Efferent fiber connections of the dorsal and deep tegmental nuclei of gudden. An experimental study in the cat

Abstract

Discrete electrolytic lesions were stereotactically placed in the dorsal and deep tegemental nuclei of Gudden in the cat. Resultant degeneration was traced employing the Fink-Heimer staining technique. This material allows the following conclusions to be drawn: (1) If components of the dorsal longitudal fasciculus do indeed arise in the dorsal tegmental nucleus, they are part of a polysynaptic pathway which makes a synapse with second order neurons either before passing to levels rostral to the trochlear nucleus or caudal to the abducens or before leaving the fasciculus. (2) Fibers originating in both the dorsal and the deep tegmental nuclei pass through the ipsilateral mammillary peduncle to terminate in the mammillary nuclei in a pattern distinctive for the nucleus of origin. The dorsal nucleus sends fibers to the lateral mammillary nucleus ipsilaterally and the dorsomedial aspect of the anterior one-third of the medial mammillary nucleus bilaterally. Fibers originating in the deep nucleus terminate in the posterior two-thirds of the ipsilateral medial mammillary nucleus, while other fibers either originating in or passing through it share the same pattern as those from the dorsal. (3) A bundle of fibers which originates in the dorsal and possibly in the deep tegmental nuclei and passes through the ipsilateral mammillary peduncle continues rostrally in the region of the medial forebrain bundle to terminate in the lateral hypothalamic and preoptic areas. (4) Both the dorsal and the deep tegmental nuclei send fibers into a tegmentopeduncular tract. These fibers terminate in the nucleus centralis superior and the inter-pendicular nucleus. (5) The dorsal tegmental nucleus sends fibers to the ipsilateral deep nucleus. The reverse may also be true.