Age-Based Developmental Biomarkers in Eye Movements: A Retrospective Analysis Using Machine Learning.

This study aimed to identify when and how eye movements change across the human lifespan to benchmark developmental biomarkers. The sample size comprised 45,696 participants, ranging in age from 6 to 80 years old (M = 30.39; SD = 17.46). Participants completed six eye movement tests: Circular Smooth Pursuit, Horizontal Smooth Pursuit, Vertical Smooth Pursuit, Horizontal Saccades, Vertical Saccades, and Fixation Stability. These tests examined all four major eye movements (fixations, saccades, pursuits, and vergence) using 89 eye-tracking algorithms. A semi-supervised, self-training, machine learning classifier was used to group the data into age ranges. This classifier resulted in 12 age groups: 6-7, 8-11, 12-14, 15-25, 26-31, 32-38, 39-45, 46-53, 54-60, 61-68, 69-76, and 77-80 years. To provide a descriptive indication of the strength of the self-training classifier, a series of multiple analyses of variance (MANOVA) were conducted on the multivariate effect of the age groups by test set. Each MANOVA revealed a significant multivariate effect on age groups (p < 0.001). Developmental changes in eye movements across age categories were identified. Specifically, similarities were observed between very young and elderly individuals. Middle-aged individuals (30s) generally showed the best eye movement metrics. Clinicians and researchers may use the findings from this study to inform decision-making on patients' health and wellness and guide effective research methodologies.

Elevated Smooth Pursuit Gain in Collegiate Athletes with Sport-related Concussion Immediately Following Injury.

Purpose: Although there is evidence that sport-related concussion (SRC) affects oculomotor function and perceptual ability, experiments are often poorly controlled and are not replicable. This study aims to test the hypothesis that there are decreased values when assessing oculomotor impairment indicating poorer performance in SRC patients. Methods: Fifteen DI athletes presenting with SRC (7 females, 8 males) and 15 student volunteers (CON) (12 females, 3 males) completed a dynamic visual acuity (DVA) task that involved answering the direction of a moving stimulus (Landolt C) while wearing a head-mounted binocular eye tracker. There were 120 trials total with 60 trials presenting at 30º per second and 60 presenting at 90º per second. Various eye movement measurements, including horizontal smooth pursuit eye movements (SPEM) gain and saccadic peak velocity, were analyzed between groups using univariate ANOVAs. Saccade count in SPEM trials, accuracy, and vision were analyzed using Kruskal-Wallis tests. Results: There was no statistical difference in saccadic peak velocity: SRC = 414.7 ± 42º/s, CON = 406.6 ± 40.6º/s. A significant difference was found between SRC patients and healthy controls in horizontal SPEM gain (SRC = 0.9 ± 0.04, CON = 0.86 ± 0.03, F(1,28) = 7.243, P = 0.012) indicating that patients demonstrated compensatory eye movements when tracking the target. There were significantly more saccades in all SPEM trials (P = 0.001). Conclusion: SRCoculomotor deficits manifest as elevated horizontal SPEM gain when assessed within 48 hours of injury and compared to healthy controls within the same age range. SRC demonstrates altered oculomotor ability. While accurate in tracking a stimulus, SRC patients may conduct less controlled eye movements.

An assessment of the clinical relevance of coracoid graft osteolysis following the Latarjet procedure: a clinical and radiological review.

