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Processing of acoustic stimuli during NREM sleep: Results from a simultaneous fMRI and EEG study
Using the novel approach of combining fMRI and EEG in sleep (1,2), the objective of the present study was to explore regional activation patterns upon different kinds of acoustic stimulation in NREM sleep. Eleven subjects (mean age 23.8 years) participated in the study following sleep deprivation. FMRI sessions were performed on a 1.5 T scanner while continuously presenting scanner noise via headphones. Four different stimuli were presented in a block design. Simultaneous polysomnographic recordings were assessed using an MR compatible device. Visual on- and off-line analysis showed that 8 subjects reached stage 2 sleep. BOLD signal increases in the auditory cortex were abolished or markedly reduced. In contrast, a negative BOLD response in sleep stage 2 was observed in various cortical brain regions. The data revealed negative BOLD signal responses within sensory and non sensory cortical areas in nonREM sleep independent of the type of acoustic stimulation.
1. Portas CM et al. Auditory processing across the sleep-wake cycle: simultaneous EEG and fMRI monitoring in humans. Neuron 28 (2000) 991–999
2. Czisch M. et al. Altered processing of acoustic stimuli during sleep: reduced auditory activation and visual deactivation detected by a combined fMRI/EEG study. NeuroImage 16 (2002) 251–258