DISTRIBUTION OF PARVALBUMIN-IMMUNOREACTIVE CELLS AND FIBERS IN THE HUMAN AMYGDALOID COMPLEX

The calcium-binding protein, parvalbumin, was localized immunohistoche mically in the human amygdaloid complex. Neuronal cell bodies and fibe rs that are immunoreactive to parvalbumin were observed in most of the amygdaloid nuclei and cortical areas. Three types of immunoreactive a spiny neurons, ranging from small spherical cells (type 1) to large mu ltipolar cells (type 2) and fusiform cells (type 3), were observed. Th e densities of the types of neurons that were parvalbumin-immunoreacti ve varied in the different regions of the amygdala. The highest densit ies of parvalbumin-immunoreactive neurons were observed in the lateral nucleus, in the magnocellular and intermediate divisions of the basal nucleus, in the magnocellular division of the accessory basal nucleus and in the amygdalohippocampal area. The regions containing the lowes t density of parvalbumin-immunoreactive cells were the paralaminar nuc leus, the parvicellular division of the basal nucleus, the central nuc leus, the medial nucleus and the anterior cortical nucleus. In general , the distribution of immunoreactive fibers and terminals paralleled t hat of immunoreactive cells. Parvalbumin-immunoreactive varicose fiber s formed basket-like plexi and cartridges around the unstained neurons , which suggests that parvalbumin is located in GABAergic basket cells and chandelier cells, respectively. The distribution of parvalbumin-i mmunoreactive profiles in the human amygdaloid complex was similar to, rather than different from that previously reported in the monkey amy gdala (Pitkanen and Amaral [1993] J. Comp. Neurol. 331:14-36). This st udy provides baseline information about the organization of GABAergic inhibitory circuitries in the human amygdaloid complex. (C) 1995 Wiiey -Liss, Inc.