K-complex

A K-complex is a waveform that may be seen on an electroencephalogram (EEG). It occurs during stage 2 NREM sleep. It is the "largest event in healthy human EEG".^[1] They are more frequent in the first sleep cycles.

K-complexes have two proposed functions:^[1] first, suppressing cortical arousal in response to stimuli that the sleeping brain evaluates not to signal danger, and second, aiding sleep-based memory consolidation.

The K-complex was discovered in 1937 in the private laboratories of Alfred Lee Loomis.^[2]

^ ^a ^b Cash S.S.; Halgren E.; Dehghani N.; et al. (2009). "Human K-Complex Represents an Isolated Cortical Down-State". Science. 324 (5930): 1084–87. Bibcode:2009Sci...324.1084C. doi:10.1126/science.1169626. PMC 3715654. PMID 19461004.
^ Loomis A.L.; Harvey E.N.; Hobart G.A. (1937). "Cerebral states during sleep as studies by human brain potentials". J Exp Psychol. 21 (2): 127–44. doi:10.1037/h0057431.

[Cash-1] Cash S.S.; Halgren E.; Dehghani N.; et al. (2009). "Human K-Complex Represents an Isolated Cortical Down-State". Science. 324 (5930): 1084–87. Bibcode:2009Sci...324.1084C. doi:10.1126/science.1169626. PMC 3715654. PMID 19461004.

[2] Loomis A.L.; Harvey E.N.; Hobart G.A. (1937). "Cerebral states during sleep as studies by human brain potentials". J Exp Psychol. 21 (2): 127–44. doi:10.1037/h0057431.

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