Benelux Congress of Zoology edition:13 location:Leuven (Belgium) date:27-28 October 2006
Loss of retinal input in a restricted region of adult cat visual cortex due to small retina lesions leads to a topographical reorganization within the sensory-deprived lesion projection zone (LPZ). This recovery coincides with changes in activity balance and gene expression. We here investigated alterations in cortical activity in primary visual area 17 in function of post-lesion survival time both inside and outside the LPZ. For this purpose, we quantified the neuronal activity by means of real-time PCR for the well-known activity marker c-fos in area 17 of cats with binocular central retinal lesions. First, we compared the activity level of the central LPZ to the peripheral intact projection zone (IPZ) along the medio-lateral axis of the brain. Second, we examined the activity gradient along the posterior-anterior axis of area 17.
Our study on the effect of retinal lesions in area 17 revealed a strong activity decrease in the LPZ along the two axes. In time, both axes exhibited a recovery of activity, implying that the LPZ became smaller in function of survival time. We also provided indisputable evidence that the influence of the central retinal lesions reaches even beyond the sensory-deprived cortical area. We indeed observed differential activity values in the peripheral IPZ compared to corresponding cortical regions in normal subjects. We conclude that changes in activity of the LPZ as well as the IPZ have an important role in processes of plasticity-mediated recovery.