On the relationship between head circumference, brain size, prenatal long-chain PUFA/5-methyltetrahydrofolate supplementation and cognitive abilities during childhood.

Head circumference in infants has been reported to predict brain size, total grey matter volume (GMV) and neurocognitive development. However, it is unknown whether it has predictive value on regional and subcortical brain volumes. We aimed to explore the relationship between several head circumference measurements since birth and distributions of GMV and subcortical volumes at later childhood. We examined seventy-four, Caucasian, singleton, term-born infants born to mothers randomised to receive fish oil and/or 5-methyltetrahydrofolate or placebo prenatal supplementation. We assessed head circumference at birth and at 4 and 10 years of age and cognitive abilities at 7 years of age. We obtained brain MRI at 10 years of age, on which we performed voxel-based morphometry, cortical surface extraction and subcortical segmentation. Analyses were controlled for sex, age, height, weight, family status, laterality and total intracranial volume. Prenatal supplementation did not affect head circumference at any age, cognitive abilities or total brain volumes. Head circumference at 4 years presented the highest correlation with total GMV, white matter volume and brain surface area, and was also strongly associated with GMV of frontal, temporal and occipital areas, as well as with caudate nucleus, globus pallidus, putamen and thalamus volumes. As relationships between brain volumes in childhood and several outcomes extend into adulthood, we have found that ages between 0 and 4 years as the optimal time for brain growth; postnatal factors might have the most relevant impact on structural maturation of certain cortical areas and subcortical nuclei, independent of prenatal supplementation.

Intraocular pressure increases after complex simulated surgical procedures in residents: an experimental study.

BACKGROUND: Surgeons' overload is one of the main causes of medical errors that might compromise patient safety. Due to the drawbacks of current options to monitor surgeons' load, new, sensitive, and objective indices of task (over)load need to be considered and tested. In non-health-care scenarios, intraocular pressure (IOP) has been proved to be an unbiased physiological index, sensitive to task complexity (one of the main variables related to overload), and time on task. In the present study, we assessed the effects of demanding and complex simulated surgical procedures on surgical and medical residents' IOP. METHODS: Thirty-four surgical and medical residents and healthcare professionals took part in this study (the experimental group, N = 17, and the control group, N = 17, were matched for sex and age). The experimental group performed two simulated bronchoscopy procedures that differ in their levels of complexity. The control group mimicked the same hand-eye movements and posture of the experimental group to help control for the potential effects of time on task and re-measurement on IOP. We measured IOP before and after each procedure, surgical performance during procedures, and perceived task complexity. RESULTS: IOP increased as consequence of performing the most complex procedure only in the experimental group. Consistently, residents performed worse and reported higher perceived task complexity for the more complex procedure. CONCLUSIONS: Our data show, for the first time, that IOP is sensitive to residents' task load, and it could be used as a new index to easily and rapidly assess task (over)load in healthcare scenarios. An arousal-based explanation is given to describe IOP variations due to task complexity.

Validation of Electroencephalographic Recordings Obtained with a Consumer-Grade, Single Dry Electrode, Low-Cost Device: A Comparative Study.

The functional validity of the signal obtained with low-cost electroencephalography (EEG) devices is still under debate. Here, we have conducted an in-depth comparison of the EEG-recordings obtained with a medical-grade golden-cup electrodes ambulatory device, the SOMNOwatch + EEG-6, vs those obtained with a consumer-grade, single dry electrode low-cost device, the NeuroSky MindWave, one of the most affordable devices currently available. We recorded EEG signals at Fp1 using the two different devices simultaneously on 21 participants who underwent two experimental phases: a 12-minute resting state task (alternating two cycles of closed/open eyes periods), followed by 60-minute virtual-driving task. We evaluated the EEG recording quality by comparing the similarity between the temporal data series, their spectra, their signal-to-noise ratio, the reliability of EEG measurements (comparing the closed eyes periods), as well as their blink detection rate. We found substantial agreement between signals: whereas, qualitatively, the NeuroSky MindWave presented higher levels of noise and a biphasic shape of blinks, the similarity metric indicated that signals from both recording devices were significantly correlated. While the NeuroSky MindWave was less reliable, both devices had a similar blink detection rate. Overall, the NeuroSky MindWave is noise-limited, but provides stable recordings even through long periods of time. Furthermore, its data would be of adequate quality compared to that of conventional wet electrode EEG devices, except for a potential calibration error and spectral differences at low frequencies.