Background: The Latarjet procedure was developed for the treatment of anterior shoulder instability in young, high-demand patients with attritional glenoid bone loss, whose risk of redislocation following primary dislocation may exceed 90%. Coracoid graft osteolysis and prominent screws are commonly observed in late computed tomography (CT) scans of patients who re-present following the procedure, but the clinical relevance of osteolysis in the overall Latarjet cohort is undetermined. We aimed to evaluate clinical and radiological outcomes in patients who underwent the Latarjet procedure, and to determine if severe coracoid graft osteolysis compromised clinical outcomes. Methods: This was a retrospective analysis of patients who underwent the open Latarjet procedure. Patients were invited via an e-questionnaire that contained a Western Ontario Shoulder Instability Index (WOSI), and queried about redislocation and reoperation since index surgery. Preoperative glenoid bone loss was calculated on CT using the best-fit circle method. Osteolysis was graded (0, screw head buried in graft; 1, screw head exposed; 2, threads exposed; 3, complete resorption/severe osteolysis) at the level of the proximal and distal screws respectively, on axial CT scans performed ≥ 12 months postoperatively. Results: Between 2011 and 2022, a single surgeon performed 442 Latarjet procedures. One hundred fifty eight patients responded to the questionnaire at median (interquartile range [IQR]) 44 (27-70) months postoperatively, among whom the median (IQR) WOSI score was 352 (142-666) points (0 = best, 2100 = worst). Recurrent anterior instability occurred in 3/158 (2%) patients. One patient required reoperation for this indication. Among patients who had CT scans ≥ 12 months postoperatively (median [IQR] 40 [29-69] months), 1 patient developed severe osteolysis around both screws (WOSI = 90), 17/62 (27%) patients developed severe osteolysis around 1 screw, all of which were proximal (median [IQR] WOSI = 235 [135-644]), and 44/62 (71%) patients did not develop severe osteolysis around either screw (median [IQR] WOSI = 487 [177-815]). There were no statistically significant differences in WOSI scores between groups based on the presence of severe osteolysis. Conclusion: The Latarjet is reliable procedure that has a low rate of redislocation and reoperation. Severe coracoid graft osteolysis occurs with time, and always affects the proximal graft first. The presence of severe osteolysis did not compromise clinical outcomes.

Integration mapping of cardiac fibroblast single-cell transcriptomes elucidates cellular principles of fibrosis in diverse pathologies.

Single-cell technology has allowed researchers to probe tissue complexity and dynamics at unprecedented depth in health and disease. However, the generation of high-dimensionality single-cell atlases and virtual three-dimensional tissues requires integrated reference maps that harmonize disparate experimental designs, analytical pipelines, and taxonomies. Here, we present a comprehensive single-cell transcriptome integration map of cardiac fibrosis, which underpins pathophysiology in most cardiovascular diseases. Our findings reveal similarity between cardiac fibroblast (CF) identities and dynamics in ischemic versus pressure overload models of cardiomyopathy. We also describe timelines for commitment of activated CFs to proliferation and myofibrogenesis, profibrotic and antifibrotic polarization of myofibroblasts and matrifibrocytes, and CF conservation across mouse and human healthy and diseased hearts. These insights have the potential to inform knowledge-based therapies.

Predicting resilience of migratory birds to environmental change.

The pace and scale of environmental change represent major challenges to many organisms. Animals that move long distances, such as migratory birds, are especially vulnerable to change since they need chains of intact habitat along their migratory routes. Estimating the resilience of such species to environmental changes assists in targeting conservation efforts. We developed a migration modeling framework to predict past (1960s), present (2010s), and future (2060s) optimal migration strategies across five shorebird species (Scolopacidae) within the East Asian-Australasian Flyway, which has seen major habitat deterioration and loss over the last century, and compared these predictions to empirical tracks from the present. Our model captured the migration strategies of the five species and identified the changes in migrations needed to respond to habitat deterioration and climate change. Notably, the larger species, with single or few major stopover sites, need to establish new migration routes and strategies, while smaller species can buffer habitat loss by redistributing their stopover areas to novel or less-used sites. Comparing model predictions with empirical tracks also indicates that larger species with the stronger need for adaptations continue to migrate closer to the optimal routes of the past, before habitat deterioration accelerated. Our study not only quantifies the vulnerability of species in the face of global change but also explicitly reveals the extent of adaptations required to sustain their migrations. This modeling framework provides a tool for conservation planning that can accommodate the future needs of migratory species.

