Neurophysiology

Question 1

Thickness of the retina

Answer 1

0.2-0.5mm

Question 2

Feed forward

Answer 2

Information is transmitted from photoreceptors to bipolar cells to ganglion cells

Question 3

Lateral flow

Answer 3

Horizontal and amacrine cell integration

Question 4

feedback

Answer 4

Information from ganglion cells is transmitted back to the photoreceptors via interplexiform cells

Question 5

Extracellular recording

Answer 5

Studies cells that respond with action potentials (amacrine and ganglion) by inserting an electrode in the retina near the cell without penetrating it

Question 6

Intracellular recording

Answer 6

Studies cells that respond with graded potentials (photoreceptors, bipolar cells, horizontal cells) by inserting a microelectrode into the cells and recording the change in electrical response

Question 7

Resting membrane potential of photoreceptors (and why)

Answer 7

-50mV due to potassium diffusing out, sodium diffusing in, and additional sodium channels (CNG channels) for influx at the outer segments

Question 8

Relative depolarization

Answer 8

Relative excitation, the state of photoreceptors in the dark

Question 9

G-protein coupled receptors

Answer 9

Membrane proteins characterized by seven transmembrane domains or subunits

Question 10

Isomerization

Answer 10

The process of absorbing light and undergoing a conformational change from 11-cis to all-trans that triggers phototransduction

Question 11

Transducin

Answer 11

A g-protein that interacts with photopigments

Question 12

cGMP purpose

Answer 12

Accumulation at sodium channels in outer segment keeps them partially open

Question 13

Phosphodiesterase

Answer 13

Released from transducin and cleaves clusters of cGMP ultimately causing hyperpolarization of the cell

Question 14

On-center bipolar cells

Answer 14

Respond with excitation when light falls on the center and inhibition when light falls on the surround

Question 15

Glutamates effect on on-center bipolar cells

Answer 15

Inhibitory effect, when light shines, glutamate production decreases and bipolar cell becomes relatively excited

Question 16

Glutamates effect on off-center bipolar cells

Answer 16

Excitatory

Question 17

Spatial antagonism

Answer 17

When light exposure elicits opposite responses depending upon whether it falls in the receptive field center or periphery

Question 18

Invaginating synapse

Answer 18

Formed by on-center bipolar cells with photoreceptors

Question 19

Conventional flat synapse

Answer 19

Formed by off-center bipolar cells and photoreceptors

Question 20

Synapse in inner layer of IPL

Answer 20

On-center bipolar cells and ganglion cells

Question 21

Synapse in outer layer of IPL

Answer 21

Off-center bipolar cells and ganglion cells

Question 22

Horizontal cells

Answer 22

enhance sharpness of images and contrast under photopic conditions, contributes to spatial summation, and responds with graded potentials

Question 23

H1 cells

Answer 23

Receive input from M and L cones, with little input from S cones

Question 24

H2 cells

Answer 24

Receive strong input from S cones, as well as input from M and L cones

Question 25

What do horizontal cells release

Answer 25

GABA upon excitation by glutamate

Question 26

GABA effects

Answer 26

Inhibitory to photoreceptors | Excites on center bipolar cells and on center ganglion cells

Question 27

Midget bipolar cells

Answer 27

receptive field center is a single M or L cone, surrounded by H1 cells Excellent visual acuity and color vision

Question 28

Diffuse bipolar cells

Answer 28

Receptive field center is many M and L cones surrounded by H1 cells, making it bad at color vision

Question 29

S-cone bipolar cells

Answer 29

Synapse only with S cones, in central retina they receive input from a single s cone

Question 30

Transient response

Answer 30

Shown by many amacrine cells that is a brief increase in activity at stimulus on and offsets

Question 31

A2 cells

Answer 31

Use glycine, rods

Question 32

A17 cells

Answer 32

Use GABA, rods

Question 33

Ganglion cells

Answer 33

Summate electrical activity of the retina

Question 34

Parvo ganglion cells

Answer 34

Smaller, 75-80% of gc population, one to one connection with midget bipolar cells leading to high spatial resolution and color discrimination

Question 35

Magno ganglion cells

Answer 35

Larger, 10% of gc population, large receptive fields, receive more from rods

Question 36

Koniocellular ganglion cells

Answer 36

Small, bistratified, receive from s-cone bipolar cells

Question 37

Melanopsin ganglion cells

Answer 37

Photosensitive, control pupillary function and circadian rhythm

Question 38

On center midget bipolar synapse with

Answer 38

On center midget ganglion cell

Question 39

Off center midget bipolar synapse with

Answer 39

off center midget ganglion cells

Question 40

On center diffuse bipolar synapse with

Answer 40

on center magno gc

Question 41

Off center diffuse bipolar synapse with

Answer 41

off center magno gc

Question 42

s cone bipolar synapse with

Answer 42

koniocellular gc

Question 43

mGluR6

Answer 43

Receptor found on the ON-center bipolar cell that causes glutamate to have an inhibitory effect

Question 44

AMPA

Answer 44

Receptor found on OFF-center bipolar cells that causes glutamate to have an excitatory effect

Question 45

Retino-geniculo-striate pathway

Answer 45

Route from the retina to the dorsal LGN that leads to conscious vision

Question 46

Spatial summation

Answer 46

As you increase the diameter of the spot of light on the center of an ON cell (Or periphery of an OFF cell), the firing rate will increase until reaching the periphery (or the center)

Question 47

Which neuron color codes (P or M)?

Answer 47

Parvo

Question 48

Which neuron has sustained temporal response (P or M)?

Answer 48

Parvo

Question 49

Which neuron has high temporal sensitivity (P or M)?

Answer 49

Magno

Question 50

Which neuron has faster transmission speed (P or M)?

Answer 50

Magno

Question 51

Which neuron shows linearity (P or M)?

Answer 51

Parvo

Question 52

Which neuron exhibits high spatial sensitivity (P or M)?

Answer 52

Parvo

Question 53

Which neuron goes to the ventral 2 layers of the LGN (P or M)?

Answer 53

Magno

Question 54

Which neuron projects to 4 c beta (P or M)?

Answer 54

Parvo