The Effect of Heart Rate Variability Biofeedback on Basketball Performance Tests

The purpose of this study is to investigate the effects of 10-week heart rate variability biofeedback training on basketball skills, free throws, and heart rate variability parameters. Twenty-four basketball players (experimental, n = 12 and control, n = 12) aged 18-24 years volunteered to participate in this study. The experimental group participated in a 10-week heart rate variability biofeedback and basketball training program, while the control group only participated in the 10-week basketball training session. Basketball free-throw performance, basketball skills, and heart rate variability tests were conducted on the experimental and control groups before and after the 10-week intervention. Consequently, we discovered that basketball free-throw performance, breathing frequency, and heart rate variability parameters, which reflect vagal modulation of parasympathetic activity, improved in participants who underwent the 10-week heart rate variability biofeedback and basketball training, and not in those who took basketball training only. Our findings propose that heart rate variability biofeedback, alongside basketball workouts, can contribute to better basketball free-throw performance potentially through improved autonomic nervous system functioning.

Daily biofeedback to modulate heart rate oscillations affects structural volume in hippocampal subregions targeted by the locus coeruleus in older adults but not younger adults

Using data from a clinical trial, we tested the hypothesis that daily sessions modulating heart rate oscillations affect older adults' volume of a region-of-interest (ROI) comprised of adjacent hippocampal subregions with relatively strong locus coeruleus (LC) noradrenergic input. Younger and older adults were randomly assigned to one of two daily biofeedback practices for 5 weeks: (1) engage in slow-paced breathing to increase the amplitude of oscillations in heart rate at their breathing frequency (Osc+); (2) engage in self-selected strategies to decrease heart rate oscillations (Osc-). The interventions did not significantly affect younger adults' hippocampal volume. Among older adults, the two conditions affected volume in the LC-targeted hippocampal ROI differentially as reflected in a significant condition × time-point interaction on ROI volume. These condition differences were driven by opposing changes in the two conditions (increased volume in Osc+ and decreased volume in Osc-) and were mediated by the degree of heart rate oscillation during training sessions.

Visualization, Self-Efficacy, and Locus of Control in a Virtual Reality Biofeedback Video Game for Anxiety Regulation

The current study aimed to identify specific feedback mechanics and psychological processes that may contribute to positive outcomes in biofeedback applications for anxiety regulation. Specifically, using a dismantling study design, the unique impact of visualizations that directly mirror users' breathing was examined in relation to anxiety regulation as well as locus of control and self-efficacy. Following an anxiety induction, participants (N = 67) were randomly assigned to play one of two variations of a biofeedback video game. In both versions, players' in-game movement was contingent on their breathing; however, the experimental condition additionally included visualizations that directly mirrored players' breathing. Changes in self-reported state anxiety and physiological arousal were measured as well as the level of internal control and self-efficacy participants experienced while playing the game. Results showed that all participants were able to effectively reduce their anxiety and arousal, but no condition differences were found. Implementing mirroring visualizations did not contribute to individuals' ability to self-regulate nor their self-efficacy or locus of control above and beyond receiving feedback based on their in-game movement. Overall, individuals who experienced higher self-efficacy and a stronger internal locus of control were better able to regulate their anxiety, but no clear links were found with changes in self-reported physiological arousal. In light of these results, we recommend the continued exploration of the role of specific design choices and intervention components as well as underlying mechanisms of change in biofeedback interventions, especially pertaining to how individuals perceive themselves and their ability to change.

Efficacy of Electromyographic Biofeedback in Muscle Recovery after Meniscectomy in Soccer Players

Electromyographic biofeedback (EMG-BF) is a therapeutic technique that has been used successfully in the rehabilitation of injuries. Although it has been applied to athletes, its use in this field is not very widespread. The objective of this study is to analyze its effectiveness in the recovery of electromyographic activity of the quadriceps after meniscectomy, evaluated through isometric contraction of the vastus lateralis. The sample comprised ten professional footballers in the Spanish League (2nd Division A) who had previously suffered a meniscus injury in their knee and had undergone a meniscectomy. The intervention consisted of EMG-BF treatment lasting between 6 and 10 sessions. The electromyographic signal was recorded using a Thought Technology ProComp Infiniti 8-channel biofeedback unit with a sampling rate of 2048 samples/second. For each session, a within-subject ABA design of 6 or 10 trials per session was used, with three pre- and three post-measures, which determined the gain for each session. The results indicated (1) improvements in all cases, (2) EMG-BF was effective, (3) the working model was statistically significant with an explained variance of between 67% and 75%, and (4) the generalizability analysis showed that the results are reliable and generalizable. The results indicate that EMG-BF is effective in neuromuscular rehabilitation after this type of intervention.

My Life in HRV Biofeedback Research

This paper reviews the published work of me along with my students and close colleagues on the topic of heart rate variability biofeedback (HRVB). It includes early research by Vaschillo documenting resonance characteristics of the baroreflex system that causes large oscillations in heart rate when breathing at resonance frequency, research on heart rate variability as a marker of parasympathetic stress response in asthma, and HRVB as a treatment for asthma and depression. Many questions about HRVB remain unresolved, and important questions for future research are listed.

Effect of a Biofeedback Intervention on Heart Rate Variability in Individuals With Panic Disorder: A Randomized Controlled Trial

OBJECTIVE

Some individuals with panic disorder (PD) display reduced heart rate variability (HRV), which may result in an increased risk of cardiovascular mortality. Heart rate variability-biofeedback (HRV-BF) training has been shown to improve the modulation of the autonomic activity. Therefore, this randomized controlled trial was conducted to investigate the effect of a 4-week HRV-BF intervention in individuals with PD. HRV-BF training improved the modulation of the autonomic activity. Therefore, with this randomized controlled trial, we aimed to investigate the effect of a 4-week HRV-BF intervention in people with PD.

METHODS

Thirty-six women and 16 men with PD (mean age = 35.85 [15.60] years) were randomly allocated either to HRV-BF with 0.1-Hz breathing as intervention group or to HRV-Sham-BF as active control group. HRV-BF was performed for 4 weeks, whereas HRV was measured both during a short-term resting condition and during a paced breathing condition before and after intervention.

