Visual System Physiology Dr. Pierce

Question 1

The photoreceptors connect to the bipolar cells and they

Answer 1

Connect to the ganglion cells that go to the brain

Question 2

When the photoreceptors are depolarized they make a

Answer 2

graded potential

Question 3

Rods and cones release glutamate

Answer 3

All the time, the amount changed
Highest in the dark

GLUTAMATE acts INHIBITORY

Question 4

When glutamate is released

Answer 4

The bipolar cell does not depolarize

Question 5

Reason the GLUTAMATE is inhibitory

Answer 5

Binds to NMDA or non-NMDA, orrr nGluR6

Bipolar cells have the nGluR6
Glutamate ——> GCPR that closes cGMP gated na+ channels
This hyperpolarizes the BIPOLAR Cells

Question 6

Activated Bipolar Cells release

Answer 6

Glutamate (EXCITATORY)——> NMDA or non-NMDA
Depolarized the ganglionic cells that sends through the optic nerve where it releases glutamate in the visual cortex

BIPOLAR CELLS send EXCITATORY NTS

Question 7

Superior Colliculus

Answer 7

Connects to the tectospinal tract —-> Anterior horns of cervical vert.
= activates motor reflexes to move eyes in the right direction
=its about the intention of movement , not fixation of a moving object
=makes map of visual space to activate motor responses

Question 8

Pectectum

Answer 8

Pupillary Reflex,

Sends ——> Edinger-Westphal then ——> Ciliary Ganglion to make the pupillary reflex

Question 9

Hypothalamus= some fibers off the optic tract form the retinohypothalamic tract. Where do they go and what is their function

Answer 9

They terminate in the Supraorptic, suprachiasmatic, and paraventricular nuclei of the Hypothalamus
They have visual input to hypo = light-dark function of neuroendocrine and circadian rhythm

Hypothalamus also gets info from MG cells

Question 10

Accessory Optic Nuclei (AON)

Answer 10

Advanced Visual Processing, nystagmus in response to prolonged large field motion

Question 11

V1

Answer 11

Primary Visual Cortex of Broadman area 17
Identify edges and contours of objects

Redirects visual input to other parts of the brain to interpret what I see

Question 12

V2

Greater part of area 18

Answer 12

Depth perception by analyzing info from both eyes

Question 13

V3a

Answer 13

IDENTIFICATION OF MOTION

Is motion happening yes or no

Question 14

V4

Answer 14

Complete processing of color inputs

LESION= Achromatopsia (if unilateral it can go unnoticed)

Question 15

MT/V5

Answer 15

TRACKS motion across a scene by direction and context of background
Neurons detect direction of a moving edge

Question 16

Oreintation Columns spawning down the 1-6 layers of the cortex

Answer 16

Neurons in a column get excited by a stimulus with the same angle of reflection of a visual line
Light hitting the kitchen table travel in a certain angle on a visual line

Question 17

Ocular Dominance Columns span all 6 layers and around

Answer 17

Respond to input from one eye only

Question 18

There are horizontal and vertical and diagonal orientation columns
What do they do

Answer 18

They are neurons that get input from that type of shape in an image

Question 19

Blobs span all 6 layers as cylinders down

Answer 19

Sensitive to color
All 3 color cones are required that send neurons to these blobs
(Stain with Cytochrome Oxidase and look like polka dots)

Question 20

Neurons mapped on the V1 primary visual cortex are through the 6 layers:

Answer 20

Stripes (Ocular Dominance Columns), Swirls (Orientation Columns), and Blobs

Question 21

Melanopsin Ganglion (MG) cells

Answer 21

1-3% of ganglion cells that sense light = MG cells
They can also sense light like photoreceptors
They use MELANOPSIN
Sensitive to BLUE LIGHT and provides regulation of circadian rhythm
(Non-image-forming light-responsive system)

Question 22

Where do the MG cells protect blue light information to

Answer 22

The Hypothalamus, Superchiasmatic Nucleus which signals the Pineal Gland to secrete melatonin in a rhythmic pattern

Question 23

The melanopsin ganglion goes with the optic nerve since it is a type of ganglionic cell and if there is an optic nerve lesion

Answer 23

You loose your circadian rhythm also

Question 24

patient with photoreceptors blindness

How will they respond to blue light pupillary reflex and circadian rhythm

Answer 24

Both stay intact

Question 25

Blue light during the day

Blue light during evening or before sleep

Answer 25

Decrease inflammation after surgery and organ damage
Treat seasonal depression, alertness, cognition

Can disrupt melatonin release and delayed 1st REM

Question 26

Processing visual information: DORSAL PATHWAY

Answer 26

WHERE PATHWAY (pitcher throws ball and you are looking at the ball movement to decide how to move your arms and swing the bat

Vision signal goes to the primary visual cortex V1—> V2/V3 —->V5/MT —->to send dorsal pathway to the parietal and frontal lobe

For associating vision with movement (complete motor acts based on what I see)

Question 27

Processing visual information: VENTRAL PATHWAY

Answer 27

WHAT PATHWAY
Visual input goes to V1 primary visual cortex—-> V2—>V4—>inferior Temporal Cortex

Interpret images (recognize symbols, copy shapes, faces)
Facial Recognition
Unilateral damage can be possible

Question 28

A glutamic GPCR that closes cGMP gated Na receptors in the retina is located where

Answer 28

On the bipolar cells responding to darkness

Question 29

Which retinal cells make action potentials

Answer 29

Ganglionic cells

Question 30

LGN

Answer 30

Regulated flow of information