Detection of lapses in responsiveness from the EEG.

A system capable of reliably detecting lapses in responsiveness ('lapses') has the potential to increase safety in many occupations. We have developed an approach for detecting the state of lapsing with second-scale temporal resolution using data from 15 subjects performing a one-dimensional (1D) visuomotor tracking task for two 1 h sessions while their electroencephalogram (EEG), facial video, and tracking performances were recorded. Lapses identified using a combination of facial video and tracking behaviour were used to train the classification models. Linear discriminant analysis was used to form detection models based on individual subject data and stacked generalization was utilized to combine the outputs of multiple classifiers to obtain the final prediction. The performance of detectors estimating the lapse/not-lapse state at 1 Hz based on power spectral features, approximate entropy, fractal dimension, and Lempel-Ziv complexity of the EEG was compared. Best lapse state estimation performance was achieved using the detector model created using power spectral features with an area under the curve from receiver operating characteristic analysis of 0.86 ± 0.03 (mean±SE) and an area under the precision-recall curve of 0.43 ± 0.09. A novel technique was developed to provide improved estimation of accuracy of detection of variable-duration events. Via this approach, we were able to show that the detection of lapse events from spectral power features was of moderate accuracy (sensitivity = 73.5%, selectivity = 25.5%).

Automated video-based measurement of eye closure for detecting behavioral microsleep.

A device capable of continuously monitoring an individual's levels of alertness in real-time is highly desirable for preventing drowsiness and microsleep related accidents. This paper presents a development of non-intrusive and light-insensitive video-based system that uses computer-vision methods to measure facial metric for identifying visible facial signs of drowsiness and behavioral microsleep. The developed system uses a remotely placed camera with a near-infrared illumination to acquire the video. The computer-vision methods are then applied to sequentially localize face, eyes, and eyelids positions to measure ratio of eye closure. The system was evaluated in frontal images of nine subjects with varying facial structures and exhibiting several ratio of eye closure and eye gaze under fully dark and ambient lighting conditions. The preliminary results showed promising results with sufficient accuracy to distinguish between fully closed, half closed, and fully open eyes.

Lapses of responsiveness: Characteristics, detection, and underlying mechanisms.

Lapses in responsiveness ('lapses'), particularly microsleeps and attention lapses, are complete disruptions in performance from approximately 0.5-15 s. They are of particular importance in the transport sector in which there is a need to maintain sustained attention for extended periods and in which lapses can lead to multiple-fatality accidents.

Measurement of BOLD changes due to cued eye-closure and stopping during a continuous visuomotor task via model-based and model-free approaches.

As a precursor for investigation of changes in neural activity underlying lapses of responsiveness, we set up a system to simultaneously record functional magnetic resonance imaging (fMRI), eye-video, EOG, and continuous visuomotor response inside an MRI scanner. The BOLD fMRI signal was acquired during a novel 2-D tracking task in which participants (10 males, 10 females) were cued to either briefly stop tracking and close their eyes (Stop +Close) or to briefly stop tracking (Stop) only. The onset and duration of eye-closure and stopping were identified post hoc from eye-video, EOG, and visuomotor response. fMRI data were analyzed using a general linear model (GLM) and tensorial independent component analysis (TICA). The GLM-based analysis identified predominantly increased blood oxygenation level dependent (BOLD) activity during eye-closure and stopping in multisensory areas, sensory-motor integration areas, and default-mode regions. Stopping during tracking elicited increased activity in visual processing areas, sensory-motor integration areas, and premotor areas. TICA separated the spatio-temporal pattern of activity into multiple task-related networks including the 1) occipito-medial frontal eye-movement network, 2) sensory areas, 3) left-lateralized visuomotor network, and 4) fronto-parietal visuomotor network, which were modulated differently by Stop +Close and Stop. The results demonstrate the merits of using simultaneous fMRI, behavioral, and physiological recordings to investigate the mechanisms underlying complex human behaviors in the human brain. Furthermore, knowledge of widespread modulations in brain activity due to voluntary eye-closure or stopping during a continuous visuomotor task is important for studies of the brain mechanisms underlying involuntary behaviors, such as microsleeps and attention lapses, which are often accompanied by brief eye-closure and/or response failures.

