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Central Modulation of Pain
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The nuclei in the thalamus that receive these projections are located either laterally (ventral posterior lateral and ventral posterior inferior nuclei and medial posterior complex) or medially in the central lateral nucleus and other intralaminar nuclei. Fibres arising from more caudal segments tend to be located laterally, and those entering from more rostral segments tend to be located in the more medial and ventral part of the tract.
The Physiology of Pain
Published in Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand, Pediatric Regional Anesthesia, 2019
Bernard Jacques Dalens, Brigitte Storme
However, the functional significance of this nucleus remains unclear, as (1) it includes neurons responsive to nonnoxious stimuli and (2) it may contain both descending projections to the spinal cord and ascending projections to the thalamus, the intralaminar nuclei, and the cerebral cortex. While the ascending projections are probably concerned with nondiscriminative pain (the motivational-directive component), the descending connections have been shown to suppress spinal unit activity. The raphe nuclei, especially the nucleus raphe magnus, and the periaqueductal gray matter play a very important role in postsynaptic inhibition (mediated by opiate-like peptides), whereas other brain stem projections to descending tracts can exert presynaptic inhibition (the inhibitory mechanisms of the “gate”).21,22
Neurotransmitters and Receptors in the Basal Ganglia
Published in W. R. Wayne Martin, Functional Imaging in Movement Disorders, 2019
In contrast, the matrix neurons receive inputs from motor, sensory, supplementary motor, and association cortices as well as from the intralaminar nuclei of thalamus.53–55 The cells of the matrix also receive dopaminergic input from the dopamine cells in the SNc and the ventral tegmental area (VTA).47,48 The level of dopaminergic input appears lower in the matrix than in the striosomes and the turnover of dopamine in the two regions is different.56 The medium spiny neurons of the matrix are GABAergic and have projections to the SNr, MGP and LGP.23,24,57 In the primate, each of these projections appears to be mediated by unique groups of neurons and there are only a limited number of striatal matrix neurons which project to all three areas.6,58–60 The cells which project to the LGP contain high concentrations of enkephalin, and therefore, there are high concentrations of enkephalinlike immunoreactivity seen in the LGP as compared to the MGP or SNr.61–63 In contrast, matrix projections to the MGP and the SNr contain high concentrations of substance P and dynorphin.63–67
Thalamic neuromodulation in epilepsy: A primer for emerging circuit-based therapies
Published in Expert Review of Neurotherapeutics, 2023
Bryan Zheng, David D. Liu, Brian B Theyel, Hael Abdulrazeq, Anna R. Kimata, Peter M Lauro, Wael F. Asaad
The thalamus is a cluster of nuclei that are grouped based on shared patterns of connectivity with cortical and subcortical areas and are enveloped within the shell-like thalamic reticular nucleus (TRN). Topographically organized thalamocortical and corticothalamic projections are the basic, modular elements around which more elaborate thalamic circuits are built. The surrounding TRN is a major source of feedforward and feedback inhibition. Meanwhile, in contrast to the principal nuclei that connect to relatively circumscribed areas of cortex, intralaminar nuclei are more diffuse structures with correspondingly broader cortical interactions. Further, the borders between principal nuclei are not always distinct and the anatomical and functional perspectives do not consistently map directly onto one another. As such, alternative classification schemes based on thalamocortical circuitry may more clearly lay the framework for therapeutic thalamic neuromodulation.
Calcitonin gene-related peptide (CGRP): role in migraine pathophysiology and therapeutic targeting
Published in Expert Opinion on Therapeutic Targets, 2020
Anne-Sophie Wattiez, Levi P. Sowers, Andrew F. Russo
Within the CNS, CGRP and its receptor are present in multiple pathways believed to play a role in migraine pathophysiology [8]. The trigeminal ganglion (located outside of the BBB) projects to the trigeminal nucleus caudalis (TNC) where second-order neurons carry the signals to the posterior thalamic area (PTA). We use PTA as a term to encompass all nuclei in the posterior thalamic area. The PTA appears to be a sensory integration center that is abnormal during migraine. Neurons in the thalamus receive input from the TNC and retinal ganglion cells [36], and several key studies have demonstrated in rodents the importance of the PTA in the development of photophobia and highlight the PTA as a possible center for the integration of light and pain [36–38]. CGRP likely contributes to this pathway as both CGRP and its receptors are present in discrete nuclei of the PTA. This is further supported by a study showing that injection of CGRP into the PTA facilitates neuronal firing [38]. Moreover, somatosensory and nociceptive stimuli from ascending pathways converge on the CGRP-producing neurons of the subparafasicular and intralaminar nuclei [39]. In humans, the posterior thalamus is known to be activated during migraine attacks and has altered functional connectivity with multiple brain regions [40,41]. Taken together, these data suggest that pre- and post-synaptic neuromodulatory actions of CGRP that have been reported in other neural circuits [42], could contribute to a state where the PTA is hypersensitive to sensory stimuli.
Time perception impairment following thalamic stroke: A case study
Published in Neuropsychological Rehabilitation, 2018
Joe Mole, Jill Winegardner, Donna Malley, Jessica Fish
Van der Werf et al. (2003) note that, although memory has received the greatest attention due to striking cases of diencephalic amnesia, thalamic damage can be associated with severe deficits in executive functioning and attention. For example, they found executive impairments in patients with lesions that included the medial dorsal nucleus, midline nuclei and/or intralaminar nuclei, and deficits in reduced complex attention following damage to the intralaminar nuclei (Van der Werf et al., 2003). Temporal disorientation has been described as a rare consequence of thalamic stroke, with an estimated prevalence of 4% within this patient group (Kumral, Gulluoglu, & Dramali, 2007).