -Binocular -Sensitive to stimulus orientation -Range of responses include color and motion direction

Astereoagnosia is.....?

-inability to recognize objects by touch

What is the size of a cortical module? a) 2x2 m b) 1x1 cm c) 0.2x0.2 cm d) 1x1 mm

0.2x0.2 cm Explanation: The measurements of a cortical module would be 2x2 mm, which would equate into 0.2*0.2 cm.

3b connects to 1 (___________ information), 2 (_________ information)

1 (texture information), 2 (size and shape information)

each eyeball has about how many axons

1 million

Give three reasons explaining why visual acuity is best when images fall on the fovea.

1) Ratio. Visual acuity improves as the ratio of photoreceptors to ganglion cells decreases. Relatively few photoreceptors feed each ganglion cell in the fovea, resulting in a low ratio, which maximizes visual acuity. 2) Pit. The fovea sits in a pit that the lateral displacement of the ganglion and bipolar cells creates above the photoreceptors. This allows light to strike the photoreceptors without passing through the other layers of retinal cells, minimizing light scatter that can blur the image. 3) Specialization of fovea cones. Visual space is not mapped to the targets of visual input uniformly. The central few degrees of the retina are over-represented in "neural space." Signals from individual cones in the fovea are represented in a larger volume of brain tissue than input from photoreceptors in peripheral regions of the retina. This specialization contributes to high acuity in central vision.

convergence

100:1

Blobs found in what layers?

2,3,5,6

dark adaptation takes how long

20 minutes

Somatosensory cortex in Broadman is...

3b (central sulcus/postcentral gyrus)

above _______ Celcius = pain

43 C

Rod length is...

500 nm (in between blue and green)

Primary visual cortex layers, mow many and names...

6

A heightened sensitivity to pain is known as a) algesia. b) hyperalgesia. c) analgesia. d) hypoalgesia.

hyperalgesia

What is true of an inhibitory neuron? a) Covered with spines b) Form only local connections c) All of the above d) Found only in layer III

Form only local connections Explanation: Inhibitory neurons lack spines, found in all cortical layers, and form only local connections.

What type of receptor do ON bipolar cells have? a) Ion channel-linked receptor b) G-protein-coupled receptor c) Ionotropic glutamate receptor d) Tyrosine-kinase recepto

G-protein-coupled receptor Explanation: ON bipolar cells have G-protein-coupled receptor that respond to glutamate with hyperpolarization.

_________ Cells Response to Light-Dark Borders

Ganglion Cells Response to Light-Dark Borders

Which cell is the only source of output from the retina? a) Bipolar cell b) Photoreceptor c) Ganglion cell d) Amacrine cell

Ganglion cell Correct Explanation: The only source of output from the retina is provided by the ganglion cells. They fire action potentials, and pass this information through the optic nerve out of the eye.

What is an important difference between ganglion cells and bipolar cells? a) Both A and C b) The concentric center-surround receptive fields of ganglion cells differs from that of bipolar cells. c) Bipolar cells fire action potentials while ganglion cells do not. d) Ganglion cells fire action potentials while bipolar cells do not.

Ganglion cells fire action potentials while bipolar cells do not. Correct Explanation: The main difference from ganglion cells and bipolar cells is that ganglion cells fire action potentials. Most ganglion cells have the same concentric center-surround receptive field organization as bipolar cells

what part of retinal information processing has action potentials?

Ganglions

primary peripheral neurotransmitter in pain processing...

Glutemate

In the dark, how does calcium enter the cone cells? a) Through cGMP-gated sodium channels b) Through the sodium-potassium pump c) Through cGMP-gated calcium channels d) Through voltage-dependent calcium channels

Guanylyl cyclase Correct Explanation: In the dark, calcium enters the cone and has an inhibitory effect on guanylyl cyclase, which synthesizes cGMP.

_____ is defined by the fact that parallel light rays are focused at a point behind the eye. a) Emmetropia b) Hyperopia c) Presbyopia d) Myopia

Hyperopia Explanation: Hyperopia, farsightedness, occurs when parallel light rays are focused at a point behind the eye.

How do ON bipolar cells respond to glutamate? a) Depolarization b) Repolarization c) Hyperpolarization d) Hypopolarization

Hyperpolarization Explanation: ON bipolar cells respond to glutamate by hyperpolarization.

