Differences in time-frequency characteristics between healthy controls and TBI patients during hypercapnia assessed via fNIRS

Damage to the cerebrovascular network is a universal feature of traumatic brain injury (TBI). This damage is present during different phases of the injury and can be non-invasively assessed using functional near infrared spectroscopy (fNIRS). fNIRS signals are influenced by partial arterial carbon dioxide (PaCO2), neurogenic, Mayer waves, respiratory and cardiac oscillations, whose characteristics vary in time and frequency and may differ in the presence of TBI. Therefore, this study aims to investigate differences in time-frequency characteristics of these fNIRS signal components between healthy controls and TBI patients and characterize the changes in their characteristics across phases of the injury. Data from 11 healthy controls and 21 TBI patients were collected during the hypercapnic protocol. Results demonstrated significant differences in low-frequency oscillations between healthy controls and TBI patients, with the largest differences observed in Mayer wave band (0.06 to 0.15 Hz), followed by the PaCO2 band (0.012 to 0.02 Hz). The effects within these bands were opposite, with (i) Mayer wave activity being lower in TBI patients during acute phase of the injury (d = 0.37 [0.16, 0.57]) and decreasing further during subacute (d = 0.66 [0.44, 0.87]) and postacute (d = 0.75 [0.50, 0.99]) phases; (ii) PaCO2 activity being lower in TBI patients only during acute phase of the injury (d = 0.36 [0.15, 0.56]) and stabilizing to healthy levels by the subacute phase. These findings demonstrate that TBI patients have impairments in low frequency oscillations related to different mechanisms and that these impairments evolve differently over the course of injury.

Altered prefrontal activation during the inhibition of eating responses in women with bulimia nervosa

BACKGROUND

The sense of 'loss of control' (LOC), or a feeling of being unable to stop eating or control what or how much one is eating, is the most salient aspect of binge eating. However, the neural alterations that may contribute to this experience and eating behavior remain poorly understood.

METHODS

We used functional near-infrared spectroscopy (fNIRS) to measure activation in the prefrontal cortices of 23 women with bulimia nervosa (BN) and 23 healthy controls (HC) during two tasks: a novel go/no-go task requiring inhibition of eating responses, and a standard go/no-go task requiring inhibition of button-pressing responses.

RESULTS

Women with BN made more commission errors on both tasks. BN subgroups with the most severe LOC eating (n = 12) and those who felt most strongly that they binge ate during the task (n = 12) showed abnormally reduced bilateral ventromedial prefrontal cortex (vmPFC) and right ventrolateral prefrontal cortex (vlPFC) activation associated with eating-response inhibition. In the entire BN sample, lower eating-task activation in right vlPFC was related to more frequent and severe LOC eating, but no group differences in activation were detected on either task when this full sample was compared with HC. BN severity was unrelated to standard-task activation.

CONCLUSIONS

Results provide initial evidence that diminished PFC activation may directly contribute to more severe eating-specific control deficits in BN. Our findings support vmPFC and vlPFC dysfunction as promising treatment targets, and indicate that eating-specific tasks and fNIRS may be useful tools for identifying neural mechanisms underlying dysregulated eating.

An Examination of the Effects of Virtual Reality Training on Spatial Visualization and Transfer of Learning

Spatial visualization ability (SVA) has been identified as a potential key factor for academic achievement and student retention in Science, Technology, Engineering, and Mathematics (STEM) in higher education, especially for engineering and related disciplines. Prior studies have shown that training using virtual reality (VR) has the potential to enhance learning through the use of more realistic and/or immersive experiences. The aim of this study was to investigate the effect of VR-based training using spatial visualization tasks on participant performance and mental workload using behavioral (i.e., time spent) and functional near infrared spectroscopy (fNIRS) brain-imaging-technology-derived measures. Data were collected from 10 first-year biomedical engineering students, who engaged with a custom-designed spatial visualization gaming application over a six-week training protocol consisting of tasks and procedures that varied in task load and spatial characteristics. Findings revealed significant small (Cohen's d: 0.10) to large (Cohen's d: 2.40) effects of task load and changes in the spatial characteristics of the task, such as orientation or position changes, on time spent and oxygenated hemoglobin (HbO) measures from all the prefrontal cortex (PFC) areas. Transfer had a large (d = 1.37) significant effect on time spent and HbO measures from right anterior medial PFC (AMPFC); while training had a moderate (d = 0.48) significant effect on time spent and HbR measures from left AMPFC. The findings from this study have important implications for VR training, research, and instructional design focusing on enhancing the learning, retention, and transfer of spatial skills within and across various VR-based training scenarios.

Combined vitamin D and magnesium supplementation does not influence markers of bone turnover or glycemic control: A randomized controlled clinical trial

High-dose vitamin D supplementation can increase total osteocalcin concentrations that may reduce insulin resistance in individuals at risk for prediabetes or diabetes mellitus. Magnesium is a cofactor in vitamin D metabolism and activation. The purpose of this study was to determine the combined effect of vitamin D and magnesium supplementation on total osteocalcin concentrations, glycemic indices, and other bone turnover markers after a 12-week intervention in individuals who were overweight and obese, but otherwise healthy. We hypothesized that combined supplementation would improve serum total osteocalcin concentrations and glycemic indices more than vitamin D supplementation alone or a placebo. A total of 78 women and men completed this intervention in 3 groups: a vitamin D and magnesium group (1000 IU vitamin D₃ and 360 mg magnesium glycinate), a vitamin D group (1000 IU vitamin D₃), and a placebo group. Despite a significant increase in serum 25-hydroxyvitamin D concentrations in the vitamin D and magnesium group compared with the placebo group (difference = 5.63; CI, -10.0 to -1.21; P = .001) post-intervention, there were no differences in serum concentrations of total osteocalcin, glucose, insulin, and adiponectin or the homeostatic model assessment of insulin resistance (HOMA-IR) among groups (P > .05 for all). Additionally, total osteocalcin (β = -0.310, P = .081), bone-specific alkaline phosphatase (β = 0.004, P = .986), and C-terminal cross-linked telopeptide (β = 0.426, P = .057), were not significant predictors of HOMA-IR after the intervention. Combined supplementation was not associated with short-term improvements in glycemic indices or bone turnover markers in participants who were overweight and obese in our study. This trial was registered at clinicaltrials.gov (NCT03134417).

