BIL268 Exam 2
on bipolar cell off bipolar cell
bipolar cells can be depolarized OR hyperpolarized by glutamate depending on the type. on bipolar cell will depolarize when light is on and depolarize when light is off. off bipolar cell will hyperpolarize if light is on.
spiral ganglion cells
bipolar from hair cell to auditory nerve
coincident detectors
for interaural time delay are inbetween the two axons from right and left but if the overlap is closer to the right side it means the left axon had more time to travel so the stimulus came from the left side
Adelta (group 3)
for pain and temp
dorsal column medial lemniscal pathway
for touch using Abeta fibers. decussates at the medullla
T is in milliseconds but frequency is in seconds so 1/T = f in 1/sec not msec
frequency from period
frequency and intensity coding of sound
frequency is coded by location. intensity is coded by firing rate of neurons and number of active neurons.
optic radiation
from LGN to striate cortex. lesions would cause blindness
path of optic nerve
from the retina to the base of the brain near pituitary gland
pathway of vision from the ganglion cells
ganglion cell axons -> optic nerve-> chiasm(partial decussation) -> optic tract -> LGN -> V1 through optic radiation -> V2 V3
colors of cones
red, green, blue
hyperalgesia
reduced threshold for pain
astigmatism
refraction in horizontal and vertical planes are different
foliate papillae vallate papillae fungiform papillae
ridges of the back side for saltiness/sourness big ones in back for bitterness small ones in front for sweetness
rods connect to ?
rods ONLY connect to ON bipolar cells. light on depolarizes these cells. (light on decreases glutamate release which then uses mglut receptor to increase depolarization of bipolar cell
pathway of sound from auditory nerve to brain
spiral ganglion -> auditory nerve -> ventral cochlear nucleus -> superior olive (both) -> lateral lemniscus -> inferior colliculus -> MGN of thalamus -> auditory cortex A1
emmetropia
state in which the eye is relaxed and focused on an object more than 6 meters or 20 feet away. The light rays coming from that object are essentially parallel, and the rays are focused on the retina without effort.
tunnel vision
cutting of the optic chiasm
macular degeneration
loss of central vision
brown-sequard syndrome
loss of ipsilateral touch and contralateral pain/temp
ageusia
loss of taste
transection of the left optic nerve
loss of vision of left eye. loss of vision in left outer and right nasal visual fields
amplitude
loudness in decibels
perilymph ion concentrations
low K+ and high Na+
white noise
many frequencies with the same intensity
auditory receptor cells convert
mechanical energy into a change in membrane polarization
receptor response of hair cells
mechanically gated K+ channels open which let K+ rush into the cell depolarizing it. (MET channels) activates voltage gated ca channels. sound stimulates from the shorter end to the higher end
Abeta (group 2)
mechanoreceptors (second largest and myelinated)
interaural time delay where
medial superior olive
pink noise
more low frequency than white noise. decreases on an angle
prestin
motor protein. electromotility of outer hair cells. change hair length to amplify the response.
MST
navigation
myopia
near sightedness. can't see far because focal point is infront of the retina. to move it back use a concave lens
impedance matching
overcome sound loss due to middle ear making up for the impedance
spinothalamic tract
pain and temp. ascend contralaterally in spinal cord
deafness in one ear
damage to the cochlear nucleus or auditory nerve on one side will damage the ipsilateral ear because it isn't binaural yet
helicotrema
connects the scala tympani and slala vestibuli at the apex of the basilar membrane
M cells versus P cells
M are larger, conduct action potential more rapidly, transient action potentials, more sensitive to low contrast stimuli. p cells have a sustained response, smaller receptive field, high contrast stimuli
ratio of M and P types ganglions
90% P, 5% M, 5% non-M-non-P
where do magno and parvo cells project to?
