Neuroscience test 3

what two cell types do bipolar cells connect

transmitting signals from photoreceptors (rods/cones) to ganglion cells

which type of bipolar cells depolarize with light

on bipolar cells

which type of bipolar cells hyperpolarize in light

off bipolar cells

list on bipolar cell signal transduction. and in what state it occurs light or dark

In darkness, glutamate binds to mGluR6 → activates a cascade that closes TRPM1 cation channels → hyperpolarization.

what type of receptor does on bipolar cells have

mGluR6 (metabotropic)

what type of receptor does off polar cells have

AMPA/Kainate (ionotropic)

prestin causes what

shortening of the inner hair cells

acetylcholine causes what when released

depolarization

Endolymph is high in what?

potassium, potassium flow into the cell

lower frequency waves travel further to the apex

the basilar membrane is stiffer at the beginning so only what frequency can met this area

high frequency

alpha motor neuron

a motor neuron that innervates extrafusal muscle fibers

gamma motor neuron

a neuron whose axons form synapses with intrafusal muscle fibers

where alpha and gamme meet tells where to c

1bs axons will be activated, it will activate inhibitory gaba, it will eventually decrease _________ activity in order to prevent muscle fatigue

d1 project to

the globus pallidus internal

d2 project to the

globus pallidus external

with no other input,

the globus pallidus internal neurons

inhibit the thalamus

have a high background activity

no movement

inhibtion

d1 receptors leads to what pathways

to a cyclic amp excitatory pathway

the indirect pathway without dopamine

makes it harder to move

Huntington's disease has less inhibition of the

globus pallidus external

Explain the difference between rapidly (fast) adapting neurons and slow adapting neurons. What different features do they signal

rapidly- fires at begging goes quiet, then fires at the end. tells you on and off set of a stimulus.

slowly adapting- fires sustained throughout . fires throughout the stimulus.

which g protein is activated in ORNs

golf

in the mucus chloride is higher _________. when calcium opens chloride channels cl- flows _____. causing ___________ of the cell.

inside the cell, out, depolarization

golf activates what

adenylyl cyclase 3

how are calcium levels restored in the olfaction pathway

the atp dependent na+/ca2+ exchanger

where are olfactory receptor molecules located

in the membrane of the cilia

receptor cells

Specialized cells in every sensory system of the body that can turn other kinds of energy into action potentials (neural impulses) that the brain can process.

graded potentials

small changes in membrane potential that by themselves are insufficient to trigger an action potential. but accumulate to trigger one

which sensory pathway conveys information directly to the brain

olfactory

horizontal cells

type of cell that receives input from receptors and delivers inhibitory input to bipolar cells. connects laterally.

what is responsible for Detecting differences in intensity of light

photoreceptors

what's the first synaptic relay in the primary visual pathway

Lateral geniculate nucleus (LGN) of thalamus

Mixing of the visual signals first occurs in the

primary visual cortex

the region of the posterior occipital lobe whose primary input is from the visual system

striate cortex also means

primary visual cortex

Pretectum

reflex control of pupil and lens

Suprachiasmatic Nucleus (SCN)

area of the hypothalamus in which the body's biological clock is located

Superior colliculus

coordination of eye/head movements with visual and other information

name the three places ganglion cells project to other than LGN

2) Pretectum - pupillary light reflex

3) Suprachiasmatic Nucleus (SCN) - circadian clock

4) Superior colliculus - coordination of eye/head movements with visual and other information

After the Lateral geniculate nucleus (LGN) of thalamus where does visual info go?

primary visual cortex

Where does the optic nerve exit?

optic disc

Where does the optic nerve go next?

optic chiasm

optic chiasm

the point at which the optic nerves from the inside half of each eye cross over and then project to the opposite half of the brain

are vision signals mixed at the thalamus?

no first mixed afterwards at striate cortex

laminar organization

Inside-out

Light passes through ganglion and bipolar cells before reaching photoreceptors

which structure does light pass through first?

ganglion and bipolar cells before reaching photoreceptors

how do other horizontal cells connect to each other

via gap junctions

Where do amacrine cells synapse?

inner plexiform layer

The location in the retina containing axons and dendrites that connect the ganglion, bipolar, and amacrine cells

where do amacrine cells receive their input from?

bipolar cells

amacrine cells release what

photoreceptors ______ in response to light

hyperpolarize

rod outer segments are shed & renewed when? what about cones?

rod outer segments are depolarized in the _________ because of the steady influx of _______

dark , na+

where do vision ganglion cells get their input from

bipolar cells

Are photoreceptors neurons?

yes but they do not generate ap

the retinoid pigment epithelium

the retinoid cycle regenerates what

the visual pigment 11-cis- retinal

rods vs cones? high sensitivity to light

rods

rods vs cones? low convergence

cones

Rods vs. Cones -- Color Sensitivity:

- only cones can detect colors

rods vs cones (location)

