PSYC 367 Lecture Notes - Mach Bands, Receptive Field, Visual Cortex
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I. The Lateral Geniculate Nucleus
1. Six Layers of LGN:
1) Lateral Geniculate Nucleus: A structure in the thalamus,
part of the midbrain, that receives input from the retinal ganglion
cells and has input and output connections to the visual cortex.
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2) Think the six layers as 6 separate pathways.
3) Two different types of information:
Parvocellular layers: layer 1—4; receive input from P
Cells which are:
o smaller—smaller receptive fields,
o important for color and fine detail;
o High correlation of activity between cone and p
cells, not perfect;
o make up about 80% of ganglion cells;
o receive input from single midget bipolar cells
from single cones in the central retina.
Magnocellular layers: layer 5 and 6; receive input
from M Cells which are:
o larger—larger receptive fields,
o important for low light vision and movement;
o High correlation of activity between rods and m
cells, not perfect (still some cones in M cells and
o make up about 10% of ganglion cells;
o receive input from diffuse bipolar cells from
hundreds rods spread out on one m cell (wider
No M cells at fovea, increase as remove further from
M cells and p cells response differently to stimuli:
o P cells’ response is slower and sustained; tonic
activity; the steady input allow to see fine detail.
o M cells response faster; fire a burst while
stimuli going on and off; no need to stay firing
to see movement; see contracts in dark light.
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