Lectures3+4-Chapter_2-BiologicalFoundations

Nature 404 871 876 the rewired animals were trained

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Unformatted text preview: he auditory pathway. Nature 404: 871-876. The rewired animals were trained to make one response (turn right) to a visual stimulus and a different response (turn left) to a sound. Sounds were presented centrally, and light stimuli were presented only in the portion of the visual field seen by the NONREWIRED visual pathway (blue arrows). Subsequently, the remaining visual thalamic nuclei on the rewired side (red LGN, LP) were destroyed, leaving the visual projection to the auditory cortex as the only pathway for visual information processing for the part of the visual field that sends information to the left thalamus. Following recovery from the lesion, animals Removing the structures that normally supply the consistently responded as though they auditory thalamus (MGN) in neonatal ferrets perceived the light stimulus presented to caused inputs carrying visual information to grow the rewired projection to be visual; these onto it, so that the input that went from the auditory responses dropped to chance levels after thalamus to the auditory cortex only contained the auditory cortex that received the visual visual information. information was destroyed. Many Sensory Brain Areas are Topographically Organized Brain areas that process sensory information have an orderly representation of the structure from which sensory signals originate. An example is the cortical representation of touch: Sensations from adjacent parts of the body cause changes in the activity of cell groups that are adjacent to each other in the somatosensory cortex. Larger amounts of cortical tissue are dedicated to parts of the body that exhibit greater sensitivity (for example, the tips of the fingers as compared to the upper arm). 1 32 Contralateral Cortical Representation Most sensory pathways are set up so that their fibres project to the opposite side of the brain. Most motor cortical pathways are set up such that motor cortex signals control muscles and movements on the opposite side of the body Note that another major brain structure that gets sensory and motor input, the cerebellum, has sensory information coming from the SAME side of the body, and has cells that give motor commands controlling muscles and movements on the same side of the body There is so far no satisfactory scientific explanation for why these projections are organiz...
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This document was uploaded on 02/16/2014.

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