Individual differences in skill acquisition and transfer assessed by dual task training performance and brain activity

Assessment of expertise development during training program primarily consists of evaluating interactions between task characteristics, performance, and mental load. Such a traditional assessment framework may lack consideration of individual characteristics when evaluating training on complex tasks, such as driving and piloting, where operators are typically required to execute multiple tasks simultaneously. Studies have already identified individual characteristics arising from intrinsic, context, strategy, personality, and preference as common predictors of performance and mental load. Therefore, this study aims to investigate the effect of individual difference in skill acquisition and transfer using an ecologically valid dual task, behavioral, and brain activity measures. Specifically, we implemented a search and surveillance task (scanning and identifying targets) using a high-fidelity training simulator for the unmanned aircraft sensor operator, acquired behavioral measures (scan, not scan, over scan, and adaptive target find scores) using simulator-based analysis module, and measured brain activity changes (oxyhemoglobin and deoxyhemoglobin) from the prefrontal cortex (PFC) using a portable functional near-infrared spectroscopy (fNIRS) sensor array. The experimental protocol recruited 13 novice participants and had them undergo three easy and two hard sessions to investigate skill acquisition and transfer, respectively. Our results from skill acquisition sessions indicated that performance on both tasks did not change when individual differences were not accounted for. However inclusion of individual differences indicated that some individuals improved only their scan performance (Attention-focused group), while others improved only their target find performance (Accuracy-focused group). Brain activity changes during skill acquisition sessions showed that mental load decreased in the right anterior medial PFC (RAMPFC) in both groups regardless of individual differences. However, mental load increased in the left anterior medial PFC (LAMPFC) of Attention-focused group and decreased in the Accuracy-focused group only when individual differences were included. Transfer results showed no changes in performance regardless of grouping based on individual differences; however, mental load increased in RAMPFC of Attention-focused group and left dorsolateral PFC (LDLPFC) of Accuracy-focused group. Efficiency and involvement results suggest that the Attention-focused group prioritized the scan task, while the Accuracy-focused group prioritized the target find task. In conclusion, training on multitasks results in individual differences. These differences may potentially be due to individual preference. Future studies should incorporate individual differences while assessing skill acquisition and transfer during multitask training.

Diverse changes in microglia morphology and axonal pathology during the course of 1 year after mild traumatic brain injury in pigs

Over 2.8 million people experience mild traumatic brain injury (TBI) in the United States each year, which may lead to long-term neurological dysfunction. The mechanical forces that are caused by TBI propagate through the brain to produce diffuse axonal injury (DAI) and trigger secondary neuroinflammatory cascades. The cascades may persist from acute to chronic time points after injury, altering the homeostasis of the brain. However, the relationship between the hallmark axonal pathology of diffuse TBI and potential changes in glial cell activation or morphology have not been established in a clinically relevant large animal model at chronic time points. In this study, we assessed the tissue from pigs subjected to rapid head rotation in the coronal plane to generate mild TBI. Neuropathological assessments for axonal pathology, microglial morphological changes, and astrocyte reactivity were conducted in specimens out to 1-year post-injury. We detected an increase in overall amyloid precursor protein pathology, as well as periventricular white matter and fimbria/fornix pathology after a single mild TBI. We did not detect the changes in corpus callosum integrity or astrocyte reactivity. However, detailed microglial skeletal analysis revealed changes in morphology, most notably increases in the number of microglial branches, junctions, and endpoints. These subtle changes were most evident in periventricular white matter and certain hippocampal subfields, and were observed out to 1-year post-injury in some cases. These ongoing morphological alterations suggest persistent change in neuroimmune homeostasis. Additional studies are needed to characterize the underlying molecular and neurophysiological alterations, as well as potential contributions to neurological deficits.

Examining Mental Workload in a Spatial Navigation Transfer Game via Functional near Infrared Spectroscopy

The goal of this study was to examine the effects of task-related variables, such as the difficulty level, problem scenario, and experiment week, on performance and mental workload of 27 healthy adult subjects during problem solving within the spatial navigation transfer (SNT) game. The study reports task performance measures such as total time spent on a task (TT) and reaction time (RT); neurophysiological measures involving the use of functional near-infrared spectroscopy (fNIRS); and a subjective rating scale for self-assessment of mental workload (NASA TLX) to test the related hypothesis. Several within-subject repeated-measures factorial ANOVA models were developed to test the main hypothesis. The results revealed a number of interaction effects for the dependent measures of TT, RT, fNIRS, and NASA TLX. The results showed (1) a decrease in TT and RT across the three levels of difficulty from Week 1 to Week 2; (2) an increase in TT and RT for high and medium cognitive load tasks as compared to low cognitive load tasks in both Week 1 and Week 2; (3) an overall increase in oxygenation from Week 1 to Week 2. These findings confirmed that both the behavioral performance and mental workload were sensitive to task manipulations.

Short-Term Effects of Meditation on Sustained Attention as Measured by fNIRS

Cognitive abilities such as attention, memory, processing time, perception, and reasoning can be augmented using some type of intervention. Within the broad range of conventional and unconventional intervention methods used in cognitive enhancement, meditation is one of those that is safe, widely practiced by many since ancient times, and has been shown to reduce stress and improve psychological health and cognitive functioning. Various neuroimaging studies using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) have shown functional and structural changes due to meditation in different types of meditation practices and on various groups of meditators. Recently, a few studies on meditation have used functional near infrared spectroscopy (fNIRS) to study the effects of meditation on cerebral hemodynamics. In this study, we examined the short-term effects of loving-kindness (LK) meditation on sustained attention using behavioral performance measures, physiological outcomes, and cognitive activity as measured by fNIRS in first-time meditators during Stroop color word task (SCWT) performance. Our results indicated that behavioral outcomes, assessed mainly on response time (RT) during SCWT performance, showed a significant decrease after meditation. As expected, physiological measures, primarily pulse pressure (PP) measured after meditation dropped significantly as compared to the before meditation measurement. For the hemodynamic measures of oxygenated-hemoglobin (HbO2), deoxygenated-hemoglobin (Hb), and total-hemoglobin (HbT), our findings show significant differences in SCWT performance before and after meditation. Our results suggest that LK meditation can result in improvements in cognitive, physiological, and behavioral outcomes of first-time meditators after a short-term session.

Relationships of hip abductor strength, neuromuscular control, and hip width to femoral length ratio with peak hip adduction angle in healthy female runners

A large peak hip adduction angle during running is a risk factor for several overuse injuries in women. The purpose of this study was to determine if female runners with a large peak hip adduction angle have differences in eccentric hip abductor muscle strength, hip neuromuscular control, and/or hip width to femoral length ratio (HW:FL) compared to those with a small angle. Hip adduction during running, hip strength, hip control, and HW:FL were measured in sixty healthy female runners (1.66 ± 0.06 m; 63.2 ± 8.3 kg; 27 ± 6 years). Data from twenty runners with the largest and twenty with the smallest peak hip adduction angles were analysed. Between-group differences in hip strength, control, and HW:FL were determined using independent t-tests (p < 0.05). Variables that were significantly different between groups were entered into a regression model. Runners in both groups had similar hip strength (p = 0.90) and control (p = 0.65). HW:FL was greater in the large peak angle group (p = 0.04), but only explained a small amount of peak hip adduction angle variance for all sixty runners (R² = 0.05). Alarge peak hip adduction angle in some healthy female runners may simply be instinctive as there were no deficiencies in the strength or neuromuscular control constructs assessed.

