Identification of vigilance lapses using EEG/EOG by expert human raters.

It is critically important for certain occupational groups to remain highly alert throughout their working day. For safety reasons, it would be useful to automatically detect lapses in performance using EEG/EOG. Automating the detection process could be simplified considerably if we could mimic human experts. Surprisingly, it is unclear to what extent human EEG raters are able to detect lapses. Consequently, we undertook a study in which 4 expert EEG raters assessed the level of alertness of 10 air traffic controllers by observing a combination of their EEG and EOG while they performed a 10 min psychomotor vigilance task (PVT). They were specifically required to identify lapses or sleep episodes that might lead to a lapse in PVT performance. A reaction time .. 500 ms was defined as a PVT lapse. There was a total of 101 lapses (mean duration = 1.00 s). Of these, only 6 lapses were detected by one or more raters and all of these were marked as ;sleep'. Overall the human expert raters were unable to reliably identify lapses based only on EEG and EOG. This poor performance suggests an automated system would need to identify subtle features not overtly visible in the EEG.

Fractal dimension of the EEG for detection of behavioural microsleeps.

The fractal dimension (FD) of EEG has been shown to be of value in the detection of epileptic seizures. In this paper, we assess its usefulness in detecting behavioural microsleeps. Fifteen non-sleep-deprived normal subjects performed two 1-hour sessions of a continuous tracking task while EEG, EOG and facial video were recorded. Higuchi's algorithm was used to calculate the FD of the EEG. Video lapses were scored independently from tracking performance by a human rater. A subset of data was rated independently by three human raters observing both tracking performance and the video rating to identify behavioural microsleep events. The mean point-biserial correlation between FD and the mean human rating was -0.213 indicating modest agreement. Crossvalidated detection performance of the FD was poor with a mean correlation (.. = -0.099). This suggests that, on its own, FD of the EEG is unlikely to be useful for detecting microsleeps.

Detecting behavioral microsleeps using EEG and LSTM recurrent neural networks.

Lapses in visuomotor performance are often associated with behavioral microsleep events. Experiencing a lapse of this type while performing an important task can have catastrophic consequences. A warning system capable of reliably detecting patterns in EEG occurring before or during a lapse has the potential to save many lives. We are developing a behavioral microsleep detection system which employs Long Short'Term Memory (LSTM) recurrent neural networks. To train and validate the system, EEG, facial video and tracking data were collected from 15 subjects performing a visuomotor tracking task for 2 1-hour sessions. This provided behavioral information on lapse events with good temporal resolution. We developed an automated behavior rating system and trained it to estimate the mean opinion of 3 human raters on the likelihood of a lapse. We then trained an LSTM neural network to estimate the output of the lapse rating system given only EEG spectral data. The detection system was designed to operate in real-time without calibration for individual subjects. Preliminary results show the system is not reliable enough for general use, but results from some tracking sessions encourage further investigation of the reported approach.

Eye movement desensitization and reprocessing (EMDR): a meta-analysis.

Eye movement desensitization and reprocessing (EMDR), a controversial treatment suggested for posttraumatic stress disorder (PTSD) and other conditions, was evaluated in a meta-analysis of 34 studies that examined EMDR with a variety of populations and measures. Process and outcome measures were examined separately. and EMDR showed an effect on both when compared with no treatment and with therapies not using exposure to anxiety-provoking stimuli and in pre post EMDR comparisons. However, no significant effect was found when EMDR was compared with other exposure techniques. No incremental effect of eye movements was noted when EMDR was compared with the same procedure without them. R. J. DeRubeis and P. Crits-Christoph (1998) noted that EMDR is a potentially effective treatment for noncombat PTSD. but studies that examined such patient groups did not give clear support to this. In sum, EMDR appears to be no more effective than other exposure techniques, and evidence suggests that the eye movements integral to the treatment, and to its name, are unnecessary.

Analysis of hyperamylasemia in patients with severe head injury.

To evaluate the influence of severe head injury (SHI) on amylase activity, we studied the amylase profile of 60 patients with SHIs and Glasgow Coma Scores less than 10. Fourteen additional multiple trauma patients without head injuries were studied as a control group. We excluded patients with pancreatic injury and abdominal trauma. Total serum amylase (TA), pancreatic isoamylase (PA), and nonpancreatic isoamylase (NPA) levels were measured on Days 0, 2, 4, 7, and 14 postinjury. Values greater than 2 SD above the normal mean were considered elevated. All SHI patients were comatose; 14 died. In the SHI group, TA increased in 23 patients, PA increased in 40, and NPA increased in 14. The source of hyperamylasemia was PA in 14, NPA in one, and mixed in 8 patients. While PA increases occurred throughout the study, NPA elevations occurred early. These increases did not correlate with shock (BP less than 80 mm Hg; 17 patients), facial trauma (24 patients), or associated injury (29 patients). On Day 7 postinjury, the mean TA (215 du%) and the mean PA (203.8 du%) were significantly elevated in the SHI patients compared to controls (122.1 du%, P less than 0.05, Wilcoxon's rank sum test). These data indicate that serum amylase is not a reliable index of pancreatic injury in patients with SHI. Severe head injury and multiple trauma activate pathways that increase amylase levels in the blood, suggesting a central nervous system regulation of serum amylase levels.

A systematic study of host defense processes in badly injured patients.

A prospective study of factors predisposing to infection in badly injured patients has disclosed: the dominant roles of two specific parameters: monocyte antigen presenting capacity, and opsonic capacity of diluted serum; the potential value of further assessment of: the predictive value of plots of activated T-cells/total T-cells versus monocyte antigen presenting capacity, the apparent protective effect of the ability to sharply increase specific IgM in response to infection, and the apparent protective effect of cytomegalovirus (CMV) infection in the first 28 days after injury against major bacterial infection; the lack of value of analysis of other T- and B-cell subsets in such patients; and the need to clarify CMV and transfusion status with respect to interpretation of such data. The specific role of variable transfusion and of specific serum immunoglobulins will require further and more discriminating study.