the visual system - motion detection

Question 1

what is the flow of information for motion detection?

Answer 1

V1 - V2 - V3 - V5.

Question 2

what pathway processes motion?

Answer 2

magnocellular (dorsal, where)

Question 3

what % of retinal cells are magnocellular?

Answer 3

10%

Question 4

are rods direction sensitive at the retina?

Answer 4

NO

Question 5

how is motion detected?

Answer 5

by analysing the temporal and spatial properties of the light

Question 6

how is motion captured at the LGN?

Answer 6

it is carried in the magnocellular pathway to layers 1 + 2.

Question 7

what cells in area V1 respond to motion?

Answer 7

complex cells.

Question 8

how to cells in V1 capture motion?

Answer 8

• each cell responds to a different angle of motion
• there is a baseline rate of firing
• no separate subregions

Question 9

what is component motion?

Answer 9

the analysis of motion in parts of objects

Question 10

what is global motion?

Answer 10

analysis of motion of the whole object.

Question 11

V1 cells only respond to ______ motion

Answer 11

component motion

Question 12

how is area v2 organised?

Answer 12

in striped columns - thick, thin and inter stripes.

Question 13

how is motion processed in V2?

Answer 13

cells respond to more complex properties than V1. Motion is processed in the thick stripes.

Question 14

where does global processing of motion occur?

Answer 14

area V5.

Question 15

how does area V5 process motion?

Answer 15

• each v% neuron responds preferentially to a particular speed AND direction.

Question 16

how is area V5 organised?

Answer 16

in columns

Question 17

what impairments can occur from damage to area V5?

Answer 17

Akinatopsia - this is the impaired perception of motion. not complete abolition as area V3 also helps to proces info.

Question 18

what 2 functions does area V3 serve in motion detection?

Answer 18

• dynamic form - the ability to maintain a representation of an object when it is in motion.
• 3D structure - a 3D picture is constructed from a 2D retinal image.

Question 19

what are microsaccades and how do they help us to process motion?

Answer 19

they are tiny eye movements.

• neurons in the visual system rapidly adapt
• this is necessary to allow the perception of a stationary object.