Influence of modified starches on mental performance and physical activity following an exhaustive bout of exercise.

Slow-releasing carbohydrates may delay the effects of fatigue after exhaustive exercise. The purpose of this study was to observe the influence that hydrothermally modified starches (HMS) and traditional maltodextrin (MAL) supplements had on physical endurance and mental performance following exhaustive exercise. Male participants completed a VO2 max and 2 days of cycling sessions using a Velotron ergometer. Cycling sessions were performed at 70% of the VO2 max workload for 150 min. Supplements were consumed 30 min before cycling and during exercise at the 120-min mark (1 g CHO/kg body weight). Brain activity was measured using a Neuroscan 64-channel electroencephalogram cap. Go-no-go and N-back tasks were performed before and after cycling bouts. Blood glucose, lactate, ketones, and urine-specific gravity were measured before, during, and after cycling. VO2 and rate of perceived exertion were recorded in 15-min intervals. Ketones increased significantly more for HMS than MAL from pre- to postcycling measurements (p < 0.05). Reaction times for go-no-go and N-back were faster for HMS postexercise. Event-related potential differences were present in both mental tasks following exhaustive exercise. HMS supplementation decreased the impact of cognitive and physical fatigue postexercise.

Roles of the Red List of Ecosystems in the Kunming-Montreal Global Biodiversity Framework.

The Kunming-Montreal Global Biodiversity Framework (GBF) of the UN Convention on Biological Diversity set the agenda for global aspirations and action to reverse biodiversity loss. The GBF includes an explicit goal for maintaining and restoring biodiversity, encompassing ecosystems, species and genetic diversity (goal A), targets for ecosystem protection and restoration and headline indicators to track progress and guide action1. One of the headline indicators is the Red List of Ecosystems2, the global standard for ecosystem risk assessment. The Red List of Ecosystems provides a systematic framework for collating, analysing and synthesizing data on ecosystems, including their distribution, integrity and risk of collapse3. Here, we examine how it can contribute to implementing the GBF, as well as monitoring progress. We find that the Red List of Ecosystems provides common theory and practical data, while fostering collaboration, cross-sector cooperation and knowledge sharing, with important roles in 16 of the 23 targets. In particular, ecosystem maps, descriptions and risk categories are key to spatial planning for halting loss, restoration and protection (targets 1, 2 and 3). The Red List of Ecosystems is therefore well-placed to aid Parties to the GBF as they assess, plan and act to achieve the targets and goals. We outline future work to further strengthen this potential and improve biodiversity outcomes, including expanding spatial coverage of Red List of Ecosystems assessments and partnerships between practitioners, policy-makers and scientists.

Minimal Detectable Change for the ImPACT Subtests at Baseline.

OBJECTIVE: To establish the minimal detectable change (MDC) of the subtests that comprise the composite scores from remotely administered Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) baselines. METHOD: Remote ImPACT baseline data from 172 (male = 45, female = 127) National Collegiate Athletic Association Division I student-athletes from the 2020 and 2021 athletic preseasons were used to calculate the MDC at the 95%, 90%, and 80% confidence intervals (CIs) for all subtest scores used to generate the four core composite scores and the impulse control composite. RESULTS: The MDCs for the verbal memory subtests at the 95% CI were 10.31 for word memory percent correct, 4.68 for symbol match total correct hidden, and 18.25 for three letters percentage correct. Visual memory subtest MDCs were 19.03 for design memory total percent correct and 4.90 for XO total correct memory. Visual motor speed subtest MDCs were 18.89 for XO total correct interference and 5.40 for three letters average counted correctly. Reaction time (RT) MDCs were 0.12 for XO average correct, 0.95 for symbol match average correct RT, and 0.28 for color match average correct. Impulse control MDCs were 5.97 for XO total incorrect and 1.15 for color match total commissions. One-way repeated measures MANOVA, repeated measures ANOVAs, and Wilcoxon signed-ranks test all suggested no significant difference between any subtests across two remote ImPACT baselines. CONCLUSIONS: The ImPACT subtest scores did not significantly change between athletic seasons. Our study suggests the subtests be evaluated in conjunction with the composite scores to provide additional metrics for clinical interpretation.

