||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
||4 – 7 Hz
||Found in locations not related to task at hand
- young children
- drowsiness or arousal in older children and adults
- 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
||8 – 12 Hz
||posterior regions of head, both sides, higher in amplitude on dominant side. Central sites (c3-c4) at rest .
- 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).
||12 – 30 Hz
||both sides, symmetrical distribution, most evident frontally; low amplitude waves
- active, busy or anxious thinking, active concentration
||30 – 100 +
- 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).