Neuronal Firing Patterns and Models
Nassir H. Sabah in 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
Ronald R. Watson, Marianne Eisinger in 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.
Consciousness, EEG, Sleep and Emotions
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
In adults at rest but awake with eyes closed but the mind wandering, the prominent feature of the EEG is a regular pattern of waves at a frequency of 8–13 Hz with an amplitude of 50–100 μV, which is most marked in the parietal and occipital lobes. This is called alpha rhythm and is associated with decreased levels of attention. When sensory stimulation or mental concentration occurs the α waves are replaced by irregular low-voltage waves at a frequency of 13–30 Hz or beta rhythm. This phenomenon is called arousal response. It is also known as desynchronization as it is associated with breaking up of highly synchronized neural activity. Gamma oscillations at 30–80 Hz are observed when a person who is aroused focuses attention on an activity or object.
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.
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 simultaneous changes in motor performance and EEG patterns in beta band during learning dart throwing skill in dominant and non-dominant hand
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Yaser Khanjari, Elahe Arabameri, Mehdi Shahbazi, Shahzad Tahmasebi, Fariba Bahrami, Ali Mobaien
Therefore, one of the important reasons for the decrease in beta wave activity in the central region can be a reduction in the cognitive load of the task and an increase in sensory-motor integration after the acquisition of skills. On the other hand, the decrease in beta wave activity in the central regions could be due to the increase of the alpha wave in this region. Since the activity of alpha and beta waves is usually inversely related to each other (Kubitz and Mott 1996), another possible reason for the decrease in beta wave activity in this area could be the simultaneous increase in alpha wave activity. However, the results of this study are inconsistent with some studies that have shown that the acquisition of a motor skill does not alter EEG activity in the beta band. For example, Ghasemian et al. (2017) in a study entitled electroencephalography pattern variations during motor skill acquisition concluded that although the performance error in a tracking task decreased with the progress of practice, the activity of the EEG pattern in the beta band in the study channels there were no significant changes (Ghasemian et al. 2017). This contradiction may be due to the fact that in this research firstly, low training sessions (one week) have been used to acquire skills, and secondly, the task studied in this research is not a sports skill (tracking tasks) that can be related to the different conditions of this research with the present research.
Related Knowledge Centers
- Electroencephalography
- Electrophysiology
- Magnetoencephalography
- Neural Oscillation
- Primary Motor Cortex
- Quantitative Electroencephalography
- Rapid Eye Movement Sleep
- Occipital Lobe
- Thalamus
- Mu Wave