Occipital and Temporal lobe

Question 1

How is information processed in the extrastriate cortex?

Answer 1

Neurons in the extrastriate cortex signal ‘global’ properties of visual scenes and objects, rather than ‘component’ properties.

Question 2

Describe the neurons in the extrastriate cortex.

Answer 2

these neurons have a larger visual receptive field and integrate info from larger parts of our FOV.
they also allow us to see colour rather than different wavelengths.

Question 3

What is the difference between neurons in V4 and V2?

Answer 3

V4 = colour sensitive - respond to wavelengths in the centre of the receptive field, depending on the wavelengths reflected by the background.
V2 = ONLY wavelength sensitive.

Question 4

describe the difference between global and component motion.

Answer 4

Component motion occurs in V1 where the cells with small receptive fields look at limited regions of the stimulus and will register component movements in different directions.
Global motions occurs in V5 where neurons look at larger parts of the FOV and register the true, overall direction.

Question 5

What are the 2 visual information processing streams?

Answer 5

Dorsal stream = Visuo-spatial (Where) and Visuo-motor (How)/

Ventral stream = Object analysis (What).

Question 6

describe evidence for visual streams WHAT/WHERE

Answer 6

Lesions in the temporal lobes of monkeys (ventral stream) had impaired object discrimination.
This was reversed when monkeys had lesions in the the dorsal stream, they had impaired object location.

Question 7

Describe evidence for visual streams WHAT/HOW.

Answer 7

Patient DF had extensive bilateral ventral-stream lesions has profound visual agnosia but intact visually guided reaching.