Chronic pain assessment: a seven-factor model.

BACKGROUND: There are many measures assessing related dimensions of the chronic pain experience (eg, pain severity, pain coping, depression, activity level), but the relationships among them have not been systematically established. OBJECTIVE: The present study set out to determine the core dimensions requiring assessment in individuals with chronic pain. METHODS: Individuals with chronic pain (n=126) completed the Beck Anxiety Inventory, Beck Depression Inventory, Beck Hopelessness Scale, Chronic Pain Coping Index, Multidimensional Pain Inventory, Pain Catastrophizing Scale, McGill Pain Questionnaire--Short Form, Pain Disability Index and the Tampa Scale of Kinesiophobia. RESULTS: Before an exploratory factor analysis (EFA) of the nine chronic pain measures, EFAs were conducted on each of the individual measures, and the derived factors (subscales) from each measure were submitted together for a single EFA. A seven-factor model best fit the data, representing the core factors of pain and disability, pain description, affective distress, support, positive coping strategies, negative coping strategies and activity. CONCLUSIONS: Seven meaningful dimensions of the pain experience were reliably and systematically extracted. Implications and future directions for this work are discussed.

Design of a modular and low-latency virtual-environment platform for applications in motor adaptation research, neurological disorders, and neurorehabilitation.

We have developed a modular virtual environment platform for movement research and rehabilitation. The system uses several networked computers running Linux to share computation. An electromagnetic tracker is the primary position tracker and both a head-mounted display and stereo goggles are used for visual display. System software is written in a combination of C++, JAVA, and Python and makes considerable use of the open-source toolkits VR Juggler and OpenSceneGraph. These are integrated with additional toolkits and custom modules written specifically for the study of motor control and rehabilitation. The system performs well with low latency, accurate calibration, and a consistently high graphics update rate. Preliminary applications have confirmed that the system is a powerful tool for sensory-motor investigation and has considerable potential as a tool for neurorehabilitation. Its primary advantage over other systems is its ability to utilize different display and input devices, and run a range of experiments simply by changing XML configuration files. Additionally, the use of powerful open-source libraries provides a feature-rich foundation for advanced features and low-cost duplication. Further work and experiments are needed to extend, further validate, and fully utilize this platform.

Event-based detection of lapses of responsiveness.

EEG spectral power has been shown to correlate with level of arousal and alertness in humans. In this paper, we assess its usefulness in the detection of lapses of responsiveness ('lapses') on an event, rather than state, basis. Eight non-sleep-deprived normal subjects performed two 1-hour sessions of a continuous tracking task while EEG and facial video were recorded. Lapses were identified by the presence of tracking flat spots or clear instances of behavioural microsleeps as identified by a human rater observing video recordings of the subject. Spectral power in the standard EEG bands was calculated using the Burg method on 16 bipolar derivations to form an EEG feature matrix. Linear discriminant analysis was used to form a classifier for each subject. The 8 classifiers were combined using stacked generalization with constrained-least squares fitting to create an overall detection model. Estimation of lapse-event detection performance required the development of a novel procedure to account for the variable duration of lapses. Event detection for the concatenated data from all 8 subjects yielded an overall sensitivity of 73.5%, selectivity of 25.5%, and accuracy of 61.2%. While the performance of this detector is modest, and not yet sufficient for real-time detection, the detection of lapses at such a high temporal resolution (1 s) is encouraging relative to previous studies which have generally tended to estimate changes in alertness on a minute-scale basis.

Functional-MRI correlates of cued slow-eye-closure and task non-responsiveness during visuomotor tracking.

