Changes in projection from locus coeruleus to lateral geniculate nucleus following ablation of visual cortex in adult rats.

The visual cortex of adult rats was unilaterally ablated. A histofluorescence study revealed an increase of noradrenergic terminals in the lateral geniculate nucleus (LGN) ipsilateral to the decortication, confirming the previous report. Corresponding to this, the frequency for encountering neurons in the locus coeruleus (LC) activated antidromically from the LGN was increased. We suggest that LC neurons whose axon terminals were damaged by ablation of the visual cortex formed new axons or axon collaterals (pruning effect) in the LGN, thus contributing, at least partly, to the increase of noradrenergic terminals therein.