COLLATERAL AFFERENT EXCITATION OF RETICULAR FORMATION OF BRAIN STEM

Abstract

The distr. of afferent collaterals to the reticular formation of the brain stem has been investigated in the cat by probing for potential changes evoked by somatic and auditory stimulation. In the case of each modality, a rich supply of collateral connections to the midbrain tegmentum, sub-and hypothalamus and ventromedial thalamus was encountered. These findings offer an explanation for a number of the generalized consequences of afferent stimulation which have been difficult to understand in terms of conduction within classical sensory paths. Specifically, they indicate that the arousing and awakening influences of sensory stimulation may be exerted indirectly, and at a subcortical level, by collateral excitation of the reticular activating system in the brain stem.