Demonstration of topographically organized projections from the hypothalamus to the pontine nuclei: An experimental anatomical study in the cat

Abstract

In 22 cats implantations and injections of horseradish peroxidase-wheat germ agglutinin (HRP-WGA) or Fluoro-Gold were placed in the pontine nuclei or the hypothalamus. The occurrence and distribution of labeled cells in the hypothalamus and of labeled terminal fibers in the pontine nuclei were mapped. Following implantations of HRP-WGA ventromedially in rostral parts of the pontine nuclei, 22-44% of all labeled cells in the brainstem and diencephalon are found in the medial mamillary nucleus ipsilateral to the implantation. Some labeled cells are also found in the supramamillary, premamillary, anterior mamillary, and tuberomamillary nuclei. Thus, labeled cells in the hypothalamus make up 33-54% of all labeled cells in the brainstem and diencephalon in such cases. In contrast, implantations and injections in mediocaudal parts of the pontine nuclei result in labeling of cells mainly in the posterior, dorsal, and lateral hypothalamic areas (terminology of Bleier: The Hypothalamus of the Cat. Baltimore: Johns Hopkins Press, '61). In these cases the labeled cells in the hypothalamus make up 16-25% of all labeled cells in the brainstem and diencephalon. Implantations in more lateral parts of the pontine nuclei label only a few cells in the hypothalamus. Following implantations of HRP-WGA in restricted parts of the hypothalamus, fibers from the medial mamillary nucleus were found to terminate ventromedially at all rostrocaudal levels of the pontine nuclei, ipsilateral to the implantation. In the rostralmost part of the pontine nuclei, the terminal labeling forms a dense, transversely oriented, c-shaped band. Fibers from the posterior and dorsal hypothalamic areas terminate medially and dorsomedially in the caudal third of the pontine nuclei. Sparse terminal labeling is also seen in lateral parts of the pontine nuclei and medially at more rostral levels. In two cases with small implantations of HRP-WGA ventromedially in rostral parts of the pontine nuclei, labeled cells are found both in the medial mamillary nucleus and the cingulate gyrus. Thus, it seems possible that fibers from the medial mamillary nucleus and the cingulate gyrus converge upon a restricted area ventromedially in rostral parts of the pontine nuclei.

The Role of the Cerebellum in Unconscious and Conscious Processing of Emotions: A Review

“…Thus, in the emotional domain, measuring cerebellar function with regards to state estimation and its ability to process and predict sequential events allows one to compare different states, integrating internal and external events at the unconscious and conscious levels. This is allowed by the cerebellar integrated functioning in the complex neural networks that subserve the unconscious and conscious components of the emotional domain [56][57][58][59][60][61][62][63][64][65].…”

“…In particular, it receives afferent nerves from the medial mammillary bodies [57,58] and multi-modal deep layers of the superior colliculus in addition to being connected bi-directionally to the hypothalamus [59] and the brainstem areas (ventral tegmental area, periaqueductal gray, and locus ceruleus) that are related to the limbic and paralimbic regions [60]. The cerebellum receives information from the paralimbic cortices in the cingulate gyrus [61] via their projections to the pontine nuclei [62,63].…”

Evidence for topographic organization in the cerebellum of motor control versus cognitive and affective processing

“…In addition to corticopontine afferents from motor and nonmotor regions, the cerebellum also receives inputs from the medial mammillary bodies engaged in memory (Aas and Brodal, 1988; Haines and Dietrichs, 1984) and multimodal deep layers of the superior colliculus. It also has reciprocal connections with the hypothalamus (Dietrichs, 1984; Haines and Dietrichs, 1984) and with brainstem areas (ventral tegmental area, periacqueductal gray, and locus ceruleus) that are linked with limbic and paralimbic regions (Snider and Maiti, 1976).…”

Acute and repetitive fronto-cerebellar tDCS stimulation improves mood in non-depressed participants

“…For example, the cerebellum has demonstrated reciprocal connections with brainstem regions linked to limbic and paralimbic regions (Snider and Maiti 1976), the hypothalamus (Aas and Brodal 1988;Haines et al 1984), as well as brainstem regions that participate in the modulation of autonomic function (Almeida et al 2002;Golanov et al 2000;Andrezik et al 1984;Miura and Reis 1969).…”