Slow-eye-closure and task non-responsiveness are important behavioural markers of microsleeps. This paper presents preliminary results on the neural correlates of voluntary slow-eye-closure and voluntary non-responsiveness during performance of a continuous visuomotor tracking task. Functional-MRI (fMRI), EEG, eye video, and tracking responses were recorded from 5 normal subjects while they performed a continuous visuomotor tracking task inside an MRI scanner for 10 min. During this time, they were cued to simultaneously stop tracking and slowly close their eyes or stop tracking without eye-closure several times. Analysis of fMRI data revealed several regions involved in cued slow-eye-closure and cued task non-responsiveness, including occipito-parietal visual regions, midline default mode regions, and fronto-parietal attention regions. These results will be of considerable value in the interpretation of changes in BOLD activation and EEG activity associated with behavioural microsleeps.

EEG-based lapse detection with high temporal resolution.

A warning system capable of reliably detecting lapses in responsiveness (lapses) has the potential to prevent many fatal accidents. We have developed a system capable of detecting lapses in real-time with second-scale temporal resolution. Data was from 15 subjects performing a visuomotor tracking task for two 1-hour sessions with concurrent electroencephalogram (EEG) and facial video recordings. The detector uses a neural network with normalized EEG log-power spectrum inputs from two bipolar EEG derivations, though we also considered a multichannel detector. Lapses, identified using a combination of video rating and tracking behavior, were used to train our detector. We compared detectors employing tapped delay-line linear perceptron, tapped delay-line multilayer perceptron (TDL-MLP), and long short-term memory (LSTM) recurrent neural networks operating continuously at 1 Hz. Using estimates of EEG log-power spectra from up to 4 s prior to a lapse improved detection compared with only using the most recent estimate. We report the first application of a LSTM to an EEG analysis problem. LSTM performance was equivalent to the best TDL-MLP network but did not require an input buffer. Overall performance was satisfactory with area under the curve from receiver operating characteristic analysis of 0.84 +/- 0.02 (mean +/- SE) and area under the precision-recall curve of 0.41 +/- 0.08.

Frequent lapses of responsiveness during an extended visuomotor tracking task in non-sleep-deprived subjects.

We investigated the occurrence of lapses of responsiveness (lapses) in 15 non-sleep-deprived subjects performing a 1D continuous tracking task during normal working hours. Tracking behaviour, facial video, and electroencephalogram (EEG) were recorded simultaneously during two 1-h sessions. Rate and duration were estimated for lapses identified by a tracking flat spot and/or video sleep. Fourteen of the 15 subjects had one or more lapses, with an overall rate of 39.3 +/- 12.9 lapses per hour (mean +/- SE) and a lapse duration of 3.4 +/- 0.5 s. We also found that subjects' performance improved towards the end of the 1-h long session, even though no external temporal cues were available. Spectral power was found to be higher during lapses in the delta, theta, and alpha bands, and lower in the beta, gamma, and higher bands, but correlations between changes in EEG power and lapses were low. In conclusion, lapses are a frequent phenomenon in normal subjects - even when not sleep-deprived - engaged in an extended monotonous continuous visuomotor task. This is of particular importance to the transport sector in which there is a need to maintain sustained attention for extended periods of time and in which lapses can lead to multiple-fatality accidents.

Canadian psychiatry residency training programs: A glance at the management structure.

OBJECTIVES: To describe the administrative functioning of all current Canadian psychiatry residency training programs (RTPs) and to suggest available improvements to existing systems. METHOD: We obtained data about the 2004 RTPs by distributing 2 questionnaires to all Canadian psychiatry RTPs. RESULTS: Residency program committees (RPCs) are mainly consultative and carry only a small amount of the workload of managing a residency program. Program directors (PDs) manage more than 80% of the work and report that the time allowance to perform their duties is suboptimal. PDs remain in office for about 5 years, departing during or at the end of a predetermined second term. CONCLUSION: RPCs bear only a small amount of the workload generated by the RTP. We piloted administrative changes that led to more equitable work distribution.

Detecting behavioral microsleeps from EEG power spectra.

