MORPHOLOGY AND FUNCTION OF THE AUTONOMOUS NERVOUS SYSTEM

The autonomic nervous system consists of the sympathetic and parasympathetic divisions. The central part is represented by supra-segmental and segmental centres. Parasympathetic segmental centres in the brain are accessory nucleus of the oculomotor nerves, superior salivary nucleus of the facial nerve, inferior salivary nucleus of the glossopharyngeal nerve and dorsal nucleus of the vagus nerve. In the spinal cord, these are the intermediate lateral nuclei. Sympathetic segmental centres in the brain are absent, and in the spinal cord, intermediate-lateral nuclei are located in the lateral horns in the eighth cervical, all thoracic and 1-2 lumbar spinal segments. The peripheral part of the autonomic nervous system is represented by pre-nodal and post-nodal branches, paravertebral, prevertebral and terminal nodes and plexuses. The intramural part of the autonomic nervous system lies in the larger part of a wide and narrow-loop net and represented with a large number of nerve cells different by their shapes and sizes and clustered as intramural nodes, or individual nerve cells included along the net loops. The autonomic plexuses of the abdominal cavity are topographically divided into celiac, superior and inferior mesenteric, abdominal aortic, mesenteric, superior and inferior hypogastric region.

Response of single units in the amygdala to stimulation of buffer nerves in cat

Electrical activity of spontaneously active units in the amygdala of 19 chloralose-anesthetized cats was monitored for changes in firing frequency during electrical stimulation of the carotid sinus (CSN) and aortic depressor (ADN) nerves. Stimulation of the CSN altered the firing frequency of 30% (73/241) of the units on both sides of the amygdala. Of these units, 47% were excited and 53% were inhibited. Stimulation of the ADN elicited a change in firing frequency of 20% (50/251) of ipsi- and contralateral units. Of these, 68% were excited and the remainder were inhibited. The average latency for all CSN responses (53 +/- 4.0 ms) was significantly longer than the average latency for ADN responses (35 +/- 3.3 ms). The majority of the responsive units were located in the central and lateral nuclei of the amygdala. Spontaneously firing units responding to both CSN and ADN stimulation were found infrequently (7%, 14/188). These results indicate that the two buffer nerves project to specific regions within the amygdala, but the CSN and the ADN follow separate pathways probably involved in reflex arcs mediating different physiological responses.