An occasional "deviant" stimulus presented in a train of frequent homogeneous "standard" stimuli elicits a negativity, called the "mismatch negativity" (MMN), in the human auditory evoked potential (AEP). The MMN occurs at approximately 100-300 ms after stimulus onset. In awake and alert subjects, the MMN appears to be elicited regardless of the level of attention, conscious awareness, or task demands. The purpose of the present thesis was to examine the attentional independence of the MMN by recording event-related potentials (ERP) to different types of stimulus change or "deviance" during natural sleep. In three separate experiments, stimulus deviations involving frequency, duration, and intensity were examined. In experiment 1, two "oddball" stimulus conditions involving auditory frequency deviance were presented to eight subjects. In the "large deviance" condition, 2000 Hz "deviant" tones were presented with 1000 Hz "standard" tones. In the "small deviance" condition, 1050 Hz deviants were used. Both stimulus conditions were presented during wakefulness, as subjects read a book, and during Stage 2, REM, and slow wave sleep (SWS). In experiment 2, two stimulus conditions involving deviations in stimulus duration were presented to eight subjects. In the "increment deviance" condition, 150 ms deviant tones were presented with 100 ms standards. In the "decrement deviance" condition, 50 ms deviant tones were used. Both conditions were presented during wakefulness (reading), and sleep stages 2, REM and SWS. In experiment 3, stimuli involving changes in auditory intensity were presented to seven subjects during a waking reading condition, Stage 2 and REM sleep. Within the same stimulus block, 80 dB "increment deviants" and 60 dB "decrement deviants" were presented with 70 dB standard tones. The results of the three studies indicated that the MMN to frequency deviance is preserved during REM sleep, and, the MMN to duration deviance may also be present in REM sleep, but is much attenuated relative to wakefulness. The detection of intensity deviance persists in REM sleep, but it is uncertain whether this is due to a true mismatch process or a deviant-related negativity specific to the REM sleep state. No MMN-like activity could be recorded to any type of stimulus deviance during NREM sleep. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/9914 |
| Date | January 1996 |
| Creators | Loewy, Derek. |
| Contributors | Campbell, Kenneth, |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 187 p. |
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