Magnocellular LGN neurons project to layer IVCα, and parvocellular LGN neurons project to layer IVCβ.
detecting bitterness
30 dif types of T2R receptors. taste binds to gpcr and stimulates phospholipase C to convert PIP2 to IP3. IP3 increases intracellular Ca+, depolarizing cell. and lets in Na+. NT release to gustatory axon is ATP.
auditory attenuation reflex?
Contraction of the tensor tympani and stapedius muscles to make the chain of ossicles more rigid, diminishing sound conduction
BE CAREFUL ABOUT EYE AND VISUAL FIELD
BE CAREFUL ABOUT WHICH EYE OR VISUAL FIELD IS DAMAGED
shape of ciliary bodies in inner and outer hair cells
C for inner and W for outer
hot and cold receptors
Cold is Adelta and C fibers Warm is C fibers Transient receptor potential channels (TRPA1- low temp (between 10 and 20 degrees. If you increase temp their activity will decrease), TRPV1) Temperature sensitive ion channels
aqueous humor versus vitreous humor
Fluid between cornea and iris. fluid between the lens and retina
nociceptors
Four subtypes: mechanical, thermal, chemical, and polymodal free unmyelinated nerve endings for pain
retinofugal projection locations
Hypothalamus: Biological rhythms, including sleep and wakefulness Pretectum: pupillary light reflex (sphinctor & dilator muscles) Superior colliculus/optic tectum: Orients the eyes in response to new stimuli
pyramidal cells in what layers
III, IVB, V, VI
analysis of motion in what striate layer?
IVB direction-sensitive neurons
spiny stellate in what layers
IVCa and IVCb
wavelength sensitive layers
IVCbeta not alpha (parvocellular)
Which of the following is a region of sensory surface that, when stimulated, changes the membrane potential of a neuron?
receptive field
pacinian corpuscle properties
Large RF, fast adaptation, HF stimuli (200-300Hz)-vibrations
sound pressure level formula
SPL = 20 log ( Px/Pref)
controls of hair cells - efferent fibers
Superior olivary complex -> olivocochlear bundle (OCB) -> HCs. lateral superior olive neurons project to the inner hair cells. superior olive medial project ot he outer hair cells
Meissner's corpuscle
Small RF, fast adaptation, LF stimuli (1-10 Hz)-texture
umami
T1R1 + T1R3
Fast Fourier Transform
convert time domain to frequency domain. number of cycles per seconds. makes a line at the frequency corresponding to the amplitude rather than showing the cycles over time
pathway of taste to brain
Taste cells -> gustatory afferent axons -> gustatory nucleus in the medulla -> ventral posterior medial (VPM) nucleus in thalamus -> primary gustatory cortex (brodmann area 36)
auditory vestibular nerve
VIII, projects to the cochlear nuclei in the medulla
AMPA kainate receptor and mGlutR6 receptors in bipolar cells
When light is on, photoreceptor cells are hyperpolarized, glutamate is not released. AMPA receptors aren't stimulated. cations don't enter the cell and the cell is hyperpolarized. these cells are turned off when light is on so they are off bipolar cells. when glutamate isn't supplied to mGlutR6 receptors because light is on, mGlutR6 stops inhibiting ion channels so now the cell can depolarize. these cells are on center because when there is light they are depolarized.
what cranial nerves are used for taste?
X, IX, VII (7, 9, 10)
Fourier's theory
a complex sound is equal to a sum of simple sounds
Achromatopsia
a rare clinical syndrome that results in a partial or complete loss of color vision despite the presence of normal functional cones in the retina.
olfactory nerve?
cranial nerve I
nerves for eye movement
abducens (6), trochlear (4), oculomotor (3). 3 pairs of muscles are lateral, medial, oblique,
inhibitory neurons
all layers, lack spines, form local connections
detecting saltiness
amiloride sensitive Na+ channel remains open so Na+ enters the cell and depolarizes causing Ca+ voltage gated channels to open and then release seratonin (or ach/gaba) onto gustatory afferent axon
auditory receptor cells
are not neurons, do not generate action potentials. specialized epithelial cells. sandwiched b/n the basilar membrane and reticular lamina.