RESULTS

HRV-BF with 0.1-Hz breathing increased HRV and reduced panic symptoms in individuals with PD. HRV-BF with 0.1-Hz breathing demonstrated an increase in the time and frequency domain parameters of HRV during the short-term resting condition (ΔPost-Pre root mean square successive differences: 5.87 [14.03] milliseconds; ΔPost-Pre standard deviation of all NN intervals: 11.63 [17.06] milliseconds; ΔPost-Pre total power: 464.88 [1825.47] milliseconds2; ΔPost-Pre power in low-frequency range 0.04-0.15 Hz: 312.73 [592.71] milliseconds2), a decrease in the heart rate during the paced breathing condition (ΔPost-Pre: -5.87 [9.14] beats/min), and a decrease in the Panic and Agoraphobia Scale (ΔPost-Pre: -3.64 [6.30]). There was no intervention effect in the HRV-Sham-BF group.

CONCLUSIONS

HRV-BF as a noninvasive and nonpharmacological treatment seems to be an important intervention option to improve reduced HRV and decrease panic symptoms in individuals with PD. Future studies are needed to establish whether these effects translate to reductions in the risk of cardiovascular disease in PD.

Asymmetric Frequency-Specific Feedforward and Feedback Information Flow between Hippocampus and Prefrontal Cortex during Verbal Memory Encoding and Recall

Hippocampus and prefrontal cortex (PFC) circuits are thought to play a prominent role in human episodic memory, but the precise nature, and electrophysiological basis, of directed information flow between these regions and their role in verbal memory formation has remained elusive. Here we investigate nonlinear causal interactions between hippocampus and lateral PFC using intracranial EEG recordings (26 participants, 16 females) during verbal memory encoding and recall tasks. Direction-specific information theoretic analysis revealed higher causal information flow from the hippocampus to PFC than in the reverse direction. Crucially, this pattern was observed during both memory encoding and recall, and the strength of causal interactions was significantly greater during memory task performance than resting baseline. Further analyses revealed frequency specificity of interactions with greater causal information flow from hippocampus to the PFC in the delta-theta frequency band (0.5-8 Hz); in contrast, PFC to hippocampus causal information flow were stronger in the beta band (12-30 Hz). Across all hippocampus-PFC electrode pairs, propagation delay between the source and target signals was estimated to be 17.7 ms, which is physiologically meaningful and corresponds to directional signal interactions on a timescale consistent with monosynaptic influence. Our findings identify distinct asymmetric feedforward and feedback signaling mechanisms between the hippocampus and PFC and their dissociable roles in memory recall, demonstrate that these regions preferentially use different frequency channels, and provide novel insights into the electrophysiological basis of directed information flow during episodic memory formation in the human brain.SIGNIFICANCE STATEMENT Hippocampal-PFC circuits play a critical role in episodic memory in rodents, nonhuman primates, and humans. Investigations using noninvasive fMRI techniques have provided insights into coactivation of the hippocampus and PFC during memory formation; however, the electrophysiological basis of dynamic causal hippocampal-PFC interactions in the human brain is poorly understood. Here, we use data from a large cohort of intracranial EEG recordings to investigate the neurophysiological underpinnings of asymmetric feedforward and feedback hippocampal-PFC interactions and their nonlinear causal dynamics during both episodic memory encoding and recall. Our findings provide novel insights into the electrophysiological basis of directed bottom-up and top-down information flow during episodic memory formation in the human brain.

A direct interareal feedback-to-feedforward circuit in primate visual cortex

The mammalian sensory neocortex consists of hierarchically organized areas reciprocally connected via feedforward (FF) and feedback (FB) circuits. Several theories of hierarchical computation ascribe the bulk of the computational work of the cortex to looped FF-FB circuits between pairs of cortical areas. However, whether such corticocortical loops exist remains unclear. In higher mammals, individual FF-projection neurons send afferents almost exclusively to a single higher-level area. However, it is unclear whether FB-projection neurons show similar area-specificity, and whether they influence FF-projection neurons directly or indirectly. Using viral-mediated monosynaptic circuit tracing in macaque primary visual cortex (V1), we show that V1 neurons sending FF projections to area V2 receive monosynaptic FB inputs from V2, but not other V1-projecting areas. We also find monosynaptic FB-to-FB neuron contacts as a second motif of FB connectivity. Our results support the existence of FF-FB loops in primate cortex, and suggest that FB can rapidly and selectively influence the activity of incoming FF signals.

Heart Rate and Breathing Are Not Always in Phase During Resonance Frequency Breathing

For many years it has been an axiom among practitioners of heart rate variability biofeedback that heart rate and breathing vary in phase with each other when people do resonance frequency breathing. When people breathe at the frequency of the baroreflex system, about 0.1 Hz, heart rate and blood pressure have been found to oscillate 180° out of phase, while heart rate and breathing are in phase (zero-degree phase). Thus breathing stimulates the baroreflex by augmenting the baroreflex response with each breath, an effect that is magnified by resonance properties in the baroreflex system. The original data on these relationships came from a study of highly athletic healthy young people. To test this relationship we analyzed phase relationship data between cardiac interbeat interval and breathing during 5-min periods of resonance frequency breathing among 24 adults from a recent study of heart rate variability biofeedback to treat adults with mild to moderate currently symptomatic asthma, ages between 18 and 70. For the specific frequency near 0.1 Hz with the highest amplitude of HRV we calculated coherence and phase between cardiac interbeat interval (IBI) and the respiration curve using the WinCPRS program. Among records with coherence > 0.8, we found a phase relationship of 109° rather than the expected 180°, with IBI changes leading breathing. We computed Spearman correlation coefficients between phase and various subject characteristics, including age, gender, height, and asthma severity. We found no relationship between phase and gender, height, or asthma physiology or symptoms. However, when controlled for gender and height, we found a moderate size significant correlation between phase and age, with younger participants having values closer to 180°, r = 0.47, p < 0.03. It is possible that cardiovascular characteristics of older people affect the phase relationship. Despite the deviation from the in-phase relationship among older individuals, breathing nevertheless stimulated the baroreflex and produced high-amplitude heart rate oscillations. Implications are discussed for HRV biofeedback training protocols. Replication in a healthy population is needed in order to determine the universality of these findings.