Gaze Control and Tactical Decision-Making Under Stress in Active-Duty Police Officers During a Live Use-of-Force Response.

Police officers during dynamic and stressful encounters are required to make rapid decisions that rely on effective decision-making, experience, and intuition. Tactical decision-making is influenced by the officer's capability to recognize critical visual information and estimation of threat. The purpose of the current study is to investigate how visual search patterns using cluster analysis and factors that differentiate expertise (e.g., years of service, tactical training, related experiences) influence tactical decision-making in active-duty police officers (44 active-duty police officers) during high stress, high threat, realistic use of force scenario following a car accident and to examine the relationships between visual search patterns and physiological response (heart rate). A cluster analysis of visual search variables (fixation duration, fixation location difference score, and number of fixations) produced an Efficient Scan and an Inefficient Scan group. Specifically, the Efficient Scan group demonstrated longer total fixation duration and differences in area of interests (AOI) fixation duration compared to the Inefficient Scan group. Despite both groups exhibiting a rise in physiological stress response (HR) throughout the high-stress scenario, the Efficient Scan group had a history of tactical training, improved return fire performance, had higher sleep time total, and demonstrated increased processing efficiency and effective attentional control, due to having a background of increased tactical training.

Virtual Reality Application for Vestibular/Ocular Motor Screening: Current Clinical Protocol Versus a Novel Prototype.

BACKGROUND: Virtual reality (VR) has been explored to improve baseline and postinjury assessments in sport-related concussion (SRC). Some experience symptoms related to VR, unrelated to concussion. This may deter use of vestibular/ocular motor screening (VOMS) using VR. Baseline VR VOMS symptomatology differentiates baseline from overall symptomatology. HYPOTHESIS: There will be no difference between current clinical manual VOMS (MAN), a clinical prototype (PRO), and VR for symptom provocation change score (SPCS) and near point of convergence (NPC) average score in a healthy population and sex differences among the 3 modes of administration. STUDY DESIGN: Cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 688 National Collegiate Athletic Association Division I student-athletes completed VOMS using 3 methods (MAN, N = 111; female athletes, N = 47; male athletes, N = 64; average age, 21 years; PRO, N = 365; female athletes, N = 154; male athletes, N = 211; average age, 21 years; VR, N = 212; female athletes, N = 78; male athletes, N = 134; average age = 20 years) over a 3-year period (2019-2021) during annual baseline testing. Exclusion criteria were as follows: self-reported motion sickness in the past 6 months, existing or previous neurological insult, attention deficit hyperactivity disorder, learning disabilities, or noncorrected vision impairment. Administration of MAN followed the current clinical protocols, PRO used a novel prototype, and VR used an HTC Vive Pro Eye head mounted display. Symptom provocation was compared using Mann-Whitney U tests across each VOMS subtest with total SPCS and NPC average by each method. RESULTS: MAN had significantly (P < 0.01) more baseline SPCS (MAN = 0.466 ± 1.165, PRO = 0.163 ± 0.644, VR = 0.161 ± 0.933) and significantly (P < 0.01) and more SPCS (MAN = 0.396 ± 1.081, PRO = 0.128 ± 0.427, VR = 0.48 ± 0.845) when compared with PRO and VR. NPC average measurements for VR (average, 2.99 ± 0.684 cm) were significantly greater than MAN (average, 2.91 ± 3.35 cm; P < 0.01; Cohen's d = 0.03) and PRO (average, 2.21 ± 1.81 cm; P < 0.01; Cohen's d = 0.57). For sex differences, female athletes reported greater SPCS with PRO (female athletes, 0.29 ± 0.87; male athletes, 0.06 ± 0.29; P < 0.01) but not in VR or MAN. CONCLUSION: Using a VR system to administer the VOMS may not elicit additional symptoms, resulting in fewer false positives and is somewhat stable between sexes. CLINICAL RELEVANCE: VOMS may allow for standardization among administrators and reduce possible false positives.

