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Brain Waves Classes

Type ~ Frequency (Hz) ~ Location ~ Normally ~ Pathologically
Delta ~ up to 4 ~ frontally in adults, posteriorly in children; 

high amplitude waves ~ adults slow wave sleep
in babies
Has been found during some continuous attention tasks 
(Kirmizi-Alsan et al. 2006) ~ subcortical lesions
diffuse lesions metabolic encephalopathy hydrocephalus
deep midline lesions
Theta ~ 4 – 7 ~ Found in locations not related to task at hand ~ 
young children drowsiness or arousal in older children and adults
idling. Associated with inhibition of elicited responses 
(has been found to spike in situations 
where a person is actively trying to repress a response or action) 
(Kirmizi-Alsan et al. 2006). ~ focal subcortical lesions
metabolic encephalopathy deep midline disorders some instances of hydrocephalus
Alpha ~ 8 – 12 ~ posterior regions of head, both sides, 
higher in amplitude on dominant side. Central sites 
(c3-c4) at rest . ~ relaxed/reflecting closing the eyes
Also associated with inhibition control, seemingly with the purpose 
of timing inhibitory activity in different locations 
across the brain (Klimesch, Sauseng, & 
Hanslmayr 2007; Coan & Allen 2008). ~ coma ~ 
Beta ~ 12 – 30 ~ both sides, symmetrical distribution, 
most evident frontally; low amplitude waves ~ alert/working
active, busy or anxious thinking, active concentration ~ benzodiazepines
Gamma ~ 30 – 150+ ~ Somatosensory cortex ~ Displays during cross-modal 
sensory processing (perception that combines two different senses, 
such as sound and sight) (Kisley & Cornwell 2006; Kanayama, Sato, 
& Ohira 2007; Nieuwenhuis, Yeung, & Cohen 2004)
Also is shown during short term memory matching of recognized objects, 
sounds, or tactile sensations (Herrmann, Frund, & Lenz 2009) ~ 
A decrease in gamma band activity may be associated with cognitive decline, 
especially when related the theta band; however, this has not been proven 
for use as a clinical diagnostic measurement yet (Moretti et al. 2009). ~ 
Mu ~ 8 – 13 ~ ~ Sensorimotor cortex. ~ Shows rest state motor neurons 
(Gastaut, 1952).[15] ~ Mu suppression could be indicative for motor 
mirror neurons working, and deficits in Mu suppression, and thus in 
mirror neurons, might play a role in autism. (Oberman et al., 2005)[16]

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