PSY2061 Lecture Notes - Lecture 5: Ocular Dominance, Visual Field Test, Scotoma
23 May 2018
School
Department
Course
Professor
Week 5
Sensory Systems
pt. 3
Organisation of Primary Visual Cortex
ā¢Functional vertical columns!
- all cells in column have some receptive ļ¬elds & ocular dominance
ā¢Ocular dominance columns!
- move horizontally, dominance of the columns changes
ā¢Retino-tropic organisation is maintained
ā¢Preference increasingly complex from retina to PVC!
- convergence of cells
Contextual Modulation of cells in PVC
ā¢Cells modulate response when presented alongside āotherā stimuli!
- as a function of perceived saliency
ā¢May explain ļ¬gure-ground segregation
ā¢Lateral connections from neighbouring cells or feedback projections from higher levels of
cortex!
!
!
Damage to Primary Visual Cortex
ā¢Scotomas!
- areas of blindness in contralateral visual ļ¬eld due to damage to primary visual cortex!
- detected by perimetry test
ā¢Completion!
- patients may be unaware of scotoma; missing details are supplied by ācompletionā.
ā¢Blind sight!
- response to visual stimuli outside conscious awareness of āseeingā!
- possible explanations for blindsight: !
*Islands of functional cells within scotoma!
*Direct connections between subcortical structures and secondary visual cortex, not
