Ch 3. The Visual Brain

Question 1

Nasal Vs. Temporal retina

Answer 1

Fibres from the nasal retina cross to the other side of the brain
Fibres from the temporal retinal stay on the same side of the brain

Question 2

3 ganglion cells and they’re layers in the LGN

Answer 2

• Parasol (M–>magnocellular)
• Midgit (P–>parvocellular)
• bistratified (B/Y–>koniocellular)

Question 3

3 things that the LGN does

Answer 3

Retinotopic Maps
Functional Specialization
Center-Surround Receptive Fields

Question 4

info from eyes to V1 stops at 2 possible places

Answer 4

LGN (later geniculate nucleus)
superior colliculus (old sys)

Question 5

S. Colliculus

Answer 5

orients eye movements, gets 10% of ganglions, site of multisens integration

Question 6

Hubel and Wisel found what?

Answer 6

• cells don’t respond to sports of light

- respond to bars on light (in V1)

Question 7

Simple cells

Answer 7

like a single orientation

Question 8

column orietntaiton

Answer 8

Adjacent columns change preference in an orderly fashion

1 millimeter across the cortex represents entire range of orientation

Question 9

Pathway: Parasol

Answer 9

parasol–>LGN Magno(flicker)–>MT (motion)–>parietal cortex(motion, motor)–>Dorsal where

Question 10

Pathway: Midgit

Answer 10

LGN (parvo, R/G detail)–>blob–>V4(colour/form)–>inferotemportal cortex(object recognition)–>Ventral What

Question 11

Pathway: Bistratified

Answer 11

Bistratified–>LGN knit (B/Y–>blobs–>V4(colour/form)–>inferotemportal cortex(object recognition)–>Ventral What

Question 12

Patient D.F

Answer 12

Ventral path damage, agnosia, could reach and do tasks okay

Question 13

Optic Ataxia

Answer 13

• Difficulty with reaching and grasping objects

- have trouble acting on things, only visually guided, close eyes and is fine

Question 14

V4

Answer 14

colour/curature, Ventral, Loss=Achromatopsia

Question 15

Achromatopsia

Answer 15

V4 colour damage

Question 16

IT

Answer 16

inferotemporal cortex, shapes, ventral, Loss=agnoisa (prosopagnosia FFA)

Question 17

MT

Answer 17

motion perception,dorsal, moving objects, dif direction responses, Loss=Akinetopsia

Question 18

Akinetopsia

Answer 18

inability to perceive motion

Question 19

IPS

Answer 19

intraparietal sulcus, dorsal, visually guided reaches & grasps, eye movements, Loss=optic ataxia

Question 20

Distributed coding

Answer 20

population coding: one cell is ambiguous but if you look at multiple cells, different response patterns of activity can uniquely define 90degrees across multiple cells.

Question 21

hypercomplex cells

Answer 21

A neuron in the visual cortex that responds to the presence of a line segment with a particular orientation that ends at a particular point within the cell’s receptive field.

Question 22

Organization of V1 (5)

Answer 22

• retniotopic maps
• cortical magnification
• oreintation selectivity and column
• colours
• occular dominance colums