Listening to Relaxing Music Improves Physiological Responses in Premature Infants: A Randomized Controlled Trial.

BACKGROUND: Premature infants are exposed to high levels of noise in the neonatal intensive care unit (NICU). PURPOSE: This study evaluated the effect of a relaxing music therapy intervention composed by artificial intelligence on respiratory rate, systolic and diastolic blood pressure, and heart rate. METHODS: A double-blind, randomized, controlled trial was conducted in the NICUs of 2 general public hospitals in Andalusia, Spain. Participants were 17 healthy premature infants, randomly allocated to the intervention group or the control group (silence) at a 1:1 ratio. To be included in the study, the subjects were to be 32 to 36 weeks of gestation at birth (M= 32.33; SD = 1.79) and passed a hearing screening test satisfactorily. The intervention lasted 20 minutes, 3 times a day for 3 consecutive days, while infants were in the incubator. Infants' heart rate, respiratory rate, and blood pressure were assessed before and after each intervention session. RESULTS: After each session, the respiratory rate decreased in the experimental group (main between-groups effect (F1,13 = 6.73, P = .022, ηpartial = 0.34). Across the sessions, the heart rate increased in the control group (main between-groups effect, F1,11 = 5.09, P = .045, ηpartial = 0.32). IMPLICATIONS FOR RESEARCH: Future studies can use this music intervention to assess its potential effects in premature infants. IMPLICATIONS FOR PRACTICE: Nurses can apply the relaxing music intervention presented in this study to ameliorate the impact of the stressful environment on premature infants.

A school-based physical activity promotion intervention in children: rationale and study protocol for the PREVIENE Project.

BACKGROUND: The lack of physical activity and increasing time spent in sedentary behaviours during childhood place importance on developing low cost, easy-toimplement school-based interventions to increase physical activity among children. The PREVIENE Project will evaluate the effectiveness of five innovative, simple, and feasible interventions (active commuting to/from school, active Physical Education lessons, active school recess, sleep health promotion, and an integrated program incorporating all 4 interventions) to improve physical activity, fitness, anthropometry, sleep health, academic achievement, and health-related quality of life in primary school children. METHODS: A total of 300 children (grade 3; 8-9 years of age) from six schools in Granada (Spain) will be enrolled in one of the 8-week interventions (one intervention per school; 50 children per school) or a control group (no intervention school; 50 children). Outcomes will include physical activity (measured by accelerometry), physical fitness (assessed using the ALPHA fitness battery), and anthropometry (height, weight and waist circumference). Furthermore, they will include sleep health (measured by accelerometers, a sleep diary, and sleep health questionnaires), academic achievement (grades from the official school's records), and health-related quality of life (child and parental questionnaires). To assess the effectiveness of the different interventions on objectively measured PA and the other outcomes, the generalized linear model will be used. DISCUSSION: The PREVIENE Project will provide the information about the effectiveness and implementation of different school-based interventions for physical activity promotion in primary school children.

Gaze entropy reflects surgical task load.

BACKGROUND: Task (over-)load imposed on surgeons is a main contributing factor to surgical errors. Recent research has shown that gaze metrics represent a valid and objective index to asses operator task load in non-surgical scenarios. Thus, gaze metrics have the potential to improve workplace safety by providing accurate measurements of task load variations. However, the direct relationship between gaze metrics and surgical task load has not been investigated yet. We studied the effects of surgical task complexity on the gaze metrics of surgical trainees. METHODS: We recorded the eye movements of 18 surgical residents, using a mobile eye tracker system, during the performance of three high-fidelity virtual simulations of laparoscopic exercises of increasing complexity level: Clip Applying exercise, Cutting Big exercise, and Translocation of Objects exercise. We also measured performance accuracy and subjective rating of complexity. RESULTS: Gaze entropy and velocity linearly increased with increased task complexity: Visual exploration pattern became less stereotyped (i.e., more random) and faster during the more complex exercises. Residents performed better the Clip Applying exercise and the Cutting Big exercise than the Translocation of Objects exercise and their perceived task complexity differed accordingly. CONCLUSIONS: Our data show that gaze metrics are a valid and reliable surgical task load index. These findings have potential impacts to improve patient safety by providing accurate measurements of surgeon task (over-)load and might provide future indices to assess residents' learning curves, independently of expensive virtual simulators or time-consuming expert evaluation.