layer VI goes where
back to LGN
binocular versus monocular visual field
binocular is what overlaps between 2 eyes so it isn't everything you see. monocular is the periphery
young-helmholtz trichromacy theory
brain assigns colors based on a comparative readout of the 3 color types. ratios of activation
ability to adapt to changes in light levels
calcium conc in cones. because light hyperpolarizes cells, we need to get back to -35 mV. when the channels close due to the breakdown of cGMP, Ca is cut off and stop inhibiting the production of cGMP, so now more cGMP can be made, opening the channels again, depolarizing back to -35
orientation columns
cells that respond to a specific angle of light and go up and down layers II to VI for analysis of shape
zonule fibers
circular ligaments that suspend the lens attached to the ciliary muscle
cataracts
clouding of the lens
neuromast
cluster of hair cells in a hair bundle
inner ear
cochlea and oval window and labyrinth
v4
color
three types of deafness
conductive, sensorineural, central
amacrine cells
connect laterally between ganglion cells and bipolar cells
horizontal cells
connect laterally between photoreceptors and bipolar cells
tip links
connect the stereocilia
pupillary light reflex
connections between the retina and neurons in the brainstem that control the muscles that constrict the pupils
rate-level function
firing rate versus intensity(stimulus level) (spikes s-1 vs dB). reaches a level where it plateaus- cant make any more action potential faster (saturation). threshold is where the firing of action potentials start. so the minimum dB necessary for the blue afferent would be 20dB. nothing to do with frequency at all. intensity (amplitude) dependent at a fixed frequency. linear relationship between threshold and saturation
retinitis pigmentosa
degernation of the photoreceptors
what is Q10dB for?
describes the degree of tuning. a smaller bandwidth makes the Q larger which means the neuron is more sharply tuned to that CF
pitch
determined by frequency (high or low tone)
place code on basilar membrane
dif locations are deformed t dif frequencies coding the frequency at a place
dark adaptation
dilation of the pupils to let more light in. regeneration of unbleached rhodopsin. adjustment of functional circuitry
unit for refractive power
diopters (1/focal distance)
focal distance
distance from the refractive surface to the point where parallel light rays converge. the reciprocal is diopters in meters.
tympanic membrane
eardrum. ossicles connect to it.
hyperopia
far sightedness. can't see up close because focal point is behind the retina. use convex lens
sweetness
gpcr. T1R2 + T1R3
presbyopia
hardening of the lens that comes with old age so use bifocal lens
audiogram
hearing level (dB) versus frequency. the curve is the threshold so you can't hear anything under it. at 0 dB that is what you are most sensitive to hearing. dif threshold of amplitude per frequency. how much the curve shifts up defines hearing loss
endolymph concentrations
high K+ and low Na+. potential of about 80 mV(more positive than perilymph)
energy, frequency, and wavelength relation
high freq= high energy, and high freq means short wavelength. frequency is speed/wavelength. shorter wavelength means larger energy so cool colors like 400 nm and gamma rays,xrays,ultraviolet are high energy. hot colors like 700 nm are lower energy and infrared, radar, etc
rods of corti
hold together the reticular lamina and basilar membrane
where is the gustatory cortex
in parietal lobe above the temporal lobe
binaural hearing starts where?
in superior olive. axon splits from ventral cochlear nucleus to go to both sides of the superior olives.
