Visual system VII

Question 1

What is blindsight

Answer 1

Damage v1 but can use vision to guide movements
Can’t see but can see = can detect things but unaware of them
Blind man - does obstacle course, can do it fine but he says he doesn’t know how he does it
Blind but can detect direction of motion

Question 2

what does blindsight show us

Answer 2

Shows us circuitry of visual processing - difference between dorsal and ventral streams and their relationship to conscious perception
Dorsal stream = use visual info to guide movement

Question 3

is blindsight common

Answer 3

noooo
Rare!!!

Question 4

what is main visual pathway

Answer 4

for conscious perception = goes through Lin to v1
To dorsal and ventral streams
This pathway is disrupted in blind sight

Question 5

what is an alternative route of visual pathway

Answer 5

goes through superior colliculus (10% rgc output) to regions of Parietal lobe and frontal lobes involved in detection of motion and controlling eye movements (orienting saccadic eye movements)
May be responsible for blind sight

Question 6

describe the alternative route = what is it

Answer 6

Retina —> superior colliculus —> dorsal stream
Not connected to v1
But is connected to regions of brain involved in movement and dorsal stream
= visual info goes directly to brain regions in dorsal stream = involved in detecting visual motion and using motion to guide movement

Question 7

describe the alternative route = is it conscious

Answer 7

no

Question 8

describe another pathway that bypasses v1= what is it

Answer 8

Another unconscious pathway
Goes from thalamus (Lgn and pulvinar) —> amygdala

Question 9

describe another pathway that bypasses v1= what is it involved in

Answer 9

Rapid, unconscious emotional responses to visual stimuli

Question 10

describe another pathway that bypasses v1= describe what it does

Answer 10

Direct connection
Enables us have fear based responses - occur faster than our conscious awareness of what we are afraid of
Ex = walking into forest and see bear shadow = feel afraid
- conscious perception = visual pathway to v1–> ventral stream —> other conscious pathways
- but feeling fear = increase hr, sweaty palms, pupils dilate = physiological = response associated with feeling of fear = happens faster than cosncious awareness or interpretation of why you are afraid = because fo direct pathway to amygdala
(Bypass conscious awareness “fear reflex”)

Question 11

describe projections to pre frontal cortex

Answer 11

Projections to prefrontal cortex are involved in visual working memory
Ventral and dorsal stream ultimately project to prefrontal cortex
= involved in working memory (ability to hold things in mind, hold and manipulate things in mind)= inputs from dorsal and ventral streams

Question 12

what is binding problem = specifically

Answer 12

How are the different components of vision - colour, form, location, motion - spread out over disparate regions of cortex, bound together to form unified coherent perception

Question 13

what is binding problem = generally

Answer 13

Dorsal and ventral streams = each have many anatomically separate regions of brain processing diff specific aspects of vision - but perceive world as unified = how is it all put together? (No single place where visual perception all comes together, do not knwo how it works)

Question 14

what is binding problem = hypothesis?

Answer 14

Diff regions become transiently synchronized with each other so can unify perceptions
Ongoing problem in cognitive neuroscience (issue in not just vision but also many systems)

Question 15

Most of what happens in brain =

Answer 15

below level of consciousness