Cognitive-behavioral therapy for insomnia and sleep hygiene in fibromyalgia: a randomized controlled trial.

Sleep disturbances play an important role in the exacerbation of pain and other troubling symptoms reported by patients with fibromyalgia (FM). The objective of this trial was to analyze the efficacy of a cognitive-behavioral therapy for insomnia (CBT-I) versus a sleep hygiene (SH) education program at improving sleep and other clinical manifestations in FM. Sixty-four FM women with insomnia were randomly assigned to the CBT-I or the SH groups, and 59 completed the treatments (30 in the CBT-I group and 29 in the SH group). Participants completed several self-report questionnaires at pre-, post-treatment and follow-ups. The CBT-I group reported significant improvements at post-treatment in several sleep variables, fatigue, daily functioning, pain catastrophizing, anxiety and depression. The SH group only improved significantly in subjective sleep quality. Patients in the CBT-I group showed significantly greater changes than those in the SH group in most outcome measures. The findings underscore the usefulness of CBT-I in the multidisciplinary management of FM.

Pulmonary rehabilitation improves sleep quality in chronic lung disease.

Sleep-related disorders are common in patients with chronic obstructive pulmonary disease (COPD) and, possibily, other lung disorders. Exercise has been shown to improve sleep disturbances. In patients with COPD, pulmonary rehabilitation (PR) produces important health benefits with improvement in symptoms, exercise tolerance, and quality of life. However, the effect of PR on sleep quality remains unknown. The aim of this observational study was to evaluate sleep quality in patients with chronic lung disease and the role of PR as a non-pharmacologic treatment to improve sleep. Sixty-four patients with chronic lung disease enrolled in an 8-week comprehensive PR program, and completed the study (48% male; obstructive [72%], restrictive [20%], mixed [8%]; 44% on supplemental oxygen). Baseline spirometry [mean (SD)]: FEV1% pred = 48.9 (17.4), FVC% pred = 72.5 (18.1), and FEV1/FVC% = 53.1 (18.9). Exercise tolerance and questionnaires related to symptoms, health-related quality of life (HRQL), and sleep quality using the Pittsburgh Sleep Quality Index (PSQI) were obtained before and after PR. 58% reported poor sleep quality (PSQI > 5) at baseline. Sleep quality improved by 19% (p = 0.017) after PR, along with significant improvements in dyspnea, exercise tolerance, self-efficacy, and HRQL. Sleep quality in patients with chronic lung disease was poor. In addition to expected improvements in symptoms, exercise tolerance, and HRQL after PR, the subgroup of patients with COPD had a significant improvement in sleep quality. These findings suggest that PR may be an effective, non-pharmacologic treatment option for sleep problems in patients with COPD.

Electrophysiological correlates of the reverse Stroop effect: Results from a simulated handgun task.

The color-word reverse Stroop (RS) effect still represents an interesting puzzle for cognitive researchers as an interference between incongruent ink colors and the meaning of the words is not always found. Here, we examined whether an unfamiliar and complex visuomotor task would produce a RS effect. Forty inexperienced shooters carried out a simulated shooting task. To test if the RS effect is related to the stimuli processing or to a late processing of the color (early and late time-windows), electroencephalographic global field power (GFP) variations were recorded with a high-impedance system (32 channels configuration in a standard monopolar montage, referenced to FCz and grounded to FPz). The color-word RS effect was reflected in the performance of 32 participants, suggesting that the strength of the association between the target and the specific response requested might be central to the RS interference. This behavioral result was paralleled by GFP modulations in 20 participants. A significant increase of the GFP for the congruent trials (e.g., the word "red" written in red ink) was recorded after stimulus presentation (conflict detection), followed by an increase for the incongruent trials (e.g., the word "red" written in green ink) just before the shooting (conflict resolution). Despite the limitations of the study, such as the inclusion of a low number of channels in the GFP analyses, the results suggest that the RS interference is easily elicited in tasks requiring an unfamiliar response, which supports the strength of association hypothesis. Moreover, as implied by the GFP modulations, the interference might occur early in time, but also in a later stage, closer to the response.