Laminar-specific cortico-cortical loops in mouse visual cortex

Many theories propose recurrent interactions across the cortical hierarchy, but it is unclear if cortical circuits are selectively wired to implement looped computations. Using subcellular channelrhodopsin-2-assisted circuit mapping in mouse visual cortex, we compared feedforward (FF) or feedback (FB) cortico-cortical (CC) synaptic input to cells projecting back to the input source (looped neurons) with cells projecting to a different cortical or subcortical area. FF and FB afferents showed similar cell-type selectivity, making stronger connections with looped neurons than with other projection types in layer (L)5 and L6, but not in L2/3, resulting in selective modulation of activity in looped neurons. In most cases, stronger connections in looped L5 neurons were located on their apical tufts, but not on their perisomatic dendrites. Our results reveal that CC connections are selectively wired to form monosynaptic excitatory loops and support a differential role of supragranular and infragranular neurons in hierarchical recurrent computations.

Comparing Effectiveness of HRV-Biofeedback and Mindfulness for Workplace Stress Reduction: A Randomized Controlled Trial

Psychophysiological disorders due to work-related stress continue to be highly costly for health systems and approaches for cost-effective and easily accessible interventions are much needed. Both heart rate variability-biofeedback (HRV-Bfb) and mindfulness-based interventions (MBI) have been empirically shown to reduce stress. This study compares these two interventions in the work context to a wait-list-control-group (WLC). In this three-armed randomized controlled trial (RCT), 69 healthy adults employed in the same organization were randomized to participate in HRV-Bfb, MBI or the WLC. Participants were assessed for psychophysiological parameters of stress (stress perception, coping, HRV parameters and cortisol) and stress related symptoms (depressive symptoms, psychological wellbeing, mindfulness and self-compassion). Participants trained using either HRV-Bfb or MBI for 6 weeks on a daily basis. Outcomes were assessed at baseline, after the intervention and at follow-up 12 weeks later. Results did not show any statistically significant differences between HRV-Bfb and MBI groups, and neither of the intervention groups (IGs) differed from the WLC. Findings suggest an overall reduction in stress for all groups, including the WLC, with mostly small to medium effect sizes. However, it is important to note that participants with higher baseline stress levels might benefit more from mindfulness and biofeedback-based stress reduction interventions. The results have to be interpreted with caution due to the relatively small sample size. MBI might have a slightly stronger effect on stress reduction in comparison to HRV-Bfb, as suggested by the effect sizes. This study highlights issues and challenges of the implementation of such interventions in corporate health management.

Development and Pilot Test of a Virtual Reality Respiratory Biofeedback Approach

Breathing exercises with biofeedback have benefits over breathing exercises without biofeedback. However, the traditional measurement of respiratory signals that is required as part of feeding back the breath incurs high cost and effort. We propose a novel virtual reality (VR) based approach to respiratory biofeedback that utilizes the positionally tracked hand controllers integrated into modern VR systems to capture and feedback the respiration-induced abdominal movements. In a randomized controlled laboratory study, we investigated the feasibility and efficacy of the developed biofeedback algorithm. In total, 72 participants performed a short breathing exercise in VR with or without respiratory biofeedback. The feedback integration resulted in a satisfactory user experience, a heightened breath awareness, a greater focus on slow diaphragmatic breathing and an increased respiratory sinus arrhythmia. This evidences that the novel biofeedback approach is low-cost, unobtrusive, usable and effective in increasing breath awareness and promoting slow diaphragmatic breathing in the context of VR-based breathing exercises. Future studies need to investigate the broader applicability and long-term effects.

Movement pattern biofeedback training after total knee arthroplasty: Randomized clinical trial protocol

INTRODUCTION

Total knee arthroplasty (TKA) reduces joint symptoms, but habitual movement compensations persist years after surgery. Preliminary research on movement training interventions have signaled initial efficacy for remediating movement compensations and restoring knee joint loading symmetry during dynamic functional tasks after TKA. The purpose of this clinical trial is to determine if physical rehabilitation that includes movement training restores healthy movement patterns after TKA and reduces the risk of osteoarthritis (OA) progression in the contralateral knee.

METHODS/DESIGN

150 participants will be enrolled into this randomized controlled trial. Participants will be randomly allocated to one of two dose-equivalent treatment groups: standard rehabilitation plus movement training (MOVE) or standard rehabilitation without movement training (CONTROL). Movement training will promote between-limb symmetry and surgical knee loading during activity-based exercises. Movement training strategies will include real-time biofeedback using in-shoe pressure sensors and verbal, visual, and tactile cues from the physical therapist. The primary outcome will be change in peak knee extension moment in the surgical knee during walking, from before surgery to six months after surgery. Secondary outcomes will include lower extremity movement symmetry during functional tasks, physical function, quadriceps strength, range of motion, satisfaction, adherence, contralateral knee OA progression, and incidence of contralateral TKA.

DISCUSSION

This study will provide insights into the efficacy of movement training after unilateral TKA, along with mechanisms for optimizing long-term physical function and minimizing negative sequelae of compensatory movement patterns.

Individual predictors of response to biofeedback training for second-language production

While recent research suggests that visual biofeedback can facilitate speech production training in clinical populations and second language (L2) learners, individual learners' responsiveness to biofeedback is highly variable. This study investigated the hypothesis that the type of biofeedback provided, visual-acoustic versus ultrasound, could interact with individuals' acuity in auditory and somatosensory domains. Specifically, it was hypothesized that learners with lower acuity in a sensory domain would show greater learning in response to biofeedback targeting that domain. Production variability and phonological awareness were also investigated as predictors. Sixty female native speakers of English received 30 min of training, randomly assigned to feature visual-acoustic or ultrasound biofeedback, for each of two Mandarin vowels. On average, participants showed a moderate magnitude of improvement (decrease in Euclidean distance from a native-speaker target) across both vowels and biofeedback conditions. The hypothesis of an interaction between sensory acuity and biofeedback type was not supported, but phonological awareness and production variability were predictive of learning gains, consistent with previous research. Specifically, high phonological awareness and low production variability post-training were associated with better outcomes, although these effects were mediated by vowel target. This line of research could have implications for personalized learning in both L2 pedagogy and clinical practice.

