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Download Neurons in visual cortex
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PLASTICITY AND POSTNATAL DEVELOPMENT Key points Early abnormal stimulation/activity leads to long-term functional deficits (in vision these deficits may be called amblyopias) Understand key features of receptive field transformations from retina through to cortex Ocular dominance: contralateral (1), to binocular (4), to ipsilateral (7) Developmental changes in neuronal structure and response properties Understand the meaning of the critical or sensitive period in young postnatal animals Knowledge of effects of visual deprivation on visual cortex Effects of strabismus (squint), partial visual deprivation on visual function Reading Nolte (4th Ed), pgs 426-430 Fitzgerald, pgs 199-202 Centre/surround organisation of receptive fields in retina and LGN Non-orientation selective, non-direction selective, monocular Neurons in visual cortex: Orientation selective, direction selective, often binocular inputs, usually respond best to elongated contours Morphological maturation of cortical neurons: development of dendritic arbours, dendritic spines and synapses Dendritic spines and synaptic density – changes with age Binocular Contra Ipsi Ocular dominance in cortex of normal and MD cats Reverse occlusion Lateral geniculate nucleus human monkey Monocular deprivation - monkey Contra Ipsi Ocular dominance in cortex of strabismic cats Partial visual deprivation – limited exposure to vertical orientations Signalling molecules and the critical period
