The effect of bipolar bihemispheric tDCS on executive function and working memory abilities

Introduction

Cognitive functioning is central to the ability to learn, problem solve, remember, and use information in a rapid and accurate manner and cognitive abilities are fundamental for communication, autonomy, and quality of life. Transcranial electric stimulation (tES) is a very promising tool shown to improve various motor and cognitive functions. When applied as a direct current stimulus (transcranial direct current stimulation; tDCS) over the dorsolateral pre-frontal cortex (DLPFC), this form of neurostimulation has mixed results regarding its ability to slow cognitive deterioration and potentially enhance cognitive functioning, requiring further investigation. This study set out to comprehensively investigate the effect that anodal and cathodal bipolar bihemispheric tDCS have on executive function and working memory abilities.

Methods

72 healthy young adults were recruited, and each participant was randomly allocated to either a control group (CON), a placebo group (SHAM) or one of two neurostimulation groups (Anodal; A-STIM and Cathodal; C-STIM). All participants undertook cognitive tests (Stroop & N Back) before and after a 30-minute stimulation/ sham/ control protocol.

Results

Overall, our results add further evidence that tDCS may not be as efficacious for enhancing cognitive functioning as it has been shown to be for enhancing motor learning when applied over M1. We also provide evidence that the effect of neurostimulation on cognitive functioning may be moderated by sex, with males demonstrating a benefit from both anodal and cathodal stimulation when considering performance on simple attention trial types within the Stroop task.

Discussion

Considering this finding, we propose a new avenue for tDCS research, that the potential that sex may moderate the efficacy of neurostimulation on cognitive functioning.

Comparing the cognitive performance of action video game players and age-matched controls following a cognitively fatiguing task: A stage 2 registered report

Recent work demonstrates that those who regularly play action video games (AVGs) consistently outperform non-gamer (NG) controls on tests of various cognitive abilities. AVGs place high demands on several cognitive functions and are often engaged with for long periods of time (e.g., over 2 h), predisposing players to experiencing cognitive fatigue. The detrimental effects of cognitive fatigue have been widely studied in various contexts where accurate performance is crucial, including aviation, military, and sport. Even though AVG players may be prone to experiencing cognitive fatigue, this topic has received little research attention to date. In this study, we compared the effect of a cognitively fatiguing task on the subsequent cognitive performance of action video game players and NG control participants. Our results indicated AVGs showed superior spatial working memory and complex attention abilities while showing no difference from NGs on simple attention performance. Additionally, we found that our cognitive fatigue and control interventions did not differentially affect the cognitive performance of AVGs and NGs in this study. This pre-registered study provides evidence that AVGs show superior cognitive abilities in comparison to a non-gaming population, but do not appear more resilient to cognitive fatigue.

M1 transcranial direct current stimulation augments laparoscopic surgical skill acquisition

The acquisition of basic surgical skills is a key component of medical education and trainees in laparoscopic surgery typically begin developing their skills using simulation box trainers. However, despite the advantages of simulation surgical training, access can be difficult for many trainees. One technique that has shown promise to enhance the deliberate practice of motor skills is transcranial electric stimulation (tES). The purpose of this study was to assess the impact of transcranial direct current stimulation (tDCS) on training induced improvements and retention of traditional time and kinematic based laparoscopic surgical skill metrics. Forty-nine medical students were randomly allocated to a neurostimulation or sham group and completed 5 training sessions of a bead transfer and threading laparoscopic task. Participants in both the sham and stimulation groups significantly improved their time and kinematic performance on both tasks following training. Although we did find that participants who received M1 tDCS saw greater performance benefits in response to training on a bead transfer task compared to those receiving sham stimulation no effect of neurostimulation was found for the threading task. This finding raises new questions regarding the effect that motor task complexity has on the efficacy of neurostimulation to augment training induced improvement and contributes to a growing body of research investigating the effects of neurostimulation on the sensory-motor performance of laparoscopic surgical skill.

