Estimated noise distributions across stages of consciousness utilizing the Fsp quantification technique.

We used the Fsp technique to quantify the influence of changing stages of consciousness on the signal-to-noise ratio of the middle latency response (MLR). The MLR and polysomnographic activity were obtained from 10 subjects during a continuous 6-hour period. The Fsp statistic was applied to the MLR data in order to determine the number of scores above a specified criterion in each stage of consciousness and time window of analysis. Results demonstrated that the number of Fsp scores exceeding the criterion of acceptance decreased with increasing depth of sleep. The awake stage yielded the greatest proportion of scores above the criterion. The background noise data were analyzed separately. The distributions of noise differed as a function of stage of consciousness.