What is the response that light has on rods and cones? a) Hyperpolarization b) Depolarization c) Repolarization d) Nothing

Hyperpolarization Explanation: On rods and cones, light causes these photoreceptors to hyperpolarize.

Under which of the following conditions will an OFF-center ganglion cell increase its firing rate? a) If a small dark spot covers the receptive field center b) None of the above will increase its firing rate c) If light is projected outside of its receptive field d) If light is projected to the center of its receptive field

If light is shone in the center of its receptive field, an OFF-center ganglion cell will fire fewer action potentials. To fire more action potentials, a small dark spot should cover the receptive field center.

When do photoreceptors release the most transmitter molecules? a) In the sunlight b) In complete darkness c) In dusk d) In artificial light

In complete darkness Explanation: The dark is the preferred stimulus for photoreceptors; hence, in complete darkness is when photoreceptors will release the most transmitter molecules.

what photosensitive chemicals are in rods vs cones

In rods, this chemical is called rhodopsin; in cones, these chemicals are called color pigment/color opsins/photopsin

Where does the LGN mostly receive its input?

In the LGN, about 80% of the excitatory synapses come from the primary visual cortex.

Hyperalgesia

Increased intensity, reduced threshhold, spontaneous in surrounding area of pain (but not in primary injury)

Photoreceptors ________________ in response to light. As a result, they release ____________ neurotransmitters at the photoreceptor/bipolar cell synapse.

hyperpolarize; less

What is true of a LGN? a) All of the above b) It is the first site in the ascending visual pathway where what we see is influenced by how we feel c) It is only a simple relay from the retina to the cortex d) It only receives input from the retina

It is the first site in the ascending visual pathway where what we see is influenced by how we feel Correct Explanation: Nonretinal inputs can be received by the LGN through the thalamus, brain stem, and the primary visual cortex. The LGN is also more than a simple relay from the retina to the cortex; it is the first site in a pathway where feelings can influence what we see.

Nociceptors and Pain Transduction

Lactic acid production leads to H+ build up in extracellular fluid Histamine depolarizes nociceptors

Horizontal connections usually occur in which layer in the striate cortex? a) Layer II b) Layer III c) Layer V d) Layer

Layer III Correct Explanation: Horizontal connections usually occur in layer III.

Which ganglion cells lack color opponency? a) None of the above b) nonM-nonP ganglion cells c) P ganglion cells d) M ganglion cells

M ganglion cells Correct Explanation: Some P ganglion cells and nonM-nonP ganglion cells have the ability of color opponency. M ganglion cells do not.

An animal zipping by will activate the

M ganglion cells (good for movement detection, but not contrast) LARGE receptive fild

Magnocellular Pathway

M type RGC to magno of LGN to IVCα to IVB IVB- binocular receptive fields here, simple and complex cells IVB- direction and orientation selectivity M channel role is analysis of object motion and guidance of motor actions

Pathway: analysis of object motion and guidance of motor actions

M-type retinal ganglion cells that project to magnocellular LGN cells, which in turn project to layer IVC of striate cortex.

Due to the distortion in retinotopy, what occurs to the neurons in the striate cortex? a) The neurons receive input identically from both the peripheral and central retina b) More neurons receive input from the peripheral retina than from the central retina c) No effect from distortion in retinotopy d) More neurons receive input from the central retina than from the peripheral retina

More neurons receive input from the central retina than from the peripheral retina Correct Explanation: Due to the distortion in retinotopy, more neurons in the striate cortex receive input from the central retina than from the peripheral retina. The distortion causes the central few degrees of the visual field to be magnified.

M channel analyses what?

Motion

The Dorsal Stream is an extension of the Motion/color pathway?

Motion (Magnocellular Pathway)

Blobs receive information from what pathways?

Motion M-type, shape/color P-type, light/dark nonM-nonP

_____ is defined by the fact that parallel light rays will converge before the retina. a) Presbyopia b) Emmetropia c) Myopia d) Hyperopia

Myopia Explanation: Myopia occurs when parallel light rays converge before the retina.

Which step does not occur in the transduction of light by rods? a) Na+ channels open b) PDE reduces the cGMP level c) Transducin activates PDE d) Light bleaches rhodopsin

Na+ channels open Explanation: First, light bleaches rhodopsin. Then, this activates transducin, which stimulates PDE to reduce the level of cGMP. With the reduction of cGMP level, Na+ channels close leading to hyperpolarization.