Influencing lumbar posture through real-time biofeedback and its effects on the kinematics and kinetics of a repetitive lifting task

BACKGROUND

Repetitive, flexed lumbar postures are a risk factor associated with low back injuries. Young, novice workers involved in manual handling also appear at increased risk of injury. The evidence for the effectiveness of postural biofeedback as an intervention approach is lacking, particularly for repetitive, fatiguing tasks.

RESEARCH QUESTION

How does real-time lumbosacral (LS) postural biofeedback modify the kinematics and kinetics of repetitive lifting and the risk of low back injury?

METHODS

Thirty-four participants were randomly allocated to two groups: biofeedback (BF) and non-biofeedback (NBF). Participants repetitively lifted a 13 kg box at 10 lifts per minute for up to 20 min. Real-time biofeedback of LS posture occurred when flexion exceeded 80% maximum. Three-dimensional motion analysis and ground reaction forces enabled estimates of joint kinematics and kinetics. Rating of perceived exertion (RPE) was measured throughout.

RESULTS

The BF group adopted significantly less peak lumbosacral flexion (LSF) over the 20 min when compared to the NBF group, which resulted in a significant reduction in LS passive resistance forces. This was accompanied by increased peak hip and knee joint angular velocities in the BF group. Lower limb moments did not significantly differ between groups. Feedback provided to participants diminished beyond 10 min and subjective perceptions of physical exertion were lower in the BF group.

SIGNIFICANCE

Biofeedback of lumbosacral posture enabled participants to make changes in LSF that appear beneficial in reducing the risk of low back injury during repetitive lifting. Accompanying behavioural adaptations did not negatively impact on physical exertion or lower limb joint moments. Biofeedback of LS posture offers a potential preventative and treatment adjunct to educate handlers about their lifting posture. This could be particularly important for young, inexperienced workers employed in repetitive manual handling who appear at increased risk of back injury.

The sonic instructor: A music-based biofeedback system for improving weightlifting technique

In this study, we assumed that correct functional movements for weightlifting can be learned with the help of a music-based biofeedback system. We compared musical feedback with verbal feedback from experienced trainers using two independent groups. The focus was on one specific movement called deadlift. Physical parameters under considerations were the spine (i.e. loss of midline stability resulting in flexion) and the forward displacement of the barbell during the repetitions relative to the mid-foot. We recruited 31 recreational weight lifters (21-42 years of age). Results revealed that both feedback types are effective in improving the movements for deadlift. No significant differences were found across the two feedback types, neither in terms of movement, nor in terms of clarity and motivation. The results suggest that the proposed feedback system is a valid tool for technology-aided training and self-training practices.

Clinical validation of a non-invasive electrodermal biofeedback device useful for reducing chronic perceived pain and systemic inflammation

BACKGROUND

This study was performed to evaluate the potential clinical usefulness of a new non-invasive electrodermal biofeedback device in reducing perceived pain levels and chronic systemic inflammation.

MATERIALS AND METHODS

This multicenter study was designed and coordinated by BioTekna, included 20 general practice medical centers, took place between June 2010 and January 2011, and was validated clinically at the National and Kapodistrian University of Athens, Greece. The study participants were 1015 Caucasian men (401) and women (614), while the placebo-treated controls were 950 Caucasian men (500) and women (450). Patients were aged between 30 and 86 years (average age about 50 years) and all suffered from chronic pain and other medically unexplained symptoms (MUS). The RegMatEx electrodermal biofeedback device (brand BioTekna - Biomedical Technologies, Marcon, Venice, Italy) was used to evaluate the clinical efficacy of electrodermal biofeedback in reducing the level of pain perceived by decreasing the chronic systemic inflammation of the subjects. All subjects received 6 × 30 min sessions of electrodermal or placebo biofeedback given twice a week over 3 weeks. Perceived pain was evaluated using the Numeric Rating Scale (NRS) for pain, while systemic inflammation was examined with measurements of morning circulating C-reactive protein (CRP) concentrations.

RESULTS

Perceived pain in the treatment group was significantly lessened in the NRS scale (p < 005), while circulating CRP concentrations were also decreased (p < 0.05). Parallel placebo studies showed no changes in perceived pain or morning serum CRP concentrations.

DISCUSSION

Use of the electrodermal biofeedback RegMatEx device was associated with reduced pain perception and decreased chronic systemic inflammation, with stability over time. This did not occur in the placebo-treated group. The symptomatology of the treated patients significantly improved in terms of pain relief as shown on the NRS scale, and this was accompanied by reported improvements in mobility, mood, and quality of life.

CONCLUSIONS

The RegMatEx electrodermal biofeedback procedure is a non-invasive and easy to use therapeutic method, free of side effects, with high patient acceptability, excellent efficacy, and duration of effect, and, hence, a valuable tool in the treatment of chronic pain and inflammation.

Advanced Spatially Specific Neurofeedback for Symptoms of Depression and Its Electroencephalographic Correlates

BACKGROUND

Biofeedback is a type of neurofeedback that delivers a graphical knowledge rich in multimedia for the brain waves and produces a feedback signal on brain activity using the multimedia skills of computers and, thus, teaches self-regulation. It has been examined as potential treatment in recent years.

PRIMARY STUDY OBJECTIVE

The aim of the present study was to recognize variations in symptoms of depression in terms of electroencephalogram (EEG) neuronal mechanisms underlying quantitative electroencephalography (QEEG) neurofeedback.

METHODS

An analytical study is presented that describes effective results for symptoms of depression corresponding to z-score standardized low-resolution electromagnetic tomography (sLORETA) neurofeeedback training.

PARTICIPANTS

The pre and post Neurofeedback EEG changes were analyzed for the EEG data corresponding to single subject whose primary complaint was depressive mood.

INTERVENTION

The z score sLORETA neurofeedback was concluded for total of 16 sessions. Where the protocol included surface z score training followed by sLORETA z- score training with identified region of interest.

PRIMARY OUTCOME MEASURES

This investigation was focused on examining the changes in brain activities for 16 sessions of neurofeedback using the EEG measures of relative power variations in frequency bands, frontal alpha asymmetry, and QEEG analysis of EEG brain waves.

