Dual stream processing

Question 1

Dorsal stream

Answer 1

Goes from V1 -> Superior Longitudinal fasciculus -> Posteroparietal cortex

Characteristics:
- Magno dominated (Parasol cells), so quick, to perietal cortex
- Where stream; input mostly motion and position
- Motor focused
- Vision for Action (uses position and shape information for visually guided action)

Lesion:
- Landmark (position) discrimination impaired
- Optic ataxia (can see shape but can’t grasp)
- Can’t match orientation but can post

Question 2

Ventral stream

Answer 2

Goes from V1-> inferior longitudinal fasciculus -> inferior temporal cortex

Characteristics:
- Parvo dominated (midget cells), so slow to temporal cortex
- What stream: input mostly color and shape
- Memory focused
- Vision for Perception (uses shape (and position) information for visual perception, memory)

Lesion:
- Object (shape) discrimination impaired
- Optic agnosia (can’t see shape but can grasp)
- Can match orientation but can’t post