Psy 405 Exam 1

Relationship: Stimulus-Physiology

-Physical stimulus and brain/body activity -ex)lights with different brightness and occipital lobe activity

How Transduction Occurs

-Proximal stimulus is translated into electrochemical energy -Retinal changes shape and detached from opsin

Inferotempral cortex

-Removal leads to specific deficits -ex) hard time identifying specific groups

Proximal Stimulus

-Stimulus registered by sensory receptors -The stimulus in proximity -ex) light rays, vibrations in ear

Chevreul Illusion

-The perceived light and dark bands at the borders, which are not present in the actual physical stimuli -Black and white gradient

Distal stimulus

-The stimulus in the distance -Object in environment -ex) tree, voice

Ventral Pathway

-What or how pathway -Below -Parietal lobe

Dorsal Pathway

-Where pathway -Above -Temporal lobe

fMRI

-more common -O2 carrying blood makes the hemoglobin more magnetic, detects changes in the magnetic response

Tiling

-neurons work together to cover an entire visual field -overlap

Areas involved in visual processing

-optic nerve -LGN -occipital lobe —primary visual cortex -striate cortex -temporal lobe -parietal lobe -frontal lobe

Relationship: Stimulus-Perception

-physical stimulus and behavior -ex) lights with different brightness and response time

PET Scan

-radioactive tracer -see different brain activity -changes in the blood flow

Visual Transduction

-retinal absorbs one photon and changes shape (isomerization) -In the dark: molecule bent -In the light:molecule straight

Lateral inhibition

-the reduction of activity in one neuron by activity in neighboring neurons -used limulus to study -Function: enhances borders and contours -highlights change in environment

Bottom-Up Processing

Based on incoming stimuli from the environment "Data based" processing

How does lateral inhibition work?

The more stimulation a receptor receives, the more it suppresses the activity of the other receptors around it.

You are looking at an apple that is sitting in front of you on the table. Light rays are bouncing off the surface of the apple and entering into your eye. In this example, the light rays would be

The proximal stimulus

Specificity coding

The representation of a specific stimulus by the firing of neurons that respond only to that stimulus. "Grandmother cell"

When transduction occurs in the eye, which of the following occurs?

The retinal changes shape and detaches from the opsin.

Which of the following statements about retinal and opsin is correct?

The retinal molecule is the larger of the two.

Which of the following statements about our perceptual systems is true?

The same physical stimuli in the environment will not always lead to the same perceptual experience.

Absolute Threshold

The smallest amount of energy needed to detect a stimulus

What evidence was provided in the book and lecture to indicate that lateral inhibition may not be the only thing responsible for the Chevreul illusion?

The strength of the illusion can be changed by placing it on a background that changes smoothly from lighter to darker from left to right.

The process by which a proximal stimulus is translated into electrochemical activity in the brain is known as

Trandsuction

Excitatory Center-Inhibitory Surround

Type of Receptive Field: stimulating center increases target response, non-center decreases it

What specific animal was used to study lateral inhibition because it was easier?

limulus

When one neuron communicates with another using neurotransmitters, the receiving neuron

may become more or less likely to fire an action potential, depending on the nature of the connection between the two neurons.

When light is focused on the retina

most of the focusing is done by the cornea and is then fine-tuned by the lens.

If the cornea and lens tend to focus light in front of the retina, the individual is suffering from

myopia (nearsightedness)

The consequence of cortical magnification is that

objects viewed at the fovea are seen more clearly than objects in the periphery.

Which of the following statements about the location of rods and cones on the retina is correct?

only cones are located at the fovea.

The blind spot is

only found in people with macular degeneration.

When testing the process of dark adaptation for cones

participants must be monochromats.

What technique/s are often used to test vision in infants?

preferential looking and visual evoked potentials

The principal of convergence in vision describes why

rods have lower visual acuity, but higher sensitivity to light.

How do selective adaptation and selective rearing differ?

selective adaptation leads to a weaker response and selective rearing leads to a stronger response to stimuli someone is exposed to.

When we see activity in the brain around the same time that someone reports a particular percept (e.g. "I see blue"), we

should be careful about saying what is causing what since correlation is not causation.

If there is a unique pattern of activity over a limited number of neurons in response to a particular stimulus, ______ coding is occurring.

sparse

If there is a specific neuron that only fires in response to a particular stimulus, ______ coding is occurring.

specificity

Research on the FFA has shown

that it responds strongly to faces, but can also show activity for stimuli that a viewer is an expert for (e.g. cars, birds, greebles).

Evidence from brain imaging has shown

that specific brain modules respond most strongly to certain types of stimuli, but there is generally activity across large portions of the brain regardless of the type of stimulus being processed.

Studies on visual acuity development in infants have shown

that there is a gradual increase in visual acuity during the first few months of life.

The shape of orientation tuning curves for simple cortical cells indicates

that they will respond to bars of light at many angles, but the strength of the response will depend on the angle.

What is the first cortical area of the brain that we see visual activity from the retina reaching?

the occipital lobe

When the receptive fields of columns in the cortex cover our visual field

they cover the entire field with substantial overlap.

