Lecture 4 - 12.01.11

Lecture 4 - 12.01.11 - 12th January 2011 Psych 120B Lecture...

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12 th January 2011 Psych 120B – Lecture 4 Visual System: Anatomy and Physiology Ganglion cells in Retina LGN Striate cortex Extra-striate cortex o Two streams Sine Wave Gratings How we see stimuli and how we see the world is based on the properties of the receptors in the eye. Spatial Frequency Sensitivity of Ganglion Cells Low frequency yields weak response Medium frequency yields strong response High frequency yields weak response There has to be a specific pattern in the stimulus for a neuron to fire in a certain way. The stimulus has to be a certain size. If the light and dark parts of a stimulus perfectly match the parts of the receptor that like light and dark, then it will fire more and there will a strong response. They are sensitive to a very specific light pattern with a spatial frequency. Leaving the Retina Signal leaves retina from the ganglion cells through the optic nerve… …crosses the optic chiasm… …arrives at LGN. LGN Topographic mapping Magnocellular layers o bottom two layers o larger cells o receive input from M ganglion cells Parvocellular layers o top four layers o smaller cells o receive input from P ganglion cells Striate Cortex (V1) Primary visual cortex = striate cortex = V1 Organization of V1 How do we know? o Mainly from single-cell recording studies o Microelectrodes (cats/monkeys in most studies) o More recently: fMRI in humans and monkeys
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Topographic map: adjacent things are adjacent in the eye/retina/thalamus etc. Cortical magnification factor
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This note was uploaded on 03/07/2011 for the course PSYCH 120B taught by Professor Shams during the Winter '09 term at UCLA.

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Lecture 4 - 12.01.11 - 12th January 2011 Psych 120B Lecture...

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