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Response properties of long‐latency event‐related potentials evoked during NREM sleep
Author(s) -
SALISBURY DEAN,
SQUIRES NANCY K.
Publication year - 1993
Publication title -
journal of sleep research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 117
eISSN - 1365-2869
pISSN - 0962-1105
DOI - 10.1111/j.1365-2869.1993.tb00094.x
Subject(s) - psychology , audiology , non rapid eye movement sleep , stimulus (psychology) , loudness , sleep stages , electroencephalography , event related potential , neuroscience , cognitive psychology , polysomnography , medicine
SUMMARY The experiments reported here sought to investigate whether the K‐complex evoked during sleep is comprised of activity from two separate physiological systems with different response properties. To that end, the parameters of stimulation in a two tone auditory ‘odd‐ball’ task were varied systematically as stimuli were presented to subjects during NREM sleep. During experiment 1, the frequency (pitch) of the odd‐ball stimulus varied systematically while intensity (loudness) was matched between tones. During experiment 2, pitch was matched between tones while the loudness of the odd‐ball stimulus was varied. The long‐latency event‐related potentials (ERPs) N2 and P3 could be dissociated from the K‐complex (N3 and P4) in response to these parametric manipulations. Information processing occurs during sleep, and is reflected in ERPs with a morphology largely analogous to those observed under similar conditions while subjects are awake. The second (K‐complex) system is sleep specific. A model was constructed to explain the activity of these two hypothesized systems. As predicted by the model, K‐complex latency was longer in Stage 2 when N2 and P3 were also active, than in Stage 4 where N2‐P3 activity was lessened. These results support the two‐system hypothesis; electrical brain activity evoked during sleep should not be considered a unitary sleep‐specific response. Furthermore, the data indicate that the K‐complex is sensitive to the physical characteristics of stimuli, that the sleeping brain processes information to a high degree, and that the ‘endogenous’ components of the ERP observed in awake humans reflect more automatic processes than previously suspected.