EEG Theta Power Activity Reflects Workload among Army Combat Drivers: An Experimental Study.

We aimed to evaluate the effects of mental workload variations, as a function of the road environment, on the brain activity of army drivers performing combat and non-combat scenarios in a light multirole vehicle dynamic simulator. Forty-one non-commissioned officers completed three standardized driving exercises with different terrain complexities (low, medium, and high) while we recorded their electroencephalographic (EEG) activity. We focused on variations in the theta EEG power spectrum, a well-known index of mental workload. We also assessed performance and subjective ratings of task load. The theta EEG power spectrum in the frontal, temporal, and occipital areas were higher during the most complex scenarios. Performance (number of engine stops) and subjective data supported these findings. Our findings strengthen previous results found in civilians on the relationship between driver mental workload and the theta EEG power spectrum. This suggests that EEG activity can give relevant insight into mental workload variations in an objective, unbiased fashion, even during real training and/or operations. The continuous monitoring of the warfighter not only allows instantaneous detection of over/underload but also might provide online feedback to the system (either automated equipment or the crew) to take countermeasures and prevent fatal errors.

A cross-cultural comparison of visual search strategies and response times in road hazard perception testing.

Road hazard perception is considered the most prominent higher-order cognitive skill related to traffic-accident involvement. Regional cultures and social rules that govern acceptable behavior may influence drivers' interpretation of a traffic situation and, consequently, the correct identification of potentially hazardous situations. Here, we aimed to compare hazard perception skills among four European countries that differ in their traffic culture, policies to reduce traffic risks, and fatal crashes: Ukraine, Italy, Spain, and Sweden. We developed a static hazard perception test in which driving scenes with different levels of braking affordance were presented while drivers' gaze was recorded. The test required drivers to indicate the action they would undertake: to brake vs. to keep driving. We assessed 218 young adult drivers. Multilevel models revealed that the scenes' levels of braking affordance (i.e., road hazard) modulated drivers' behavior. As the levels of braking affordance increased, drivers' responses became faster and their gaze entropy decreased (i.e., visual search strategy became less erratic). The country of origin influenced these effects. Ukrainian drivers were the fastest and Swedish drivers were the slowest to respond. For all countries, the decrement in response times was less marked in the case of experienced drivers. Also, Spanish drivers showed the most structured (least erratic) visual search strategy, whereas the Italians had the most rigid (most constant) one. These results suggest that road hazard perception can be defined cross-culturally, with cultural factors (e.g., traffic climate, legislation) modulating response times and visual search strategies. Our results also support the idea that a multimodal assessment methodology is possible for mass testing of road hazard perception and its outcomes would be relevant to understand how different traffic cultures shape driving behavior.

Nasal skin temperature reveals changes in arousal levels due to time on task: An experimental thermal infrared imaging study.

Infrared thermography, thanks to technological developments and lowering prices, is now getting considerable attention as a potential arousal monitor in the safety industry. Nasal skin temperature might be a valid index to track physiological variations due to reduced arousal levels, and its use could prevent a drowsiness-related deterioration of performance. However, the few studies that have investigated nasal skin temperature in applied settings have had inconsistent results. Here, we assessed the validity of nasal skin temperature to monitor changes in arousal levels (from alertness to drowsiness). The participants performed a 2-h simulated driving task while we simultaneously recorded their nasal skin temperature, brain activity (we used frontal delta electroencephalographic [EEG] activity as the reference index of alertness), and driving performance (speeding time). For those variables, we calculated growth curve models. We also collected subjective ratings of alertness and fatigue before and after the driving session. We found that the nasal skin temperature showed a cubic trajectory (it increased for the first 75 min, and then it began to decrease, but such deceleration gradually diminished over time). As expected, frontal delta EEG activity showed an inverted U-shaped quadratic trend (EEG power increased for the first hour and half, and gradually decreased during the last thirty minutes). The speeding time exhibited a similar pattern of change. Subjective sleepiness and fatigue increased after the task. Overall, our results suggest that nasal skin temperature seems to be a valid measure of arousal variations while performing a complex and dynamic everyday task.

