The Physiological Basis of Neuromuscular Relaxation

The fundamental role of the hypothalamus and particularly of its sympathetic division in the emotional process has been established by the classical investigations of Bard,¹ Ranson,² Hess,³ and many others. Recent work^4,5 showing that emotional reactions may be evoked by stimulation and ablation of rhinencephalic structures suggests that hypothalamic excitability and emotional reactivity depend not only on reflex stimuli but also corticohypothalamic interrelations.^6,7 Neither these facts nor the finding that impulses from the reticular formation are necessary for the maintenance of hypothalamic excitability and wakefulness⁹ have altered the central role which the hypothalamus plays in the emotional process. They seem to imply, however, that changes in hypothalamic excitability may be achieved either via the cortex or through reflexes involving the hypothalamus. The apparent parallelism between the state of excitability of the hypothalamus and emotional reactivity makes an investigation of the factors determining hypothalamic excitability a matter of importance for clinical