Influence of preoptico-anterior and posterior hypothalamus on midline thalamic neurons

The present study was aimed at understanding the influence of the posterior hypothalamus (PH) and the preoptico-anterior hypothalamus (PO-AH) on the neurons of the midline thalamus (MTh) in encéphale isolé cats. A majority of the influenced neurons of the MTh showed increased firing on stimulation of the PH. Although the number of neurons showing increased or decreased firing on PO-AH stimulation were nearly equal, stimulus bound increased firing in many neurons was followed by a prolonged decreased firing. It is likely that the hypothalamo-thalamic circuit constitutes a parallel pathway to the reticulo-thalamic circuit for alteration of the cortical EEG.