interaural time difference
in the lateral superior olive
anosmia
inability to smell (if the olfactory axons are severed)
retinoblastoma
inactivate RB1 gene that encodes the retinoblastoma protein. cancer of the retina
labeled line and population coding
information is represented by the absolute amount of activity in each individual element within the array. Population coding is when one smell/taste activates a few receptors/cells and then the responses combine to define that smell. One smell can activity several receptors in different ways a population code is a neural representation in which information is conveyed by relative amounts of activity across multiple, differentially sensitive elements of an array (large number of broadly tuned neurons)
inner hair cells versus outer hair cells
inner hair cells project to multiple ganglion cells. multiple outer hair cells combine onto one ganglion cell because there are more outer than inner
layers in the LGN
input from the two eyes is kept separate. 1,4,6 for contralateral. 2,3,5 for ipsilateral. layer 1 is at the bottom (ventral). layers 1,2 magnocellular. 3-6 parvocellular
parallel processing
inputs from dif eyes, info about light and dark, Different receptive fields and response properties of retinal ganglion cells: M- and P- cells, and nonM-nonP cells
volley theory
intermediate sound frequencies are represented by the pooled activity of a number of phase locked neurons for low frequency sounds
presbycusis
is the most common type of Sensorineural Hearing Loss caused by the natural aging of the auditory system. It occurs gradually and initially affects the ability to hear higher pitched (higher frequency) sounds.
strabismus esotropia exotropia
lack of alignment or coordination between the eyes due to the extraocular muscles. cross eyed wall eyed
ruffini's endings
large receptive field, large, slow adapting
binocular neurons
layer III
ocular dominance columns in what layer
layer IV has alternating input from the two eyes - monocular
where do koniocellur axons go?
layers 1 and 3 of the striate
blobs
layers II, III, V, VI from koniocellular (nonMnonP) - not layers I and IV. monocular
ambylopia
lazy eye. poor visual acuity
posterior chamber
located behind the iris and in front of the lens
olfactory transduction
odorants -> membrane odorant receptor proteins -> gpcr -> adenylyl cyclase -> cAMP -> binds to a cyclic nucleotide gated cation channel -> lets in Na and Ca+ -> open Ca+ activated Cl- channels letting Cl- exit the cell -> depolarization. this process, the receptor potential happens in the cilia but this triggers action potentials in the soma of the receptor cell and those action potential propagate on the olfactory nerve axon to the olfactory bulb. same receptor cells go to the same glomerulus in the olfactory bulb, mapping the scents together. synapse to a second order neuron in the glomerulus. then goes directly to the olfactory cortex and temporal lobe without passing the thalamus
conscious perception of smell pathway
olfactory tract to olfacotyr tubercle to the medial dorsal nucleus of the thalamus to the orbitofrontal cortex
tonotopic maps
on basilar membrane, within each auditory relay nuclei, the medial geniculate nucleus, and auditory cortex
organ of corti
on the basilar membrane (in scala media). contains the auditory receptors
what cells fire action potential in the retina?
only the ganglion cells fire action potentials. the bipolar and photoreceptor cells release NTs and use membrane potential.
outer ear
pinna to the tympanic membrane (ear canal)
how does the ear increase the sound?
pressure = force/area. the oval window has a smaller area which makes the pressure larger there than the tympanic membrane. moves fluids
Pretectum and optic tectum functions
pretectum controls the size of the pupil and certain eye movements. optic tectum commands eye movement and head orienting to fovea.
glacuoma
progressive loss of vision associated with elevated intraocular pressure. pressure in aqueous humor so vision is lost from the periphery inward
Aa (group 1)
proprioceptor (largest and myelinated for fastes reponse)
what meets the oval window and round window
scala tympani for round window and scala vestibuli for oval window (on top)
otoacoustic emission
sensor for sound. look at the basilar membrane amplitude of live versus dead animals. it is tuned to frequencies in the live but levels off in the dead
basilar membrane
separates the scala media from the scala tympani
reissner's membrane
separates the scala vestibuli from the scala media
what NTs are released by sour salty sweet bitter umami?
seratonin for sour and salty. ATP for bitter, sweet, umami
overview of sound path in ear:
sound moves the tympanic membrane -> tympanic membrane moves the ossicles -> ossicles move the oval window -> oval window moves fluid in the cochlea -> response in sensory neurons
detecting sourness
sourness is usually due to acidity. H+ comes in the amiloride sensitive sodium channel and blocks the K+ channels, which depolarizes the membrane.
