Thalamoamygdaloid connections studied by the method of retrograde transport.

On the basis of retrograde horseradish peroxidase transport from nuclei ot the amygdaloid body of the rat to the thalamus, it was found that several groups of thalamic nuclei send fibers to the amygdala. These are: (i) nuclei of posterior region of thalamus and neighboring area of the tegmentum - peripeduncular nucleus, suprageniculate-limitans nucleus, (ii) midline nuclei - paraventricular nucleus, parataenial nucleus, nucleus reuniens, (ii) intralaminar nuclei - central medial nucleus, parafascicular nucleus, (iv) medidorsal nucleus. There are two main systems of thalamoamygdaloid connections. One of them arising in the posterior region of the thalamus terminates in the lateral nucleus of the amygdala and the lateral part of its central nucleus. The other system begins in the intralaminar and midline nuclei and in the mediodorsal nucleus of the thalamus. It reaches the remaining nuclei of the amygdala. Amygdalopetal connections of the interlaminar and middline nuclei of the thalamus, especially those arising in the paraventricular and parataenial nucleus, are mostly bilateral.