Detecting Mental Workload in Surgical Teams Using a Wearable Single-Channel Electroencephalographic Device.

OBJECTIVE: To assess the sensitivity of an electroencephalographic (EEG)-based index, the prefrontal beta power, to quantify the mental workload in surgeons in real scenarios. Such EEG-based index might offer unique and unbiased measures of overload, a crucial factor when designing learning and training surgical programs. DESIGN: The experiment followed a 2 × 2 × 2 within subjects design with 3 factors: (1) Surgical Role during the surgery (primary surgeon vs. assistant surgeon), (2) the Surgical Procedure (laparo-endoscopic single-site [LESS] surgery vs. multiport laparoscopic surgery [MPS]), and (3) the Suturing Techniques (interrupted vs. continuous suture). SETTING: The study was carried out at the Advanced Multi-Purpose Simulation and Technological Innovation Complex situated at IAVANTE (Granada, Spain). METHODS: Four surgical teams (primary surgeon and assistant surgeon, experts in MPS) performed 8 surgical exercises on porcine models, under different task complexities. They performed 2 suturing techniques (continuous and interrupted), employing a low complex procedure (MPS) and a high complex procedure (LESS). Surgeons acted as the primary surgeon during half of the exercises, and, as the assistant surgeon, during the rest of them. Simultaneously, we monitored EEG prefrontal EEG beta power spectra of both surgeons, using 2 synchronized wearable EEG devices. We also collected performance and subjective data. RESULTS: Surgical complexity modulated prefrontal beta power. LESS surgery caused significant higher prefrontal beta power for both suturing techniques for both surgical roles which indicates higher demands than MPS. Perceived task complexity, overall surgical evaluation, and laparoscopic execution time confirmed EEG-based results. Finally, subjective ratings of surgical complexity differentiated between surgical roles within the same exercise, even when prefrontal beta power did not. CONCLUSIONS: To detect mental overload when surgeons are engaged with complex surgeries, real or simulated, is still guesswork. EEG-based indices have great potential as objective and nonintrusive measures to assess mental overload in surgeons. Furthermore, EEG-based indices might play a relevant role in monitoring surgeons and residents' cognitive state during their training.

The effects of flight complexity on gaze entropy: An experimental study with fighter pilots.

We studied the effects of task load variations as a function of flight complexity on combat pilots' gaze behavior (i.e., entropy) while solving in-flight emergencies. The second company of the Spanish Army Attack Helicopter Battalion (n = 15) performed three sets of standardized flight exercises with different levels of complexity (low [recognition flights], medium and high [emergency flights]). Throughout the flight exercises we recorded pilots' gaze entropy, as well as pilots' performance (assessed by an expert flight instructor) and subjective ratings of task load (assessed by the NASA-Task Load Index). Furthermore, we used pilots' electroencephalographic (EEG) activity as a reference physiological index for task load variations. We found that pilots' gaze entropy decreased ∼2% (i.e., visual scanning became less erratic) while solving the emergency flight exercises, showing a significant decreasing trend with increasing complexity (p < .05). This is in consonance with the ∼12% increase in the frontal theta band of their EEG spectra during said exercises. Pilots' errors and subjective ratings of task load increased as flight complexity increased (p-values < .05). Gaze data suggest that pilots used nondeterministic visual patterns when the aircraft was in an error-free state (low complexity), and changed their scanning behavior, becoming more deterministic, once emergencies occurred (medium/high complexity). Overall, our findings indicate that gaze entropy can serve as a sensitive index of task load in aviation settings.

Gaze-based Technology as a Tool for Surgical Skills Assessment and Training in Urology.

