抄録
Orientation selectivity of cortical cells can be modified by restricting early visual experience (orientation plasticity). We have studied the orientation plasticity by use of cylindrical lens goggles, which were chronically mounted to kittens for restricted exposure to a single orientation. Optical imaging of intrinsic signals elucidated that a remarkable over-representation of the experienced orientation was induced in the visual cortical areas 17 and 18 in kittens reared with the goggles. In order to examine the temporal profile of the orientation plasticity during development, we mounted the goggles for vertical orientation exposure to kittens with different ages for two weeks. We conducted optical imaging in the visual cortex of the goggles-reared kittens to examine how orientation preferences of responsive pixels were distributed in areas 17 and 18. Using the over-representation index characterizing the dominance of the experienced orientation over the other orientations, we evaluated the level of plasticity as a function of the age of the kitten when goggle-rearing was started. The results indicated that the over-representation of the experienced orientation was most prominent in kittens reared with goggles during postnatal 3 to 4 weeks and declined by 8 weeks of age. We also used electrophysiological and histochemical analyses to confirm the findings obtained by optical imaging. The sensitive period profile of the orientation plasticity may be similar to that of the ocular dominance plasticity, suggesting that different functional columns share common mechanisms for their developmental plasticity. [Jpn J Physiol 54 Suppl:S166 (2004)]