The effect of computer mouse mass on target acquisition performance among action video gamers

Advances in human performance have shifted research attention from individuals towards understanding the effects that equipment can have on their performance. In esports, the effect of gaming peripherals on performance has only recently been explored. In this study, we investigated the effect of computer mouse mass on gaming skill. 72 video game players performed a target acquisition task, a pertinent composite skill in first-person shooter (FPS) video games, while using computer mice that varied only by their mass (50g, 60g, 90g & 100g). Results showed that participants were 4% faster and 9% more accurate with 50g, 60g, and 90g mice compared to the 100g mouse. They were also 34% more accurate and 14% more precise when using lower control-display gain and preferred lighter mice (50g and 60g) when performing the skill at a lower control-display gain. Taken together, using a lighter mouse at lower sensitivity may augment target acquisition performance among video gamers.

A Random Forest approach to identify metrics that best predict match outcome and player ranking in the esport Rocket League

Notational analysis is a popular tool for understanding what constitutes optimal performance in traditional sports. However, this approach has been seldom used in esports. The popular esport "Rocket League" is an ideal candidate for notational analysis due to the availability of an online repository containing data from millions of matches. The purpose of this study was to use Random Forest models to identify in-match metrics that predicted match outcome (performance indicators or "PIs") and/or in-game player rank (rank indicators or "RIs"). We evaluated match data from 21,588 Rocket League matches involving players from four different ranks. Upon identifying goal difference (GD) as a suitable outcome measure for Rocket League match performance, Random Forest models were used alongside accompanying variable importance methods to identify metrics that were PIs or RIs. We found shots taken, shots conceded, saves made, and time spent goalside of the ball to be the most important PIs, and time spent at supersonic speed, time spent on the ground, shots conceded and time spent goalside of the ball to be the most important RIs. This work is the first to use Random Forest learning algorithms to highlight the most critical PIs and RIs in a prominent esport.

The effect of sleep restriction on cognitive performance in elite cognitive performers: a systematic review

STUDY OBJECTIVES

To synthesize original articles exploring the effects of sleep restriction on cognitive performance specifically for Elite Cognitive Performers, i.e. those who engage in cognitively demanding tasks with critical or safety-critical outcomes in their occupation or area of expertise.

METHODS

Backward snowballing techniques, gray literature searches, and traditional database searches (Embase, MEDLINE, Web of Science, Google Scholar, PSYCinfo, and SportDiscus) were used to obtain relevant articles. A quality assessment was performed, and the risk of training effects was considered. Results were narratively synthesized. Fourteen articles fit the criteria. Cognitive outcomes were divided into three categories defined by whether cognitive demands were "low-salience," "high-salience stable," or "high-salience flexible."

RESULTS

Low-salience tests (i.e. psychomotor vigilance tasks & serial reaction tests), mainly requiring vigilance and rudimentary attentional capacities, were sensitive to sleep restriction, however, this did not necessarily translate to significant performance deficits on low-salience occupation-specific task performance. High-salience cognitive outcomes were typically unaffected unless when cognitive flexibility was required.

CONCLUSIONS

Sleep restriction is of particular concern to occupations whereby individuals perform (1) simple, low-salience tasks or (2) high-salience tasks with demands on the flexible allocation of attention and working memory, with critical or safety-critical outcomes.

Insomnia, sleepiness, anxiety and depression among different types of gamers in African countries

Gaming has increasingly become a part of life in Africa. Currently, no data on gaming disorders or their association with mental disorders exist for African countries. This study for the first time investigated (1) the prevalence of insomnia, excessive daytime sleepiness, anxiety and depression among African gamers, (2) the association between these conditions and gamer types (i.e., non-problematic, engaged, problematic and addicted) and (3) the predictive power of socioeconomic markers (education, age, income, marital status, employment status) on these conditions. 10,566 people from 2 low- (Rwanda, Gabon), 6 lower-middle (Cameroon, Nigeria, Morocco, Tunisia, Senegal, Ivory Coast) and 1 upper-middle income countries (South Africa) completed online questionnaires containing validated measures on insomnia, sleepiness, anxiety, depression and gaming addiction. Results showed our sample of gamers (24 ± 2.8 yrs; 88.64% Male), 30% were addicted, 30% were problematic, 8% were engaged and 32% were non-problematic. Gaming significantly contributed to 86.9% of the variance in insomnia, 82.7% of the variance in daytime sleepiness and 82.3% of the variance in anxiety [p < 0.001]. This study establishes the prevalence of gaming, mood and sleep disorders, in a large African sample. Our results corroborate previous studies, reporting problematic and addicted gamers show poorer health outcomes compared with non-problematic gamers.

