14 Hz Q8-13 Hz4-7 Hz3-5 Hz (minimum)QAmplitudeLow amplitudeHigh amplitudeHigh amplitudeQLarge amplitude (Maximum)QCharacteristic Feature:* Low-voltage, high frequency desynchronized electrical activity* Can be produced by any form of sensory stimulation or mental concentration, such as solving arithmetic problems alpha rhythm gets replaced by beta, therefore beta rhythm known as alpha blockFrequency of alpha rhythm is decreased by:* Old age* Low blood glucose* Low body temperature* Low levels of adrenal glucocorticoids* High arterial PaCO2* SleepRecorded in:* Newborn infants* Stage 1 of NREM sleep* Emotional stress* in adults particularly disappointment and frustration* Many brain disorders* Accentuated in children when they are crying* High-voltage, low frequency synchronized electrical activity.* Evoked by overbreathing* Seen in pathological states in which thalamocortical transmission is blocked,such as coma. * Beta rhythm is also known as arousal or alerting response, because it is correlated with the aroused, alert state * Presence of intracranial tumor act as a source of delta wave activity.* In metabolic encephalopathy, Delta waves are seen predominantly due to a decrease in the consciousness.">