We investigated the behavioral correlates of the activity of serotonergic and non-serotonergic neurons in the nucleus raphe pallidus (NRP) and nucleus raphe obscurus (NRO) of unanesthetized and unrestrained cats. The animals were implanted with electrodes for recording single unit activity, parietal oscillographic activity, and splenius, digastric and masseter electromyographic activities. They...

Serotonin (5-HT) plays an important role in sensitization of defensive reflexes in Aplysia, and is also involved in several aspects of arousal, such as the control of locomotion and of heart rate. In the preceding paper, we showed that tail-nerve shock, a noxious stimulus that readily induces sensitization, increases the firing rate of a large number of serotonergic neurons throughout the centr...

The monoaminergic hypothesis of depression posits that this illness results from a deficit in serotonin (5-HT), noradrenaline, and dopamine signaling in the brain. Of these monoamines, the serotonergic system has been the one most strongly implicated in the pathophysiology and treatment of mood disorders. Although this relationship has not been proven, many findings indirectly support this hypo...

T he conventional pathophysiological view of the mechanism of neurocardiogenic syncope involves the activation of peripheral baroreceptors, as occurs in the Bezold-Jarisch reflex, in which there is a reflex withdrawal of sympathetic tone and an increase in parasympathetic tone. The result of these changes is a dramatic fall in blood pressure with or without excessive bradycardia, leading to a r...