Chapter 10 - The central visual system Flashcards
What is the retinofugal projection?
The neural pathway that leaves the eye beginning with the optic nerve.
What parts does the retinofugal projection consist of?
The optic nerve, the optic chiasm and the optic tract.
What is a decussation?
The crossing of a fiber bundle from one side of the brain to the other.
What do most axons of the optic tract innervate?
The lateral geniculate nucleus of the dorsal thalamus.
What is the optic radiation?
The projection from the LGN to cortex.
What does the LGN do?
It is the gateway to the visual cortex and therefore conscious visual perception.
It has a layerized structure and that it processes information at each of these layers.
What is retinotopy?
An organization whereby neighboring cells in the retina feed information to neighboring places in the target structures.
For example: the LGN and the striate cortex. The two dimensional surface of the retina is mapped onto the two-dimensional surface of the subsequent structure.
What does having a binocular recptive field?
They actually have two receptive fields, one in the ipsilateral and another on the contralateral eye.
What are simple cells?
Neurons in V1 that receive convergin input from from three or more LGN cells with receptive fields that are aligned along one axis.
What are complex cells?
Neurons in V1 that do not have distinc ON and OFF regions and are not simple cells.
What is a cortical module?
Each cortical module contains ocular dominancs columns, orientation columns and cytochrome oxidase blobs to fully analyze a portion of the visual fields.
What is the dorsal stream?
Areas V2, V3, MT (or V5)
What does area MST do?
Three roles have been proposed:
- Navigation
- directing eye movement
- motion perception
What does area V4 do?
It is concerned with shape and color perception.
What does area IT do?
It is concerned with visual perception and visual memory.
