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Richard Caton discovered electrical activity in the cerebral hemispheres of rabbits and monkeys and presented his findings in 1875. [4] Adolf Beck published in 1890 his observations of spontaneous electrical activity of the brain of rabbits and dogs that included rhythmic oscillations altered by light, detected with electrodes directly placed on the surface of the brain. [5]
Beta waves, or beta rhythm, are neural oscillations (brainwaves) in the brain with a frequency range of between 12.5 and 30 Hz (12.5 to 30 cycles per second). Several different rhythms coexist, with some being inhibitory and others excitory in function.
Traditional classification of the frequency bands, that are associated to different functions/states of the brain and consist of delta, theta, alpha, beta and gamma bands. . Due to the limited capabilities of the early experimental/medical setup to record fast frequencies, for historical reason, all oscillations above 30 Hz were considered as high frequency and were difficult to investigate.
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 ...
In rats, theta wave rhythmicity is easily observed in the hippocampus, but can also be detected in numerous other cortical and subcortical brain structures. Hippocampal theta waves, with a frequency range of 6–10 Hz, appear when a rat is engaged in active motor behavior such as walking or exploratory sniffing, and also during REM sleep. [3]
The proposed answer lies in a wave that, originating in the thalamus, sweeps the brain from front to back, 40 times per second, drawing different neuronal circuits into synch with the precept [sic], and thereby bringing the precept [sic] into the attentional foreground. If the thalamus is damaged even a little bit, this wave stops, conscious ...
As different conscious states can be associated with different dominant brainwave frequencies, [4] it is hypothesized that brainwave entrainment might induce a desired state. Researchers have found, for instance, that acoustic entrainment of delta waves in slow wave sleep had the functional effect of improving memory in healthy subjects. [5]
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.