Basal Ganglia
Anne Morel in Stereotactic Atlas of the Human Thalamus and Basal Ganglia, 2007
The series of maps presented in Figures 4.1 to 4.47 were derived from case Hb7 where sections from the left and right hemispheres were cut in the frontal and sagittal planes, respectively. The distance between maps are given in millimeters “in vivo” in each drawing. Similar conventions to those described in Chapter 3 for the thalamic atlas were applied here, with additional areas indicated in many maps by dotted lines that represent the patch/matrix organization of the striatum, as well as differential staining in the pallidum and subthalamic nucleus. Whole pallidum, STh, and part of the striatum and SN are also represented in the maps of the thalamic atlas in Chapter 3 (Figs. 3.1-3.13 and 3.18-3.25). Structures outside the basal ganglia, such as parts of the hypothalamus, amygdala, and adjoining cortex, are not delimited in detail.
Syndromes of disturbances of consciousness and cognition
Vincent K. Omachonu, Joel E. Ross in Textbook of Clinical Neuropsychiatry and Behavioral Neuroscience, Third Edition, 2012
Disturbances in the level of consciousness reflect dysfunction of either the ascending reticular activating system (ARAS) (Parvizi and Damasio 2003), the thalamus, or the cortex. The ARAS is a midline brainstem structure which extends from the rostral pontine tegmentum up into the mesencephalic tegmentum, where it lies ventral to the periaqueductal gray matter. Fibers from the ARAS then extend up into the thalamus, specifically to the thalamic intralaminar nuclei and the reticular nucleus, and subsequently fibers from the thalamus project to the cortex. In addition to this efferent pathway of the ARAS, there is also a subsidiary, extratha- lamic pathway, which ascends from the ARAS, and then passes on through the hypothalamus toward the frontal cortex.
Schizophrenia
William T. Blows in The Biological Basis of Mental Health, 2016
Sleep has remained a mysterious phenomenon since humans began thinking about it. It does seem illogical for humans and animals to spend a large part of their lives sleeping when they could be doing other things, not to mention that during sleep humans are significantly less able to protect or defend themselves against attack. REM sleep is identified by the rapid movement of the eyes beneath the closed lids, and appears to be the lightest form of sleep. Areas that promote sleep include the ventrolateral preoptic nucleus (VLPN) in the anterior hypothalamus. Restless legs syndrome (RLS) is a situation in which sleep is disturbed by a constant need to move the legs rhythmically in order to prevent the onset of unpleasant sensations. Modafinil is a central nervous system (CNS) stimulant used to treat narcolepsy, with or without cataplexy. It increases histamine from the hypothalamus and increases dopamine in various parts of the brain, including the nucleus accumbens.
A Volumetric MRI Analysis of Hypochondriac Patients
Published in Klinik Psikofarmakoloji Bülteni-Bulletin of Clinical Psychopharmacology, 2010
Murad Atmaca, Semih Sec, Hanefi Yildirim, Alperen Kayali, Sevda Korkmaz
ABSTRACT No volumetric brain magnetic resonance imaging (MRI) study has been performed in hypochondriac patients to date. In the present study, we aimed to volumetrically evaluate the orbito-frontal cortex (OFC), anterior cingulate, caudate nucleus, and thalamus. The volumes of the OFC, thalamus, caudate nucleus, and anterior cingulate cortex were measured in 16 treatment-naive hypochondriac patients and 16 healthy control subjects. Volumetric measurements were made with T1-weighted coronal MRI images, with 1.5-mm-thick slices, at 1.5T and were done blindly. Hypochondriac patients had significantly smaller mean left and right OFC, and greater left but not right thalamus volumes compared with healthy controls. There was no difference in regard to caudate and anterior cingulate volumes for either side between groups. The Hamilton Depression Rating Scale (HDRS) scores were not associated with any volumetric parameter studied. Age at onset showed a significant relationship to left OFC, and left thalamus volumes. Duration of illness also exhibited a significant association with left OFC, and left thalamus volumes. In conclusion, this morphometric MRI study showed that patients with hypochondriasis had smaller left and right OFC and significantly greater left thalamus volumes compared to healthy controls. Taken together, our findings suggest that abnormalities in the OFC and thalamus seem to play an important role in the pathophysiology of hypochondriasis.
A case of central post-stroke pain with beneficial response to electroconvulsive therapy: a proton magnetic resonance spectroscopy study
Published in The Pain Clinic, 2002
S. Fukui, S. Shigemori, S. Nosaka
We present a 58-year-old male chronic post-stroke central pain patient, whose pain resulted from left thalamic hemorrhage, and whose pain had failed to respond to standard pain treatment, but was resolved by electroconvulsive therapy (ECT). To investigate the potential role of neural function in ECT's analgesic effect, the patient underwent a proton magnetic resonance spectroscopy (1H-MRS) on a 2 × 2 × 2 cm voxel in the thalamus bilaterally before and after a course of unilateral ECT.The N-acetylaspartate-to-creatine (NAA/Cr) ratio, which reflects neural function, was calculated on the voxel of the thalamus. Before ECT, the left to right thalamus NAA/Cr ratio was 62.3%. The NAA/Cr ratio of the left thalamus increased 32.0% after ECT,compared to the ratio before ECT.The results from the 1H-MRS suggest that improvement of neural dysfunction in the thalamus may be related to the analgesic efficacy of ECT.
Receptive Field Properties of Trigeminothalamic Neurons in the Rostral Trigeminal Sensory Nuclei of Cats
Published in Somatosensory & Motor Research, 1994
This study described topographic and receptive field representation in the region of the rostral trigeminal nuclei, and evaluated whether thalamic neurons from the principal sensory nucleus relay muscle afferent information to the thalamus. Extracellular single-unit activity was recorded from anesthetized cats. Units were tested for responses to natural stimuli (i.e., air bursts, brushing, light pressure, and pinch) applied to the face and oral cavity, electrical stimulation of the masseter nerve, and ramp-and-hold movements of the jaw. The receptive fields and physiological properties for 110 units were studied; we were able to verify the recording site for 96 of these units. Most of the units had discrete receptive fields in the oral cavity, skin, hair, and masseter muscle. Only 2 units received convergent inputs. Stimulation of the ipsilateral and contralateral ventroposteromedial nucleus of the thalamus was performed to identify antidromically activated units. The results showed that the dorsal principal sensory nucleus received its input primarily from the oral cavity. Most of the units (85%) that were activated by antidromic stimulation from the ipsilateral thalamus were located in this nucleus. In contrast, 82% of the units that projected to the contralateral thalamus were located in the ventral principal sensory nucleus. A complete somatotopic representation of the ipsilateral face and oral cavity was observed in the ventral principal sensory nucleus. Although 24 units had muscle receptive fields, none were activated by stimulation of the ipsilateral thalamus, and only 1 responded to stimulation of the contralateral thalamus. Most of the units that were not antidromically driven were recorded outside of the cytoarchitectual boundaries of the principal sensory nucleus. Retrograde labeling of the rostral trigeminal nuclei indicated that most of the neurons in the dorsal principal sensory nucleus projected to the ipsilateral thalamus, whereas those in the ventral principal sensory nucleus projected to the contralateral thalamus. Taken together, these observations do not support the presence of a substantial relay for muscle afferent input from the dorsal principal sensory nucleus to the ventrobasal thalamus in cats.