Use of simulation as a needs assessment to develop a focused team leader training curriculum for resuscitation teams

Background

Many inpatients experience cardiac arrest and mortality in this population is extremely high. Simulation is frequently used to train code teams with the goal of improving these outcomes. A key step in designing such a training curriculum is to perform a needs assessment. We report on the effectiveness of a simulation-based training program for residents designed using unannounced in-situ simulation cardiac arrest data as a needs assessment.

Methods

In order to develop the curriculum for training, a needs assessment was done using in-situ simulation. Prior to instruction, residents were assessed in their ability to lead a simulated resuscitation using a standardized checklist. During the intervention phase, residents participated in didactic and team training. The didactic training consisted of pharmacology review, ACLS update and TeamSTEPPS training. Residents took turns as code team leader in three simulation sessions. Rapid cycle deliberate practice (RCDP) was employed as part of simulation sessions. All residents returned, for post-intervention assessment. Mean pre-post test scores were analyzed to determine if there was a significant difference.

Results

Twenty-seven residents participated. Mean pre-training assessment score was 47.6 (95% CI 37.5-57.9). The mean post-training assessment score was 84.4 (95% CI 79.0-89.5). The mean time to defibrillation after pads were placed in scenario with shockable rhythm decreased from 102.2 seconds (95% CI 74.0-130.5) to 56.3 (95% CI 32.7-79.8).

Conclusion

Using unannounced in-situ cardiac arrest simulations as a needs assessment, a simulation-based training program was developed that significantly improved resident performance as team leader. Future work is needed to determine if this improvement translates into patient benefits and is sustainable. However, in-situ simulation is a promising tool for curriculum development.

Motor Performance, Mental Workload and Self-Efficacy Dynamics during Learning of Reaching Movements throughout Multiple Practice Sessions

The human capability to learn new motor skills depends on the efficient engagement of cognitive-motor resources, as reflected by mental workload, and psychological mechanisms (e.g., self-efficacy). While numerous investigations have examined the relationship between motor behavior and mental workload or self-efficacy in a performance context, a fairly limited effort focused on the combined examination of these notions during learning. Thus, this study aimed to examine their concomitant dynamics during the learning of a novel reaching skill practiced throughout multiple sessions. Individuals had to learn to control a virtual robotic arm via a human-machine interface by using limited head motion throughout eight practice sessions while motor performance, mental workload, and self-efficacy were assessed. The results revealed that as individuals learned to control the robotic arm, performance improved at the fastest rate, followed by a more gradual reduction of mental workload and finally an increase in self-efficacy. These results suggest that once the performance improved, less cognitive-motor resources were recruited, leading to an attenuated mental workload. Considering that attention is a primary cognitive resource driving mental workload, it is suggested that during early learning, attentional resources are primarily allocated to address task demands and not enough are available to assess self-efficacy. However, as the performance becomes more automatic, a lower level of mental workload is attained driven by decreased recruitment of attentional resources. These available resources allow for a reliable assessment of self-efficacy resulting in a subsequent observable change. These results are also discussed in terms of the application to the training and design of assistive technologies.

Sedentary behavior time as a predictor of hemoglobin A1c among adults, 40 to 59 years of age, living in the United States: National Health and Nutrition Examination Survey 2003 to 2004 and 2013 to 2014

BACKGROUND

Sedentary behavior activities have been associated with an increased risk of type 2 diabetes. Aim: Our aim was to determine whether sedentary behavior time (SBT) is predictive of hemoglobin A1c (HbA1c) ≥ 6.5% (48 mmol/mol).

METHODS

We used cross-sectional data, adults 40 to 59 years of age, from the National Health and Nutrition Examination Survey (NHANES) for 2003 to 2004 and 2013 to 2014. Responses to questions on the Physical Activity Questionnaire regarding time watching television/videos, and time spent sitting in front of a computer per day were compiled into tertiles. Binary logistic regression analysis was used to determine whether SBT was a predictor of a HbA1c ≥ 6.5% adjusting for age, sex, race and ethnicity, and body mass index.

RESULTS

In a univariate model, adults reporting ≥ 8 hours of SBT in NHANES 2003-2004 had 2.02 increased odds of a HbA1c ≥ 6.5% (OR = 2.02, 95% CI: 1.31, 3.13, p < 0.0001) compared to adults reporting ≤ 3 hours. After adjusting the regression model for age, sex, race and ethnicity, and body mass index, adults reporting ≥ 8 hours of SBT in NHANES 2003 to 2004 had 1.72 increased odds of HbA1c ≥ 6.5% (OR = 2.02, 95% CI: 1.10, 2.68, p < 0.0001) compared to adults reporting ≤ 3 hours of SBT. Reported SBT was not a predictor of HbA1c ≥ 6.5% for NHANES 2013 to 2014.

CONCLUSION

Reported SBT was a predictor of HbA1c ≥ 6.5% among adults, 40 to 59 years of age, in NHANES 2003 to 2004, but was not a predictor in 2013 to 2014.

Low dietary magnesium intake alters vitamin D-parathyroid hormone relationship in adults who are overweight or obese

Vitamin D metabolism is dependent on magnesium (Mg) as a cofactor; therefore, poor Mg status may alter the relationship between vitamin D metabolite serum 25-hydroxyvitamin D (s25OHD) and serum parathyroid hormone (sPTH). We hypothesized that low dietary Mg intake may alter sPTH response to s25OHD in a population with excess body weight, thereby leading to a worsening of cardiometabolic health. To explore this hypothesis, we conducted a cross-sectional study on adults who were either overweight or obese (owt/ob). Dietary Mg intake was measured using a Mg food frequency questionnaire (MgFFQ). Body composition information was measured using Dual Energy X-ray Absorptiometry (DXA). Blood samples were obtained for all biochemical analyses. A total of 57 participants, 22 to 65 years of age, with a body mass index between 25 to 45 kg/m² were divided into 3 groups, according to dietary Mg intake percentiles (Low Mg Group = <33 percentile, Medium Mg Group = 33 to 66 percentile, High Mg Group = >66 percentile). Higher s25OHD was negatively associated with lower sPTH in the High Mg Intake group (r = -0.472, P = .041), but not in other groups. A positive relationship between s25OHD and serum high-molecular weight adiponectin concentrations was observed in the High Mg Group (r = 0.532, r = 0.022), but not in other groups. Serum Interleukin-6 concentrations were negatively associated with s25OHD (r = -0.316, P = .017) for the entire study group. Based on these results, our study demonstrated that a low dietary Mg intake may alter PTH response to 25OHD.

