The document provides an overview of visual processing in the brain. It describes the two major visual pathways - the dorsal pathway which processes motion and travels to the parietal cortex, and the ventral pathway which processes colour and form and travels to the temporal cortex. It outlines the key stages of visual processing from the retina through the lateral geniculate nucleus and into the primary and higher-level visual cortices.

1. Overview of Visual Processing Dorsal pathway: Where?
To post. parietal cortex
The retina:
MOTION (+ motion illusions)
rods and cones
horizontal cells 1* visual
bipolar cells Lateral geniculate cortex:
amacrine cells nucleus of thalamus: V1
V2
ganglion cells LGN (optic radiation) V3
(onto optic nerve) V4
V5
light V6
http://www.circadian.org/biorhyt.html V7
http://en.wikipedia.org/wiki/Two-streams_hypothesis
Ventral pathway: What?
To inferior temporal cortex
Colour and form (+ illusory
contours)
Bipolar cells Ganglion cells LGN Visual Cortex
Midget Parvocellular cells 4 parvocellular layers spiny stellate neurons What?
majority, smaller receptive fields, 4th layer of sublayer A
slower, colour vision, sustained response = 4C-alpha, simple cell?
Amacrine?+? Magnocellular cells 2 magnocellular layers spiny stellate neurons, Where?
larger receptive fields, convergence, 4th layer of sublayer B
faster, more sensitive, detect motion, transient reponse = 4C-beta, complex cell?

2. Cortical columns
cortical column (somatosensory):
a vertical column of the cortical layers that has a near identical receptive field, but each layer corresponds to a different modality.
orientation column:
is a vertical column in which each layer displays the same pinwheels:
orientational preference for the stimulus, every 1mm a different orientation organisation of orientation columns
ocular dominance:
tiger stripe:
0.5mm wide cortical strips that prefer input from either retina
organisation of ocular dominance columns
hypercolumn:
1-2mm^2 cortical column responding to all orientations of a stimulus, both retinae and performing colour analysis of differently sized visu
fields
amblyopia:
disorder of the visual system resulting from a deficiency in optic information from one eye reaching the cortex, which results in cortical
development that makes it impossible to recover the function
http://www.pnas.org/content/102/11/4158/F2.expansion.html
http://en.wikibooks.org/wiki/Consciousness_Studies/
The_Neuroscience_Of_Consciousness