RESULTS

Even though impressive results were observed for neurofeedback in terms of power variations and QEEG analysis, no clear conclusions could be made about frontal alpha variations. Augmented alpha activity and reduced beta activity were observed, which accounts for the relaxation. A clear linear relation is noticeable for changes across the sessions as compared within changes within the sessions. Also, low-resolution electromagnetic tomography (LORETA) showed current sources improved toward a normative range, specifically in the insula and anterior cingulate. However, frontal alpha symmetry variations produced no significant conclusions. This may be due to medication effects, the single case design of research, to unsatisfactory denoising techniques followed in signal processing.

CONCLUSION

This exploratory study in terms of EEG measurements may eventually expand the eminence of neurofeedback as an alternative to treatment of depression. The present report demonstrates the need to further investigate tomographic neurofeedback with a more rigorous randomized controlled trial with a large effect size and using other EEG measures.

Voluntary Control of Agonist Premotor Silence Preceding Limb Movements of Maximal Effort

The ability to gain voluntary control over agonist premotor silence through electromyographic (EMG) feedback was examined in healthy subjects performing maximal horizontal elbow flexions. Subjects exhibiting premotor silence on at least 50% of the pretest trials showed significantly greater peak angular velocity than subjects who produced the silent period on fewer than 20% of the trials during the pretest. The latter subjects acquired control of agonist premotor silence with practice and graphic feedback regarding their EMG patterns. The subjects who were the most successful in learning to produce the silent period increased their angular velocity to the level of the subjects who naturally exhibited the inhibition. The less successful subjects showed smaller increases in velocity. The data provide further evidence that premotor silence is primarily under central influence, that its control can be acquired, and that it may be functionally related to contractile rate.

The effect of stride length on lower extremity joint kinetics at various gait speeds

Robot-assisted training is a promising tool under development for improving walking function based on repetitive goal-oriented task practice. The challenges in developing the controllers for gait training devices that promote desired changes in gait is complicated by the limited understanding of the human response to robotic input. A possible method of controller formulation can be based on the principle of bio-inspiration, where a robot is controlled to apply the change in joint moment applied by human subjects when they achieve a gait feature of interest. However, it is currently unclear how lower extremity joint moments are modulated by even basic gait spatio-temporal parameters. In this study, we investigated how sagittal plane joint moments are affected by a factorial modulation of two important gait parameters: gait speed and stride length. We present the findings obtained from 20 healthy control subjects walking at various treadmill-imposed speeds and instructed to modulate stride length utilizing real-time visual feedback. Implementing a continuum analysis of inverse-dynamics derived joint moment profiles, we extracted the effects of gait speed and stride length on joint moment throughout the gait cycle. Moreover, we utilized a torque pulse approximation analysis to determine the timing and amplitude of torque pulses that approximate the difference in joint moment profiles between stride length conditions, at all gait speed conditions. Our results show that gait speed has a significant effect on the moment profiles in all joints considered, while stride length has more localized effects, with the main effect observed on the knee moment during stance, and smaller effects observed for the hip joint moment during swing and ankle moment during the loading response. Moreover, our study demonstrated that trailing limb angle, a parameter of interest in programs targeting propulsion at push-off, was significantly correlated with stride length. As such, our study has generated assistance strategies based on pulses of torque suitable for implementation via a wearable exoskeleton with the objective of modulating stride length, and other correlated variables such as trailing limb angle.

Wearable Sensor-Based Exercise Biofeedback for Orthopaedic Rehabilitation: A Mixed Methods User Evaluation of a Prototype System

The majority of wearable sensor-based biofeedback systems used in exercise rehabilitation lack end-user evaluation as part of the development process. This study sought to evaluate an exemplar sensor-based biofeedback system, investigating the feasibility, usability, perceived impact and user experience of using the platform. Fifteen patients participated in the study having recently undergone knee replacement surgery. Participants were provided with the system for two weeks at home, completing a semi-structured interview alongside the System Usability Scale (SUS) and user version of the Mobile Application Rating Scale (uMARS). The analysis from the SUS (mean = 90.8 [SD = 7.8]) suggests a high degree of usability, supported by qualitative findings. The mean adherence rate was 79% with participants reporting a largely positive user experience, suggesting it offers additional support with the rehabilitation regime. Overall quality from the mean uMARS score was 4.1 out of 5 (SD = 0.39), however a number of bugs and inaccuracies were highlighted along with suggestions for additional features to enhance engagement. This study has shown that patients perceive value in the use of wearable sensor-based biofeedback systems and has highlighted the benefit of user-evaluation during the design process, illustrated the need for real-world accuracy validation, and supports the ongoing development of such systems.

Development of a multichannel current-EMG system for coherence modulation with visual biofeedback

By means of biofeedback, neuromotor control can be modified. Recent biofeedback experiments have used the power of the electromyogram of one muscle in different frequency bands to control a two-dimensional cursor. However, the human body usually requires coherent activation of multiple muscles to achieve daily life tasks. Additionally, electromyography (EMG) instrumentation has remained the same for decades, and might not be the most suitable to measure coherent activations from pennated muscles according to recent experiments by von Tscharner and colleagues. In this study, we propose the development of a multichannel current-based EMG amplifier to use intermuscular coherence as the control feature of a visual biofeedback system. The system was used in a leg extension protocol to voluntarily increase intermuscular coherence between the vastii muscles. Results from ten subjects show that it is possible to increase intermuscular coherence through visual biofeedback. Such a system can have applications in endurance training and rehabilitation.

Assessing heart rate variability biofeedback as an adjunct to college recovery housing programs

Heart rate variability biofeedback (HRV BFB) shows promise as an adjunct intervention for individuals receiving treatment for substance use disorder (SUD), potentially due to its capacity to reduce craving and negative affect. The present study sought to examine the utility of integrating HRV biofeedback into a college recovery housing program and gauging its ability to reduce craving and negative affect in young adults in remission from SUD. Forty-six residents of an SUD recovery house at a public university in the northeastern United States took part in a non-randomized controlled trial. The active intervention was 12 weeks of HRV BFB performed over a college semester. The control intervention was a semester-long, waitlist condition. Changes in craving, perceived stress, anxiety, and depressive symptoms were measured across time during the active HRV BFB intervention and compared to changes that occurred during the waitlist period using piecewise regression analyses. Significant reductions in craving were noted during HRV BFB, but not during the waitlist control condition; however, the difference in slopes between conditions was not statistically significant. Levels of self-reported craving, stress, anxiety, and depression varied substantially between participants and across time. The results suggest that use of HRV BFB in the college recovery setting as a tool to help reduce craving warrants further examination, particularly among individuals with elevated craving. Added value of HRV BFB comes from the fact that it can be easily and affordably implemented in everyday life.

