Limits...
An automated sleep-state classification algorithm for quantifying sleep timing and sleep-dependent dynamics of electroencephalographic and cerebral metabolic parameters.

Rempe MJ, Clegern WC, Wisor JP - Nat Sci Sleep (2015)

Bottom Line: Automated state scoring can minimize the burden associated with state and thereby facilitate the use of shorter epoch durations.Error associated with mathematical modeling of temporal dynamics of both EEG slow-wave activity and cerebral lactate either did not differ significantly when state scoring was done with automated versus visual scoring, or was reduced with automated state scoring relative to manual classification.Machine scoring is as effective as human scoring in detecting experimental effects in rodent sleep studies.

View Article: PubMed Central - PubMed

Affiliation: Mathematics and Computer Science, Whitworth University, Spokane, WA, USA ; College of Medical Sciences and Sleep and Performance Research Center, Washington State University, Spokane, WA, USA.

ABSTRACT

Introduction: Rodent sleep research uses electroencephalography (EEG) and electromyography (EMG) to determine the sleep state of an animal at any given time. EEG and EMG signals, typically sampled at >100 Hz, are segmented arbitrarily into epochs of equal duration (usually 2-10 seconds), and each epoch is scored as wake, slow-wave sleep (SWS), or rapid-eye-movement sleep (REMS), on the basis of visual inspection. Automated state scoring can minimize the burden associated with state and thereby facilitate the use of shorter epoch durations.

Methods: We developed a semiautomated state-scoring procedure that uses a combination of principal component analysis and naïve Bayes classification, with the EEG and EMG as inputs. We validated this algorithm against human-scored sleep-state scoring of data from C57BL/6J and BALB/CJ mice. We then applied a general homeostatic model to characterize the state-dependent dynamics of sleep slow-wave activity and cerebral glycolytic flux, measured as lactate concentration.

Results: More than 89% of epochs scored as wake or SWS by the human were scored as the same state by the machine, whether scoring in 2-second or 10-second epochs. The majority of epochs scored as REMS by the human were also scored as REMS by the machine. However, of epochs scored as REMS by the human, more than 10% were scored as SWS by the machine and 18 (10-second epochs) to 28% (2-second epochs) were scored as wake. These biases were not strain-specific, as strain differences in sleep-state timing relative to the light/dark cycle, EEG power spectral profiles, and the homeostatic dynamics of both slow waves and lactate were detected equally effectively with the automated method or the manual scoring method. Error associated with mathematical modeling of temporal dynamics of both EEG slow-wave activity and cerebral lactate either did not differ significantly when state scoring was done with automated versus visual scoring, or was reduced with automated state scoring relative to manual classification.

Conclusions: Machine scoring is as effective as human scoring in detecting experimental effects in rodent sleep studies. Automated scoring is an efficient alternative to visual inspection in studies of strain differences in sleep and the temporal dynamics of sleep-related physiological parameters.

No MeSH data available.


Related in: MedlinePlus

Sleep-state percentages in human-scored versus machine-scored 10-second epoch data.Notes: Data from the BA strain (left column) and the B6 strain (right column), were binned into 60-minute intervals. Graphs represent the percentage of each interval spent in wake (A and B), SWS (C and D), and REMS (E and F). Open circles represent machine-scored data and filled circles represent human-scored data. Dark and light phases are indicated by black and white bands at the top of each panel.Abbreviations: B6, C57BL/6J mice; BA, BALB/CJ mice; REMS, rapid-eye-movement sleep; SWS, slow-wave sleep.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4562753&req=5

f4-nss-7-085: Sleep-state percentages in human-scored versus machine-scored 10-second epoch data.Notes: Data from the BA strain (left column) and the B6 strain (right column), were binned into 60-minute intervals. Graphs represent the percentage of each interval spent in wake (A and B), SWS (C and D), and REMS (E and F). Open circles represent machine-scored data and filled circles represent human-scored data. Dark and light phases are indicated by black and white bands at the top of each panel.Abbreviations: B6, C57BL/6J mice; BA, BALB/CJ mice; REMS, rapid-eye-movement sleep; SWS, slow-wave sleep.

Mentions: When data were processed in 10-second epochs, the scoring algorithm scored more epochs as SWS than did human scoring (Table 2; F1,20=37.6; P<0.001; main effect of scoring method), at the expense of both REMS (F1,20=54.0; P<0.001; main effect of scoring method) and wake (F1,20=40.0; P<0.001; main effect of scoring method). The absence of a significant time × scoring method interaction (F23,920=1, P>0.05) for any of the three states indicates that there was not a time-of-day–specific bias in the disagreement between scoring methods. Of epochs scored as wake by a human, 10% in BA and 10% in B6 were not scored as wake by machine. The human versus machine scoring discrepancy resulted in a 5% (B6 mice) to 7% (BA mice) reduction in total wake time over 24 hours with machine scoring relative to human scoring (Figure 4A and B; main effect of scoring method, F1,20=40.0; P<0.001). Of epochs scored as REMS by a human, 33% in BA and 25% in B6 were not scored as REMS by machine. Consequently, the number of epochs scored as REMS over 24 hours was reduced by 13% (BA mice) to 14% (B6 mice; Figure 4E and F; main effect of scoring method, F1,20=37.6; P<0.001). Epochs scored as either of the two desynchronized states by human scoring were more likely to be scored as SWS by machine. Thus, the number of epochs scored as SWS by machine exceeded that of human scoring by 10% in BA and 13% in B6 (Figure 4C and D; main effect of scoring method, F1,20=54.0; P<0.001). Bias in the machine scoring was not strain-specific, as strain × scoring method interaction was not significant for any of the three states (F1,20=1.6; P>0.2).