Assessing between-officer variability in responses to a live-acted deadly force encounter as a window to the effectiveness of training and experience.

We aimed to infer the effectiveness of officers' training and experience by assessing consistency of behavioural responses between them. If officers facing the same scenario respond in similar ways, this implies their use of shared cognition, through acquired in-common tactical knowledge. Officers (n = 42) responded to a live-acted scenario in which an assailant ultimately discharged his weapon. Triangulated camera positions assessed their movement patterns, final positions, and weapon responses relative to when the assailant fired his weapon. We also assessed the officers' visual search and gathered information regarding their experience and rest. Our second aim was to examine sources of variability in the officers' responses. We found extensive variability in all aspects of the response. Experience did not impact spatial or temporal behavioural responses. However, longer hours awake and lower reported rest negatively impacted officers' responses. We conclude that officers had insufficient training and experience to demonstrate in-common knowledge.Practitioner summary: Police officers showed high spatial and temporal variability in response to the same scenario. This implies inadequate tactical training, and is supported by our finding that training and experience did not impact performance. Instead, the officers' variability was constrained by their visual search, and the hours awake before being tested.

Is gaze cuing more like endogenous or exogenous orienting?

People shift their attention in the direction of another person's gaze. This phenomenon, called gaze cuing, shares properties with purely endogenous (i.e., "deliberate") and purely exogenous (i.e., "reflexive") control of spatial attention. For example, as with purely endogenous orienting, gaze cues appear at visual fixation; yet, as with purely exogenous orienting, gaze cues elicit shifts of attention rapidly after their appearance. Prior experiments have shown that when controlled endogenously versus exogenously, the effects of attention upon the processing of targets are dramatically different. Briand and Klein (1987; see also Briand, 1998) showed that endogenous orienting is additive with opportunities for illusory conjunctions, whereas exogenous orienting is interactive. Klein (1994) showed that endogenous orienting is interactive with nonspatial expectancies, whereas exogenous orienting is additive. In the present project, we applied this double-dissociation strategy to attention controlled by gaze cues. In Experiment 1, gaze cuing effects (in accuracy) were additive with opportunities for illusory conjunctions (akin to endogenous control), whereas in Experiment 2, gaze cuing was additive with the nonspatial expectancy effect (akin to exogenous orienting). Therefore, in the nature of its effects upon performance, gaze cuing functions like a hybrid of endogenous and exogenous orienting. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Slippage of the attentional beam when searching in space and in time.

"Slippage" of attention in time and space has been studied separately, using visual search (e.g., Snyder, 1972) and rapid serial visual presentation (RSVP) (e.g., McLean, Broadbent, & Broadbent, 1982). The primary purpose of the current study was to see if we could replicate these findings of slippage and if we did, to use individual differences to explore relationships between slippage in the temporal and spatial domains. The participants identified and localized targets in visual search and in RSVP sequences. In Experiment 1, we used visual search and RSVP tasks closely replicating the methods of Snyder and McLean et al. In Experiment 2, we closely equated the two tasks as far as possible while maintaining the crucial space/time difference. Consistent with the previous studies, and reflecting binding errors (or slippage) in both space and time, erroneously reported identities were predominantly from items adjacent to the targets. Correlations between measures of the slippage in space (visual search) and time (RSVP) were near zero, suggesting that different attentional 'beams' bind features in space and time, a possibility that is consistent with other behavioural as well as neuropsychological evidence.

Preliminary Examination of Guardian Cap Head Impact Kinematics Using Instrumented Mouthguards.