phototransduction (dark current)
steady influx of Na+ giving -35 mV instead of -70 mV. cGMP is always produced and it is what opens the Na+ channels. enzyme guanylyl cyclase makes cGMP. absorption of light causes a change in retinal which activates opsin. stimulates a gpcr called transducin which then activates phosphodiesterase, which breaks down cGMP. when cGMP is gone, the Na+ chnnel closes. the membrane is hyperpolarized in response to light.
Which of the following is the major source of synaptic input to the LGN?
striate cortex (80%) - not ganglion cells as you'd expect. also brain stem supplies for alertness
layer V to where?
suerior coliculus and pons
where do hair cells form synapses
synapse on neurons whose cell bodies are in the spiral ganglion within the modiolus
inner plexiform layer inner nuclear layer outer plexiform layer outer nuclear layer
synapses b/n bipolar cells, amacrine cells, and ganglion cells inner nuclear layer is bipolar cells, amacrine cells, horizontal cells outer plexiform layer is synapses b/n horizontal cells, bipolar cells, and photoreceptor cells. outer nuclear layer is photoreceptor cells
dif between taste receptors and olfactory receptors
taste receptors aren't neurons. don't have an axon. olfactory receptors are neurons
what are the codes for olfaction?
temporal and spatial. particular odors are organized in a spatial map in the glomeruli but also timing of action potentials defines a smell
muscles in the middle ear
tensor tympani muscle attaches to the malleus and wall of the middle ear. stapedius muscle. when they contract the ossicles become more rigid so sound conduction is diminished.
visual acuity
the ability to distinguish two points of light close toe achother. depends on spacing of photoreceptors in the retina and the precision of the eye's refraction
tympanic membrane separates...
the auditory canal and middle ear are separated by
cochlea and basilar membrane base to apex
the basilar membrane gets wider towards the apex while the cochlea narrow. stiffness decreases from base to apex. apex is most flexible like a flipper
phase locking
the frequency of the sound is the same as the frequency of the action potentials
retinofugal projection
the neural pathway that leaves the eye beginning with the optic nerve (fugal means away)
names of ossicles
the ossicle attached to the tympanic membrane is the malleus. connects to incus. connects to stapes which connects to the oval window
tuning curve
threshold dB versus frequency. shows best sensitivity, bandwidth, characteristic frequency, Q10dB. Q10dB = CF/BW
magnocellular neurons project where?
to IVCa -> IVB -> out
parvocellular pathway in striate cortex
to IVCb -> III, II (right and left begin to mix) for fine object shape
cochlea
tranforms physical motion of the oval window into a neural response.
ossicles
transfer movement of the tympanic membrane into movements of the oval window.
stellate cells
triangular with many dendrites. in layers IVCa and IVCb of the striate
dif between tuning curve and audiogram
tuning curve is at the cellular level and the audiogram is overall
middle ear
tympanic membrane and ossicles
types of spiral ganglion cells
type I is from the inner hair cells to the ganglia. can be one inner hair cell to many ganglion. large. 95% type II is from the outer hair cells to the ganglia. since there are many outer hair cells many converge onto one ganglion (many to one) 5% small unipolar
attentuation reflex
uses the muscles of the middle ear to tighten the ossicles so that sound won't amplify. protection against loud sounds. takes 50-100msec so sudden sound can still damage your ears
nuclei of thalamus for dif senses
ventral posterior medial (VPM) for taste. medial dorsal nucleus for olfaction. lateral geniculate nucleus (LGN) for vision
optic disk
where optic nerve fibers are and where blood vessels originate. no photoreceptors. blind spto
fovea
where the retina is thinnest. no ganglion or bipolar cells, just cones. center of retina
