The biological and evolutionary foundations of sleep and dreams
Frederick L. Coolidge, Ernest Hartmann in Dream Interpretation as a Psychotherapeutic Technique, 2018
In this stage we are still awake but resting with our eyes closed. On the EEG will appear a very beautiful semi-symmetrical wave, known as alpha. It was first described in 1929 by Berger, a German psychiatrist. Alpha waves are of moderately large amplitude, and occur in most people at a frequency of about 10 Hz (cycles per second) with a range from 9 to 12 Hz. Alpha waves are all fairly similar and rhythmic which adds to their beauty. Alpha is most clearly produced over the back part (posterior) of the skull (over the occipital lobes or the primary visual processing part of the cortex). Most people produce alpha but approximately 30% do not, and we do not know the reasons why. I still remember my disappointment when I was first working in a sleep lab and wired myself up, plugged myself into the EEG, and found that I did not produce alpha.
ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
Alpha waves constitute the 8-12 Hz component of the cortical EEG (see ELECTROENCEPHALOGRAM). In humans, alpha waves dominate the EEG when the subject is sitting still with the eyes closed, and are most prominent in the occipital cortex. They can be blocked by gross bodily movements. Alpha-like EEG activities have been recorded from the sensory and motor cortices in a variety of species including human, baboon, cat and rat, and these are called mu rhythm, wicket rhythm, rythme en arceau, rythme de veille immobileand sensorimotor rhythm. All these EEG activities are likely to share common thalamocortical rhythm-generating mechanisms.
Bioelectric and Biomagnetic Signal Analysis
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam in Introduction to Computational Health Informatics, 2019
Alpha-waves range from 8 to 13 Hz, is found on the posterior (back), parietal and occipital region of the brain and has an amplitude around 20–200 microvolts. Alpha-waves appear only during the time a person is awake, relaxed and mentally alert with eyes closed without any engagement in activities. Alpha-waves disappear during sleeping and are replaced by asynchronous waves when a person is involved in intense activities.
Solving a Problem by Insight: A Neuropsychological Approach
Published in The Neurodiagnostic Journal, 2018
Alpha waves typically originate from the surface of the occipital lobe of the brain during relaxed wakefulness and with the eyes closed. The occipital lobe contains the primary visual cortex and is responsible for visuospatial processing (Carlson and Heth 2009). The thalamus also produces alpha activity (Domino et al. 2009). This deep inner section of the brain plays an integral part in the regulation of consciousness and relays environmental stimuli to be processed in their respective areas of the brain (Leonard 2006). The thalamus is also functionally connected to the hippocampus, which is well known for its involvement in the consolidation of spatial, episodic, and autobiographical experience (Steriade and Llinás 1988; Cohen and Eichenbaum 1993; Aggleton et al. 2010) from short-term into long-term memory (Wood et al. 2011). Interestingly, the hippocampus in the right hemisphere of the brain—often regarded as the creative and intuitive hemisphere—is remarkably highlighted during the very moment of insight as it is perceived using a fMRI (Jing and Kazuhisa 2003).
A spatial profile difference in electrical distribution of resting-state EEG in ADHD children using sLORETA
Published in International Journal of Neuroscience, 2020
Mojtaba Jouzizadeh, Reza Khanbabaie, Amir Hossein Ghaderi
Alpha wave is known to be related to attention and alertness, which is the dominant frequency in the posterior regions in EC and relaxed wakeful condition [53]. A study by Koehler et al. reported significantly a higher alpha band power density for adult ADHD compared to control subjects [54]. In a study conducted by Bresnahan and Barry, it has been reported that adult ADHD group had more power in the alpha band compared to the control subjects [49]. Also, White et al. found elevated alpha power in adults with ADHD compared to normal adults while performing an attention test [Integrated Visual and Auditory Continuous Performance Test (IVA)] [55]. While some ADHD studies have described an elevated level of alpha power compared to healthy controls [49,51,54], others have found a reduced level [15,37,56], or no significant differences [48,57]. Our finding is reinforcing the importance of Alpha wave in the attention deficit of the ADHD children, in that we found a significant increase in alpha frequency band power.
Predicting functional outcomes after stroke: an observational study of acute single-channel EEG
Published in Topics in Stroke Rehabilitation, 2020
Jeffrey Rogers, Sandy Middleton, Peter H. Wilson, Stuart J. Johnstone
Stroke is associated with immediate brain changes resulting from the suppression of oxygen and glucose supply, including a biochemical cascade that can lead to cell death and cerebral infarction.1–3 Electroencephalography (EEG) is sensitive to the effects of these acute changes in cerebral blood flow4,5 and neural metabolism.6,7 Such changes can be identified through the disruption or deterioration of normal electrical activity within the four classical frequency bands: delta, theta, alpha, and beta. Delta and theta are primarily associated with a low state of arousal, and a prominence of these slow frequency waves is reported in individuals with neurological disease or injury.8 Faster frequency alpha waves are associated with a state of relaxation and readiness, while beta waves mainly occur when an individual is actively engaged in mental effort.8 In particular, EEG obtained in the acute stage after stroke (i.e. <72 h) is often associated with the rapid appearance of slow delta frequency waves and attenuation of faster alpha frequency activity.9–13
Related Knowledge Centers
- Electroencephalography
- Electrophysiology
- Magnetoencephalography
- Neural Oscillation
- Primary Motor Cortex
- Quantitative Electroencephalography
- Rapid Eye Movement Sleep
- Occipital Lobe
- Thalamus
- Mu Wave