Does dendritic growth underly recovery from neonatal occipital lesions in rats

Rats were given lesions of visual cortex on postnatal day 4 or 10, or in adulthood. Ninety days later they were trained on a horizontal-vertical stripes discrimination task and a visual-spatial navigation task. None of the operated rats acquired the tasks. The brains were processed for Golgi-Cox staining and dendritic arborization was quantified in the layer III pyramidal cells in somatosensory cortex. Relative to normal control brains, the neurons of the day 4 and adult operates showed a reduction in dendritic branching, whereas the neurons of the day 10 operates had a significant increase in dendritic arborization. This arborization may be related to enhanced somatosensory function but does not support recovery of visually-guided behavior.