Active neurogenesis is responsible for learning activities, memory and spatial orientation (32) and modulation of theta rhythm
Both hypnosis and mindfulness meditation states feature higher levels of activity in areas where theta frequency brain waves are prominent, especially the ACC (235,236) and the hippocampus, source of these theta rhythms
. (237) These altered states of consciousness, then, offer unique access to the mind's higher-order control of awareness and focused attention.
Figures 2-5 show the spectra of the EEG signal and the filter passbands for alpha, beta, delta, and theta rhythms
The study of theta rhythm
generation as well as its alterations in several neurological pathologies has received a great deal of attention [8, 84].
It has been shown that temporary inactivation of PPT results in the suppression of theta rhythm
(63) indicating that the functional integrity of PPT is critical for the occurrence of hippocampal synchronization at theta frequency and thus PPT is also one of the important sites in the brainstem reticular formation for theta generation (63).
Acute caffeine abstinence also produced changes in EEG (increased theta rhythm
) that has previously been linked to the common withdrawal symptom of fatigue.
One pattern, called the theta rhythm
, predominates in rats during REM sleep and exploring behavior.
Slow, low-frequency rhythms -- theta rhythms
-- dance in the front of your brain, acting like the conductors of an orchestra.
Meanwhile, synchronisation -- when theta rhythms
from different areas of the brain synchronize with one another -- allows separate brain areas to communicate with one another.
The Mind Mirror is 'a portable ECG machine that could monitor the alpha, beta and theta rhythms
from each brain hemisphere (left and right neo-cortex) simultaneously.'
Based on the above description, the most interesting and hopefully revealing are delta and theta rhythms
, which have already been correlated with different brain disorders, and alpha rhythm, because it represents the awake state that is most easily measured without distractions (subject is relaxed without mental activity).