Structural organization of the thoracic nucleus of the spinal cord of the cat after destruction of the amygdaloid body of the brain

Abstract

The amygdaloid body (AB) of the brain has long been of interest as a structure which in anatomical and functional terms occupies an intermediate position between the neocortex and subcortical formations [9], as a part of the limbic system with integrative and modulating influences on a number of basic body functions [5, 11,15,16]. Autoradiography [6,7] has been used to study the organization of the descending connections of the central part of the AB with brainstem structures [4], particularly the midbrain reticular formation, the substantia nigra, the nucleus ruber, and the ventral part of the central gray matter. Injections of horseradish peroxidase into brain stem structures [7] (the nucleus ruber and the midbrain reticular formations) were followed by the detection of labeled neurons in the medial part of the central nucleus of the AB, with occasional neurons being found in the magnocellular part of the basal nucleus. After injection of horseradish peroxidase into the substantia gelatinosa of the posterior horn of the first cervical segment of the spinal cord, only occasional labeled neurons were seen in the medial part of the central nucleus of the AB [6].Analysis of published data [7,8] leads to the conclusion that the structural and functional connections of the AB with brain and, particularly, spinal cord formations have received inadequate study [11]. The connections of the AB with sensory centers of the spinal cord (including the thoracic nucleus) have not been the subject of direct investigations in humans or animals [13,14].