Neighboring locations on the retina project to neighboring locations in a) The striate cortex b) The LGN c) Other retinal cells d) All of the above

Neighboring locations on the retina project to neighboring locations in the LGN.

Does the optic chiasm synapse?

No (instead, come together to form optic radiation

hat would be the response if white light bathed the entire receptive field of a R+G- cell? a) Activation of the receptive field surround, leading to an inhibitory response b) No response c) Activation of the receptive field center and partial activation of the surround, leading to a weaker excitatory response d) Activation of the receptive field center, leading to an excitatory response

No response Correct Explanation: Since white light contains all the visible wavelengths of light, both the center and surround will be activated. Thus, the center and surround will cancel each other out leading to no response.

Blob Pathway

NonM-nonP to koniocellular of LGN to blobs in layers II and III Circular receptive fields, complex mix of color opponency and center-surround organizations Analysis of object colors Color analyses

photoreceptors always____ to light

hyperpolarizes

intrinsicly -- retino ganglion cells project to where?

hypothalamus

What is FALSE in regards to an OFF-center ganglion cell? a) Dark in the center of the cell causes it to depolarize b) Dark in the center of the cell will make it fire more action potentials c) None of the above d) Dark in the surround of the cell causes it to hyperpolarize

None of the above Correct Explanation: In an OFF-center ganglion cell, dark in the center of the cell causes it to depolarize; dark in the surround of the cell causes it to hyperpolarize. To fire more action potentials, dark in the center of the cell is needed as well.

Which choice is NOT a characteristic of the LGN? a) None of the above b) Different types of retinal information are kept separate through the various layers c) It is separated into 6 layers; the two ventral layers contain larger neurons d) Input from the two eyes is kept separate

None of the above Explanation: The LGN is separated into 6 different layers; with the larger neurons located in the two ventral layers. These layers also allow different types of retinal information to be kept separate. Input from the two eyes is also kept separate as well through the LGN.

What is FALSE of Rhodopsin? a) It contains retinal, derived from vitamin A b) It goes through a process called bleaching. c) None of the above are false d) It contains opsin, a protein with 7 transmembrane alpha helices

None of the above are false Explanation: Rhodopsin contains opsin, a protein with 7 transmembrane alpha helices. It also contains retinal which is derived from vitamin A. In addition, it goes through a process called bleaching

In layers III and IVB, and axon may form synapses with the dendrites of which cell? a) Pyramidal cells b) Ganglion cells c) Spiny stellate cells d) All of the above

Pyramidal cells Correct Explanation: Axons in layers III and IVB may form synapses with the dendrites of pyramidal cells of all layers.

what is the retina attached to?

RPE (pigmented retinal epithelium)

why is the pupil is black?

RPE (pigmented retinal epithelium); lack of pigment = red eyes=

What is responsible for a cell in layer VI receiving information from the same part of the retina as does a cell above it in layer IV? a) Horizontal connections b) Vertical connections c) Radial connections d) Diagonal connections

Radial connections Correct Explanation: Radial connections maintain the retinotopic organization established in layer IV; hence a cell in layer VI can receive information from the same part of the retina as does a cell in layer IV.

Descending Pain Control Pathways /Regulation of Pain Pathway (Top Down)

Raphe Nuclei produce serotonin

Why does red light have an effect in the green OFF surround? a) Red wavelengths of light are partially absorbed by green cones b) Red wavelengths of light absorbed by red cones lead to the stimulation of the green cones c) The green cones fully absorb the red wavelengths of light leading to a complete inhibitory response d) Red wavelengths of light does NOT have an effect in the green OFF surround

Red wavelengths of light are partially absorbed by green cones Explanation: Green cones in the green OFF surround can partially absorb red wavelengths of light to inhibit the response in the cell.

________ have receptive fields that have center-surround structure and are sensitive to variables such as contrast and the wavelength of light. a) Retinal ganglion cells b) Extrastriate cortex c) Photoreceptors d) Striate cortex

Retinal ganglion cells Explanation: Retinal ganglion cells have receptive fields that have center-surround structure which are sensitive to variables such as contrast and the wavelength of light.

rhodopsin is located where

in an Opsin of Cones

Which of the following statements about phototopic vision is incorrect? a) The cone cells in the fovea contribute to phototopic visual acuity b) The visual acuity on the central fovea is due to the lateral displacement of the cells above the photoreceptors, allowing light to strike the photoreceptors without passing through the other retinal cell layers c) The most spatial sensitivity occurs in the central fovea d) The maximal visual acuity is accomplished when the image is focused on the peripheral retina

The maximal visual acuity is accomplished when the image is focused on the peripheral retina Correct Explanation: Photopic condition would occur in daytime lighting. Hence, mainly cones will be used. Cones are usually found in the fovea, and rods are usually found in the peripheral retina.

