title: Amplitude modulation following responses in awake and sleeping humans--a comparison for 40 Hz and 80 Hz modulation frequency.
abstract: There have been several studies, which suggest that the amplitude of amplitude modulation following responses (AMFR) is correlated to the state of vigilance, similar to the 40 Hz event-related potentials. The aim of the present study was to compare the dependency of the AMFR-amplitude from the state of sleep for 40 Hz and 80 Hz modulation frequency. Eight normal hearing adults were investigated during natural and drug-induced sleep. The stimuli used were sinusoidally amplitude-modulated tones of 1 kHz carried frequency and 40 or 80 Hz modulation frequency at 60 dB nH stimulation level. For 40 Hz modulation frequency an increase of EEG-activity in the Delta-and Theta-band during periods of sleep correlates significantly with a decreased AMFR-amplitude whereas for 80 Hz no significant relation between stage of sleep and AMFR-amplitude could be found. The results suggest that in audiological use of 40 Hz-AMFR the state of vigilance should be monitored and stabilized at a high level.
authors.affiliation: Department of Experimental Audiology, Otto-von-Guericke-University, Magdeburg, Germany. joachim.pethe@medizin.uni-magdeburg.de
authors.forename: J
authors.initials: J
authors.lastname: Pethe
authors.forename: H
authors.initials: H
authors.lastname: Von Specht
authors.forename: R
authors.initials: R
authors.lastname: Mühler
authors.forename: T
authors.initials: T
authors.lastname: Hocke
mesh_terms: D000328:Adult; D004569:Electroencephalography; D006309:Hearing / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*