China
Africa
Explore chapters and articles related to this topic
Neuronal Firing Patterns and Models
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
An important example of synchronized oscillatory activity between different areas of the brain is the thalamocortical network, involving feedback loops between the thalamus and various areas of the cerebral cortex either directly or through other brain structures, such as the basal ganglia or the cerebellum (Chapter 12). Different frequencies of oscillation are prominent, depending on mental activity and the state of the brain. For example, gamma-band frequencies are associated with conscious perception, selective concentration on tasks, learning, and short-term memory. The alpha rhythm is prominent, particularly in the occipital-parietal regions of the cortex in the awake, relaxed state, with the eyes closed and in tasks that heavily involve working memory. Alpha activity is diminished in the attentive, visually-dependent state. Gamma-band oscillations are prominent in rapid-eye-movement (REM) sleep, whereas lower frequencies, in the delta and theta ranges, are prominent in non-rapid-eye-movement (NREM) sleep.
Psychological Effects of Exercise for Disease Resistance and Health Promotion
Published in Ronald R. Watson, Marianne Eisinger, Exercise and Disease, 2020
Although there are a number of problems associated with attempting to infer psychological states from the electroencephalogram (EEG), it is generally agreed that subjective, behavioral, and psychophysiological correlates of relaxed wakefulness are associated with increased alpha brain activity (i.e., EEG in the 8 to 13 Hz frequency band) and decreased beta brain wave activity (i.e., EEG in the 14 to 40 Hz band) changes. Increases in alpha activity have been observed to follow acute aerobic exercise.27,76,102,106 However, these studies are inconclusive because they have generally lacked control conditions or statistical analyses, and it is unclear whether standardized electroenceph- alographic recording techniques were employed. Also, with the exception of a study by Boutcher and Landers,76 the studies did not measure concomitant changes in subjective feelings of anxiety. Many studies have only examined the alpha frequency band. Many factors unrelated to anxiety can affect the alpha rhythm (e.g., attention, blood sugar level, opening and closing the eyes). Blood pH changes due to exercise might also influence brain wave activity.107 Also, perspiration could induce an artifact by decreasing electrode impedance and consequently increasing the strength of the recorded signal in all frequency bands. Limited psychological and physiological meaning can be ascribed to one frequency band without knowing what occurs in the other frequency bands.
The Sleeping Brain
Published in Hanno W. Kirk, Restoring the Brain, 2020
The sleep EEG (NREM) is characterized by slower frequencies and often higher voltage than that seen during wakefulness. As the focused waking alpha rhythm begins to wane, it is often replaced by theta activity, particularly in the temporal and frontal regions, with accompanying clinical manifestations of drowsiness. As noted above, the interaction between Process C and Process S plays a critical role in the timing and quality of sleep and, thereby, the regulation of vigilance. The core symptoms of ADHD can be induced in otherwise healthy children with sleep deprivation.77 When one considers that children probably have, on average, greater than one hour less sleep compared to 100 years ago,78 it seems quite plausible that perturbations of sleep may underpin the semiology of many persons with ADHD.
Human resting-state EEG and radiofrequency GSM mobile phone exposure: the impact of the individual alpha frequency
Published in International Journal of Radiation Biology, 2022
Jasmina Wallace, Lydia Yahia-Cherif, Christophe Gitton, Laurent Hugueville, Jean-Didier Lemaréchal, Brahim Selmaoui
Between cortical oscillations divided into bands by frequency, the alpha band has received great attention from scientists, whereas initially for many decades it has been considered as passive and idling state of the brain (Pfurtscheller et al. 1996). With recent studies, the alpha band seems to be a pure cognitive signal with an active role in relaxed wakefulness processing (for review (Başar 2012), (Klimesch 2012)) with an amplitude of about 10 to 45 µV (Cacioppo et al. 2007). Topographically, its greatest amplitude is localized over the posterior regions at the occipito-temporal and parietal regions (Niedermeyer and da Silva 2005) and can best be seen during resting periods in which the subjects have the eyes closed (Barry et al. 2007). Its rhythmic activity is commonly attributed in the range of about 8–12 Hz which most likely is generated in thalamo-cortical feedback loops as well as in the cortex (Klimesch 1997; da Silva 2013). The alpha rhythm is blocked or attenuated by attention processes and it was showed to play a direct role in alertness, attention and consciousness state (Palva and Palva 2007). Specifically, in cognitive tasks, the lower alpha (8–10 Hz) suppression (or desynchronization) is associated with a task-unspecific increase in attentional demands. On the other hand, event-related changes indicate that the upper alpha (10–12 Hz) desynchronization is positively correlated with semantic long-term memory performance, processing of sensory semantic information and stimulus specific expectancy (Klimesch 1999; Minarik et al. 2018).
The effects of Jin’s three-needle acupuncture therapy on EEG alpha rhythm of stroke patients
Published in Topics in Stroke Rehabilitation, 2018
Xuejie Yang, Haibo Yu, Tao Zhang, Xiaozhou Luo, Li Ding, Bing Chen, Da Li, Xingxian Huang, Xiaoli Guo, Jie Jia
Although Jin’s three-needle acupuncture had been used and proved to be effective for stroke rehabilitation, its mechanism remains unclear. A hypothesis was that acupuncture took effect by regulating the cerebral blood flow (CBF). Both clinical and animal studies showed that acupuncture could increase the CBF velocity5,6. On the other hand, the change of CBF was always accompanied with electrophysiological activities7,8. EEG activity was found to be significantly positively correlated with rheoencephalogram amplitude-frequency parameter in children7. Especially, the change of the alpha rhythm (8–13 Hz) has been shown to be a spatial correspondence to the CBF response, and the alpha power was significantly correlated with the CBF amplitude8. Therefore, we assumed that acupuncture would also influence EEG activity, especially the alpha rhythm, which might provide the electrophysiological mechanism of the curative effect of acupuncture for stroke rehabilitation.
A “hot crossed buns” sign, orthostatic syncope & gait ataxia point to probable multiple systems atrophy with dysarthria and slowed fluency suspicious for associated cognitive impairment
Published in Cogent Medicine, 2018
Anthony C. Torres, Garet J. Zaugg, Nasir Tufail, Paul H. Janda
Laboratory testing revealed elevated triglycerides and the HgbA1c was diagnostic for diabetes mellitus. The vasculatides panel was negative. Cerebral spinal fluid (CSF) studies yielded normal cell counts with mild elevation of glucose and protein (95mg/DL and 63mg/DL, respectively). CSF studies for cytology yielded no malignant cells; inflammatory cells were observed and consistent with the diagnosed traumatic subarachnoid hemorrhage. A paraneoplastic panel revealed no evidence of a paraneoplastic neurologic disorder. The rapid plasma regain test was nonreactive and serologic tests for HIV and hepatitis serology were negative. On electroencephalography, a normal appearing, posterior dominant alpha rhythm was appreciated. Non-contrasted brain CT scan demonstrated a stable small, left frontal subarachnoid hemorrhage, consistent with a traumatic etiology. On MRI of the brain, disproportionate cerebellar and pontine atrophy was appreciated and axial fluid-attenuated inversion recovery (FLAIR) sequences demonstrated a hyperintense crossed appearance of the pons as known as the hot-crossed-buns sign (Figure 1). For the MRI, Gadolinium contrast was used; there was no evidence of abnormal enhancement.