During scotopic light levels, which part of the eye is the most sensitive? a) None of the above b) The peripheral retina c) The central fovea d) The blind spot

The peripheral retina Explanation: Since rods work during scotopic light levels, the peripheral retina part of the eye would be the most sensitive. This is where the most rods are located.

What will happen when a shadow passes over a photoreceptor?

The photoreceptor will depolarize, releasing more transmitter molecules Explanation: Photoreceptors are depolarized in the dark and hyperpolarized by light. Since the dark is the preferred stimulus for photoreceptors, they will release more transmitter molecules if a shadow passes over them

In retinotopy, why is the representation often distorted? a) Uniform sampling of cells in the retina b) The presence of more ganglion cells with receptive fields in or near the fovea c) The uniform sampling of retinal cells, themselves, reflect a distortion d) The presence of more ganglion cells in the periphery

The presence of more ganglion cells with receptive fields in or near the fovea Explanation: The presence of more ganglion cells with receptive fields in or near the fovea compared to the periphery is what causes the representation to be distorted. This distortion is due to the retinal cells not sampling uniformly.

What is the role of the visual cortex input to the LGN?

The role of the visual cortex input to the LGN is to modulate input from the LGN to the cortex.

layers indicates...

division of labor

What is parallel processing in the visual system?

There are separate, parallel channels or pathways from retinal to cortex that process different facets of the visual scene. They use different subsets of neurons and have distinctive receptive field properties. For example, the parvocellular-interblob pathway. analyzes object shape and the magnocellular pathway analyzes object motion. These pathways are "parallel" because they use different retinal, LGN, and cortical neurons in their retinofugal projections. They possess distinctive receptive field properties (e.g., large vs. small, transient vs. sustained) in all three locations. Other examples of parallel pathways include the blob pathway specialized for object color, and the inputs from the two eyes, which remain segregated until inputs from the two eyes converge in the superficial layers of the striate cortex

What would be the response of an M ganglion cell to red light? a) Activation of receptive field surround b) No response c) There would be a response, but it would not be color specific. d) Activation of receptive field center

There would be a response, but it would not be color specific. Correct Explanation: M ganglion cells lack color opponency; hence their response is not color specific. This is due to the receiving of input from more than one type of cone in their receptive field center and surround.

Which of the following is true of bipolar cells? a) They are categorized into ON and OFF cells b) Light will always depolarize bipolar cells c) They receive indirect synaptic input from photoreceptors in the receptive field center d) All of the above are true

They are categorized into ON and OFF cells Correct Explanation: Bipolar cells are categorized into two categories: ON and OFF. Depending on which bipolar cell it is, light can either depolarize or hyperpolarize the cell. Bipolar cells also receive DIRECT synaptic input from photoreceptors in the receptive field center.

What is an example of parallel processing? a) Processing depth between two eyes b) Both A and B c) None of the above d) Independent streams of information about dark and light from ganglion cells

Two parallel streams of information are compared in the central visual system to create depth, the distance of an object from the observer. A second example arises from the ON and OFF- center ganglion cells in the retina; independent streams of information about dark and light are processed there.

Hot vs cold

Warm receptors to C only Cold receptors to Aδ and C fibers

How does Dark adaptation occur? (what process)

a biochemical process in which rhodopsin, the rod photopigment, regenerates after being bleached in the light. (information from more rods is available to ganglion cells.)

you are unable to see anything in the left visual field. Where has the retinofugal pathway been damaged?

a transection of the right optic tract, resulting in blindness in the left visual field as viewed through either eye.

The somatic sensory cortex, like other areas of the neocortex, is a layered structure. Thalamic inputs to S1 terminate mainly in layer a) IV b) I c) III d) V e) II

a) IV

Shingles-Herpes zoster is an infection of ________________________

dorsal root ganglion

why are dashboard lights not red?

driving at night uses rod vision, so if a light is red, it can "blind" you by turning off rods

Choose CORRECT statements about scotopic conditions. a. occurs in nighttime lighting b. occurs in daytime lighting c. primarily rods contribute to vision d. primarily cones contribute to vision a) a, c b) b, c c) a, d d) b, d

a, c Correct Explanation: In scotopic conditions, or in nighttime lighting, rods mainly contribute to vision.