Taxonomies of psychological individual differences: biological perspectives on millennia-long challenges

This Editorial highlights a unique focus of this theme issue on the biological perspectives in deriving psychological taxonomies coming from neurochemistry, neuroanatomy, neurophysiology, genetics, psychiatry, developmental and comparative psychology-as contrasted to more common discussions of socio-cultural concepts (personality) and methods (lexical approach). It points out the importance of the distinction between temperament and personality for studies in human and animal differential psychophysiology, psychiatry and psycho-pharmacology, sport and animal practices during the past century. It also highlights the inability of common statistical methods to handle nonlinear, feedback, contingent, dynamical and multi-level relationships between psychophysiological systems of consistent psychological traits discussed in this theme issue.This article is part of the theme issue 'Diverse perspectives on diversity: multi-disciplinary approaches to taxonomies of individual differences'.

The effect of heart rate variability biofeedback training on stress and anxiety: a meta-analysis

BACKGROUND

Some evidence suggests that heart rate variability (HRV) biofeedback might be an effective way to treat anxiety and stress symptoms. To examine the effect of HRV biofeedback on symptoms of anxiety and stress, we conducted a meta-analysis of studies extracted from PubMed, PsycINFO and the Cochrane Library.

METHODS

The search identified 24 studies totaling 484 participants who received HRV biofeedback training for stress and anxiety. We conducted a random-effects meta-analysis.

RESULTS

The pre-post within-group effect size (Hedges' g) was 0.81. The between-groups analysis comparing biofeedback to a control condition yielded Hedges' g = 0.83. Moderator analyses revealed that treatment efficacy was not moderated by study year, risk of study bias, percentage of females, number of sessions, or presence of an anxiety disorder.

CONCLUSIONS

HRV biofeedback training is associated with a large reduction in self-reported stress and anxiety. Although more well-controlled studies are needed, this intervention offers a promising approach for treating stress and anxiety with wearable devices.

The role of feedback in implicit and explicit artificial grammar learning: a comparison between dyslexic and non-dyslexic adults

The importance of feedback for learning has been firmly established over the past few decades. The question of whether feedback plays a significant role in the statistical learning abilities of adults with dyslexia, however, is currently unresolved. Here, we examined the role of feedback in grammaticality judgment, type of structural knowledge, and confidence rating in both typically developed and dyslexic adults. We implemented two artificial grammar learning experiments: implicit and explicit. The second experiment was directly analogous to the first experiment in all respects except training format: the standard memorization instruction was replaced with an explicit rule-search instruction. Each experiment was conducted with and without performance feedback. While both groups showed significantly improved learning in the feedback-based explicit artificial grammar learning task, only the typically developed adults demonstrated higher levels of conscious structural knowledge. The present study demonstrates that the basis for the grammaticality judgment of adults with dyslexia differs from that of typically developed adults, regardless of increase in the level of explicitness.

Feedback from higher to lower visual areas for visual recognition may be weaker in the periphery: Glimpses from the perception of brief dichoptic stimuli

Eye movements bring attended visual inputs to the center of vision for further processing. Thus, central and peripheral vision should have different functional roles. Here, we use observations of visual perception under dichoptic stimuli to infer that there is a difference in the top-down feedback from higher brain centers to primary visual cortex. Visual stimuli to the two eyes were designed such that the sum and difference of the binocular input from the two eyes have the form of two different gratings. These gratings differed in their motion direction, tilt direction, or color, and duly evoked ambiguous percepts for the corresponding feature. Observers were more likely to perceive the feature in the binocular summation rather than the difference channel. However, this perceptual bias towards the binocular summation signal was weaker or absent in peripheral vision, even when central and peripheral vision showed no difference in contrast sensitivity to the binocular summation signal relative to that to the binocular difference signal. We propose that this bias can arise from top-down feedback as part of an analysis-by-synthesis computation. The feedback is of the input predicted using prior information by the upper level perceptual hypothesis about the visual scene; the hypothesis is verified by comparing the feedback with the actual visual input. We illustrate this process using a conceptual circuit model. In this framework, a bias towards binocular summation can arise from the prior knowledge that inputs are usually correlated between the two eyes. Accordingly, a weaker bias in the periphery implies that the top-down feedback is weaker there. Testable experimental predictions are presented and discussed.

[Modified stapled transanal rectal resection combined with perioperative pelvic floor biofeedback therapy in the treatment of obstructed defecation syndrome]

OBJECTIVE

To investigate the clinical efficacy and safety of modified stapled transanal rectal resection (STARR) combined with perioperative pelvic floor biofeedback therapy (POPFBFT) in treating obstructed defecation syndrome (ODS).

METHODS

Thirty female ODS patients underwent modified STARR (resection and suture was performed in rectocele with one staple) combined with POPFBFT in Department of Colorectal and Anal Surgery, The First Hospital of Jilin university from October 2013 to March 2015. Before the modified STARR, patients received a course of POPFBFT (20 min/time, 2 times/d, 10 times as a course), and another 2 courses were carried out in clinic after discharge. Efficacy evaluation included general conditions of patients, morbidity of postoperative complication, overall subjective satisfaction (excellent: without any symptoms; good: 1 to 2 times of laxatives per month and without the need of any other auxiliary defecation; fairly good: more than 3 times of laxatives per month ; poor: with no improvement; excellent, good, fairly good are defined as effective), Longo ODS score (range 0 to 40 points, the higher the score, the more severe the symptoms), gastrointestinal quality of life index(GIQLI)(range 0 to 144 points, the lower the score, the more severe the symptoms), anorectal manometry and defecography examination. The follow-up lasted 12 months after operation (ended at April 2016).

