16-18. Visual system Flashcards
In the visual pathway, info is sent to the visual cortex via the optic nerve and the…
Lateral geniculate nucleus
which region is responsible for orientating the eyes/skull towards stimuli?
superior colliculus
type of photoreceptors in peripheral retina?
rods
which type of photoreceptor has the highest convergence?
rods
Name of muscle in anterior eye
cilliary muscle
what do the zonule fibres allow
for the lens to be stretched
which area in the eye has the highest visual acuity?
fovea
where do the blood vessels of the eye originate from?
optic disc
what 2 parts are the retina split into?
nasal and temporal
which part of the photoreceptors release NT?
pedicle
name 4 retinal cells
- bipolar
- horizontal
- ganglion
- amacrine
what is stereopsis
depth perception
what 2 visual fields do we have? what do each of them mean?
binocular = using both eyes monocular = uses 1 eye
describe brief visual pathway overview - 3
- retina
- lateral geniculate nucleus of thalamus
- primary visual cortex
where do visual tracts decussate?
optic chiasm
nerve coming from the eye
optic nerve
what is the full visual field
area which is viewed by both eyes
what is the full visual field divided into?
left and right visual hemi-fields
what is the binocular visual field?
area of overlap between right and left hemi-fields
what is a fixation point?
image which we are focusing on
which side of the eye is the nasal retina on?
medial
describe stereopsis
comparing the fixation point (which projects onto the fovea) with other points that lie on the retina
will far disparities be closer or further away from the fovea?
closer
where does the retino-fugal pathway start and stop?
starts at retina
stops at striate cortex
which component controls pupillary light constriction? - where exactly in the brain is this?
pretectum - midbrain
where is visual info processed
lateral geniculate nucleus of thalamus
what is blind sight?
visual which is not dependent on the processing from primary visual areas of the cortex
which 2 areas of the brain are thought to be used for blind sight>
- superior colliculus
2. amygdala
which brain lobe is the striate cortex located?
occipital
brodmann’s areas for visual processing- which is the primary visual processing area?
17 (v1), 18 and 19
in the striate cortex - what is the function of the dorsal stream?
motion processing
in the striate cortex - what is the function of the ventral stream?
visual details, face selective cells
which cells do we have more of; rods or cones?
rods
where are these cells concentrated?
i) rods
ii) cones
i) periphery
ii) fovea
which photoreceptor detects colour?
cones
do rod cells have high or low visual acuity?
low
describe convergence of rods to ganglions
high
describe convergence of cones to ganglions
low
in what light setting are rods used?
low lighting
how many pigments do cones use - what are they?
3 - blue red green
how many pigments do rods use - what are they?
1 - rhodopsin
describe wavelength of the following pigments
i) blue
ii) green
iii) red
i) short
ii) medium
iii) long
which region is responsible for orientating the eyes/head towards a visual stimulus?
superior colliculus
describe glutamate release and cell polorisation when a photon of light hits a cell
- no release of glutamate
- cell hyperpolarisation
what happens to glutamate release and BC activity when:
light inputs onto a photoreceptor directly connected to an ON BC cell
decreased glutamate release
BC depolarises - activity increases
what happens to glutamate release and BC activity when:
light inputs onto a photoreceptor directly connected to an OFF BC cell
decreased glutamate release
BC hyperpolarises - activity decreases
describe the highest level of response for on OFF bipolar cell in terms of centre and surround
dark in centre
light in surround
