Lecture 9: Motion Perception II

Question 1

What happens in the MT (V5)

Answer 1

where the magnocellular cells in the straite coretx send input (possible motion pathway)

Question 2

What sort of feature are cells in MT area sensitive

Answer 2

Direction

Question 3

describe the organisation of MT cells

Answer 3

Similar to V1 cells - the cells that are orientated the same have are in specific organisation

Question 4

Describe Albright et al 1984 reserach

Answer 4

measured preferred direction of cells by loweinng electrode in and measuring the activity. Found occasional 180 shifts and was explained by cells being arranged in specific direction columns with each cellliking the same direction (just reinforcing the organisation of the cells)

Question 5

How to measure motion coherence

Answer 5

Like a random dot pattern but moving - have the dots moving in a uniform direction, no correlation or things in between

Question 6

In the motion random dot patterns what can you manipulate?

Answer 6

Direction (noise) and speed

Question 7

Descirbe Newsome and Pare (1988)

Answer 7

Lowered electrode whilst doing a task and mapped out receptive fields to work out direction. Then dropped small bit of acid to lesion the area (only part of visual field damaged). Measured two tasks and motion coherence thresholds: control (spatial frequency) - no diff; experimental (dot moving task) - did worse in the lesioned area and had very poor performance on motion task - shows MT necessary for motion perception

Question 8

Salzman et al 1990 - describe

Answer 8

They stimulated the cell to record how this changes response - when stimulating upward direction cell and show them dot motion of 0% they will still report upward motion - shows MT cells are causal to motion perception

Question 9

Zeki et al 1993 - imaging studies on humans

Answer 9

Looked at brain activity when looking at illusion called enigma pattern and found pattern stimulates MT