Textbook Notes (363,103)
Canada (158,195)
Psychology (2,948)
PSY280H1 (40)
Chapter 4

Ch4 Textbook Notes

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University of Toronto St. George
Christine Burton

CHAPTER 4 THE VISUAL CORTEX AND BEYONDFollowing the Signals from Retina to Cortex The Visual System the pathway that neural signals follow once they leave the retinamost of the signals travel out of the eye to the lateral geniculate nucleus LGN in the thalamusthen travel to the primary visual receiving area striate cortex in the occipital lobefrom there signals are transmitted to the temporal lobe or to the parietal lobe some signals also reach areas in the frontal lobesuperior colliculus an area involved in controlling eye movements and other visual behavioursProcessing in the Lateral Geniculate Nucleus Receptive Fields of LGN Neuronsrecordings show that LGN neurons have the same centresurround configuration as retinal ganglion cellsthus they respond best to small sports of light on the retinaInformation Flow in the Lateral Geniculate Nucleus90 of fibres in the optic nerve arrive at the LGN 10 go to superior colliculusLGN also receives signals from the cortex the brain stem other neurons in the thalamus and from other neurons in the LGNit then sends its output to the cortexLGN receives more input back from the cortex than it receives from the retinasmallest signal in diagram is from the LGN to the cortexsuggests that one purpose of the LGN is to regulate neural information as it flows from the retina to the cortexalso organizes information flowing through itOrganization by Left and Right EyesLGN is a bilateral structure one in the left and one in the right hemisphereviewing a cross section of a nuclei reveals six layers each receives signals from only one eye2 3 5 receive signals from the ipsilateral eye on the same side of the body as the LGN1 4 6 contralateral eye on the opposite side of the body from the LGNthus each eye sends half of its neurons to the LGN located in the left hemisphere half to the LGN located in the right hemispheresignals from each eye are sorted into different layers so the information is kept separateOrganization as a Spatial Mapwhen looking at an object eg cup points A B C are imaged on points A B C on the retinaeach place on the retina corresponds to a specific place on the LGNthis correspondence between points on the LGN and retina creates a retinotopic mapwhat this map looks like can be determined by recording from neurons in the LGNmethod determining retinotopic maps by recording from neurons p76
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