EEG spectral power has been shown to correlate with level of arousal and alertness in humans. In this paper, we assess its usefulness in the detection of behavioral microsleeps (BMs). Eight non-sleep-deprived normal subjects performed two 1-hour sessions of a continuous tracking task while EEG and facial video were recorded. BMs were identified independent of tracking performance by a human rater by viewing the video recordings. Spectral power, normalized spectral power, and power ratios in the standard EEG bands were calculated using the Burg method on 16 bipolar derivations to form an EEG feature matrix. PCA was used to reduce the dimensionality of the feature matrix and linear discriminant analysis used to form a classifier for each subject. The 8 classifiers were combined using stacked generalization to create an overall detection model and N-fold cross-validation used to determine its performance (Phi=0.30 +/- 0.05, mean +/- SE). While modest, the detection of BMs at such a high temporal resolution (1 s) has not been achieved previously other than by our group.

Widespread access to predictive models in the motor system: a short review.

Recent behavioural and computational studies suggest that access to internal predictive models of arm and object dynamics is widespread in the sensorimotor system. Several systems, including those responsible for oculomotor and skeletomotor control, perceptual processing, postural control and mental imagery, are able to access predictions of the motion of the arm. A capacity to make and use predictions of object dynamics is similarly widespread. Here, we review recent studies looking at the predictive capacity of the central nervous system which reveal pervasive access to forward models of the environment.

Common encoding of novel dynamic loads applied to the hand and arm.

In manual action, the relationship between a given motor command and the ensuing movement depends on the dynamics of both the arm and hand-held objects. Skilled performance relies on the brain learning both these dynamics, and previous studies have examined how people adapt to novel loads applied to either the hand or the arm. In this study, we ask whether these different kinds of load are represented independently as a result of changes in cutaneous feedback and hand-arm coordination. We used a robotic apparatus that could either apply forces to an object held in the subject's hand or directly to the segments of the arm. We tested whether subjects could retain learning of a force field applied to the hand after subsequently experiencing the opposing field applied to the arm (or vice versa), or whether retrograde interference would be observed. In separate experiments, we used force fields and torque fields that were linearly related to either hand or joint velocities, respectively. Our finding of complete interference between opposing fields suggests that loads applied to the arm and hand are not represented independently by the sensorimotor system. This interference occurred despite markedly different cutaneous inputs that were directly related to the movement task. This result suggests that the brain represents dynamics independently of these sensory inputs. In addition, we found that the rate at which subjects adapted to a given force field, specified either in hand or joint coordinates, was independent of whether the forces were applied to the hand or arm segments.

Administrative restructuring of a residency training program for improved efficiency and output.

OBJECTIVES: Canadian residency training programs (RTP) have a program director (PD) and a residency program committee (RPC) overseeing program administration. Limited guidance is available about the ideal administrative structure of an RTP. This article describes administrative load in Canadian RTPs, presents a novel approach to delegating core administrative tasks within the RTP, and provides initial impressions of positive outcomes following implementation of this new system. METHOD: All PDs of Canadian psychiatry RTPs were surveyed with respect to their program administrative structure, involvement of their training committees, and the percentage of work done by the PD compared to the rest of the RPC. At Queen's University, program domains were created representing well-defined areas within the RTP, each being assigned a program domain manager. RESULTS: RPCs were mainly consultative, averaging 14 members. The average PD: RPC workload ratio was 80:20. Three programs allowed for 50% of the program director's time to be dedicated to serving that position, with an average time dedication of 37%. CONCLUSION: The position of PD in psychiatry requires an average of 37% of the program director's time, while carrying an estimated 82% of the administrative workload. The program domain manager administration system implemented at Queen's University enabled the PD to be simultaneously up to date with all major areas of the program while experiencing a substantial decrease in the administrative workload, achieved through increased work contribution of the RPC. This system encourages closer involvement of RPC members in decision making and development of their program domains, allowing the PD more time for developing, implementing and overseeing innovations across the RTP spectrum. Furthermore, it has led to a PD: RPC workload shift from a ratio of 90:10 to one of about 60:40. Essentially, this resulted in a more efficient and adaptable RPC and RTP.

Scaling down motor memories: de-adaptation after motor learning.