A proposed function for lateral inhibition is

to enhance the perception of borders and contours.

For the two visual processing pathways in the brain, the pathway associated with the identity of objects is the ____ pathway.

ventral

Refractive Myopia

The cornea and/or the lens bends the light too much

When using the method of limits to determine absolute threshold, the threshold is determined by

The crossover point

For neurons within a 1mm hypercolumn in primary visual cortex

all of the receptive fields will be in the same general area of visual space.

In the studies done by Ungerleider and Mishkin, if a monkey had part of its parietal lobe removed, it would have trouble figuring out where the food was

based on the location of a landmark.

In the studies done by Ungerleider and Mishkin, if a monkey had part of its temporal lobe removed, it would have trouble figuring out where the food was

based on the shape of objects.

Macular Degeneration

- Fovea and small surrounding area are destroyed - Creates a "blind spot" on retina - Most common in older individuals

Hyperopia

-"farsighted" -inability to see close objects clearly -focal point BEHIND retina -eyeball is too short -can lead to eye strain and headache

Myopia

-"nearsightedness" -inability to see far objects clearly -image focused in FRONT of retina

Presbyopia

-"old eye" -lens hardens and is weakened by ciliary muscles -distance of focal point increases -corrective lens needed for close activities

Convergence in Vision

-126 million rods and cones converge to 1 million ganglion cells -Higher convergence of rods than cones -Rods: lower acuity and higher sensitivity to light -Cones: higher acuity and lower sensitivity to light

Receptive Fields

-3 fibers -flattened retina -receptors that affect the firing rate if a neuron -convergence -determined by monitoring single cell responses

Cones

-3 types -Small and tapered -In the fovea and peripheral retina -6 million -Gradual adaptation to dark -How to measure dark adaptation? Use light on retina to only stimulate _______ -Most sensitive at 560 nm

Hermann Grid

-A geometrical display that results in the illusion of dark areas at the intersection of two white "corridors." This perception can be explained by lateral inhibition. -Wavy lines make illusion go away

Selective Rearing

-A procedure in which animals are reared in special environments. An example of selective rearing is the experiment in which kittens were reared in an environment of vertical stripes to determine the effect on orientation selectivity of cortical neurons. -Neurons responding to specific stimuli will be more predominant

Lens

-Adjusts shape for objects in distance -20% of focusing

Relationship: Physiology-Perception

-Behavior and brain/body activity -Response time and occipital love activity

Action Potential

-Communication between neurons -Intensity is the frequency in a time frame

Cornea

-Fixed -80% of focusing

Rods

-One type -Large and cylindrical -Only in the peripheral retina -120 million -Sensitive to light, faster adaptation to dark -How to measure dark adaptation? Monochromats -More sensitive to short-wavelengths of light (blues and greens)

Parts of photo receptors

-Opsin (large protein) -Retinal (light sensitive molecule)

Researching visual activity in infants

-PL (look at one vs the other) -VEP (EEG) -Infants have shorter and thicker cones

Visual Pigment Regeneration

1. Retinal changes shape 2. Opsin separates 3. Retinal shows bleaching 4. Retinal and opsin recombine to respond to light

Inhibitory-center-Excitatory-surround

A center-surround receptive field in which stimulation of the center causes an inhibitory response and stimulation of the surround causes an excitatory response

Which of the following statements about action potentials is true?

Action potentials can occur spontaneously.

Sparce coding

An object is represented by the pattern of firing of a small number of neurons Midpoint between specificity and population coding

Transduction

Changes in environmental energy to nerve impulses. Proximal stimulus reaches the rest of the brain

Which of the following statements best describes the relationship between the physical intensity of a stimulus and our perception of it?

Changes in perception are not necessarily equal to changes in stimulus intensity.

Which of the following statements accurately describes the process of dark adaptation?

Cones finish adapting more quickly, but rods eventually have greater sensitivity.

Effects if lateral inhibition

Dark edges are darker and light edges are lighter when next to one another

You are looking at a car parked across the street. Light rays are bouncing off the surface of the car and entering into your eye. In this example, the car would be the

Distal stimulus

Purkinje Shift

Enhanced sensitivity to short wavelengths during dark adaptation when the shift from cone to rod vision occurs

Axial Myopia

Eyeball is too long

Method of Limita

How absolute threshold is measured

EBA

Identifies bodies

FFA

Identifies faces

PPA

Identifies spatial layouts

Top-Down Processing

Information based on previous knowledge "knowledge-based" processing

Why was the Limulus (horseshoe crab) used to study lateral inhibition?

Larger nerve fibers were easier to record from individually.

According to the principle of transformation, there are a series of steps through which physical objects become conscious perceptions. Which of the following would be an example of the specific step of transduction when looking at an apple?

Light is absorbed by receptors in the eye which causes them to send an electrical signal.

When using PET or fMRI to measure brain activity

PET uses a radioactive tracer while fMRI uses differences in magnetic properties based on blood oxygen levels.