Calculating Heart Rate Variability from ECG Data from Youth with Cerebral Palsy During Active Video Game Sessions

The aim of this study was to generate a method for calculating heart rate variability (HRV) from electrocardiogram (ECG) waveforms. The waveforms were recorded by a HR monitor that participants (youth with cerebral palsy (CP)) wore during active video game (AVG) sessions. The AVG sessions were designed to promote physical activity and fitness (aerobic performance) in participants. The goal was to evaluate the feasibility of AVGs as a physical therapy (PT) intervention strategy. The maximum HR (mHR) was determined for each participant and the Target Heart Rate Zone (THRZ) was calculated for each of three exercise phases in the 20 min AVG session: (warm-up at 40-60% mHR, conditioning at 60-80% mHR, and cool down at 40-60% mHR). Each participant played three 20 min games during the AVG session. All games were played while sitting on a bench because many youth with CP cannot stand for extended periods of time. Each game condition differed with participants using hand icons only, hand and feet icons together or feet icons only to collect objects. The objective of the game (called KOLLECT) is to collect objects to gain points and avoid hazards to not lose points. Hazards were used in the warm-up and cool down phases only to promote slower, controlled movement to maintain HR in the target heart rate zone (THRZ). There were no hazards in the conditioning phase to promote higher levels and more intense physical activity. Analytic methods were used to generate HRV (selected time-domain and frequency-domain measures) from ECG data to examine aerobic workload. Recent applications of HRV indicate that short-term measurements (5 min bouts) are appropriate and that HRV biofeedback may help improve symptoms and the quality of life in a variety of health conditions. Although HR is a well-accepted clinical measure to examine aerobic performance and intensity in PT interventions, HRV may provide information of the autonomic system functions, recovery and adaptation during AVG sessions.

Use of a hybrid-abdominal wound simulated patient in the ACS/ASE medical student simulation skills curriculum

OBJECTIVE

We incorporated a hybrid-abdominal wound simulation to teach/assess the acquisition of three essential clinical skills in the ACS/ASE Medical Student Simulation-based Surgical Skills Curriculum.

METHOD

Third year students (N = 43) attended a workshop based on the ACS/ASE surgical skills curriculum for drain care/removal, staple removal and Steri-Strip application. Following a didactic session and demonstration using a simulated patient, student skill acquisition was assessed using the ACS/ASE module rating tool. Student interest/perceived usefulness of the workshop was evaluated using Keller's Motivational Survey.

RESULTS

We used median scores to identify low proficiency (n = 20; scores 17-28) and high proficiency (n = 23; scores 29-35) groups. The high proficiency group was more knowledgeable, performed better drain care, had a higher global score and was more confident than the low proficiency group. The students rated the workshop highly based on the Keller's Motivational Survey.

CONCLUSION

All students were proficient in the procedure tasks and communication skills and most felt that the course was beneficial. The ACS/ASE Medical Student Simulation-based Surgical Skills Curriculum was successfully integrated into our third year surgical clerkship.

A rodent brain-machine interface paradigm to study the impact of paraplegia on BMI performance

BACKGROUND

Most brain machine interfaces (BMI) focus on upper body function in non-injured animals, not addressing the lower limb functional needs of those with paraplegia. A need exists for a novel BMI task that engages the lower body and takes advantage of well-established rodent spinal cord injury (SCI) models to study methods to improve BMI performance.

NEW METHOD

A tilt BMI task was designed that randomly applies different types of tilts to a platform, decodes the tilt type applied and rights the platform if the decoder correctly classifies the tilt type. The task was tested on female rats and is relatively natural such that it does not require the animal to learn a new skill. It is self-rewarding such that there is no need for additional rewards, eliminating food or water restriction, which can be especially hard on spinalized rats. Finally, task difficulty can be adjusted by making the tilt parameters.

RESULTS

This novel BMI task bilaterally engages the cortex without visual feedback regarding limb position in space and animals learn to improve their performance both pre and post-SCI.Comparison with Existing Methods: Most BMI tasks primarily engage one hemisphere, are upper-body, rely heavily on visual feedback, do not perform investigations in animal models of SCI, and require nonnaturalistic extrinsic motivation such as water rewarding for performance improvement. Our task addresses these gaps.

CONCLUSIONS

The BMI paradigm presented here will enable researchers to investigate the interaction of plasticity after SCI and plasticity during BMI training on performance.

Clinicopathological Features and Management of Appendiceal Mucoceles: A Systematic Review

Appendiceal mucoceles (AMs) are rare mucin-containing neoplasms with malignant potential. Lack of evidence-based data exists defining clinicopathological features for management. MEDLINE search between 1995 and 2015 was performed using search criteria “Appendix mucocele.” Systematic review of patient-, pathologic-, and treatment-related characteristics was performed and data analyzed. Among 276 cases of non-perforated AMs, 163 (59%) patients were female, with variable and nonspecific presentation. Patients were treated with appendectomy (52.1%), right hemicolectomy (17.6%), partial cecectomy (17.2%), and ileocecetomy (13.1%). Pathologic evaluation revealed the following: cystadenoma/low-grade appendiceal mucinous neoplasm (54%), unspecified/benign (25%), retention cyst (14.1%), cystadenocarcinoma (4.2%), and mucosal hyperplasia (2.9%). All 11 (4.2%) patients with cystadenocarcinoma were female ( P = 0.004), odds ratio for malignancy 1.07 times higher for women. Synchronous colonic malignancy was reported in three patients (27%) with cystadenocarcinoma ( P = 0.007), odds ratio of 12.1. AMs have low risk for malignancy. Treatment should begin with appendectomy-only and subsequently guided by pathologic diagnosis.

Clinicopathological Features and Management of Appendiceal Mucoceles: A Systematic Review

Appendiceal mucoceles (AMs) are rare mucin-containing neoplasms with malignant potential. Lack of evidence-based data exists defining clinicopathological features for management. MEDLINE search between 1995 and 2015 was performed using search criteria "Appendix mucocele." Systematic review of patient-, pathologic-, and treatment-related characteristics was performed and data analyzed. Among 276 cases of non-perforated AMs, 163 (59%) patients were female, with variable and nonspecific presentation. Patients were treated with appendectomy (52.1%), right hemicolectomy (17.6%), partial cecectomy (17.2%), and ileocecetomy (13.1%). Pathologic evaluation revealed the following: cystadenoma/low-grade appendiceal mucinous neoplasm (54%), unspecified/benign (25%), retention cyst (14.1%), cystadenocarcinoma (4.2%), and mucosal hyperplasia (2.9%). All 11 (4.2%) patients with cystadenocarcinoma were female (P = 0.004), odds ratio for malignancy 1.07 times higher for women. Synchronous colonic malignancy was reported in three patients (27%) with cystadenocarcinoma (P = 0.007), odds ratio of 12.1. AMs have low risk for malignancy. Treatment should begin with appendectomy-only and subsequently guided by pathologic diagnosis.

