PHSL 3061 Lecture 2: Topic 4 - Sensory Systems (Zahs) for Course Packet
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TOPIC 4:
Sensory Systems
NOTES & Exam Questions
Physiology 3061/5061 Kathleen Zahs, Ph.D.
October 4, 2018 – October 8 2018
VISUAL SYSTEM
Learning Objectives
1. Know the general functions of the major classes of cells in the retina:
photoreceptors – phototransduction
bipolar cells – encode contrast
retinal ganglion cells – output cells of the retina
2. Know the function of the lateral geniculate nucleus (and be able to generalize to the
functions of other sensory “relay” nuclei of the thalamus).
3. Know how the receptive field properties of cells in the primary visual pathway change as one
progresses from photoreceptors to cells of the primary visual cortex (serial processing).
photoreceptors – hyperpolarize in response to light, magnitude of
hyperpolarization depends on brightness of light
bipolar cells – hyperpolarize or depolarize (graded potentials), center-surround
receptive fields, encode local contrast
retinal ganglion cells -- information conveyed by frequency of action potentials,
center-surround receptive fields, encode local contrast
lateral geniculate cells -- information conveyed by frequency of action potentials,
center-surround receptive fields, encode local contrast, response influenced by
non-retinal inputs from attention centers and feedback from cortex
primary visual cortical cells -- information conveyed by frequency of action
potentials, respond to bars of light of a particular orientation, “edge detectors,”
first place where information from the two eyes is combined
4. Be aware of the two “streams” for processing visual information (parallel processing)
b) Dorsal (parietal) stream – spatial aspects of vision
a) Ventral (temporal) stream – high resolution form vision, color
Reading assignment: Vander’s Human Physiology, 15th edition, pages
189-200, 205-216