The Color-Word Stroop Task Does Not Differentiate Cognitive Inhibition Ability Among Esports Gamers of Varying Expertise

This study set out for the first time to identify whether gamers of low, intermediate, and elite skill level in a prominent esports game, Counter-Strike: Global Offensive, demonstrated increasingly superior performance on a test of a specific cognitive skill (cognitive inhibition). Here we tested low, intermediate, and high ranked gamers and compared their performance on a color-word Stroop Task and also compared the performance of players in each gaming rank group to non-gamers. Contrary to our hypothesis, the Stroop Task did not differentiate significantly gamers of varying expertise. Although, we found that when considering both accuracy and response times, elite gamers performed significantly better than both intermediate and low ranked gamers on the simple choice reaction time condition and both elite and novice gamers performed significantly better than intermediate ranked gamers on the incongruent condition (a measure of cognitive inhibitory ability).

Visual feedback is not necessary for recalibrating the vestibular contribution to the dynamic phase of a perturbation recovery response

Our recent work demonstrated that vision can recalibrate the vestibular signal used to re-establish equilibrium following a platform perturbation. Here, we investigate whether vision provided during a platform perturbation can recalibrate the use of vestibular reafference during the dynamic phase of the perturbation response. Dynamic postural responses were examined during a series of five forward perturbations to the body, while galvanic vestibular stimulation (GVS) selectively altered vestibular feedback and LCD occlusion spectacles controlled visual availability. Responses with and without vision were compared. The presence of GVS caused 1.78 ± 0.19 cm of medio-lateral (ML) body motion toward the anode during the initial 3 s of the dynamic postural response across perturbations. This dynamic ML response was attenuated across perturbations 1-3 independent of visual availability, resulting in a significant reduction of ML center of mass and pressure deviations (p < 0.01, ƞ² = 0.27). That is, the vestibular influence on the ML perturbation response could be altered but vision was not necessary for this adaptation. After removing GVS, the ML response component reversed in direction toward the cathode with a magnitude that was not significantly different to the amount of response attenuation seen when GVS was present (- 0.95 ± 0.19 cm; p = 0.99, ƞ² = 0.00). This suggested that the use of a GVS-altered vestibular signal during dynamic perturbation responses could be recalibrated, but that visual feedback was likely not responsible. Alternative mechanisms to explain the recalibration process are discussed.

eSports: A new window on neurocognitive expertise?

Understanding the neurological changes that take place as expertise develops is a central topic in both cognitive psychology and cognitive neuroscience. Here, we argue that video games, despite previous misconceptions, are an excellent model environment from which one can examine the development of neurocognitive expertise. Of particular relevance we argue is the area of esports, which encompass video/computer games played within the medium of cyberspace competitively and increasingly professionally. The massive scale of participation, controlled environments, structured skill ratings, pervasive social nature, and large repositories of data, together make esports potentially a very fruitful area for scientific research to increase our understanding of a new era of cognitive athletes. This chapter reviews the progress and prospects for esports research with a particular focus on the effects of gaming on neurocognition. We also outline some exciting new avenues and techniques from which we hope to further elucidate the benefits of esports on the brain.

