Lecture 10

vision part 2

intrinsically photosensitive ganglion cells express ____

melanopsin

melanopsin

enables direct depolarization

rods express ___

rhodopsin

cones express ___

opsins

rhodopsin convert ___ —> ___ when exposed to light

11-cis-retinal, all-trans-retinal

phototransduction in the light

1. __

2. __

3. __

light activates transducin, cGMP is hydrolyzed, closure of Na and Ca channels

transducin is a _______

2nd messenger

phototransduction in the darkness

1. __

2. __

3. __

increased cGMP is present, opening of Ca and Na channels, NT release

ON-center ganglion cells have ___ APs with light in receptive field

more

ON-center ganglion cells have ___ APs with decreased light in receptive field

no

OFF-center ganglion cells have ___ APs with light in receptive field

no

OFF-center ganglion cells have ___ APs with decreased light in receptive field

more

ON/OFF ganglion cells

• __

• __

respond transiently to increases and decreases in light, located at receptive field center

ON bipolar cell in increased light in center

1. __

2. __

3. __

4. __

5. __

center cone cell hyperpolarized, ON bipolar cell depolarized, glutamate released, Glutamate binds to NMDA and AMPA receptors, ON center ganglion cell fires

ON bipolar cell in decreased light in center

1. __

2. __

3. __

4. __

center cone cell depolarized, glutamate released, glutamate binds to mGluR6 receptor, ON bipolar cell hyperpolarized

OFF bipolar cell in increased light in center

1. __

2. __

center cone cell is hyperpolarized, OFF bipolar cell is hyperpolarized

OFF bipolar cell in decreased light in center

1. __

2. __

3. __

4. __

5. __

6. __

7. __

center cone cell depolarized, glutamate released, glutamate binds AMPA, bipolar cell depolarized, glutamate released, glutamate binds AMPA and NMDA, ganglion cell fires

horizontal cells use ___

GABA

amacrine cells use ___

GABA, glycine, Ach, dopamine, glutamate

lateral interactions in the retina allow _____

ganglion cells to be sensitive

retino-recipient brain regions

process image forming info

retino-no-recipient brain regions

process non image forming info

list retino-recipient brain regions

LGN, V1, superior colliculus

list retino-no-recipient brain regions

superchiasmatic nucleus, olivary pretectal nucleus

the superchiasmatic nucleus is located in the _____

hypothalamus

retina

decodes info about color, contrast, luminence, and motion

retinal ganglion cells

transmit feature specific info in parallel channels

parallel channels

1. __

2. __

3. __

4. __

5. __

6. __

7. __

8. __

9. __

retina, retinal ganglion cells, optic nerve, optic chiasm, optic tract, ganglion cell axons terminate on retino brain regions, optic radiation, V1

retino-geniculo-cortical pathway

1. __

2. __

3. __

retina, LGN, layer 4 of V1

thalamocortical pathway: ____ to ____

LGN, V1

visual field deficits

results from damage to retino-geniculo-cortical pathway

anopsias

large visual field deficits

hemianopsia

half of both visual fields are affected

where would this deficit be?

right optic nerve

where would this deficit be?

optic chiasm

where would this deficit be?

right optic tract

where would this deficit be?

right V1

the LGN has __, __, and __, ganglion cells

P, M, K

K ganglion cells are _____

in between layers

P ganglion cells are projected from_____

cones

M ganglion cells are projected from ____

rods

cerebral cortex

integrates info arriving at V1

the V1 has ____ arrangement

columnar

V1 Layer 1:

outermost

V1 layer 6:

innermost

V1 layers 2, 3, 5, 6:

• __

• __

hold pyramidal neurons, release glutamate to subcortical and cortical targets

V1 layer 4:

• __

• __

• __

has spiny stellate neurons, target of LGN axons, appears as stripes (striate cortex)

preferred orientation

• __

• __

peak of tuning curve, orientation of a stimulus to which a cortical neuron maximally responds

edges

neuron’s preferred orientation

extrastriate visual areas

other cortical areas devoted to visual processing of info from V1

ventral stream

• __

• __ to __

• __

recognize object or scene, V1 to inferior temporal cortex (temporal lobe), what pathway

dorsal stream

• __

• __ to __

• __

analysis of motion and spatial relationships, V1 to medial temporal area (parietal lobe), where pathway

Pupillary light reflex purpose

let in more light in dark conditions

Pupillary light reflex steps

1. __

2. __

3. __

4. __

5. __

retina, pretectum, EW nucleus, ciliary ganglion, pupillary constrictor muscle

accomodation is controlled by ____

EW neurons

accomodation when viewing something near vs far:

ciliary muscle thickens and round up lens

how lens shape is determined

zonule fibers exert tension vs lens elasticity

near response

when viewing a close object, accommodation, convergence, and constriction are required for optimal activity

extraocular eye muscles

redirect focus

conjugate eye movements

coorperating extraocular eye muscles so that binocular fixation is maintained

smooth pursuit

eyes shift position in a slow, smooth, continuous motion to track a moving object, ie watching a plane

saccadic eye movements

rapid eye movements to redirect focus, ie watching a baseball in a game

saccadic suppression

prevents blurring of object as it sweeps across retina