Gamma wave. Gamma waves A gamma wave is a pattern of neural oscillation in humans with a frequency between 25 and 100 Hz, though 40 Hz is typical. According to a popular theory, gamma waves may be implicated in creating the unity of conscious perception (the binding problem). However, there is no agreement on the theory; as a researcher suggests: Whether or not gamma wave activity is related to subjective awareness is a very difficult question which cannot be answered with certainty at the present time. History Gamma waves were initially ignored before the development of digital electroencephalography as analog electroencephalography is restricted to recording and measuring rhythms that are usually less than 25 Hz. One of the earliest reports on them was in 1964 using recordings of the electrical activity of electrodes implanted in the visual cortex of awake monkeys. Linked to unity of consciousness?
History of idea A lead article by Andreas K. Opposing evidence Brain During Meditation. Brain Activity During Meditation The brain is an electrochemical organ (machine) using electromagnetic energy to function.
Electrical activity emanating from the brain is displayed in the form of brainwaves. They range from the high amplitude, low frequency delta to the low amplitude, high frequency beta. During meditation brain waves alter. The four categories of these brainwaves: Beta Waves or beta rhythm, is the term used to designate the frequency range of human brain activity between 12 and 30 Hz (12 to 30 transitions or cycles per second). Alpha Waves are electromagnetic oscillations in the frequency range of 8Ð12 Hz arising from synchronous and coherent (in phase / constructive) electrical activity of thalamic pacemaker cells in humans.
Theta Waves is an oscillatory pattern in EEG signals recorded either from inside the brain or from electrodes glued to the scalp. Delta Waves are high amplitude brain waves with a frequency of oscillation between 0Ð4 hertz. Theta State ShareThis. Electroencephalography. Simultaneous video and EEG recording of two guitarists improvising.
Electroencephalography (EEG) is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. In clinical contexts, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, usually 20–40 minutes, as recorded from multiple electrodes placed on the scalp. Diagnostic applications generally focus on the spectral content of EEG, that is, the type of neural oscillations that can be observed in EEG signals. EEG is most often used to diagnose epilepsy, which causes obvious abnormalities in EEG readings. It is also used to diagnose sleep disorders, coma, encephalopathies, and brain death. History Hans Berger In 1934, Fisher and Lowenback first demonstrated epileptiform spikes. In 1947, The American EEG Society was founded and the first International EEG congress was held.
Rythme cérébral. Un article de Wikipédia, l'encyclopédie libre.
Les caractéristiques des rythmes cérébraux dépendent de l'état psychologique et, le cas échéant, pathologique de la personne chez qui on les enregistre. Ainsi, l'enregistrement de l'activité rythmique cérébrale permet d'étudier les phases du sommeil ou de caractériser des maladies neurologiques, telles que l'épilepsie. Un exemple d'oscillation neurale est celle des félins : une oscillation neurale située proche de l'hypothalamus entraîne la contraction du larynx et par voie de conséquence le ronronnement. Principaux rythmes cérébraux observés chez l'être humain[modifier | modifier le code] Une seconde de signal EEG. Les activités électriques cérébrales rythmiques sont classées selon leur fréquence : Rythmes cérébraux et stades du sommeil[modifier | modifier le code] Un adulte éveillé émet habituellement des ondes alpha et beta.
Perspectives et applications[modifier | modifier le code]