Event-related potential measures of gap detection threshold during natural sleep

• Event-related potentials were used to provide an estimate of the gap detection threshold during sleep.
• Gap detection thresholds could be accurately estimated while the subject was awake using the amplitude of N1, peaking at about 100 ms and also during stage N2 of sleep using the amplitude of P2, peaking at about 200 ms.
• Only larger suprathreshold gaps were able to elicit N1 and P2 during REM sleep.

ObjectiveThe minimum time interval between two stimuli that can be reliably detected is called the gap detection threshold. The present study examines whether an unconscious state, natural sleep affects the gap detection threshold.MethodsEvent-related potentials were recorded in 10 young adults while awake and during all-night sleep to provide an objective estimate of this threshold. These subjects were presented with 2, 4, 8 or 16 ms gaps occurring in 1.5 duration white noise.ResultsDuring wakefulness, a significant N1 was elicited for the 8 and 16 ms gaps. N1 was difficult to observe during stage N2 sleep, even for the longest gap. A large P2 was however elicited and was significant for the 8 and 16 ms gaps. Also, a later, very large N350 was elicited by the 16 ms gap. An N1 and P2 was significant only for the 16 ms gap during REM sleep.SignificanceERPs to gaps occurring in noise segments can therefore be successfully elicited during natural sleep. The gap detection threshold is similar in the waking and sleeping states.