Filling the Gap: Simulation-based Crisis Resource Management Training for Emergency Medicine Residents

Introduction

In today’s team-oriented healthcare environment, high-quality patient care requires physicians to possess not only medical knowledge and technical skills but also crisis resource management (CRM) skills. In emergency medicine (EM), the high acuity and dynamic environment makes CRM skills of physicians particularly critical to healthcare team success. The Accreditation Council of Graduate Medicine Education Core Competencies that guide residency program curriculums include CRM skills; however, EM residency programs are not given specific instructions as to how to teach these skills to their trainees. This article describes a simulation-based CRM course designed specifically for novice EM residents.

Methods

The CRM course includes an introductory didactic presentation followed by a series of simulation scenarios and structured debriefs. The course is designed to use observational learning within simulation education to decrease the time and resources required for implementation. To assess the effectiveness in improving team CRM skills, two independent raters use a validated CRM global rating scale to measure the CRM skills displayed by teams of EM interns in a pretest and posttest during the course.

Results

The CRM course improved leadership, problem solving, communication, situational awareness, teamwork, resource utilization and overall CRM skills displayed by teams of EM interns. While the improvement from pretest to posttest did not reach statistical significance for this pilot study, the large effect sizes suggest that statistical significance may be achieved with a larger sample size.

Conclusion

This course can feasibly be incorporated into existing EM residency curriculums to provide EM trainees with basic CRM skills required of successful emergency physicians. We believe integrating CRM training early into existing EM education encourages continued deliberate practice, discussion, and improvement of essential CRM skills.

Changes in motor performance and mental workload during practice of reaching movements: a team dynamics perspective

Few investigations have examined mental workload during motor practice or learning in a context of team dynamics. This study examines the underlying cognitive-motor processes of motor practice by assessing the changes in motor performance and mental workload during practice of reaching movements. Individuals moved a robotic arm to reach targets as fast and as straight as possible while satisfying the task requirement of avoiding a collision between the end-effector and the workspace limits. Individuals practiced the task either alone (HA group) or with a synthetic teammate (HRT group), which regulated the effector velocity to help satisfy the task requirements. The findings revealed that the performance of both groups improved similarly throughout practice. However, when compared to the individuals of the HA group, those in the HRT group (1) had a lower risk of collisions, (2) exhibited higher performance consistency, and (3) revealed a higher level of mental workload while generally perceiving the robotic teammate as interfering with their performance. As the synthetic teammate changed the effector velocity in specific regions near the workspace boundaries, individuals may have been constrained to learn a piecewise visuomotor map. This piecewise map made the task more challenging, which increased mental workload and perception of the synthetic teammate as a burden. The examination of both motor performance and mental workload revealed a combination of both adaptive and maladaptive team dynamics. This work is a first step to examine the human cognitive-motor processes underlying motor practice in a context of team dynamics and contributes to inform human-robot applications.

Multisubject "Learning" for Mental Workload Classification Using Concurrent EEG, fNIRS, and Physiological Measures

An accurate measure of mental workload level has diverse neuroergonomic applications ranging from brain computer interfacing to improving the efficiency of human operators. In this study, we integrated electroencephalogram (EEG), functional near-infrared spectroscopy (fNIRS), and physiological measures for the classification of three workload levels in an n-back working memory task. A significantly better than chance level classification was achieved by EEG-alone, fNIRS-alone, physiological alone, and EEG+fNIRS based approaches. The results confirmed our previous finding that integrating EEG and fNIRS significantly improved workload classification compared to using EEG-alone or fNIRS-alone. The inclusion of physiological measures, however, does not significantly improves EEG-based or fNIRS-based workload classification. A major limitation of currently available mental workload assessment approaches is the requirement to record lengthy calibration data from the target subject to train workload classifiers. We show that by learning from the data of other subjects, workload classification accuracy can be improved especially when the amount of data from the target subject is small.

Memory Consolidation and Contextual Interference Effects with Computer Games

Some investigators of the contextual interference effect contend that there is a direct relation between the amount of practice and the contextual interference effect based on the prediction that the improvement in learning tasks in a random practice schedule, compared to a blocked practice schedule, increases in magnitude as the amount of practice during acquisition on the tasks increases. Research using computer games in contextual interference studies has yielded a large effect ( f = .50) with a random practice schedule advantage during transfer. These investigations had a total of 36 and 72 acquisition trials, respectively. The present study tested this prediction by having 72 college students, who were randomly assigned to a blocked or random practice schedule, practice 102 trials of three computer-game tasks across three days. After a 24-hr. interval, 6 retention and 5 transfer trials were performed. Dependent variables were time to complete an event in seconds and number of errors. No significant differences were found for retention and transfer. These results are discussed in terms of how the amount of practice, task-related factors, and memory consolidation mediate the contextual interference effect.

Motivation in computer-assisted instruction

OBJECTIVES/HYPOTHESIS

Computer-aided instruction (CAI) is defined as instruction in which computers play a central role as the means of information delivery and direct interaction with learners. Computer-aided instruction has become mainstream in medical school curricula. For example, a three-dimensional (3D) computer module of the larynx has been created to teach laryngeal anatomy. Although the novelty and educational potential of CAI has garnered much attention, these new technologies have been plagued with low utilization rates. Several experts attribute this problem to lack of motivation in students. Motivation is defined as the desire and action toward goal-oriented behavior. Psychologist Dr. John Keller developed the ARCS theory of motivational learning, which proposed four components: attention (A), relevance (R), concentration (C), and satisfaction (S). Keller believed that motivation is not only an innate characteristic of the pupil; it can also be influenced by external factors, such as the instructional design of the curriculum. Thus, understanding motivation is an important step to designing CAI appropriately. Keller also developed a 36-item validated instrument called the Instructional Materials Motivation Survey (IMMS) to measure motivation. The objective of this study was to study motivation in CAI. Medical students learning anatomy with the 3D computer module will have higher laryngeal anatomy test scores and higher IMMS motivation scores. Higher anatomy test scores will be positively associated with higher IMMS scores.