If we run a study where we measure the overall activity in your occipital cortex as a function of how quickly you are able to respond, we would be measuring the

Physiology-Perception Relationship

How neurons are arranged in the visual cortex

Receptive fields at the same location are within a column

Population Coding

Representation of a particular object by the pattern of firing of a large number of neurons Large number of stimuli

Signals from the retina tend to move through other brain structures in the following order:

Retina, LGN (Lateral Geniculate Nucleus), V1 (Primary Visual Cortex), Temporal and Parietal lobes.

Max firing rate of off-center

Ring around central receptive field

Which of the following is true about the spectral sensitivity of rods and cones?

Rods and each type of cone have higher relative sensitivity to different wavelengths of light.

Which of the following is true about the spectral sensitivity of rods and cones?

Rods are most sensitive to short wavelengths (like those we associate with blues and greens).

Cortical Magnification

Small area of fovea is represented by a large area on the visual cortex

What was the paradox of perception noted by Huth and colleagues?

Specific brain modules respond most strongly to certain types of stimuli, but there is generally activity across large portions of the brain regardless of the type of stimulus being processed.

Max firing rate of on-center

Spot across central receptive field

If we run a study where we show you lights with different levels of brightness and record how quickly you can respond to each, we would be measuring the

Stimulus-Perception Relationship

If we run a study where we vary the color of stimuli and measure how quickly you can respond to each color we would be measuring the

Stimulus-perception relationship

If we run a study where we show you lights with different levels of brightness and record the overall activity in your occipital cortex for each light intensity, we would be measuring the

Stimulus-physiology relationship

Which of the brain modules identified in humans has been identified as an area that responds best to face stimuli?

The FFA

Which of the brain modules identified in humans has been identified as an area that responds best to spatial layouts?

The PPA

In studies of stimulus perception, we use the method of limits in order to determine

The absolute threshold

Distributed representation

The idea that specific cognitive functions activate many areas of the brain fMRI

What evidence was provided in the book and lecture to indicate that lateral inhibition may not be the only thing responsible for the Hermann Grid illusion?

The illusion weakens/goes away if the lines in it are made wavy.

Where are neurotransmitters stored and released from neurons?

The vesicles at the end of the axon

According to the lateral inhibition theory of the Hermann Grid, we perceive gray spots at the intersections because

There is the maximum amount of lateral inhibition at these points since they are surrounded by the largest amount of white space.

When the receptive fields of columns in the cortex cover our visual field, why is this called "Tiling?"

They cover the entire field like tiles covering a floor or wall.

When our perception is altered by previous knowledge or expectations, this is an effect of

Top-down processing

Why does selective adaptation occur?

When the same neurons are activated for an extended period (seconds-minutes), their firing rate decreases temporarily.

When using PET or fMRI to measure brain activity

You should subtract the brain activity associated with a control condition from the activity associated with the condition you are interested in.

For a nerve fiber in the optic nerve that has an off-center receptive field, we would see the maximum rate of firing if

a donut shaped ring of light fell across the outer parts of the receptive field.

When it comes to the electromagnetic spectrum, without the aid of external devices, humans can see

a relatively narrow range between ultraviolet and infrared light.

For a nerve fiber in the optic nerve that has an on-center receptive field, we would see the maximum rate of firing if

a spot of light fell across the central part of the receptive field.

The principal of convergence in vision describes why

cones have higher visual acuity, but lower sensitivity to light.

How does lateral inhibition make it easier to see changes in lightness?

dark edges appear darker and light edges appear lighter when they are next to one another.

In primary visual cortex, moving across the cortex within a 1mm hypercolumn brings you to neurons that are sensitive to _______, while moving more than 1mm to another hypercolumn brings you to neurons that are sensitive to______.

different orientations; different locations on the retina

Further research has suggested that the dorsal visual processing pathway may also be described as the _______ pathway.

how

The intensity of a stimulus can be conveyed by

how many action potentials occur in a set time frame.

If the cornea and lens tend to focus light behind the retina, instead of on it because a person was born with shorter than normal eyeballs, the individual is suffering from

hyperopia (farsightedness)

When cortical magnification occurs for an object

it's processed by a larger portion of the brain and is perceived more clearly.

If a bar of light falls on the receptive field of a simple cortical cell

its firing rate will be at maximum when the bar is at a specific angle, and get gradually slower as the bar moves further from that angle.

To test if there is a difference in how size is processed for perception and action, Ganel and colleagues had participants

judge and grasp lines in a simulated depth display.

In selective rearing programs, kittens raised in an environment where they only saw horizontal bars

were unable to perceive vertical bars.

For the two visual processing pathways in the brain, the dorsal pathway is often described as the _____ pathway, while the ventral pathway is described as the ______ pathway.

where; what

If you stare at a black and white grating at a particular angle for a while

you will have a harder time seeing gratings the closer they are to that angle.

Retinitis Pigmentosa

—Genetic disease -Rods are destroyed first, fovea cones later -No peripheral vision -Sever cases lead to blindness