This is also seen in people with depression, particular with too much alpha frontally. Alpha tends to be highest in the right hemisphere, and too little alpha in the right hemisphere correlates with negative behaviours such as social withdrawal. Alpha waves aid overall mental co-ordination, calmness and alertness, mind/body integration and learning. It is the resting state for the brain, not unlike a car idling at a stoplight. Alpha is considered the вЂњpower of nowвЂќ, being here and in the present of the moment. Often more tonic and diffuse, and elicits and coordinates memory.ДЄlpha waves (8-12 Hz) dominate during moments of quiet thought, and similar meditative states. Hippocampal Theta: Has been found in the posterior cingulate, entorhinal cortex, hypothalamus and amygdala. This suggests that the anterior cingulate cortex is involved in regulating the emotional state from restless anxiety to focused relaxation. When anxiety is medicated, the signal is restored. When anxious and restless, the signal is reduced or even eliminated. It mainly appears when one is performing a task requiring focused concentration, and its amplitude increases with the task load. Frontal midline theta is thought to originate from the anterior cingulate. It also appears during hypnosis and deep meditation.

This rhythm is associated with working memory, episodic encoding and retrieval. The frequency of frontal midline theta varies from 5-7.5 Hz, with an average of 6Hz. This midline theta is associated with opening the sensory gate to the hippocampus for intermediate storage of episodic information. Theta in people with attention disorders is often seen more towards the front of the brain.ДЇrontal Midline Theta: Sinusoidal and high in amplitude (1-10 second bursts), generally occurs in response to events (ie. Too much theta in the left hemisphere is thought to result in lack of organisation, whereas too much theta on the right results in impulsivity. When we are awake, excess theta levels can result in feeling scattered or day-dreamy, and is commonly reported in ADHD. Cortical theta is observed frequently in young children, but in older children and adults, it tends to appear during meditative, drowsy, or sleeping states (but not during the deepest stages of sleep). Theta waves (4-8 Hz) are particularly involved in day-dreaming and sleep. Because delta is active within brain networks that connect the cortex and insula with the hypothalamus and the brainstem, delta is closely involved with the physiological interface between the brain and the body.В During delta wave sleep, neurons are globally inhibited byВ gamma-aminobutyric acidВ (GABA). Research suggests that cortical circuits generate delta <1Hz, whereas higher-frequency delta rhythms are an intrinsic property of thalamacortical cells and intracortical network interactions.В Importantly, delta may also reflect general neurotransmitter activity, specifically dopamine and acetylcholine. Sleep walking and talking tend to occur while delta production is high. It has been found that individuals with various types of brain injuries produce delta waves in waking hours, making it extremely difficult to perform conscious tasks. An excess of delta waves when a person is awake may result in learning disabilities and ADHD, and make it extremely difficult to focus. At this stage, healing and regeneration are stimulated, and are considered essential for the restorative properties of sleep. Delta Waves (1-4 Hz) are slow brainwaves, which begin to appear in stage 3 of the sleep-cycle, and by stage 4 dominate almost all EEG activity.

Memory alpha measure of a man