STUDY DESIGN

Prospective, randomized, controlled trial.

METHODS

After obtaining institutional review board approval, 100 medical students (mean age 25.5 ± 2.5, 49% male) were randomized to either the 3D computer module (n = 49) or written text (n = 51). Information content was identical in both arms. Students were given 30 minutes to study laryngeal anatomy and then completed the laryngeal anatomy test and IMMS. Students were categorized as either junior (year 1 and 2) or senior (year 3 and 4).

RESULTS

There were no significant differences in anatomy scores based on educational modality. There was significant interaction of educational modality by year [F(1,96) = 4.12, P = 0.045, ω(2)  = 0.031]. For the total score, there was a significant effect of year [F(1,96) = 22.28, P < 0.001, ω(2)  = 0.178], with seniors (15.4 ± 2.6) scoring significantly higher than juniors (12.8 ± 3.1). For the motivational score, the total IMMS score had two significant effects. With educational modality [F(1,96) = 5.18, P = 0.025, ω(2)  = 0.041], the 3D group (12.4 ± 2.8) scored significantly higher than the written text group (11.7 ± 3.2). With year [F(1,96) = 25.31, P < 0.001, ω(2)  = 0.198], seniors (13.4 ± 3.0) scored significantly higher than juniors (10.8 ± 2.5). Pearson's correlation showed positive associations (r = 0.22-0.91) between anatomy scores and IMMS motivation scores (P < 0.05).

CONCLUSION

Computer-aided instruction conferred no measurable educational benefit over traditional written text in medical students; however, CAI was associated with higher motivational levels. Computer-aided instruction was found to have a greater positive impact on senior medical students with higher anatomy and motivational scores. Higher anatomy scores were positively associated with higher motivational scores. Computer-aided instruction may be better targeted toward senior students.

LEVEL OF EVIDENCE

N/A. Laryngoscope, 126:S5-S13, 2016.

Using Mean Absolute Relative Phase, Deviation Phase and Point-Estimation Relative Phase to Measure Postural Coordination in a Serial Reaching Task

The objectives of this communication are to present the methods used to calculate mean absolute relative phase (MARP), deviation phase (DP) and point estimate relative phase (PRP) and compare their utility in measuring postural coordination during the performance of a serial reaching task. MARP and DP are derived from continuous relative phase time series representing the relationship between two body segments or joints during movements. MARP is a single measure used to quantify the coordination pattern and DP measures the stability of the coordination pattern. PRP also quantifies coordination patterns by measuring the relationship between the timing of maximal or minimal angular displacements of two segments within cycles of movement. Seven young adults practiced a bilateral serial reaching task 300 times over 3 days. Relative phase measures were used to evaluate inter-joint relationships for shoulder-hip (proximal) and hip-ankle (distal) postural coordination at early and late learning. MARP, PRP and DP distinguished between proximal and distal postural coordination. There was no effect of practice on any of the relative phase measures for the group, but individual differences were seen over practice. Combined, MARP and DP estimated stability of in-phase and anti-phase postural coordination patterns, however additional qualitative movement analyses may be needed to interpret findings in a serial task. We discuss the strengths and limitations of using MARP and DP and compare MARP and DP to PRP measures in assessing coordination patterns in the context of various types of skillful tasks. Key pointsMARP, DP and PRP measures coordination between segments or joint anglesAdvantages and disadvantages of each measure should be considered in relationship to the performance taskMARP and DP may capture coordination patterns and stability of the patterns during discrete tasks or phases of movements within a taskPRP and SD or PRP may capture coordination patterns and stability during continuous oscillating movement tasks.

An exploration of grip force regulation with a low-impedance myoelectric prosthesis featuring referred haptic feedback

Background

Haptic display technologies are well suited to relay proprioceptive, force, and contact cues from a prosthetic terminal device back to the residual limb and thereby reduce reliance on visual feedback. The ease with which an amputee interprets these haptic cues, however, likely depends on whether their dynamic signal behavior corresponds to expected behaviors—behaviors consonant with a natural limb coupled to the environment. A highly geared motor in a terminal device along with the associated high back-drive impedance influences dynamic interactions with the environment, creating effects not encountered with a natural limb. Here we explore grasp and lift performance with a backdrivable (low backdrive impedance) terminal device placed under proportional myoelectric position control that features referred haptic feedback.

Methods

We fabricated a back-drivable terminal device that could be used by amputees and non-amputees alike and drove aperture (or grip force, when a stiff object was in its grasp) in proportion to a myoelectric signal drawn from a single muscle site in the forearm. In randomly ordered trials, we assessed the performance of N=10 participants (7 non-amputee, 3 amputee) attempting to grasp and lift an object using the terminal device under three feedback conditions (no feedback, vibrotactile feedback, and joint torque feedback), and two object weights that were indiscernible by vision.

Results

Both non-amputee and amputee participants scaled their grip force according to the object weight. Our results showed only minor differences in grip force, grip/load force coordination, and slip as a function of sensory feedback condition, though the grip force at the point of lift-off for the heavier object was significantly greater for amputee participants in the presence of joint torque feedback. An examination of grip/load force phase plots revealed that our amputee participants used larger safety margins and demonstrated less coordination than our non-amputee participants.

Conclusions

Our results suggest that a backdrivable terminal device may hold advantages over non-backdrivable devices by allowing grip/load force coordination consistent with behaviors observed in the natural limb. Likewise, the inconclusive effect of referred haptic feedback on grasp and lift performance suggests the need for additional testing that includes adequate training for participants.

Tactile Feedback of Object Slip Facilitates Virtual Object Manipulation

Recent advances in myoelectric prosthetic technology have enabled more complex movements and interactions with objects, but the lack of natural haptic feedback makes object manipulation difficult to perform. Our research effort aims to develop haptic feedback systems for improving user performance in object manipulation. Specifically, in this work, we explore the effectiveness of vibratory tactile feedback of slip information for grasping objects without slipping. A user interacts with a virtual environment to complete a virtual grasp and hold task using a Sensable Phantom. Force feedback simulates contact with objects, and vibratory tactile feedback alerts the user when a virtual object is slipping from the grasp. Using this task, we found that tactile feedback significantly improved a user's ability to detect and respond to slip and to recover the slipping object when visual feedback was not available. This advantage of tactile feedback is especially important in conjunction with force feedback, which tends to reduce a subject's grasping forces and therefore encourage more slips. Our results demonstrate the potential of slip feedback to improve a prosthesis user's ability to interact with objects with less visual attention, aiding in performance of everyday manipulation tasks.

