Lecture 9 - The Visual System (Part 3) Higher Visual Processing

Question 1

What do the downstream projections that extend from V1 project to?

Answer 1

visual association areas

Question 2

What are some of the visual association areas?

Answer 2

anything past V1 so V2, V4, MT

Question 3

What is the magnocellular where or dorsal pathway?

Answer 3

it is important for spatial vision and the motion detection; pathway intersects with the parietal lobe which is important for attending to moving stimuli in one’s environment; moving optical illusions
V1—>V2—->MT—–> parietal lobe

Question 4

What is the parvocellular or what or ventral pathway?

Answer 4

-responsible for object recognition like word form and face recognition; pathway intersects with the temporal lobe and passes through the visual word form area and the fusiform gyrus
V1—->V2—–>V4—–>temporal lobe

Question 5

What cells does the magnocellular layer originate from?

Answer 5

parasol cells in the retina and they detect motion and they project to the magnocellular layers of the LGN; receive information from photoreceptors and are RGCs that are large and fast conducting and they relay their projections to the magnocellular layers of the LGN which are layers 1,2

Question 6

What are the cell associated with the parvocellular pathway?

Answer 6

midget cells which are RGCs which project to the layers 3-6 of the LGN and they are smaller cone driven cells and exist in a one to one ratio with cones

Question 7

In the occipital-temporal gyrus what region is associated with face identification?

Answer 7

fusiform face gyrus or the fusiform face area

Question 8

What is prosopagnosia?

Answer 8

-can see but not recognize faces
-come from the stroke or other injury which affects the right fusiform face gyrus

Question 9

What region is associated with identifying places and why is it heavily associated with memory?

Answer 9

parahippocampal gyrus and is known as the primary place area or PPA; is lateral to the hippocampus

Question 10

What region is associated with identifying shapes and objects?

Answer 10

lateral occipital cortex LOC

Question 11

What region is associated with recognizing words and orthographic processing and where is it located?

Answer 11

visual word form area; VWFA; in the left-occipital temporal region

Question 12

What happens in dyslexia?

Answer 12

language regions in the left temporal lobe have abnormal connectivity with the VWFA

Question 13

What is the pupillary light reflex?

Answer 13

an involuntary motor response to light which causes pupil dilation in response to insufficient light and pupil constriction in response to excess light

Question 14

What are the synaptic pit stops in the pupillary light reflex?

Answer 14

1. intrinsically photosensiitve RGCs which express melanopsin in the retina project to the pretectal nucleus
2. neurons in the pretectal nucleus project to the autonomic edinger-westphal nucleus (associated with the oculomotor nerve)
3. EW neurons project back to the eye to synapse onto the ciliary ganglia and muscles which causes the pupil size to change

RGCs in retina—-> pretectal nucleus—->edinger-westphal nucleus—->ciliary ganglia and muscles —> pupils change

Question 15

What does the retinohypothalamic pathway regulate?

Answer 15

circadian rhythms and sleep

Question 16

What are the pit stops of synapses of the retinohypothalamic pathway?

Answer 16

RGCs in the retina intrinsically photosensiitve —-> suprachiasmatic nucleus or SCN in the hypothalamus (central clock in regulating circadian rhythyms)—->hypothalamic paraventricular nucleus PVN (also mediates hunger)—->descending projections sent to the superior cervical ganglia in the spinal cord (part of sympathetic branch)—–> send ascending signal to the pineal gland which affects melatonin production

Question 17

What is the tectospinal pathway?

Answer 17

-involved in integrating auditory and visual sensory information in order to coordinate eye movements

Question 18

Where does the tectospinal pathway originate from?

Answer 18

optic tectum (superior colliculus) —–> synapses onto auditory and visual subcortical structures