OBJECTIVE: To assess the sensitivity of gaze-based metrics in detecting cognitive demands imposed by surgical procedures. We analyzed urologists' gaze entropy and velocity while performing 2 standardized high-fidelity simulated stone procedures with different levels of complexity. METHODS: Using a wearable eye tracker device (mounted onto an eyeglass frame), we measured gaze entropy and velocity in 15 urologists, members of the Andalusian health-care system, while they performed an extraction of a stone in the bladder (low complexity) and an extraction of a stone in the lumbar ureter (high complexity). We also collected performance and subjective data. RESULTS: Gaze entropy and velocity were significantly higher when surgeons performed the most complex surgical procedure: the visual exploration pattern became less stereotyped (ie, more random) and faster. Surgeons' performance and perceived task complexity differed accordingly, confirming the gaze-based results. CONCLUSION: Gaze-based metrics might have great potential as objective and nonintrusive indices to assess surgeons' cognitive (over)load, potentially being a complementary assessment tool to quantify the learning curve for surgical procedures.

Quantifying the cognitive cost of laparo-endoscopic single-site surgeries: Gaze-based indices.

BACKGROUND: Despite the growing interest concerning the laparo-endoscopic single-site surgery (LESS) procedure, LESS presents multiple difficulties and challenges that are likely to increase the surgeon's cognitive cost, in terms of both cognitive load and performance. Nevertheless, there is currently no objective index capable of assessing the surgeon cognitive cost while performing LESS. We assessed if gaze-based indices might offer unique and unbiased measures to quantify LESS complexity and its cognitive cost. We expect that the assessment of surgeon's cognitive cost to improve patient safety by measuring fitness-for-duty and reducing surgeons overload. METHODS: Using a wearable eye tracker device, we measured gaze entropy and velocity of surgical trainees and attending surgeons during two surgical procedures (LESS vs. multiport laparoscopy surgery [MPS]). None of the participants had previous experience with LESS. They performed two exercises with different complexity levels (Low: Pattern Cut vs. High: Peg Transfer). We also collected performance and subjective data. RESULTS: LESS caused higher cognitive demand than MPS, as indicated by increased gaze entropy in both surgical trainees and attending surgeons (exploration pattern became more random). Furthermore, gaze velocity was higher (exploration pattern became more rapid) for the LESS procedure independently of the surgeon's expertise. Perceived task complexity and laparoscopic accuracy confirmed gaze-based results. CONCLUSION: Gaze-based indices have great potential as objective and non-intrusive measures to assess surgeons' cognitive cost and fitness-for-duty. Furthermore, gaze-based indices might play a relevant role in defining future guidelines on surgeons' examinations to mark their achievements during the entire training (e.g. analyzing surgical learning curves).

Monitoring driver fatigue using a single-channel electroencephalographic device: A validation study by gaze-based, driving performance, and subjective data.

Driver fatigue can impair performance as much as alcohol does. It is the most important road safety concern, causing thousands of accidents and fatalities every year. Thanks to technological developments, wearable, single-channel EEG devices are now getting considerable attention as fatigue monitors, as they could help drivers to assess their own levels of fatigue and, therefore, prevent the deterioration of performance. However, the few studies that have used single-channel EEG devices to investigate the physiological effects of driver fatigue have had inconsistent results, and the question of whether we can monitor driver fatigue reliably with these EEG devices remains open. Here, we assessed the validity of a single-channel EEG device (TGAM-based chip) to monitor changes in mental state (from alertness to fatigue). Fifteen drivers performed a 2-h simulated driving task while we recorded, simultaneously, their prefrontal brain activity and saccadic velocity. We used saccadic velocity as the reference index of fatigue. We also collected subjective ratings of alertness and fatigue, as well as driving performance. We found that the power spectra of the delta EEG band showed an inverted U-shaped quadratic trend (EEG power spectra increased for the first hour and half, and decreased during the last thirty minutes), while the power spectra of the beta band linearly increased as the driving session progressed. Coherently, saccadic velocity linearly decreased and speeding time increased, suggesting a clear effect of fatigue. Subjective data corroborated these conclusions. Overall, our results suggest that the TGAM-based chip EEG device is able to detect changes in mental state while performing a complex and dynamic everyday task as driving.