Rods in periphery, cones in fovea/ center

rods vs cones? shape

rods: large and cylindrical

cones: small and tapered

rods vs cones? which outer segments contains stacked discs

rods

rods vs cones? important for dim light and motion detection

rods

rods vs cones? important for vision acuity and details

cones

rods vs cones? high convergence

rods

what are rods constantly releasing in the dark

glutamate

Rods in light: what is first activated/ causes light sensitivity

rhodopsin

rhodopsin

the pigment in rod cells that causes light sensitivity

Rods in light: rhodopsin activates what

g protein transducin

rods in the light: transducin

activates and stims cGMP phosphodiesterase (PDE)

rods in the light: phosphodiesterase

decreases the second messenger cGMP

converts cGMP to GMP

rods in the light: decreasing the second messenger cGMP causes

cyclic GMP- gated channels to close

rods in the light: when cyclic GMP- gated channels start to close. what can no longer can come in and what is there a efflux of

na/ca++ no longer come in. k+ efflux

rods in light: when na/ca++ no longer come in. k+ efflux what occurs

hyperpolarization and decreased glutamate release

what effect does calcium have on guanylyl cyclase.

how is this effected in light?

it inhibits it.

in light this inhibtion is removed, increasing cGMP synthesis, opening channels

guanylyl cyclase

enzyme that catalyzes transformation of GTP to cyclic GMP

what effect does calcium have on rhodopsin kinase? how is this effected in light.

it inhibits it. in light this inhibtion is removed, increasing rhodopsin phosphorylation, arrestin binds, rhodopsin activation time decrease, decreasing sensitivity.

what effect does calcium have on phosphodiesterase? how is this effected in light.

it enhances phosphodiesterase activity. in light activity decreases, cgmp levels increase, channels open = adaption

what effect does calcium have on cgmp channels? how is this effected in the light.

ca2+ typically comes in on these channels making it hard for the cgmp to bind to the channels. in light they are gone. So cgmp binds alot easier to the channels to open them.

what 3 things do calcium inhibit that in its absence allow for photoadaptation?

rhodopsin kinase

guanylyl cyclase

binding of cgmp to cgmp channels

Receptive field of a visual cell

is the retinal area that, when stimulated, affects the firing of that cell

Receptive field

the region of the sensory surface that, when stimulated, causes a change in the firing rate of that neuron

refers to the specific area of the visual field to which a particular neuron or group of neurons in the visual system responds

Receptive field

what effect does glutamate have on ON bipolar cells

inhibits

When light hits the photoreceptor, it hyperpolarizes and stops releasing glutamate, thus disinhibiting the ON bipolar cell. This results in the bipolar cell being activated.

what effect does glutamate have on OFF bipolar cells

EXCITES

OFF bipolar cells are depolarized (and thus activated) when there is more glutamate released by the photoreceptors (which occurs when there is less light). When light hits the photoreceptor and hyperpolarizes it (decreasing glutamate release), the OFF bipolar cell becomes inhibited.

When light is in the center of the receptive field, the OFF bipolar cell is

inhibited/ hyperpolarized

When light is in the receptive field surround, the OFF bipolar cell is

excited

When light is in the center of the receptive field, the ON bipolar cell gets

excited/ depolarized

When light is in the surrounding area of the receptive field, the ON bipolar cell's activity is

inhibited

The center-surround organization of the receptive field is a crucial feature of ganglion cells, and this contrast-based system allows the brain to detect

edges and patterns in visual scenes.

An ON-center ganglion cell is ________ when light hits the center of its receptive field and _______ when light hits the surround.

excited, inhibited

The ON-center ganglion cell's center region is activated by ______ bipolar cells, which themselves are activated when the photoreceptors (e.g., cones or rods) in the center of the receptive field _________.

ON, receive light

The surround is instead processed by ___________, which are activated by darkness and inhibit the center's response when

off bipolar cells, stimulated by light in the surround area.

An OFF-center ganglion cell is inhibited when light hits the ___________ and excited when light hits

center of its receptive field, the surround.

what do bipolar cells release

glutamate

When a photoreceptor in the center of the receptive field becomes activated by light, it not only sends signals to the connected bipolar cell but also stimulates_______ which do what to what where

horizontal cells. These horizontal cells inhibit the activity of neighboring photoreceptors that are part of the surround region, effectively reducing their activity and ensuring that the surround responds oppositely to the center.

Exhibits adaptation in responses - firing rate is not a measure of absolute light intensity but signals the difference from background level

The RPE cells are responsible for ingesting and digesting

the shed outer segments of photoreceptor cells

The RPE cells perform phagocytosis, a process in which they engulf and digest the shed outer segments of photoreceptor cells. This prevents the buildup of debris that could damage the photoreceptors.

Each Olfactory Sensory Neuron (OSN) expresses how many receptors

one Olfactory Receptor