Changes in thalamic projection to the barrelfield of rat after neonatal lesions sparing one whisker.

The thalamic input to the barrelfield of rats with a solitary mystacial vibrissa (C3) intact was examined using succinic dehydrogenase techniques. Rats were lesioned on postnatal day (PD) 1 and brains examined at either 7, 12, 21 or 28 days later. The resultant segmentation in the hemisphere contralateral to the lesioned muzzle consisted of fused rows (A to E). At all ages row C differed from the other rows in that the center of the row was enlarged and separated from the row on either side of it. Thus the presence of a single vibrissa is sufficient to organize the thalamic input to its barrel.