The inferior temporal (IT) cells are stimulated by ____. a. color b. motion c. abstract shape d. learning a) b, c b) a, c c) b, d d) a, d

a, c Explanation: The inferior temporal cells are stimulated by color and abstract shape.

More axons being sent to LGN to or from V1?

from the V1 to LGN (surprising, we don't know why this is, important for feedback) also connections to brain stem= flash of white light; modification, altertness

which receptive field belongs to layer 3 of LGN?

binocular receptive feild

sml means

blue, Green, red (small mediuum and long; wavelength)

What is the main neurotransmitter of the eye?

glutemate (more in dark vs light)

The axons of the spinothalamic tract and medial lemniscus a) occupy overlapping regions in the ventral posterior nucleus of the thalamus. b) both terminate in the ventral posterior nucleus of the thalamus. c) terminate in different nuclei of the thalamus. d) synapse over an equivalent area of the thalamus.

both terminate in the ventral posterior nucleus of the thalamus. Correct Explanation: The spinothalamic tract and trigeminal lemniscal axons synapse over a wider region of the thalamus than those of the medial lemniscus. Some of the axons terminate in the ventral posterior nucleus, just as the medial lemniscal axons do, but the touch and pain systems still remain segregated there by occupying separate regions of the nucleus.

how can Capsaicin can be analgesic (pain reducing)?

by depleting substance P from nerve endings

ganglion cels are the only cells in the´direct pathway which

have action potientials AND are on ALL TEH TIME (it is only a matter of how fast aka firing rate)

Cytochrome oxidase staining (mitochondrial enzyme) indicates what?

high metabolism/activity

Which of the following is an incorrect statement regarding photoreceptor transduction?

cGMP is broken down by guanylyl cyclase when the photopigment absorbs light Explanation: Guanylyl cyclase is the enzyme responsible for the production of cGMP.

Which of the following is an incorrect statement regarding photoreceptor transduction? a) cGMP, produced in the photoreceptor can open Na+ channel that allow the membrane potential to depolarize in the dark b) Light reduces cGMP, causing the Na+ channels to close, and the membrane potential becomes more negative c) cGMP is broken down by guanylyl cyclase when the photopigment absorbs light d) The photopigment in the membrane of the stacked disks in the rod outer segments is called rhodopsin

cGMP is broken down by guanylyl cyclase when the photopigment absorbs light Explanation: Guanylyl cyclase is the enzyme responsible for the production of cGMP.

the receptive feild 2 parts ... ?

center and surround (center communicate directly-- surround communicaes via horoontal cells... affected by cells, making the surround react opposite to center) ame stimulus (light ) different effects

if you cut off the vibrisae of a rat, the brain region dedicated to this sensation will do what?

change (possibly disappear) somatotopic map is plastic

sunlight makes rhodopsin make cGMP....

close Na+ cells (aka "the dark current"), repolarize cell

NonM-non-P collect ________ information

color

photopic

color vision

ventral stream impairment would result in what problems?

color vision or analyzing shapes

What are the majority of color-sensitive neurons called? a) color-opponent cells b) color-same cells c) color-different cells d) color-sensitive cells

color-opponent cells Correct Explanation: The majority of color-sensitive neurons are named color-opponent cells.

The amplification of differences in the activity of neighboring neurons is known as a) contrast enhancement. b) lateral inhibition. c) somatic modulation. d) somatic transformation.

contrast enhancement. Correct Explanation: Information is usually transformed as it is passed from one neuron to the next in a sensory pathway. One common transformation is the amplification of differences in the activity of neighboring neurons, also known as contrast enhancement.

