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Due to the density of its neural layers, the hippocampus generates some of the largest EEG signals of any brain structure. In some situations the EEG is dominated by regular waves at 4–10 Hz, often continuing for many seconds. This EEG pattern is known as the hippocampal theta rhythm. It has also been called Rhythmic Slow Activity (RSA), to ...
When an EEG shows interictal epileptiform discharges (e.g. sharp waves, spikes, spike-and-wave, etc.) it is confirmatory of epilepsy in nearly all cases (high specificity), however up to 3.5% of the general population may have epileptiform abnormalities in an EEG without ever having had a seizure (low false positive rate) [8] or with a very low ...
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.
LGS is a combination of atonic absences, tonic seizures, cognitive deterioration, and slow spike-wave activity in the EEG. This syndrome usually results from focal, multifocal, or diffuse brain damage and can be divided into symptomatic and cryptogenic types.
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 ...
Electroencephalography (EEG) EEG records the brain's spontaneous electrical activity over a short period of time, usually 20–40 minutes, as recorded from multiple electrodes on the scalp. [26] Microsleeps have EEG shift to slower frequencies (from alpha to theta waves). [27] Functional magnetic resonance imaging (fMRI)
While slow waves and sleep spindles are present in stages 2 and 3, stage 2 sleep is characterized by a higher prevalence of spindles, while slow waves dominate the EEG during stage 3. [22] [21] Slow-wave sleep is an active phenomenon probably brought about by the activation of serotonergic neurons of the raphe system. [23] The slow-wave seen in ...
SMR waves . The sensorimotor rhythm (SMR) is a brain wave. It is an oscillatory idle rhythm of synchronized electric brain activity. It appears in spindles in recordings of EEG, MEG, and ECoG over the sensorimotor cortex. For most individuals, the frequency of the SMR is in the range of 7 to 11 Hz. [1]