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 V6http://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 CortexMidget 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?
Cortical columnscortical 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 columnsocular dominance: tiger stripe:0.5mm wide cortical strips that prefer input from either retina organisation of ocular dominance columnshypercolumn:1-2mm^2 cortical column responding to all orientations of a stimulus, both retinae and performing colour analysis of differently sized visuﬁeldsamblyopia:disorder of the visual system resulting from a deﬁciency in optic information from one eye reaching the cortex, which results in corticaldevelopment 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