CONTEXT: Guardian Caps (GCs) are currently the most popular external helmet-add on designed to reduce the head impact magnitude experienced by American football players. GCs have been endorsed by influential professional organizations, however few studies evaluating the efficacy of GCs are publicly available. OBJECTIVE: The objective of this study is to present preliminary on-field head kinematics data for NCAA Division I American football players using instrumented mouthguards through closely matched pre-season workouts both with and without GCs. DESIGN: Case Series. SETTING: The study took place during the 2022 American football pre-season. PATIENTS OR OTHER PARTICIPANTS: 25 Male NCAA Division I student-athletes participating in American football completed some portion of the 6 workouts included in this study. Of the 25 total participants, 7 completed all 6 workouts using their instrumented mouthguards. MAIN OUTCOME MEASURE(S): The peak linear acceleration (PLA), peak angular acceleration (PAA) and total impacts were collected using instrumented mouthguards (iMG) during 3 pre-season workouts using traditional helmets (TRAD), and 3 with Guardian Caps used in additional to a traditional helmet (GC). The TRAD and GC values for PLA, PAA and total impacts were analyzed using ANOVAs. RESULTS: There was no significant difference between the collapsed mean values for the entire sample between TRAD and GC for PLA (TRAD=16.3±2.0, GC=17.2±3.3Gs; p=0.20), PAA (TRAD=992.1±209.2, GC=1029.4±261.1rad/s2; p=0.51 and the total amount of impacts (TRAD=9.3±4.7, GC=9.7±5.7; p=0.72). Similarly, no difference was observed between TRAD and GC for PLA (TRAD=16.1±1.2, GC=17.2±2.79Gs; p=0.32), PAA (TRAD=951.2±95.4, GC=1038.0±166.8rad/s2; p=0.29 and total impacts (TRAD=9.6±4.2, GC=9.7±5.04s; p=0.32) between sessions for the7 repeated players. CONCLUSIONS: These data suggest no difference in head kinematics data (PLA, PAA and total impacts) when GCs are worn. This study suggests GCs may not be effective in reducing the magnitude of head impacts experienced by NCAA Division I American football players.

Widespread retreat of coastal habitat is likely at warming levels above 1.5 °C.

Several coastal ecosystems-most notably mangroves and tidal marshes-exhibit biogenic feedbacks that are facilitating adjustment to relative sea-level rise (RSLR), including the sequestration of carbon and the trapping of mineral sediment1. The stability of reef-top habitats under RSLR is similarly linked to reef-derived sediment accumulation and the vertical accretion of protective coral reefs2. The persistence of these ecosystems under high rates of RSLR is contested3. Here we show that the probability of vertical adjustment to RSLR inferred from palaeo-stratigraphic observations aligns with contemporary in situ survey measurements. A deficit between tidal marsh and mangrove adjustment and RSLR is likely at 4 mm yr-1 and highly likely at 7 mm yr-1 of RSLR. As rates of RSLR exceed 7 mm yr-1, the probability that reef islands destabilize through increased shoreline erosion and wave over-topping increases. Increased global warming from 1.5 °C to 2.0 °C would double the area of mapped tidal marsh exposed to 4 mm yr-1 of RSLR by between 2080 and 2100. With 3 °C of warming, nearly all the world's mangrove forests and coral reef islands and almost 40% of mapped tidal marshes are estimated to be exposed to RSLR of at least 7 mm yr-1. Meeting the Paris agreement targets would minimize disruption to coastal ecosystems.

Using Solution History to Control Hydrogel Properties of a Perylene Bisimide.

pH dependence on water soluble aggregates is well-known in the field of low molecular weight gelators (LMWGs), with different aggregates sometimes having very different properties depending on their final pH. This aggregation determines their applications and performance. Here, we investigate the pH dependence of perylene bisimide gels; initially solutions are formed at a high pH and gels form as the pH is decreased. We find it is not only the final pH but also the starting pH that can impact the resulting gel. We use small angle neutron scattering (SANS), rheology, 1 H NMR spectroscopy and absorption spectroscopy to examine the effect of starting pH on gelation kinetics and final gel properties. Adjusting the solution from pH 9 (where there are few or no aggregates) to pH 6 results in the formation of different worm-like micelles than the ones directly formed at pH 6, leading to again gels with different mechanical properties. This work highlights the importance of controlling the pH of solutions before gelation, but also opens up more possible morphologies and therefore more properties from the same molecule.

