ANAT 321 Lecture Notes - Lecture 15: Optic Chiasm, Ganglion Cell, Retina Horizontal Cell

• School: McGill University
• Department: Anatomy & Cell Biology
• Course: ANAT 321
• Professor: David Ragsdale

Document Summary

Cone synapses on bipolar cell synapses on retinal ganglia. Light photons absorbed by photoreceptor hyperpolarize reduce glutamate release relieves inhibition on bipolar cell, bipolar cell depolarized retinal ganglion increase firing rate. Photoreceptors & bipolar cells don"t generate action potentials, release glutamate. Light intensity translates into graded glutamate release, function of graded membrane potential. Retinal ganglia cells always firing ap (baseline firing rate), can be modulated up or down. Glutamate depolarizes horizontal cell inhibits presynaptic terminal of next cone. Light on side photoreceptor, hyperpolarized, glutamate reduced hyperpolarizes horizontal cell, releases less inhibitory nt next photoreceptor has less inhibition, releases more glutamate hyperpolarizes bipolar cell inhibits firing of retinal ganglia cell. Light on nearby photoreceptor inhibits centre retina ganglia cell firing. Image happening in fovea, but more photoreceptors in pathway further from fovea (larger rf, less acuity; but more sensitive from more photoreceptors) Ganglion cells have receptive fields more complex than photoreceptors.