Term
| Lesions to different segments of the optic nerve results in what? |
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Definition
| Scotoma: Portions of the visual field that are non-functional |
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Term
| Lesion to right optic nerve results in what? |
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Definition
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Term
| Lesion in Optic Chiasm results in? |
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Definition
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Term
| Lesion to right optic tract results in? |
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Definition
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Term
| Why does the transection of one side of the optic nerve result in the other side being blind? |
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Definition
| Most of the optic fibers cross over at the optic chiasm |
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Term
| The 2 ventral layers are composed __ cells with ___ receptive fields, and are ___ numerous than ____ cells. These detect ___ of a stimulus and _____. |
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Definition
| The 2 ventral layers are composed of M cells with large receptive fields and are less numerous than P cells. These detect gross features of a stimulus and it's movement.l |
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Term
| The 4 dorsal layers are composed of __ cells with _____ receptive fields and are ____ numerous than ____ cells, and detect ____ detail. |
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Definition
| The 4 dorsal layers are composed of P cells with small receptive fields and are more numberous than M cells, and detect fine detail (perception of form and color) |
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Term
| Why does a lesion in the right optic tract cause left hemiretina blindness? |
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Definition
| Because there is contrateral and ipsalateral inputs from the nasal and temporal hemiretina projections which synapse to the Parvocellular and Magnocellular channels on the Primary Visual Cortex. |
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Term
| Where is the Primary Visual Cortex (V1) located and what does it receive? |
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Definition
| It is located in the occipital lobe and receives projections from optic radiation. |
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Term
| What does the Primary visual cortex respond to? |
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Definition
- simple features: edges, orientations and contrast borders
- spatial organization of visual scene
- particular cells responds to specific orientations (EX: one cell responds to vertical, versus being unresponsive to horizontal orientation)
- specific locations
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Term
| What are the columns of the Primary Visual Cortex devoted to? |
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Definition
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Term
| What are the oriented columns of the Primary visual cortex devoted to? |
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Definition
| responding to a specific axis of rotation, which results in neurons responding to a single axis of orientation |
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Term
Why does the visual cortex become active during Braille reading in people blind from a young age? |
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Definition
The visual cortex has a degree of plasticity which allows for the perception of a vision associated touch stimulus such as reading braille However, discriminating a key from a coin does not activate the visual cortex, but the somatosensory cortex like the rest of us. |
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Term
| Where does the Magnocellular input go? |
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Definition
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Term
| What does the parvocellular input go? |
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Definition
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Term
| List in order the pathway from the Primary Visual Cortex (V1) Dorsally! |
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Definition
V1 → MT → MST → (Other Dorsal Areas)
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Term
| List in order the pathway from the Ventral area of V1 |
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Definition
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Term
| Where does the ventral stream receive it's information from and what does it tell us? |
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Definition
| Parvocelluar input, and because these cells have small receptive fields and perceive fine detail they tell us WHAT the object is |
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Term
| Where does the Dorsal stream receive it's information from and what does it tell us? |
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Definition
| Magnocellular input, and because these cells have large receptive fields and respond best to gross movement they tell us Where an object is and How it is moving |
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Term
| What does the Medial Temporal portion of the Dorsal Stream respond to? |
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Definition
| It responds specifically to visual motion and allows the perception of correlated movement. |
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Term
| What are the effects of MT lesions? |
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Definition
| Reduced ability to perceive visual mon, and inability to perceive the motion of correlated moving stimuli. |
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Term
| What does the Medial Superior Temporal perceive? |
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Definition
| Perceives optic flow and the perception of more complex form of motion |
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Term
| Where does the dorsal stream areas converge? |
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Definition
| The posterior parietal cortex |
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Term
| What do V4 cells respond to? |
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Definition
| textures and surfaces, many cells respond to specific sizes and densities of textures. |
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Term
| What do IT cells respond to? |
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Definition
| different types of shapes |
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Term
| Where are vertical saccades produced |
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Definition
| Mesencephalic reticular formation |
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Term
| Where are horizontal saccades produced? |
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Definition
| The paramedian pontine reticular formation |
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Term
| How is the fovea represented in the superior colliculous |
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Definition
| In rostral cells which fire during fixation (omnipause cells) |
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Term
How is the periphery represented in the superior colliculous (SC) |
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Definition
| In caudal cells which fire during saccades (burst cells) |
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Term
| Where are caudal cells inhibited from? |
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Definition
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Term
| Where do the caudal cells receive excitatory input from? |
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Definition
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Term
| What happens when the caudal cell begin to fire? |
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Definition
| They inhibit the rostral cells and a saccade is produced. |
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