The impact of fibromyalgia symptoms on brain morphometry.

Fibromyalgia (FMS) is a complex clinical syndrome that includes many symptoms beyond chronic pain. The studies that have addressed brain morphometry in FMS have had very heterogeneous results. Thus, the question of which specific FMS symptoms and clinical features-pain, but also psychological distress, sleep-related problems, health status, and medication intake-impact on brain morphometry remains open. Here, we wanted to determine if brain changes in FMS are "symptom-related" more than "diagnostic-related". We performed an observational study of 46 premenopausal women (23 FMS patients and 23 age-matched healthy participants). Magnetic resonance images were analyzed using voxel-based morphometry and subcortical segmentation. We used multiple regression models to assess the associations between total and local brain volumes and FMS clinical characteristics. Furthermore, we calculated associations between subcortical structures' shapes and volumes and FMS clinical characteristics. Larger psychological distress, anxiety, and sleepiness, and higher analgesic consumption accounted for 38 % of FMS patients' smaller total gray matter volume (GMV). For both groups, local decrements of GMV in the medial orbitofrontal cortex were associated to larger psychological distress. Local increases of GMV were positively related to pain scores (superior frontal gyrus), psychological distress (cerebellum), anxiety (medial orbitofrontal cortex), and sleepiness (frontal superior medial cortex). FMS clinical characteristics were also associated to deformations in subcortical structures and volumes changes. This study reveals that total and local GMV changes in FMS go beyond the traditional "pain matrix" alterations. We demonstrated that brain morphology is altered by pain, but also by clinical characteristics that define the FMS experience.

Fatigue in the military: towards a fatigue detection test based on the saccadic velocity.

Fatigue is a major contributing factor to operational errors. Therefore, the validation of objective and sensitive indices to detect fatigue is critical to prevent accidents and catastrophes. Whereas tests based on saccadic velocity (SV) have become popular, their sensitivity in the military is not yet clear, since most research has been conducted in laboratory settings using not fully validated instruments. Field studies remain scarce, especially in extreme conditions such as real flights. Here, we investigated the effects of real, long flights on SV. We assessed five newly commissioned military helicopter pilots during their aviation training. Pilots flew Sikorsky S-76C helicopters, under instrumental flight rules, for more than 2 h (ca. 150 min). Eye movements were recorded before and after the flight with an eye tracker using a standard guided-saccade task. We also collected subjective ratings of fatigue. SV significantly decreased from the Pre-Flight to the Post-Flight session in all pilots by around 3% (range: 1-4%). Subjective ratings showed the same tendency. We provide conclusive evidence about the high sensitivity of fatigue tests based on SV in real flight conditions, even in small samples. This result might offer military medical departments a valid and useful biomarker of warfighter physiological state.

Driving time modulates accommodative response and intraocular pressure.

Driving is a task mainly reliant on the visual system. Most of the time, while driving, our eyes are constantly focusing and refocusing between the road and the dashboard or near and far traffic. Thus, prolonged driving time should produce visual fatigue. Here, for the first time, we investigated the effects of driving time, a common inducer of driver fatigue, on two ocular parameters: the accommodative response (AR) and the intraocular pressure (IOP). A pre/post-test design has been used to assess the impact of driving time on both indices. Twelve participants (out of 17 recruited) completed the study (5 women, 24.42±2.84years old). The participants were healthy and active drivers with no visual impairment or pathology. They drove for 2h in a virtual driving environment. We assessed AR and IOP before and after the driving session, and also collected subjective measures of arousal and fatigue. We found that IOP and AR decreased (i.e., the accommodative lag increased) after the driving session (p=0.03 and p<0.001, respectively). Moreover, the nearest distances tested (20cm, 25cm, and 33cm) induced the highest decreases in AR (corrected p-values<0.05). Consistent with these findings, the subjective levels of arousal decreased and levels of fatigue increased after the driving session (all p-values<0.001). These results represent an innovative step towards an objective, valid, and reliable assessment of fatigue-impaired driving based on visual fatigue signs.