Neurophysiological effects of experimental intracranial hypertension on three different structures of the brain stem in the cat. Rostrocaudal deterioration.

Modifications if multi-unit activity are analyzed during experimental intracranial hypertension in the cat at three levels of the brain stem red nucleus (NR), nucleus giganto-cellularis (Gc), and lateral geniculate body (GO). An initial increase of activity is observed in NR and Gc, which is followed by a fall of activity. This fall is sooner and more important for the rostral structures than for the caudal ones. In GO, activity decreases as soon as intracranial hypertension starts. These results are similar to those already recorded in the mesencephalic and bulbar reticular formation. They are discussed on the basis of monoamine levels and local CBF variations studied in the brain stem, following the same protocol. The higher sensitivity of rostral brain stem structures to intracranial hypertension is correlated to the clinical concept of rostro-caudal deterioration.