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Chapter 9 - Visual Perception (Retinal ganglion cells (RGC) (Magnocellular…
Chapter 9 - Visual Perception
Retinal ganglion cells (RGC)
Magnocellular cells (M-cells)
sensitive to light, but not color
most information through rods
found in the retina
Parvocellular cells (P-cells)
sensitive to color, but not light
most information through cones
found in the fovea
Routes to the Visual Brain
RGC axons seperate whhen they enter the brain
all P axons and some M axons form a pathway
geniculostriate system
Starts in the retina
crosses the lateral geniculate nucleus in the thalamus
travels to layer IV of the primary visual cortex in occipital lobe
forms a bride between thalamus and striate cortex
one route to parietal lobe
one route to temporal lobe
Both systems end in either temporal or parietal lobe
to parietal lobe is called dorsal stream
AKA what stream as it identifies a stimulus
to temporal lobe is ventral stream
AKA the how stream as it controls movements to or from the stimulus
remaining M axons form a pathway
tectopulvinar system
starts in the eye
through midbrain tectum to the pulvinar
function is to bypass the occipital visual regions and send connections to parietal and temporal
many RGCs are photosensitive, aka pRGCs
act as photoreceptors
partly form the retinohypothalamic tract
play a role in circadian rythms and expansion/contraction of pupil in response to light