Trigeminal Touch Pathway is which cranial nerve? innervated from the neck up

cranial nerve V (seperate from Dorsal Column-Medial Lemniscal Pathway, for touch)

dark current is opened by (closed by...)

cyclic GMP (closed by light via activation of a G protein that catalyses it)

When a dorsal root is cut, the corresponding dermatome on that side of the body does not lose all sensation. How many adjacent dorsal roots would need to be cut to result in a loss of sensation? a) 2 b) 4 c) 1 d) 3

d) 3

Which of the following statements is false? a) Moving electrical stimulation around S1 will cause sensations to "move" across the body. b) The neurosurgeon Wilder Penfield mapped the cortex of neurosurgical patients. c) Brain operations can be performed in awake patients because brain tissue lacks receptors of somatic sensation. d) The receptive fields of many S1 neurons produce a very disorderly map of the body on the cortex.

d) The receptive fields of many S1 neurons produce a very disorderly map of the body on the cortex.

Nociception-sensory process, can be controlled by ________

higher centers

Somatotopic Map: size of cortical region indicates...

how important it is (i.e rats and whiskers being more sensitive than paws)

Homunuculus shows...

how much cortical power is dedicated to each part

Which of the following statements is false? a) Axons of secondary neurons that receive input from temperature-sensitive cells immediately decussate and ascend in the contralateral spinothalamic tract. b) The organization of the temperature pathway is virtually identical to that of the pain pathway. c) Axons of cells responding to temperature synapse within the substantia gelatinosa of the dorsal horn. d) Warm receptors are coupled to Aδ and C fibers, whereas cold receptors are coupled only to C fibers.

d) Warm receptors are coupled to Aδ and C fibers, whereas cold receptors are coupled only to C fibers.

data is sometimes lost via....?

data compression

Phosphodiasphorase does what?

degrades cGMP

first order neurons ...

deliever sensory info to CNS

ON-center bipolar cells ____________ in response to light in the receptive field center. (less glutamate release)

depolarize

parallel processing

depth (near vs far ), light vs dark, red green, blue yellow channel, movement (still vs moving)

Naloxone is antagonist for ___________________.

endogenous opioids (and antagonize the placebo effect)

when the extra ocular lenses

esotopia (cross-eyed)

what parts of the visual cortex are not retinotoic?

face and object recognition areas are not retinotopcs

IT (of the ventral stream) is unique bc it responds to what....?

faces

is the fastest axon fat or thin?

fat

Nociceptors

free endings of C fibers (unmyleinated) and Aδ fibers (lightly myelinated). Mechanically gated channels depolarize when stretched or deformed OR in response to chemicals (proteases, substance P, ATP, K+, bradykinin, H+/protons)

Prostaglandins do not elicit overt pain, but instead a) increase the sensitivity of nociceptors to other stimuli. b) serve as the enzyme that leads to bradykinin formation. c) cause long-lasting intracellular changes that make heat-activated ion channels more sensitive. d) cause the release of histamine from mast cells.

increase the sensitivity of nociceptors to other stimuli. Correct Explanation: Prostaglandins are chemicals generated by the enzymatic breakdown of phospholipids. Aspirin and other nonsteroidal anti-inflammatory drugs inhibit the enzyme required for prostaglandin synthesis.

what is glaucoma?

increased intra-ocular pressure, damages optic nerves

Aspirin and other nonsteroidal anti-inflammatory drugs are a useful treatment for hyperalgesia because they

inhibit the enzyme required for prostaglandin synthesis. Explanation: Prostaglandins are chemicals generated by the enzymatic breakdown of phospholipids. Aspirin and other nonsteroidal anti-inflammatory drugs inhibit the enzyme cyclooxygenase, which is required for prostaglandin synthesis.

In Melzack's and Wall's gate theory of pain, activity of an Aα or Aβ axon will

inhibit the projection neuron. Explanation: Activity in the non-nociceptive mechanoreceptor can suppress, or close the "gate" on, nociceptive signals before they can proceed to the spinothalamic tract.

light in the surround is inhibiting or not?

inhibiting

Contrast enhancement via lateral inhibition is due primarily to a) relay via inhibitor synapses to dorsal column nucleus neurons. b) inhibitory interneurons between cells. c) equal increases in firing rates of all cells projecting onto a dorsal column nucleus neuron. d) synaptic gain by dorsal root ganglion cells.

inhibitory interneurons between cells. Correct Explanation: Inhibitory interneurons greatly amplify the activity of a cell with increased firing rates and its neighbors, leading to significant contrast enhancement.