Online visual cues can compensate for deficits in cutaneous feedback from the dorsal ankle joint for the trailing limb but not the leading limb during obstacle crossing

Precise control of the ankle is required to safely clear the ground during walking. Skin input contributes to proprioception about the ankle joint, during both passive movements and level walking. How skin might contribute to proprioceptive control of the ankle during a more complex functional task such as obstacle avoidance is unknown. The purpose of this study was to investigate skin contribution from the dorsum of the ankle joint to safely cross an obstacle, and examine the interaction between vision and skin. It was hypothesized that the lead and trail limbs would be influenced primarily by visual information and skin cues, respectively. Eleven healthy adults crossed an obstacle with either (1) intact sensory input (control) (2) reduced skin input using a topical anesthetic (anesthesia), (3) reduced visual input of the lower half of the visual field (partial vision) or (4) simultaneous reduction of skin and vision (paired). Kinematic measures of phase-dependent changes during these conditions were examined while subjects crossed the obstacle with their anesthetised foot as either the leading or trailing limb. Interestingly, lead limb toe trajectory was significantly affected both by deficits in visual and skin input, although the joint angle strategies differed across these sensory conditions. Subjects increased lead hip flexion with partial vision but increased hip roll with skin anesthesia relative to control. In contrast, trail limb toe trajectory was affected only by visual sensory loss. Overall visual feedback and skin input from the ankle dorsum differentially affect lead and trail limb kinematics to successfully cross an obstacle. Interestingly, it appears vision is not entirely able to compensate for reduced skin input during obstacle crossing.

Vision can recalibrate the vestibular reafference signal used to re-establish postural equilibrium following a platform perturbation

Visuo-vestibular recalibration, in which visual information is used to alter the interpretation of vestibular signals, has been shown to influence both oculomotor control and navigation. Here we investigate whether vision can recalibrate the vestibular feedback used during the re-establishment of equilibrium following a perturbation. The perturbation recovery responses of nine participants were examined following exposure to a period of 11 s of galvanic vestibular stimulation (GVS). During GVS in VISION trials, occlusion spectacles provided 4 s of visual information that enabled participants to correct for the GVS-induced tilt and associate this asymmetric vestibular signal with a visually provided 'upright'. NoVISION trials had no such visual experience. Participants used the visual information to assist in realigning their posture compared to when visual information was not provided (p < 0.01). The initial recovery response to a platform perturbation was not impacted by whether vision had been provided during the preceding GVS, as determined by peak centre of mass and pressure deviations (p = 0.09). However, after using vision to reinterpret the vestibular signal during GVS, final centre of mass and pressure equilibrium positions were significantly shifted compared to trials in which vision was not available (p < 0.01). These findings support previous work identifying a prominent role of vestibular input for re-establishing postural equilibrium following a perturbation. Our work is the first to highlight the capacity for visual feedback to recalibrate the vertical interpretation of vestibular reafference for re-establishing equilibrium following a perturbation. This demonstrates the rapid adaptability of the vestibular reafference signal for postural control.

Baseline skin information from the foot dorsum is used to control lower limb kinematics during level walking

The aim of the current study was to explore the role of dorsal foot skin on the joint kinematics of gait during level walking. Twelve volunteers experienced sensory perturbations with either reduced dorsal skin feedback using topical anesthetic, reduced visual feedback of the lower visual field, or a combination of both cutaneous and visual reductions (paired). The visual condition was introduced to impose a greater reliance on skin input (goggles occluded lower visual field input). Our results showed that a reduction in skin input, alone, resulted in significant angular position changes at both the ankle and knee joints through swing (increased flexion, p < 0.010), despite preservation of minimal toe clearance (MTC; p = 0.908). Conversely, a reduction in lower visual field input resulted in a greater minimal toe clearance affect (MTC; p < 0.001), a slight increase in dorsiflexion at the ankle (p = 0.046), yet no effect on angular position changes for the knee (p = 0.110). The locomotor changes observed following a reduction in cutaneous feedback from the foot dorsum suggest an important role of the skin over this region for the regulation of level ground walking. Interestingly, it appears that these healthy young adults were able to compensate for the reduced skin information while preserving locomotor efficiency via a maintained ground clearance (MTC). Our data also demonstrated an interaction between skin and visual inputs; vision appears to have a less dominant role compared to skin in controlling the joint positions through swing phase of gait. This work is the first to highlight the influence of reduced cutaneous input from the dorsum of the foot on locomotor strategies.