Adaptation changes the spatial frequency tuning of adult cat visual cortex neurons |
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Authors: | M Bouchard P-C Gillet S Shumikhina S Molotchnikoff |
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Institution: | (1) Département de Sciences Biologiques, Université de Montréal, CP 6128 Succ. Centre-ville, H3C 3J7 Montréal, QC, Canada |
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Abstract: | The modular layout of striate cortex is arguably a hallmark of all cortical organization. Neurons of a given module or domain
respond optimally to very few specific properties, such as orientation or direction. However, it is possible, under appropriate
conditions, to compel a neuron to respond preferentially to a different optimal property. In anesthetized cats, prepared for
electrophysiological recordings in the visual cortex, we applied a spatial frequency (SF) that differs (by 0.25–3.0 octaves)
from the optimal one for 7–13 min without interruption. This application shifted the tuning curve of the cell mainly in the
direction of the imposed SF. Indeed, results indicate an attractive push occurring more frequently (50%) than a repulsive
(30%) shift in cortical cells. The increase of responsivity is band-limited and is around the imposed SF, while flanked responses
remained unmodified in all conditions. We hypothesize that the observed reversible plasticity is obtained by a modulation
of the balance between the strengths of the respective synaptic inputs. These changes in preferred original optimal spatial
frequencies may allow a dynamic reaction of cortex to a new environment and particularly to ‘‘zoom’’ cellular activity toward
persistent stimuli in spite of the tuning inherited from genetic programming of response properties and environmental conditions
during critical periods in new born animals. |
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Keywords: | Visual cortex Short term plasticity Spatial frequency tuning Vision |
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