Central Visual System Flashcards
Some axons of the optic tract that don’t go to the LGN go here to synchronize sleep and wakefulness with light-dark cycles and contribute to other biological rhythms
Hypothalamus
What happens when the input from one eye is blocked from reaching V1?
Ocular dominance columns are lost. Activity drives structure
Why do perceptual illusions occur?
Same dimensions, brain is producing a 3D interpretation of a 2D image
How many layers are in the LGN?
6
This can cause lack of perfection of motion (see the world in a series of snapshots)
Stroke
Extrastriate stream of perception and object recognition, extension of V1 Parvo-interblob and blob pathways
Ventral
Crossing over of these is completed after the optic chiasm
Retinal ganglion cell axons
Have shifted orientation selectivity
Tangential cells
How is info separated in the central visual system?
Parallel pathways for analyzing different features of input
Made of optic nerve, optic chasm, and optic tract
Retinofugal pathway
These animals were used to study the central visual system
Cat and rhesus monkey
V1 to V2 to V3 to V4 to It to other ventral areas. V2 can also communicate directly with V4
Ventral stream
These neurons exist locally in all layers of V1
Inhibitory neurons
Koniocellular LGN neurons project to these V1 areas
Layers 2 and 3
2x2 mm patch of cortex containing 2 sets of ocular dominance columns, 16 blobs, inter blobs, and all 180 degrees of orientation. These are all of the computational tools we would need to analyze a specific part of our visual field. It is a theoretical model
Cortical module
4C layer insensitive to wavelength
4C alpha
These cells project out of V1
Pyramidal cells
Located anterior to the pituitary (in front of it - towards the forehead)
Optic chiasm
Radial columns of cells through several layers have this orientation preference
The same orientation preference
Part of the tectum, involved in orienting eyes with new stimulus
Superior colliculus
Respond to activity in any one of their converging input lines (any simple cell)
Complex cells
These RGCs connect to the magnocellular LGN
M type
Layers of LGN with small center surround, center response of sustained firing
3-6 (parvocellular)
Ventral stream, receives input from Parvo-interblob and blob pathways
V4