Continuous monitoring of brain dynamics with functional near infrared spectroscopy as a tool for neuroergonomic research: empirical examples and a technological development

Functional near infrared spectroscopy (fNIRS) is a non-invasive, safe, and portable optical neuroimaging method that can be used to assess brain dynamics during skill acquisition and performance of complex work and everyday tasks. In this paper we describe neuroergonomic studies that illustrate the use of fNIRS in the examination of training-related brain dynamics and human performance assessment. We describe results of studies investigating cognitive workload in air traffic controllers, acquisition of dual verbal-spatial working memory skill, and development of expertise in piloting unmanned vehicles. These studies used conventional fNIRS devices in which the participants were tethered to the device while seated at a workstation. Consistent with the aims of mobile brain imaging (MoBI), we also describe a compact and battery-operated wireless fNIRS system that performs with similar accuracy as other established fNIRS devices. Our results indicate that both wired and wireless fNIRS systems allow for the examination of brain function in naturalistic settings, and thus are suitable for reliable human performance monitoring and training assessment.

A P300-based EEG-BCI for spatial navigation control

In this study, a Brain Computer Interface (BCI) based on the P300 oddball paradigm has been developed for spatial navigation control in virtual environments. Functionality and efficacy of the system were analyzed with results from nine healthy volunteers. Each participant was asked to gaze at an individual target in a 3×3 P300 matrix containing different symbolic navigational icons while EEG signals were collected. Resulting ERPs were processed online and classification commands were executed to control spatial movements within the MazeSuite virtual environment and presented to the user online during an experiment. Subjects demonstrated on average, ∼89% online accuracy for simple mazes and ∼82% online accuracy in longer more complex mazes. Results suggest that this BCI setup enables guided free-form navigation in virtual 3D environments.

Functional near-infrared spectroscopy-based correlates of prefrontal cortical dynamics during a cognitive-motor executive adaptation task

This study investigated changes in brain hemodynamics, as measured by functional near infrared spectroscopy, during performance of a cognitive-motor adaptation task. The adaptation task involved the learning of a novel visuomotor transformation (a 60° counterclockwise screen-cursor rotation), which required inhibition of a prepotent visuomotor response. A control group experienced a familiar transformation and thus, did not face any executive challenge. Analysis of the experimental group hemodynamic responses revealed that the performance enhancement was associated with a monotonic reduction in the oxygenation level in the prefrontal cortex. This finding confirms and extends functional magnetic resonance imaging and electroencephalography studies of visuomotor adaptation and learning. The changes in prefrontal brain activation suggest an initial recruitment of frontal executive functioning to inhibit prepotent visuomotor mappings followed by a progressive de-recruitment of the same prefrontal regions. The prefrontal hemodynamic changes observed in the experimental group translated into enhanced motor performance revealed by a reduction in movement time, movement extent, root mean square error and the directional error. These kinematic adaptations are consistent with the acquisition of an internal model of the novel visuomotor transformation. No comparable change was observed in the control group for either the hemodynamics or for the kinematics. This study (1) extends our understanding of the frontal executive processes from the cognitive to the cognitive-motor domain and (2) suggests that optical brain imaging can be employed to provide hemodynamic based-biomarkers to assess and monitor the level of adaptive cognitive-motor performance.

Tangram solved? Prefrontal cortex activation analysis during geometric problem solving

Recent neuroimaging studies have implicated prefrontal and parietal cortices for mathematical problem solving. Mental arithmetic tasks have been used extensively to study neural correlates of mathematical reasoning. In the present study we used geometric problem sets (tangram tasks) that require executive planning and visuospatial reasoning without any linguistic representation interference. We used portable optical brain imaging (functional near infrared spectroscopy--fNIR) to monitor hemodynamic changes within anterior prefrontal cortex during tangram tasks. Twelve healthy subjects were asked to solve a series of computerized tangram puzzles and control tasks that required same geometric shape manipulation without problem solving. Total hemoglobin (HbT) concentration changes indicated a significant increase during tangram problem solving in the right hemisphere. Moreover, HbT changes during failed trials (when no solution found) were significantly higher compared to successful trials. These preliminary results suggest that fNIR can be used to assess cortical activation changes induced by geometric problem solving. Since fNIR is safe, wearable and can be used in ecologically valid environments such as classrooms, this neuroimaging tool may help to improve and optimize learning in educational settings.

Detection of attention shift for asynchronous P300-based BCI

Brain-computer interface (BCI) provides patients suffering from severe neuromuscular disorders an alternative way of interacting with the outside world. The P300-based BCI is among the most popular paradigms in the field and most current versions operate in synchronous mode and assume participant engagement throughout operation. In this study, we demonstrate a new approach for assessment of user engagement through a hybrid classification of ERP and band power features of EEG signals that could allow building asynchronous BCIs. EEG signals from nine electrode locations were recorded from nine participants during controlled engagement conditions when subjects were either engaged with the P3speller task or not attending. Statistical analysis of band power showed that there were significant contrasts of attending only for the delta and beta bands as indicators of features for user attendance classification. A hybrid classifier using ERP scores and band power features yielded the best overall performance of 0.98 in terms of the area under the ROC curve (AUC). Results indicate that band powers can provide additional discriminant information to the ERP for user attention detection and this combined approach can be used to assess user engagement for each stimulus sequence during BCI use.

Reconstructing surface EMG from scalp EEG during myoelectric control of a closed looped prosthetic device

In this study, seven able-bodied human subjects controlled a robotic gripper with surface electromyography (sEMG) activity from the biceps. While subjects controlled the gripper, they felt the forces measured by the robotic gripper through an exoskeleton fitted on their non-dominant left arm. Subjects were instructed to identify objects with the force feedback provided by the exoskeleton. While subjects operated the robotic gripper, scalp electroencephalography (EEG) and functional near infrared spectroscopy (fNIRS) were recorded. We developed neural decoders that used scalp EEG to reconstruct the sEMG used to control the robotic gripper. The neural decoders used a genetic algorithm embedded in a linear model with memory to reconstruct the sEMG from a plurality of EEG channels. The performance of the decoders, measured with Pearson correlation coefficients (median r-value = 0.59, maximum r-value = 0.91) was found to be comparable to previous studies that reconstructed sEMG linear envelopes from neural activity recorded with invasive techniques. These results show the feasibility of developing EEG-based neural interfaces that in turn could be used to control a robotic device.