Transneural Autoradiography

inject 1 eyeball to see where radioactivity goes to in the brain (depicts Ocular dominance columns in layer 4)

Gate theory of pain

interneuron inhibits pain projection neuron

example of inernuclear

interneurons

4a has what type?

interneurons (Inhibitory neurons in all layers, local only) (also found in every layer)

In addition to the ventral posterior nucleus, other spinothalamic tract axons end in the ________ nucleus of the thalamus. a) lateral geniculate b) medial geniculate c) dorsomedial d) intralaminar

intralaminar Correct Explanation: The intralaminar nuclei of the thalamus is divided into anterior and posterior groups, and further subdivided into smaller nuclei named by their position or relationship to adjacent structures

The zone of Lissauer a) is a tract adjacent to the dorsal horn of the spinal cord. b) is a tract adjacent to the intermediate zone of the spinal cord. c) is a tract adjacent to the ventral horn of the spinal cord. d) receives axons from the ventral roots of spinal nerves.

is a tract adjacent to the dorsal horn of the spinal cord. Correct Explanation: Small-diameter pain fibers have their cell bodies in the segmental dorsal root ganglia, and they enter the dorsal horn of the spinal cord. The fibers branch immediately, then travel a short distance up and down the spinal cord in a region called the zone of Lissauer

rhodopsin undergoes a conformational change , when...

it comes into contact with light

________: histamine binding activates TRPV1 channels, which are also activated by heat and capsaicin

itch

cGMP role

key in the lock to hyperpolarize cell (K+ closed)

inbetween layers

koniocellular layers (axons from nonM-non-P-type cells synapse here)

Pacinian corpuscles and Ruffini's endings have _________ receptive fields

large

Why are ipRGCs not ideal for fine pattern vision? a) A large number of ipRGCs b) large receptive fields. c) small dendritic fields. d) none of the above

large receptive fields. Explanation: Due to large receptive fields and the small number of ipRGCs, ipRGCs are not ideal for fine pattern vision. Large receptive fields are due to their large dendritic fields.

P-types have ____ sustained response

larger. detect fine detail

what does the thalamus do besides "relay" information?

lateral inhibition, Inhibitory interactions and most importantly: signal modification

what characterizes layer IVCβ?

layer IVCβ center-surround color-opponency (parvocellular)

Koniocellular to ....

layers II and III

What part of the visual field is represented in the left LGN?

left LGN, the left eye (ipsilateral) axons synapse on cells in layers 2, 3, and 5. the right (contralateral) eye axons synapse on cells in layers 1, 4, and 6.

Ocular dominance columns....

left and right eye inputs in stripes (only in layer 4!!)

why do older people need glasses (presbyopia)

lens becomes less flexible bc proteins are not renewed

near sighted

lens focuses and the beams lose bosu before reaching retina

far sighted

lens makes focus of light focus too FAR from the

The cells in the koniocellular layers have center-surround receptive fields that are either: _________ or ____________

light-dark or color-opponent.

retinitis pigmentosa

loss of peripheral and night vision

Retinofugal projection is made of...

made of optic nerve, optic chiasm and optic tract

layers 1 and 2 of LGN

magnocellular layers (axons from M-type cells synspse here)

In Melzack's and Wall's gate theory of pain, the interneuron is both excited by the ________ and inhibited by the ________. a) mechanoreceptor axon; nociceptive signals b) nociceptive signals; Aα or Aβ axons c) C fiber; pain axons d) spinothalamic tract; dorsal column

mechanoreceptor axon; nociceptive signals Explanation: By this arrangement, activity in the pain axon alone maximally excited the projection neuron, allowing nociceptive signals to rise to the brain. However, if the large mechanoreceptive axon fires concurrently, it activates the interneuron and suppresses nociceptive signals.

Trpm8 is activated by..... (2)

menthol or below 25 Celcious

Several brain regions have been implicated in pain suppression. The most well studied is the periaqueductal gray matter of the a) medulla oblongata. b) pons. c) midbrain. d) thalamus.

midbrain. Explanation: The periaqueductal gray wraps around (peri = "around") the cerebral aqueduct (or mesencephalic duct) that connects the third ventricle to the fourth ventricle

what animals were especially used to expirement on the visual system?

monkeys and cats

Outside IVC is where (more or less) complex stimuli are processed

more complex stimuli (demonstrated via orientation selectivity-- neuron only rapidly fies for 1 SPECIFIC orientation of a bar)

amplification due to...

multiple G protein can be acted on

What visual feilds cross over at the level of eyeballs?

