In EEG the frequency 8-10 hz and amplitude 50-100 (pv)
(Alpha): (273Ganong 24th edition; 1015- A.K. Jain 5th)Main features of Normal EEG rhythmEEG RhythmFrequency (Hz)Amplitude (mV)Associated Features1. Alpha (a)8-1250-100Present maximally in the occipital and parieto occipital areas when the eyes are closed2. Beta (P)14-305-10Generally seen in frontal region (normal awake pattern) commonly seen in infants3. Theta (0)4-710Often found over the parietal and temporal areas (normal in children and in early sleep)4. Delta (5)1 - 4 (Lowest)20 - 200Usually appears during sleep; can be produced by over breathing or evidence of organic brain disease when seen in awake stateA Gamma rhythm (30 - 80 Hz) - often seen when a individual is aroused andfocuses attension on something* May be a mechanism to bind together sensory information into a single percept and action* This is often replaced by irregular fast activity as the individual initiates motor activity in response to the strimulus* Typical spike and rounded waves pattern is characteristic petitmal epilepsy***
Alpha
Beta
Theta
Delta
Nervous System