RESULTS

Average age of 30 patients was 57(46 to 72) years and Longo ODS score of every patient was ≥9 before operation. The modified STARR was completed successfully in all the 30 patients with average operation time of 25 (18 to 34) min and average hospital stay of 6(4 to 9) d. Postoperative complications included pain(20%, 6/30), urinary retention (16.7%, 5/30), anorectal heaviness (6.7%, 2/30), and fecal urgency(26.7%, 8/30). Anaorectal heaviness and fecal urgency disappeared within 3 months. No severe complications, such as postoperative bleeding, infection, rectovaginal fistula, anastomotic dehiscence and anal incontinence were observed. The effective rate of overall subjective satisfaction was 93.3%(28/30) during the follow-up of 12 months. There was no significant difference in Longo ODS score between pre- POPFBFT and pre-operation (pre- POPFBFT: 32.95±3.22, pre-operation: 32.85±3.62, t=1.472, P=0.163). Compared with pre-POPFBFT, Longo ODS score at 1 week after operation decreased (t=4.306, P=0.000), moreover, score at 1 month after operation was lower than that at 1 week (13.05±7.49 vs. 15.00±7.17, t=7.322, P=0.000), while no significant differences were found among 1, 3, 6, 12 months after operation (F=2.111, P=0.107). Likewise, there was no significant difference in GIQLI score between pre-POPFBFT and pre-operation (pre-POPFBFT: 79.39±17.14, pre-operation: 76.65±17.56, t=1.735, P=0.096). Compared with the pre-POPFBFT, GIQLI score at 1 week after operation increased (t=4.714, P=0.000), moreover, GIQLI score at 1 month after operation was higher than that at 1 week (102.26±19.24 vs 91.31±21.35, t=5.628, P=0.000), while no significant differences were found among 1, 3, 6, 12 months after operation(F=1.211, P=0.313). In comparison with pre- POPFBFT, parameters of defecography examination at 12 months after operation showed obvious improvement: the rectocele decreased from (34.1±0.4) mm to (3.1±0.3) mm (t=6.847, P=0.000), anorectal angle during defecation increased from (123.8±6.7)degree to (134.7±8.5)degree, enlargement of anorectal angle during defecation increased from (29.1±3.5)degree to (37.1±5.3)degree, while no significant differences in descend of perineum, anorectal angles at rest as well as parameters of anorectal manometry were found (all P>0.05).

CONCLUSION

Modified STARR combined with POPFBFT is safe and effective for ODS patients.

[Relaxation treatments and biofeedback for anxiety and somatic stress-related disorders]

INTRODUCTION

Relaxation techniques (TR) and biofeedback (BFB) are widely used in psychiatric and psychological practice for the treatment for anxiety and stress-related disorders.

METHODS

An examination of studies focusing on the correlates of psychophysiology of relaxation and biofeedback has been done, in addiction to controlled therapeutic studies that describes clinical aspects, efficacy and limits.

RESULTS

There are different TR and BFB procedures, but they have the same goal and same physiological modifications, resulting in stress and anxiety reduction. There is a proven action to musculoskeletal, neuroendocrine and autonomic nervous system, showing similar results. Very few data on immune changes are available. Meta-Analysis show superior efficacy to no treatment or placebo in anxiety disorders, tension headache, bruxism, temporomandibular pain syndrome, rehabilitation and prevention of ischemic heart disease. Moderate efficacy is shown for chronic low back pain, cancer-related pain, rheumatoid arthritis and gastrointestinal disorders; data for essential hypertension are controversial. Variability of techniques, procedures, sampling problems, non-systematic make definitive conclusions difficult. TR and BFB are often used in combination with cognitive-behavioral and educational techniques. The association of the active relaxation technique facilitates generalization and self-control during stress situation and outside the training session.

CONCLUSIONS

TR and BFB are effective for anxiety and somatic stress-related disorders, associated with coping and quality of life improvement and affordable costs; they are minimally invasive but needing an active participation in the treatment process. Some limits are responders' prediction, continuity of practice and limited effectiveness for depression disorders. Finally, it is shown that they are real psychosomatic therapies that are able to produce somatic peripheral changes (neuroendocrine, neurovegetative and muscular systems) generated by the mind and secondary to the involvement of central neurotransmitter circuits.

Biofeedback Signals for Robotic Rehabilitation: Assessment of Wrist Muscle Activation Patterns in Healthy Humans

Electrophysiological recordings from human muscles can serve as control signals for robotic rehabilitation devices. Given that many diseases affecting the human sensorimotor system are associated with abnormal patterns of muscle activation, such biofeedback can optimize human-robot interaction and ultimately enhance motor recovery. To understand how mechanical constraints and forces imposed by a robot affect muscle synergies, we mapped the muscle activity of seven major arm muscles in healthy individuals performing goal-directed discrete wrist movements constrained by a wrist robot. We tested six movement directions and four force conditions typically experienced during robotic rehabilitation. We analyzed electromyographic (EMG) signals using a space-by-time decomposition and we identified a set of spatial and temporal modules that compactly described the EMG activity and were robust across subjects. For each trial, coefficients expressing the strength of each combination of modules and representing the underlying muscle recruitment, allowed for a highly reliable decoding of all experimental conditions. The decomposition provides compact representations of the observable muscle activation constrained by a robotic device. Results indicate that a low-dimensional control scheme incorporating EMG biofeedback could be an effective add-on for robotic rehabilitative protocols seeking to improve impaired motor function in humans.

Psychological treatment of comorbid asthma and panic disorder in Latino adults: Results from a randomized controlled trial

Confusion between panic and asthma symptoms can result in serious self-management errors. A cognitive behavior psychophysiological therapy (CBPT) intervention was culturally adapted for Latinos consisting of CBT for panic disorder (PD), asthma education, differentiation between panic and asthma symptoms, and heart rate variability biofeedback. An RCT compared CBPT to music and relaxation therapy (MRT), which included listening to relaxing music and paced breathing at resting respiration rates. Fifty-three Latino (primarily Puerto Rican) adults with asthma and PD were randomly assigned to CBPT or MRT for 8 weekly sessions. Both groups showed improvements in PD severity, asthma control, and several other anxiety and asthma outcome measures from baseline to post-treatment and 3-month follow-up. CBPT showed an advantage over MRT for improvement in adherence to inhaled corticosteroids. Improvements in PD severity were mediated by anxiety sensitivity in CBPT and by depression in MRT, although earlier levels of these mediators did not predict subsequent improvements. Attrition was high (40%) in both groups, albeit comparable to CBT studies targeting anxiety in Latinos. Additional strategies are needed to improve retention in this high-risk population. Both CBPT and MRT may be efficacious interventions for comorbid asthma-PD, and CBPT may offer additional benefits for improving medication adherence.

