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Gamma rhythm

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Eeg gamma

Gamma waves

A gamma wave is a pattern of brain waves, associated with perception and consciousness. Gamma waves are produced when masses of neurons emit electrical signals at the rate of around 40 times a second (40 hertz or Hz), but can often be between 26 and upwards of 70 Hz. By one definition, gamma waves are manifest at 24 Hz and higher, though researchers have recognized that higher level cognitive activities occur when lower frequency gamma waves suddenly double into the 40 Hz range. Research has shown gamma waves are continuously present during low voltage fast neocortical activity (LVFA), which occurs during the process of awakening and during active rapid eye movement (REM) sleep. Some researchers do not distinguish gamma waves as a distinct class but include them in beta brain waves.

Linked to higher reasoning faculties

Gamma waves are involved in higher mental activity. Transient periods of synchronized firing over the gamma waveband, of entire banks of neurons from different parts of the brain, have been proposed as a mechanism for bringing a distributed matrix of cognitive processes together to generate a coherent, concerted cognitive act, such as perception. For example, it has been suggested that gamma waves are associated with solving the binding problem. Recent studies have shown that recognition of new insights occur when patterns jump from 20 to 40 Hz.

It is believed by neuroscientists that gamma activity occurs when various chemical messengers foster efficient communications across large swaths of brain tissue.

Gamma and Negative Emotions

Gamma waves also seem to be envolved in the processing of negative stimuli. Not only are they more prominent in parts of the brain that relate to emotions such as the amygdala, but according to Oya et al. (2002), when subjects were presented with negative stimuli, there was an increase in gamma power compared to when presented with neutral or positive stimuli. Moreover, Oathes et al. (2008) that those with General Anxiety Disorder (GAD) had higher delta waves after a anxiety inducing procedure.

See also

External links

  • - 'A Sampling from Chapter 3' Biofeedback, Neurofeedback and Epilepsy, Sally Fletcher (2005)
  • - 'Thinking in Synchrony', Henry Gee (February, 1999)


  • Bruce Bower (2004). Synchronized thinking. Brain activity linked to schizophrenia, skillful medication. Science News 166 (20): 310.
  • Brain Waves ("40Hz") Research. Brain Waves ("40Hz") Research. URL accessed on June 16, 2005.
  • Are neocortical gamma waves related to consciousness?. National Library of Medicine PubMed. URL accessed on June 16, 2005.
  • Oya, H., Kawasaki, H., Howard, M.A., Adolphs, R., 2002. Electrophysiological
    responses in the human amygdala discriminate emotion categories of complex
    visual stimuli. Journal of Neuroscience 22, 9502–9512.
  • Oathes, D. J., Ray, W. J., Yamasaki, A. S., Borkovec, T. D., Castonguay, L. G., Newman, M. G., & Nitschke, J. (2008). Worry, generalized anxiety disorder, and emotion: Evidence from the EEG gamma band. Biological Psychology, 79(2), 165-170. doi:10.1016/j.biopsycho.2008.04.005

Further reading

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