Although adaptation to novel motor tasks is sometimes a very slow process, de-adaptation is usually extremely rapid. Such rapid de-adaptation is seen in dynamic learning in which subjects can take hundreds of movements to learn a novel force environment but only a few movements to de-adapt back to a normal or "null" force environment. We investigated whether this effect is unique to the null environment or reveals a more general rapid adaptation mechanism by studying how subjects behave when their dynamic environment changes. We observed that after learning a dynamic force field, subjects took longer to de-adapt when the forces were turned off than to adapt to a novel scaled-down version of the experienced field. This demonstrates that rapid adaptation is not unique to the "null" force environment. Moreover, we examined subjects' ability to adapt from a learned field to either a scaled down field or to a field in which the sign of the forces changed. Even though in both conditions the required change in force output was identical, subjects were significantly faster at adapting to the scaled down field. The result suggests that rapid de-adaptation reflects a capacity to scale down the relative contribution of existing control modules to the motor output.

Internal models underlying grasp can be additively combined.

Our ability to additively combine two learned internal models was investigated by studying the forces people generate when lifting objects with a precision grip. Subjects were required to alternately lift two objects of identical physical appearance but differing weight. Grip force scaling prior to lift-off was used to estimate the output of the internal model associated with each object. Appropriate internal models were formed when alternately lifting two objects of different weight. The objects were then combined by stacking them one upon the other, and the combined object was lifted. Results show that subjects can additively combine internal models of object dynamics but the sum is biased by a default estimate of the object's weight.

Delirium in hospital: an underreported event at discharge.

OBJECTIVE: Delirium, an important event in hospital, is associated with significant mortality and morbidity. Most patients with delirium recover fully; however, when left untreated, delirium may progress to stupor, coma, or death. Delirium is less likely to resolve completely in elderly patients in whom persistent cognitive deficits commonly occur. The extent to which this information is available to family doctors after discharge was investigated. METHOD: A total of 31 patients with delirium who were referred to consultation-liaison psychiatry were assessed using standardized measures. Medical services completed discharge summaries on these patients; a chart review captured the extent to which the diagnosis of delirium and the involvement of psychiatry was recorded in the discharge summaries. RESULTS: In structured discharge summaries, a reference to delirium occurrence was found in 55% of cases. In unstructured discharge summaries, the reporting was much lower (16% of cases). Delirium was more likely to be reported in women than in men, when it was more severe, or when it was the principal reason for admission, rather than when it occurred during an admission for some other reason. CONCLUSIONS: Delirium episodes that occur during a period of hospitalization for treatment of any medical disorder are underreported, even when specifically diagnosed. Structured discharge summaries tend to increase the rate of reporting.

Motor learning and prediction in a variable environment.

Traditional studies of motor learning and prediction have focused on how subjects perform a single task. Recent advances have been made in our understanding of motor learning and prediction by investigating the way we learn variable tasks, which change either predictably or unpredictably over time. Similarly, studies have examined how variability in our own movements affects motor learning.

Simulating closed- and open-loop voluntary movement: a nonlinear control-systems approach.

In many recent human motor control models, including feedback-error learning and adaptive model theory (AMT), feedback control is used to correct errors while an inverse model is simultaneously tuned to provide accurate feedforward control. This popular and appealing hypothesis, based on a combination of psychophysical observations and engineering considerations, predicts that once the tuning of the inverse model is complete the role of feedback control is limited to the correction of disturbances. This hypothesis was tested by looking at the open-loop behavior of the human motor system during adaptation. An experiment was carried out involving 20 normal adult subjects who learned a novel visuomotor relationship on a pursuit tracking task with a steering wheel for input. During learning, the response cursor was periodically blanked, removing all feedback about the external system (i.e., about the relationship between hand motion and response cursor motion). Open-loop behavior was not consistent with a progressive transfer from closed- to open-loop control. Our recently developed computational model of the brain--a novel nonlinear implementation of AMT--was able to reproduce the observed closed- and open-loop results. In contrast, other control-systems models exhibited only minimal feedback control following adaptation, leading to incorrect open-loop behavior. This is because our model continues to use feedback to control slow movements after adaptation is complete. This behavior enhances the internal stability of the inverse model. In summary, our computational model is currently the only motor control model able to accurately simulate the closed- and open-loop characteristics of the experimental response trajectories.