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Neurodegeneration
Published in Ibrahim Natalwala, Ammar Natalwala, E Glucksman, MCQs in Neurology and Neurosurgery for Medical Students, 2022
Ibrahim Natalwala, Ammar Natalwala, E Glucksman
The motor cortex and the supplementary motor area predominantly project excitatory glutamatergic fibres to the spinal cord (lateral corticospinal tract), striatum and thalamus. The striatum consists of the caudate nucleus and the putamen, separated anatomically by the internal capsule. It comprises chiefly medium spiny neurones which are inherently inhibitory (GABAergic). The striatum projects inhibitory fibres to the globus pallidus interna (GPi) and substantia nigra pars reticularis (SNr). This pathway is known as the direct pathway since the GPi and SNr inhibit the thalamus (via the inhibitory ansa lenticularis projections) and hence if the striatum inhibits them, the thalamus is allowed to transmit excitatory output to the cerebral cortex and striatum (positive feedback loop).
Specific Synonyms
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
Entopeduncular nucleus (W&W, p. 964 [Fig. 7.102]) Nucleus of the ansa lenticularis (ibid.)
Melanocyte-Stimulating Hormone in the Central Nervous System
Published in Mac E. Hadley, The Melanotropic Peptides, 1988
Bibie M. Chronwall, Thomas L. O’Donohue
Radioimmunoassay for α-MSH in microdissected areas of discrete regions of rat brain show the highest concentrations in the median eminence and the dorsomedial nucleus, followed by the arcuate and the periventricular nuclei of both the hypothalamus and thalamus. The ventral part of the interstitial nucleus, ansa lenticularis, the paraventricular, posterior hypothalamic, and rhomboid nuclei contain moderate levels, as do the central gray and dorsal raphe (Table 1). Several studies show consistent data in rat,2,17 cat,18 and human.19,20 Discrete regions of the rat brain show a diurnal rhythm of immunoreactive α-MSH content.21
White matter tracts involved by deep brain stimulation of the subthalamic nucleus in Parkinson’s disease: a connectivity study based on preoperative diffusion tensor imaging tractography
Published in British Journal of Neurosurgery, 2020
François Vassal, Domitille Dilly, Claire Boutet, Frédérique Bertholon, David Charier, Benjamin Pommier
The STN is a deep grey matter nucleus located within the diencephalon, which is densely connected to other basal ganglia as well as to distinct, distributed cerebral cortex territories. Based on its receiving (monosynaptic) afferents from the cerebral cortex, the STN has been divided into sensorimotor, associative and limbic anatomo-functional territories.21–23 Furthermore, the STN is surrounded by WM fibre tracts passing through the subthalamic region to reach the thalamus.24,25 These WM fibre tracts include the ansa lenticularis and lenticular fasciculus originating in the (ipsilateral) globus pallidus pars interna, and the DRTT originating in the contralateral cerebellar hemisphere. The lenticular fasciculus and the zona incerta separate the dorsal STN from the ventral thalamus. The possibility that electric field propagation to these neighbouring structures contributes to the therapeutic effects of STN-DBS has been postulated.26–28 However, to date, a clearer picture of the brain networks that are modulated by STN-DBS has yet to emerge.
Deep brain stimulation for trigeminal autonomic cephalalgias
Published in Expert Review of Neurotherapeutics, 2018
Giuseppe Messina, Giovanni Broggi, Vincenzo Levi, Angelo Franzini
Due to the localization of the pHyr in the proximity of the diencephalic–mesencephalic junction [38], and also noting that the PET activation in CH patients is found in the most anterior portion of ventral tegmental area (VTA), some authors advocate the latter as the real target for CCH [39–41]; however, it is also known that such procedures have a low spatial resolution, thus reducing the problem to a mere terminological [rather than a neurophysiological] one, considering the region-at-the-border in object. Fontaine, in 2010, raised the issue about the real position of the electrodes positioned in CCH patients, located posterior to the mammillary bodies [and still localized according to our previous reported coordinates [2 mm lateral, 3 mm posterior, and 5 mm inferior to the MCP]; according to the authors, the electrodes were not located within the posterior hypothalamus, but instead in the mesencephalic gray matter (comprising gray mesencephalic substance, the red nucleus, the fascicle retroflexus, the dorsal longitudinal fascicle, the nucleus of ansa lenticularis, the medial longitudinal fascicle) [42,43]. This is because conventionally the mammillary bodies are considered the posterior-most region of the hypothalamus, and also by the nomenclature used by Hassler [43]. Important physiological and connectivity differences exist between the two structures. The pHyr has important connections with the trigeminal system [44], with the limbic forebrain, remaining hypothalamic regions, brainstem reticular formation, the PAG matter, and the TCC. The latter structures seem to be reasonably involved in the sleep–wake cycle, defense–escape behavior, and cardiovascular system, all features related to CCH. Conversely, the dopaminergic VTA, per se, seems to be more involved in complex functions related to motivational behavior and reward [44].
Deep brain stimulation and stereotactic-assisted brain graft injection targeting fronto-striatal circuits for Huntington’s disease: an update
Published in Expert Review of Neurotherapeutics, 2022
Thomas Kinfe, Alessandro Del Vecchio, Martin Nüssel, Yining Zhao, Andreas Stadlbauer, Michael Buchfelder
Notably, the first stereotactic procedure, performed in 1947, was a pallidotomy carried out to alleviate motor symptoms in an HD patient. The stereotactic-assisted ablation of the pallidal zone was intended to interrupt the pallidal outflow pathways, in particular the pallido-fugal projections of the ansa lenticularis [30].