Fiber dissection and 3-tesla diffusion tensor tractography of the superior cerebellar peduncle in the human brain: emphasize on the cerebello-hypthalamic fibers

Abstract

Experimental studies in various species using tract-tracing techniques showed clear evidence of the presence of cerebellohypothalamic projections. However, these connections were not clearly described in humans. In the present study we aimed to describe the direct cerebello-hypothalamic connections within the superior cerebellar peduncle (SCP) using fiber dissection techniques on cadaveric brains and diffusion tensor tractography (DTI) in healthy adults. Fiber dissection was performed in a stepwise manner from lateral to medial on 6 cerebral hemispheres. The gray matter was decorticate and fiber tracts were revealed. The SCP was exposed and the fibers were traced distally using wooden spatulas. The MRI examinations were performed in seven cases using 3-tesla 3T unit. The direct cerebello-hyothalamic pathways were exposed using high-spatialresolution DTI. The present study using both fiber dissection and DTI in adult human showed direct cerebello-hypothalamic fibers within the SCP. The SCP fibers course anterolateral to the cerebral aqueduct reaching the level of the red nucleus of the midbrain. The majority of the fibers crosses over and reached the contralateral diencephalic structures and some of these fibers terminated at the contralateral anterior hypothalamic area. Some of the uncrossed SCP fibers reached the ipsilateral diencephalic structures and terminated at the ipsilateral posterior hypothalamic area. We further reported the close relationship of the SCP with the MCP, lateral lemniscus, red nucleus and substantia nigra. In the DTI evaluations of the SCP we exposed unilateral left cerebello-hypothalamic fibers in five cases and bilateral cerebello-hypothalamic fibers in two cases. The present study demonstrates the direct cerebello-hypothalamic connections within the SCP for the first time using fiber dissection and DTI technique in the human brain. The detailed knowledge of the cerebello-hypothalamic fibers can outline the unexplained deficit that may occur during regional surgery.

Neurobiological and behavioural outcomes of biofeedback-based training in autism: a randomized controlled trial

“… 61 The SCP is the main WM tract by which information from the cerebellum transmits to the rest of the brain, connecting the cerebellum to the midbrain, basal ganglia 64 , 65 and hypothalamus. 66 WM microstructure of the SCP has been shown to be associated with proprioception in non-autistic adults, 67 motor skills in autistic children, 68 and motor skills, expressive language, and IQ in preterm-born children (some of whom were autistic). 69 In the present study, we found corroborating evidence for the role of the SCP in motor and communication skills in that there were overlapping ODI and ICVF clusters in the right SCP associated with motor ability as well as a cluster in the superior portion of the SCP associated with autism symptom severity change.…”

The Role of the Human Hypothalamus in Food Intake Networks: An MRI Perspective

“…More recently, a direct cerebello-hypothalamic tract was described in Human. Indeed, DTI results reported fibers projecting from the cerebellar nuclei to the contralateral anterior HT and ipsilateral posterior HT ( 83 ). The cerebellar-hypothalamic connection seems to allow for the convergence of non-limbic information to the limbic system through the hypothalamic and septal nuclei.…”

Networking of the Human Cerebellum: From Anatomo-Functional Development to Neurosurgical Implications

“…Even if less frequently reported in comparison with the supratentorial compartment, in-vivo and ex-vivo methods were also adopted for investigating cerebellar WM anatomy. The most recent available studies reported detailed exposition and threedimensional representation of different gray and WM structures, focusing on reciprocal relationships and practical surgical implications, mainly concerning the indications, advantages, limitations, and possible risks of specific approaches (32)(33)(34)(35)(36).…”

“…For example, several Authors discussed about existence and functional role of reciprocal connections between the cerebellum and the hypothalamus. After previous evidence in animal models using track-tracing and electrophysiology methods, direct cerebello-hypothalamic connections passing through the SCP have been recently described also in the human brain using fiber dissection and DTI technique (2,32,75,76). Even if the functional orientation (afferent or efferent) of this pathway needs to be clarified, these results would confirm the effective participation of the cerebellum in typical hypothalamic processing, such as cardiovascular osmolarity regulation, feeding behavior, energy balance, and weight control (77,78).…”