Event‐related potential measures of the disruptive effects of trains of auditory stimuli during waking and sleeping states

Abstract

SUMMAR Y Acoustic backup alarms have been reported to particularly disrupt sleep. The present study simulated backup alarms by presenting trains of five consecutive 500 ms duration audible tones, with the time between the onset of each tone being 1 s and the time between trains (offset to onset) between 15 and 20 s. In different conditions, the tones were set at either 80 or 60 dB sound pressure level (SPL). Twelve young adults spent two consecutive nights in the laboratory. Stimuli were presented only on the second night. Measures of traditional sleep architecture (sleep stages) were not affected by the acoustic trains. Event-related potentials were also measured following presentation of the stimuli. In the waking state, the initial 80 dB stimulus elicited a large amplitude N1, peaking at about 100 ms, followed by a positive peak, P3, peaking at about 325 ms. N1 was attenuated following presentation of the 60 dB stimulus. The amplitude of N1 was much reduced following presentation of the subsequent second to fifth stimuli in the train. During non-rapid eye movement (NREM) sleep, the initial 80 dB stimulus elicited a large and later negativity (N350) that was reduced in amplitude for the 60 dB stimulus. A K-Complex (a composite N350 and a much larger N550) was elicited following 35% of the initial 80 dB tones and 12% of the initial 60 dB tones. The amplitude of N550 did not, however, significantly vary as a function of stimulus SPL. During REM sleep, N1 continued to be elicited by the initial louder stimulus, but the later positive wave was not apparent. A late negativity peaking at about 350 ms was, however, apparent. When queried the next morning, subjects rarely indicated that the stimulus presentations disturbed their sleep. This might be because of the absence of the late positivity. The presence of the long latency negativities (N350 and N550) might serve to protect sleep from obtrusive sound during sleep.k e y w o r d s backup acoustic alarm, construction noise, sleep disturbance, sleep, EEG

The effects of very slow rates of stimulus presentation on event-related potential estimates of hearing threshold

“…Our results concerning rate effects on the morphology of the N1 elicited by the highest intensity level stimulus (45 dB nHL) replicate those of previous studies (Budd et al, 1998;Campbell et al, 2005;Giard et al, 1994). The scalp distribution of N1 changed from a fronto-central maximum when stimuli were presented rapidly, to a central maximum when stimuli were presented very slowly.…”

“…This is surprising in light of the extensive literature showing much larger N1 amplitudes at slow compared to fast presentation rates, with studies indicating that the N1 elicited by an 80-dB SPL tone burst may double in amplitude at very slow rates (Budd et al, 1998;Campbell et al, 2005). Lightfoot and Kennedy (2006) were similarly unsuccessful in their attempts to counter N1-P2 response degradation over time, in spite of the fact that previous studies have reported some of their manipulations to significantly affect response amplitude.…”

“…At ISIs above 10 s, the N1 response does not show such a response decrement over time (Budd et al, 1998;Campbell et al, 2005); the scalp distribution of N1 also changes from a fronto-central focus (observed at faster rates) to a more central focus (Hari et al, 1982), and this change is attributable to the elicitation of the non-specific N1. Importantly, the supratemporal and non-specific N1 subcomponents are believed to have different functional significance.…”

The processing of infrequently-presented low-intensity stimuli during natural sleep: An event-related potential study

“…When stimulus intensity increases and presentation rate decreases, the amplitude of N1, reflecting the output of the transient detector system, becomes more prominent. [4][5][6][7] The results of the present study are in accordance with these findings. Further, in the Näätänen model, when the output of the transient detector system reaches a critical level, processing in the central executive controlling cognitive resources is interrupted and attention is involuntarily switched to the processing of the auditory stimuli.…”

“…[4] When the rate of stimulus presentation is slowed, the amplitude of N1 also increases and changes from its usual fronto-central maximum to a more central maximum. [5][6][7] A large number of studies have now indicated that the amplitude of N1 varies directly with the intensity level of the auditory stimulus.…”