Tonic, Phasic, and Transient EEG Correlates of Auditory Awareness in Drowsiness.
Abstract
During drowsiness, human perfoimance in responding to above-threshold auditory targets tends to vary irregularly over periods of 4 min and longer. These pefformance fluctuations are accompanied by distinct changes in the frequency spectrum of the electroencephalo- gram (EEG) on three time scales: (I) during minute-scale and longer periods of intermittent responding mean activity levels in the (<4 Hz) delta and (4-6 Hz) fl%eta bands and at the sleep spindle frequency (14 Hz) are higher than during alert performance. (2) In most subjects, 4-6 Hz theta EEG activity begins to increase and gamma band activity above 35 Hz hegins to decrease, about 10 5 hefore pr-sentations of undetected targets, while hefore detected targets, 4-6 Hz amplitude decreases and gamma hand amplitude increases. Both these amplitude differences last 15-20 5 and occur in parallel with event-related cycles in target detection prohahility. In the same periods, alpha and sleep-spindle frequency amplitudes also show prominent 15-20 5 cycles, but these are not phase locked to pefformance cycles. (3) A second or longer after undetected targets, amplitude at intermediate (10-25 Hz) frequencies decreases hriefly, while detected targets are followed by a transient amplitude increase in the same latency and frequency range.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1995
- Accession Number
- ADA359336
Entities
People
- Scott Makeig
- Tzyy-Ping Jung
Organizations
- Naval Health Research Center