nasal ones (not temporal ones)

orientation selectivity

neuron only rapidly fires for 1 SPECIFIC preferred orientation of a bar (this is maintained radially through the layers of the LGN, but not laterally)

scotopic

night sight

does Pain have a fancy structure at the end, or myelin?

no

What would you expect in regard to serotonin release onto dorsal horn cells following electrical stimulation of and simultaneous naloxone injections into the periaqueductal gray? a) none of the above b) no effect c) decrease d) increase

no effect Correct Explanation: Electrical stimulation of the periaqueductal gray normally stimulates cells of the raphe nuclei in the brainstem, increasing serotonin release onto nociceptive cells of the dorsal horn, inhibiting them. Simultaneous infusions of naloxone (an opioid receptor antagonist) would block the analgesic effects induced by electrical stimulation of the PAG (thus, serotonin release from the raphe would be decreased)

Layer 1 has what type of neurons

no neurons

Do M-types have opponency

no. but they do recieve information from all 3 pathways

substance P is made by

nociceptors (influences histamine)

The cells in the koniocellular layers receive inputs from the ___________ types of retinal ganglion cells

nonM-nonP

partial decussation

not all from 1 eye is transferred to the other side of the brain

off type bipolar cells signal to...

off type ganglion cells

photopigment is located where?

on the "disk part" of rods and cones

pituitary tumor would create what affect on sight due to effect on optic chiasm?

only allow sight of nasal hemifeilds (tunnel vision)

at the fovea do rods or cones exist?

only cones

direction selectivity

only lights up when something moves across its selective feild in a SPECIFIC direction (either top to bottom or certain angle or Left to right , but NOT the other way around) example, putting the slides in, the cats columns would fire up

LGN input from both eyes or one per side?

only one eye or the other!

cranial nerve II is.....

optic nerve

how does optic tract project to cortex?

optic radiation (formed by optic chiasm axons)

central part of visual field (fovea) is over or underrepresented?

overrepresented (more ganglion cells near fovea)

receptive feild of bipolar cells

peripheral retina (lots of rods in 1 cell)

melinopson

photoreceptor, depolarized in the light (intrinsically photosensitive ganglion cells)

outerplexiform

photoreceptors

Horizontal cells influence the activity of... a) photoreceptors, ganglion cells b) bipolar cells, amacrine cells c) ganglion cells, bipolar cells d) photoreceptors, bipolar cells

photoreceptors, bipolar cells Explanation: Horizontal cells pass information laterally to influence the activity of photoreceptors and bipolar cells.

reflex control of pupil and lens (i.e. why both pupuls

pretectum (part of midbrain aka part of tectum)

lateral inhibition purpose?

promote contrast enhancement

3a in somatory sensation comes from

proprioception

Endorphins are relatively small _________, or ________. While receptors for endorphins are widely distributed in the CNS, they are particularly concentrated in areas that process or modulate _________ information.

proteins; peptides; nociceptive

ciliary ganglion is vital for what?

pupil reflex

during daylight rhodopsin is bleached from what color to what color?

purple to yellow

layer -- has the most of what types of cells

pyraidal cells (thick apical dendrite, basal dendrites, project to other regions)

At the cellular level, endorphins exert effects by a) suppressing the release of glutamate from synaptic terminals. b) depolarizing presynaptic membranes. c) depolarizing postsynaptic membranes. d) increasing the release of glutamate from synaptic terminals.

suppressing the release of glutamate from synaptic terminals. Correct Explanation: These effects at the cellular level lead to endorphin-containing neurons in the spinal cord and brain stem preventing the passage of nociceptive signals through the dorsal horn and into higher levels of the brain where the perception of pain is generated.

pain pathway vs touch (dorsal column)

synapses closer to the dorsal surface (superfiicial) Substantia gelatinosa and zone of Lissauer, AND immediate crossover

intrinsically photosensitive ganglion cells

synchronize circadian rhythm (even when s.o. blind!) HUGE DENDRITIC FEILD

does it take more take more photons to activate a cone or a rod?

take more photons to activate a cone than a rod

What visual feilds cross over at the level of opric chiasm?

temporal hemifeild

what is layer 4c?

the "recieving" layer-- projects radially (up and down)(not trasgental) like a loading dock

Layers 2 and 3 tend to project to

the cortex V2, V3, etc (cell bodies in LGN)

What is "accomadation" in the eye?

the lens changing shape

why this set up

to compare and contrast; seeing defferences in intensity and borders