An automated sleep-state classification algorithm for quantifying sleep timing and sleep-dependent dynamics of electroencephalographic and cerebral metabolic parameters.

Rempe MJ, Clegern WC, Wisor JP - Nat Sci Sleep (2015)

Sleep-state percentages in human-scored versus machine-scored 10-second epoch data.Notes: Data from the BA strain (left column) and the B6 strain (right column), were binned into 60-minute intervals. Graphs represent the percentage of each interval spent in wake (A and B), SWS (C and D), and REMS (E and F). Open circles represent machine-scored data and filled circles represent human-scored data. Dark and light phases are indicated by black and white bands at the top of each panel.Abbreviations: B6, C57BL/6J mice; BA, BALB/CJ mice; REMS, rapid-eye-movement sleep; SWS, slow-wave sleep.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562753&req=5

f4-nss-7-085: Sleep-state percentages in human-scored versus machine-scored 10-second epoch data.Notes: Data from the BA strain (left column) and the B6 strain (right column), were binned into 60-minute intervals. Graphs represent the percentage of each interval spent in wake (A and B), SWS (C and D), and REMS (E and F). Open circles represent machine-scored data and filled circles represent human-scored data. Dark and light phases are indicated by black and white bands at the top of each panel.Abbreviations: B6, C57BL/6J mice; BA, BALB/CJ mice; REMS, rapid-eye-movement sleep; SWS, slow-wave sleep.
Mentions: When data were processed in 10-second epochs, the scoring algorithm scored more epochs as SWS than did human scoring (Table 2; F1,20=37.6; P<0.001; main effect of scoring method), at the expense of both REMS (F1,20=54.0; P<0.001; main effect of scoring method) and wake (F1,20=40.0; P<0.001; main effect of scoring method). The absence of a significant time × scoring method interaction (F23,920=1, P>0.05) for any of the three states indicates that there was not a time-of-day–specific bias in the disagreement between scoring methods. Of epochs scored as wake by a human, 10% in BA and 10% in B6 were not scored as wake by machine. The human versus machine scoring discrepancy resulted in a 5% (B6 mice) to 7% (BA mice) reduction in total wake time over 24 hours with machine scoring relative to human scoring (Figure 4A and B; main effect of scoring method, F1,20=40.0; P<0.001). Of epochs scored as REMS by a human, 33% in BA and 25% in B6 were not scored as REMS by machine. Consequently, the number of epochs scored as REMS over 24 hours was reduced by 13% (BA mice) to 14% (B6 mice; Figure 4E and F; main effect of scoring method, F1,20=37.6; P<0.001). Epochs scored as either of the two desynchronized states by human scoring were more likely to be scored as SWS by machine. Thus, the number of epochs scored as SWS by machine exceeded that of human scoring by 10% in BA and 13% in B6 (Figure 4C and D; main effect of scoring method, F1,20=54.0; P<0.001). Bias in the machine scoring was not strain-specific, as strain × scoring method interaction was not significant for any of the three states (F1,20=1.6; P>0.2).

Bottom Line: Automated state scoring can minimize the burden associated with state and thereby facilitate the use of shorter epoch durations.Error associated with mathematical modeling of temporal dynamics of both EEG slow-wave activity and cerebral lactate either did not differ significantly when state scoring was done with automated versus visual scoring, or was reduced with automated state scoring relative to manual classification.Machine scoring is as effective as human scoring in detecting experimental effects in rodent sleep studies.

View Article: PubMed Central - PubMed

Affiliation: Mathematics and Computer Science, Whitworth University, Spokane, WA, USA ; College of Medical Sciences and Sleep and Performance Research Center, Washington State University, Spokane, WA, USA.

ABSTRACT

Introduction: Rodent sleep research uses electroencephalography (EEG) and electromyography (EMG) to determine the sleep state of an animal at any given time. EEG and EMG signals, typically sampled at >100 Hz, are segmented arbitrarily into epochs of equal duration (usually 2-10 seconds), and each epoch is scored as wake, slow-wave sleep (SWS), or rapid-eye-movement sleep (REMS), on the basis of visual inspection. Automated state scoring can minimize the burden associated with state and thereby facilitate the use of shorter epoch durations.

Methods: We developed a semiautomated state-scoring procedure that uses a combination of principal component analysis and naïve Bayes classification, with the EEG and EMG as inputs. We validated this algorithm against human-scored sleep-state scoring of data from C57BL/6J and BALB/CJ mice. We then applied a general homeostatic model to characterize the state-dependent dynamics of sleep slow-wave activity and cerebral glycolytic flux, measured as lactate concentration.

Results: More than 89% of epochs scored as wake or SWS by the human were scored as the same state by the machine, whether scoring in 2-second or 10-second epochs. The majority of epochs scored as REMS by the human were also scored as REMS by the machine. However, of epochs scored as REMS by the human, more than 10% were scored as SWS by the machine and 18 (10-second epochs) to 28% (2-second epochs) were scored as wake. These biases were not strain-specific, as strain differences in sleep-state timing relative to the light/dark cycle, EEG power spectral profiles, and the homeostatic dynamics of both slow waves and lactate were detected equally effectively with the automated method or the manual scoring method. Error associated with mathematical modeling of temporal dynamics of both EEG slow-wave activity and cerebral lactate either did not differ significantly when state scoring was done with automated versus visual scoring, or was reduced with automated state scoring relative to manual classification.

Conclusions: Machine scoring is as effective as human scoring in detecting experimental effects in rodent sleep studies. Automated scoring is an efficient alternative to visual inspection in studies of strain differences in sleep and the temporal dynamics of sleep-related physiological parameters.

No MeSH data available.


Related in: MedlinePlus