Preliminary Examination of Guardian Cap Head Impact Data Using Instrumented Mouthguards.

Purpose The objective of this study is to present preliminary on-field head kinematics data for NCAA Division I American football players through closely matched pre-season workouts both with and without Guardian Caps (GCs). Methods 42 NCAA Division I American football players wore instrumented mouthguards (iMMs) for 6 closely matched workouts, 3 in traditional helmets (PRE) and 3 with GCs (POST) affixed to the exterior of their helmets. This includes 7 players who had consistent data through all workouts. Results There was no significant difference between the collapsed mean values for the entire sample between PRE and POST for peak linear acceleration (PLA) (PRE=16.3, POST=17.2Gs; p=0.20), Peak Angular Acceleration (PAA) (PRE=992.1, POST=1029.4rad/s2; p=0.51 and the total amount of impacts (PRE=9.3, POST=9.7; p=0.72). Similarly, no difference was observed between PRE and POST for PLA (PRE=16.1, POST=17.2Gs; p=0.32), PAA (PRE=951.2, POST=1038.0rad/s2; p=0.29 and total impacts (PRE=9.6, POST=9.7; p=0.32) between sessions for the 7 repeated players. Conclusion These data suggest no difference in head kinematics data (PLA, PAA and total impacts) when GCs are worn. This study suggests GCs are not effective in reducing the magnitude of head impacts experienced by NCAA Division I American football players.

Concussed Neural Signature is Substantially Different than Fatigue Neural Signature in Non-concussed Controls.

Traumatic brain injuries can result in short-lived and long-lasting neurological impairment. Identifying the correct recovery timeframe is challenging, as balance-based metrics may be negatively impacted if testing is performed soon after exercise. Thirty-two healthy controls and seventeen concussed individuals performed a series of balance challenges, including virtual reality optical flow perturbation. The control group completed a backpacking protocol to induce moderate fatigue. Concussed participants had lower spectral power in the motor cortex and central sulcus when compared to fatigued controls. Moreover, concussed participants experienced a decrease in overall theta band spectral power while fatigued controls showed an increase in theta band spectral power. This neural signature may be useful to distinguish between concussed and non-concussed fatigued participants in future assessments.

Theta tACS impairs episodic memory more than tDCS.

Episodic memory deficits are a common consequence of aging and are associated with a number of neurodegenerative disorders (e.g., Alzheimer's disease). Given the importance of episodic memory, a great deal of research has investigated how we can improve memory performance. Transcranial electrical stimulation (TES) represents a promising tool for memory enhancement but the optimal stimulation parameters that reliably boost memory are yet to be determined. In our double-blind, randomised, sham-controlled study, 42 healthy adults (36 females; 23.3 ± 7.7 years of age) received anodal transcranial direct current stimulation (tDCS), theta transcranial alternating current stimulation (tACS) and sham stimulation during a list-learning task, over three separate sessions. Stimulation was applied over the left temporal lobe, as encoding and recall of information is typically associated with mesial temporal lobe structures (e.g., the hippocampus and entorhinal cortex). We measured word recall within each stimulation session, as well as the average number of intrusion and repetition errors. In terms of word recall, participants recalled fewer words during tDCS and tACS, compared to sham stimulation, and significantly fewer words recalled during tACS compared with tDCS. Significantly more memory errors were also made during tACS compared with sham stimulation. Overall, our findings suggest that TES has a deleterious effect on memory processes when applied to the left temporal lobe.