An optical brain computer interface for environmental control

A brain computer interface (BCI) is a system that translates neurophysiological signals detected from the brain to supply input to a computer or to control a device. Volitional control of neural activity and its real-time detection through neuroimaging modalities are key constituents of BCI systems. The purpose of this study was to develop and test a new BCI design that utilizes intention-related cognitive activity within the dorsolateral prefrontal cortex using functional near infrared (fNIR) spectroscopy. fNIR is a noninvasive, safe, portable and affordable optical technique with which to monitor hemodynamic changes, in the brain's cerebral cortex. Because of its portability and ease of use, fNIR is amenable to deployment in ecologically valid natural working environments. We integrated a control paradigm in a computerized 3D virtual environment to augment interactivity. Ten healthy participants volunteered for a two day study in which they navigated a virtual environment with keyboard inputs, but were required to use the fNIR-BCI for interaction with virtual objects. Results showed that participants consistently utilized the fNIR-BCI with an overall success rate of 84% and volitionally increased their cerebral oxygenation level to trigger actions within the virtual environment.

Childhood trauma and adult self-reported depression

Adverse childhood experiences (ACEs) are plentiful within our society however the consequences that stem from these experiences are not often addressed particularly their impact on mental wellness. Given that ACEs have negative neurodevelopmental influences that persist over the lifespan this paper will present findings from a study that examined the relationship between ACEs and self-reported depression among low-income ethnic minority populations who live in an urban setting. Findings highlight the importance of research on the prevalence of and risks for multiple types of childhood maltreatment, particularly in the somewhat neglected area of self-reported depression. Statistical significance was found for most ACEs and clinical significance was noted for several ACEs. Efforts to mitigate and prevent depression will likely benefit from preventing ACEs and treating individuals exposed to them. Discernment that ACEs lead to risk behaviors that subsequently increase the likelihood of depression could provide insight that can improve prevention efforts.

Using MazeSuite and functional near infrared spectroscopy to study learning in spatial navigation

MazeSuite is a complete toolset to prepare, present and analyze navigational and spatial experiments¹. MazeSuite can be used to design and edit adapted virtual 3D environments, track a participants' behavioral performance within the virtual environment and synchronize with external devices for physiological and neuroimaging measures, including electroencephalogram and eye tracking.

Functional near-infrared spectroscopy (fNIR) is an optical brain imaging technique that enables continuous, noninvasive, and portable monitoring of changes in cerebral blood oxygenation related to human brain functions^2-7. Over the last decade fNIR is used to effectively monitor cognitive tasks such as attention, working memory and problem solving^7-11. fNIR can be implemented in the form of a wearable and minimally intrusive device; it has the capacity to monitor brain activity in ecologically valid environments.

Cognitive functions assessed through task performance involve patterns of brain activation of the prefrontal cortex (PFC) that vary from the initial novel task performance, after practice and during retention¹². Using positron emission tomography (PET), Van Horn and colleagues found that regional cerebral blood flow was activated in the right frontal lobe during the encoding (i.e., initial naïve performance) of spatial navigation of virtual mazes while there was little to no activation of the frontal regions after practice and during retention tests. Furthermore, the effects of contextual interference, a learning phenomenon related to organization of practice, are evident when individuals acquire multiple tasks under different practice schedules^13,14. High contextual interference (random practice schedule) is created when the tasks to be learned are presented in a non-sequential, unpredictable order. Low contextual interference (blocked practice schedule) is created when the tasks to be learned are presented in a predictable order.

Our goal here is twofold: first to illustrate the experimental protocol design process and the use of MazeSuite, and second, to demonstrate the setup and deployment of the fNIR brain activity monitoring system using Cognitive Optical Brain Imaging (COBI) Studio software¹⁵. To illustrate our goals, a subsample from a study is reported to show the use of both MazeSuite and COBI Studio in a single experiment. The study involves the assessment of cognitive activity of the PFC during the acquisition and learning of computer maze tasks for blocked and random orders. Two right-handed adults (one male, one female) performed 315 acquisition, 30 retention and 20 transfer trials across four days. Design, implementation, data acquisition and analysis phases of the study were explained with the intention to provide a guideline for future studies.

Optical brain monitoring for operator training and mental workload assessment

An accurate measure of mental workload in human operators is a critical element of monitoring and adaptive aiding systems that are designed to improve the efficiency and safety of human-machine systems during critical tasks. Functional near infrared (fNIR) spectroscopy is a field-deployable non-invasive optical brain monitoring technology that provides a measure of cerebral hemodynamics within the prefrontal cortex in response to sensory, motor, or cognitive activation. In this paper, we provide evidence from two studies that fNIR can be used in ecologically valid environments to assess the: 1) mental workload of operators performing standardized (n-back) and complex cognitive tasks (air traffic control--ATC), and 2) development of expertise during practice of complex cognitive and visuomotor tasks (piloting unmanned air vehicles--UAV). Results indicate that fNIR measures are sensitive to mental task load and practice level, and provide evidence of the fNIR deployment in the field for its ability to monitor hemodynamic changes that are associated with relative cognitive workload changes of operators. The methods reported here provide guidance for the development of strategic requirements necessary for the design of complex human-machine interface systems and assist with assessments of human operator performance criteria.

Sliding-window motion artifact rejection for Functional Near-Infrared Spectroscopy

Functional Near-Infrared Spectroscopy (fNIR) is an optical brain monitoring technology that tracks changes in hemodynamic responses within the cortex. fNIR uses specific wavelengths of light, introduced at the scalp, to enable the noninvasive measurement of changes in the relative ratios of deoxygenated hemoglobin (deoxy-Hb) and oxygenated hemoglobin (oxy-Hb) during brain activity. This technology allows the design of portable, safe, affordable, noninvasive, and minimally intrusive monitoring systems that can be used to measure brain activity in natural environments, ambulatory and field conditions. However, for such applications fNIR signals can get prone to noise due to motion of the head. Improving signal quality and reducing noise, can be especially challenging for real time applications. Here, we study motion artifact related noise especially due to poor and changing sensor coupling. We have developed a simple and iterative method that can be used to automate the preprocessing of data to identify segments with such noise for exclusion and this method is also suitable for real time applications.

Toward improved sensorimotor integration and learning using upper-limb prosthetic devices

To harness the increased dexterity and sensing capabilities in advanced prosthetic device designs, amputees will require interfaces supported by novel forms of sensory feedback and novel control paradigms. We are using a motorized elbow brace to feed back grasp forces to the user in the form of extension torques about the elbow. This force display complements myoelectric control of grip closure in which EMG signals are drawn from the biceps muscle. We expect that the action/reaction coupling experienced by the biceps muscle will produce an intuitive paradigm for object manipulation, and we hope to uncover neural correlates to support this hypothesis. In this paper we present results from an experiment in which 7 able-bodied persons attempted to distinguish three objects by stiffness while grasping them under myoelectric control and feeling reaction forces displayed to their elbow. In four conditions (with and without force display, and using biceps myoelectric signals ipsilateral and contralateral to the force display,) ability to correctly identify objects was significantly increased with sensory feedback.