Lecture 10- vision + touch

Question 1

receptive field:
How do you identify it?

Answer 1

The area of visual space where the presence of light influences the activity of the neuron

to identify:
-Record form the neuron as the animal maintains focus on a central fixation point
-then shine a light in the different areas of visual space to see where the light alters the spiking activity of the neuron.

Question 2

Photoreceptor cells:
Bipolar cells:

Answer 2

Photo: when the appropriate wavelength of the light is in the receptive field of a photoreceptor cell, the cell hyper polarizes and releases less glutamate into the downstream bipolar cells.

bipolar: Inherit their receptive field from the photoreceptor cell that connect to them. There are ON and OFF

Question 3

ON vs OFF bipolar cells

Answer 3

ON: depolarizes and releases more glutamate. Excited by light in the center and inhibited by light in the surround

OFF: hyperpolarizes and releases less glutamate. Inhibited by light in the center and excited by light in the surround.

Question 4

Third cell pathways:

Answer 4

retinal ganglion cells inherit their receptive field from the bipolar cells that connect to them, but they integrate information from many ON and OFF bipolar cells, which make their receptive fields more complicated.

Question 5

Simple cells:

Answer 5

In the primary visual cortex are sensitive to lines of light, and their receptive fields are typically organized in a center surround fashion.

Question 6

Primary visual cortex:

Answer 6

-have larger receptive fields than the retinal ganglion. Activated when the line of light is detected in the receptive field.

-cells respond best to vertical lines

• good at identifying areas with sharp transitions between light and dark (borders, edges, corners)

Question 7

Visual association cortex:

Answer 7

-all of the occipital lobe surrounding the primary visual cortex. It extends into the parietal and temporal lobes, forming the dorsal and ventral streams of visual info processing

Question 8

Striate cortex vs extrastiate:

Answer 8

striate: synonymous with the visual cortex
Extrastriate: synonymous with the visual association cortex

Question 9

Dorsal stream of visual info:

Answer 9

-starts in primary visual cortex and ends in posterior and parietal
-involved in identifying spatial location
-encodes where objects are, if they are moving and how you should move to interact or avoid.

Question 10

Ventral streams in primary visual cortex:

Answer 10

-starts in primary visual cortex and ends in inferior temporal.
-involved with identifying form (object and colour)

Question 11

Monocular vision, binocular and depth perception:

Answer 11

mono: v1 neurons respond to visual input from just one eye

bino: v1 neurons respond to visual input from 2 eyes.

depth: monocular cues that can be used to estimate depth (size, detail, movement), cues are used to appreciate depth looking at 2 dimensional images.

Question 12

Stereopsis:

Answer 12

-perception of depth emerges from the fusion of two slightly different projections of an image on the two retinas.
-the different between the images from two eyes is called retinal disparity.
-Helpful when planning movements to interact with objects in moving space.