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Consciousness, EEG, Sleep and Emotions
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 locus coeruleus, a group of neurons containing norepinephrine (noradrenaline) as a neurotransmitter, is found in the pontine reticular formation. The raphe nuclei are formed by another group of neurons lying in the midline of the pons. Some of these neurons in the pons and midbrain send axons to excite or inhibit the thalamus. Neural impulses from the reticular formation can modulate the activity of the thalamic pacemakers and thus influence cortical neuronal excitability. The intralaminar and anterior thalamic nuclei are non-specific nuclei of the thalamus which excite the cerebral cortex. Axons from the non-specific nuclei can also stimulate inhibitory interneurons linked to the thalamic nuclei to produce drowsiness. Lesions diffusely affecting the cerebral hemispheres or directly affecting the reticular activating system can impair consciousness.
Treatment of Chronic Fatigue Syndrome
Published in Jay A. Goldstein, Chronic Fatigue Syndromes, 2020
It is suggested that locus ceruleus inhibition of hippocampal activity produces anxiety. Benzodiazepines may reduce generalized anxiety but not sodium lactate induced panic. Since benzodiazepine receptors are dense in limbic structures, it may be that these anxiolytics act there but not in the brain stem. There are well-known pathways from the limbic system to the locus ceruleus. Gorman et al. suggest that “repeated stimulation of limbic neurons by brain stem discharge lowers the threshold to excitatory postsynaptic stimulation in the limbic lobe until `subpanic’ stimulation is capable of maintaining the ‘kindled’ anticipatory anxiety. Thus, even without the further occurrence of panic, the limbic area continues to have a reduced threshold for response to various stressors.” It may be that the hyperventilation that accompanies panic attacks causes reduced cerebral blood flow in the limbic system and is thereby responsible for the symptoms of hyperventilation syndrome. In our CFS SPECT scan population, the patients who chronically hyperventilated (as determined by end-tidal pCO2) could be symptomatically distinguished from those who did not only by the presence of fibromyalgia tender points. Addition of agents which markedly increase cerebral blood flow, such as calcium channel blockers (except for nimodipine) and acetazolamide, do not often reduce such symptoms. Patients with anxiety disorders, however, have normal, or increased, cerebral blood flow.89 Acetazolamide lowers brain pH but causes hyperventilation.
Genetically Epilepsy-Prone Rats
Published in Carl L. Faingold, Gerhard H. Fromm, Drugs for Control of Epilepsy:, 2019
Phillip C. Jobe, Pravin K. Mishra, John W. Dailey
We are now evaluating the various noradrenergic terminal fields for potential roles in seizure regulation in the GEPR by use of lesioning techniques.55 The role of topographically defined forward order graded deficits has been evaluated in GEPR-3s using three infusion sites for 6-hydroxydopamine (6-OHDA): (1) locus ceruleus; (2) dorsal noradrenergic bundle; and the (3) A-l medullary area. All three lesions clearly increase predisposition, as evidenced by enhancement of audiogenic seizure severity. The lesion of the locus ceruleus causes a widespread depletion of central nervous system NE. The lesion of the dorsal bundle depletes forebrain and midbrain NE while sparing the pons-medulla, cerebellum, brainstem, and spinal cord. The A-l lesion spares most of the forebrain areas but depletes NE in the amygdala, midbrain, pons-medulla, cerebellum, and spinal cord.
Correlations with REM sleep behavior disorder severity in isolated rapid eye movement sleep behavior disorders patients
Published in International Journal of Neuroscience, 2023
Sang Jin Kim, Eun Ju Chung, Ki-Hwan Ji, Mi-Ri Kang, Jin Yong Hong, Sunseong Lee, Ji Sun Park, Jungsu S. Oh, Jae Seung Kim, Suk Yun Kang
The correlation between pain and visuospatial dysfunction with RBD severity may be associated with RBD pathophysiology. This pathophysiology is currently poorly understood, but RBD is thought to be associated with several nuclei in the pontomedullary brainstem that include the locus coeruleus, subcoeruleus/sublateral dorsal nucleus, laterodorsal tegmental nuclei, the PPN, and medullary magnocellular reticular formation [8]. These nuclei play a role in pain modulation, visuospatial attention, and cognition including visuospatial function and memory [24–26]. The locus coeruleus is a norepinephrine-producing nucleus in the dorsal pons, and projects to the brain widely and is involved in homeostasis, sensory processing, and cognitive and motor function [24,26]. The raphe nuclei are serotonin-producing nuclei in the midline from the medulla to the midbrain and are also involved in sensory processing that includes pain, heat, touch [27], and visual orientation [28]. One recent study reported increased thermal detection threshold in iRBD patients, and they assumed that peripheral small nerve fibers might be associated because they did not find a difference in laser evoked potentials and conditioned pain modulation between iRBD patients and controls. However, more studies are needed, because they did not perform skin biopsies to check nerve pathology and did not assess the presence and severity of pain in iRBD patients [29]. Besides, there was no PSG data to determine RBD severity in that study.
Cognitive workload during verbal abstract reasoning in Parkinson’s disease: a pilot study
Published in International Journal of Neuroscience, 2021
Sanghee Moon, Melike Kahya, Kelly E. Lyons, Rajesh Pahwa, Abiodun E. Akinwuntan, Hannes Devos
Pupillary response is a reliable and valid measurement for cognitive workload that has been utilized in individuals with PD who have or are at risk of cognitive impairment [11,12]. Pupils dilate when individuals perform cognitive tasks and subside quickly after the task is completed. Pupillary response induced by cognitive tasks is linked with the activation of locus coeruleus-norepinephrine system. The locus coeruleus primarily produces norepinephrine which plays an important role in the regulation of cognitive functions including attention, learning, memory, and decision making [13]. The underlying mechanism of the connection between pupil dilation and locus coeruleus activity is not fully understood, but neuroimaging showed correlations between pupil dilation and locus coeruleus activity during cognitive tasks [14]. The pupillary response can be accurately measured by pupillometric devices such as an eye tracker [15]. These eye tracking devices measure changes in pupil size, which in turn reflects changes in cognitive workload during cognitive tasks [16]. Pupillary response during cognitive tasks has been investigated in different studies examining processing speed, attention, and arithmetic tasks in neurodegenerative conditions [11, 17,18]. Abstract reasoning, however, includes the ability to relate different concepts on a complex level through evaluating and applying previous knowledge in problem-solving by using theories, metaphors, and complex analogies [7].
Diffusion tensor imaging findings in children with sluggish cognitive tempo comorbid Attention Deficit Hyperactivity Disorder
Published in Nordic Journal of Psychiatry, 2020
Gül Ünsel-Bolat, Muharrem Burak Baytunca, Burcu Kardaş, Melis İpçi, Sevim Berrin İnci İzmir, Onur Özyurt, Mehmet Cem Çallı, Eyüp Sabri Ercan
The internal capsule was reported in the previous ADHD studies [43,45,46]. Only a few studies found an association between ADHD and FA values in cerebral peduncle [45] and fornix [47]. The limbic system that includes fornix has important implications in memory, emotion, and behaviors. The role of the fornix in memory function was described previously in the previous studies such as memory deficits or amnesia [48–50]. Also, deep brain stimulation of fornix in patients has grown in the past years to treat learning and memory deficits [51]. Additionally, locus coeruleus that have projections to the fornix responsible for maintaining vigilance and responsiveness to unexpected environmental stimuli. These clinical implications related to fornix are important. Because SCT symptoms were associated with memory deficits and deficits in maintaining vigilance previously [10,26,52].