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Sleep stages are characterized by spectral content of EEG: for instance, stage N1 refers to the transition of the brain from alpha waves (common in the awake state) to theta waves, whereas stage N3 (deep or slow-wave sleep) is characterized by the presence of delta waves. [107] The normal order of sleep stages is N1 → N2 → N3 → N2 → REM.
Alpha waves again gained recognition in the early 1960s and 1970s with the creation of a biofeedback theory relating to brain waves (see below). Such biofeedback, referred to as a kind of neurofeedback , relating to alpha waves is the conscious elicitation of alpha brainwaves by a subject.
Beta waves were discovered and named by the German psychiatrist Hans Berger, who invented electroencephalography (EEG) in 1924, as a method of recording electrical brain activity from the human scalp. Berger termed the larger amplitude, slower frequency waves that appeared over the posterior scalp when the subject's eye were closed alpha waves ...
Theta waves generate the theta rhythm, a neural oscillation in the brain that underlies various aspects of cognition and behavior, including learning, memory, and spatial navigation in many animals. [ 1 ] [ 2 ] It can be recorded using various electrophysiological methods, such as electroencephalogram (EEG), recorded either from inside the ...
They are generated in widespread cortical locations [1] though they tend to predominate over the frontal parts of the brain. [5] Both K-complex and delta wave activity in stage 2 sleep create slow-wave (0.8 Hz) and delta (1.6–4.0 Hz) oscillations. However, their topographical distribution is different, and the delta power of K-complexes is ...
Electroencephalogram (EEG) is also used to detect abnormal brain waves and activity that is reflected as slow waves, or spikes on the recordings. For occipital epilepsy, commonly identified abnormalities on the EEG when a seizure is not occurring (inter-ictal) includes posterior lateralized slow waves, asymmetrical alpha and photic following ...
Slow-wave sleep contrasts with rapid eye movement sleep (REM), which can only occur simultaneously in both hemispheres. [6] In most animals, slow-wave sleep is characterized by high amplitude, low frequency EEG readings. This is also known as the desynchronized state of the brain, or deep sleep.
Acetylcholine is known to promote wakefulness in the basal forebrain. Stimulating the basal forebrain gives rise to acetylcholine release, which induces wakefulness and REM sleep, whereas inhibition of acetylcholine release in the basal forebrain by adenosine causes slow wave sleep.