Cortical vs. Subcortical Vision Flashcards
Subdivisions of which pathway allow us to recognize and identify complex visual scenes? (it is the target of 90% of the axons in the optic tract)
Retinogeniculostriate pathway
Which are older, cortical or subcortical pathways?
Subcortical pathways
How is the superior colliculus organised?
It has a layered anatomical organisation
Where are neurons that receive info from the retinal ganglion cells located?
In the superficial layers of the superior colliculi
What connects the 3rd and 4th ventricles?
The cerebral aqueduct
What do the superficial layers of the superior colliculus provide?
A (distorted) retinotopic map of the visual field of the opposite hemifield (because more neurons are devoted to the center than the outside)
What causes contralateral cortical blindness, and what does having it cause?
It’s caused by unilateral removal of the visual areas in the cortex.
Blindness causes an animal to stop orientating towards a stimulus in the contralateral hemifield to the damage - it’s devastating
What is the “Sprague Effect”?
The restoration of orientating toward the cortically blind hemifield
Can visual orientating responses be restored in the cortically blind hemifield? How?
By removing the contralesional superior colliculus, or by cutting the fibers that connect the two superior colliculi
Why does the Sprague Effect happen?
Results from cutting inhibitory fibers that originate in another nearby structure and project to the superior colliculus on the same side as the cortical lesion
What does ipsilateral mean?
Same side
What does disrupting subcortical vision in rodents cause?
Impaired ability to orient toward the position of a stimulus (localisation)
What does disrupting cortical vision in rodents cause?
Disruption of object discrimination
What does hemianopic mean?
Blind on one half because the info isn’t processed (info still gathered though)
What is a scotoma?
A blind spot