Jaw Clenching: Muscle and Joint Forces, Optimization Strategies

Realistic masticatory muscle and temporomandibular joint forces generated during bilateral jaw clenching are largely unknown. To determine which clenching directions load masticatory muscles and temporomandibular joints most heavily, we investigated muscle and joint forces based on feedback-controlled electromyograms of all jaw muscles, lines of action, geometrical data from the skull, and physiological cross-sectional areas acquired from the same individuals. To identify possible motor control strategies, we applied objective functions. The medial pterygoid turned out to be the most heavily loaded muscle for all bite directions. Biting with accentuated horizontal force components provoked the highest loading within the medial and lateral pterygoids. The largest joint forces were also found for these bite directions. Conversely, the lowest joint forces were detected during vertical biting. Additionally, joint forces with a clear posterior orientation were found. Optimization strategies with the elastic energy as objective function revealed the best fit with the calculated results.

Balance Improvement Effects of Biofeedback Systems with State-of-the-Art Wearable Sensors: A Systematic Review

Falls and fall-induced injuries are major global public health problems. Balance and gait disorders have been the second leading cause of falls. Inertial motion sensors and force sensors have been widely used to monitor both static and dynamic balance performance. Based on the detected performance, instant visual, auditory, electrotactile and vibrotactile biofeedback could be provided to augment the somatosensory input and enhance balance control. This review aims to synthesize the research examining the effect of biofeedback systems, with wearable inertial motion sensors and force sensors, on balance performance. Randomized and non-randomized clinical trials were included in this review. All studies were evaluated based on the methodological quality. Sample characteristics, device design and study characteristics were summarized. Most previous studies suggested that biofeedback devices were effective in enhancing static and dynamic balance in healthy young and older adults, and patients with balance and gait disorders. Attention should be paid to the choice of appropriate types of sensors and biofeedback for different intended purposes. Maximizing the computing capacity of the micro-processer, while minimizing the size of the electronic components, appears to be the future direction of optimizing the devices. Wearable balance-improving devices have their potential of serving as balance aids in daily life, which can be used indoors and outdoors.

STATES OF PSYCHOPHYSIOLOGICAL FUNCTIONS OF ELITE ATHLETES IN DIFFERENT AGING GROUPS

The influences of aging peculiarities in elite athletes on the psychophysiological states on the stage of the maximum capacity were studied. Three groups of athletes with different age were studied. The first group was composed of the athletes aged 18-20, the second one included athletes aged 21-25, the third group included athletes aged 26-34, and were the members of the team of Ukraine in Greco-Roman wrestling. We revealed that elite athletes of older age group were significantly different from the younger by the presence of a large fatigue with the decline of autonomy when forming strategies of sports activities and more perfect the mechanism of autonomic reactions. The aging deterioration of perception of visual information in elite athletes of older age group manifested in a significant decrease of productivity, efficiency and speed for comparison with the groups of younger athletes. Also, in elite athletes older age group there is a significantly higher level of tension of autonomic regulation of heart rhythm compared with young athletes and the presence of more optimal activation of the sympathetic division of the autonomic nervous system.

Real-time estimation of aerodynamic features for ambulatory voice biofeedback

The development of ambulatory voice monitoring devices has the potential to improve the diagnosis and treatment of voice disorders. In this proof-of-concept study, real-time biofeedback is incorporated into a smartphone-based platform that records and processes neck surface acceleration. The focus is on utilizing aerodynamic measures of vocal function as a basis for biofeedback. This is done using regressed Z-scores to compare recorded values to normative estimates based on sound pressure level and fundamental frequency. Initial results from the analysis of different voice qualities suggest that accelerometer-based estimates of aerodynamic parameters can be used for real-time ambulatory biofeedback.

[IMPACT OF INDIVIDUAL PERSONALITY FEATURES ON ABILITY TO VOLUNTARY REGULATION OF EXPRESSION EEG ALPHA AND BETA FREQUENCIES]

The ability to voluntary control severity of alpha- and beta-2 frequency bands in the parietal and frontal cortical areas was investigated at 17 volunteers using biofeedback. The impact of different personality traits on the effectiveness of control was evaluated. According to the data, it was easier task to decrease expression beta-2 frequency in the frontal cortex than to decline the power of alpha frequency in the parietal cortex. The effectiveness of voluntary control of brain activity is influenced by personality features as extraversion, psychoticism, neuroticism, mobility and steadiness of nerve processes, level of person anxiety.

[Individual Types Reactivity of EEG Oscillations in Effective Heart Rhythm Biofeedback Parameters in Adolescents and Young People in the North]

A single session of heart rate variability (HRV) biofeedback in apparently healthy young people and adolescents aged 14-17 years in order to increase vagal effects on heart rhythm and also electroencephalograms were carried out. Different variants of EEG spectral power during the successful HRV biofeedback session were identified. In the case of I variant of EEG activity the increase of power spectrum of alpha-, betal-, theta-components takes place in all parts of the brain. In the case of II variant of EEG activity the reduction of power spectrum of alpha-, betal-, theta-activity in all parts of the brain was observed. I and II variants of EEG activity cause more intensive regime of cortical-subcortical interactions. During the III variant of EEG activity the successful biofeedback is accompanied by increase of alpha activity in the central, front and anteriofrontal brain parts and so indicates the formation of thalamocortical relations of neural network in order to optimize the vegetal regulation of heart function. There was an increase in alpha- and beta1-activity in the parietal, central, frontal and temporal brain parts during the IV variant of EEG activity and so that it provides the relief of neural networks communication for information processing. As a result of V variance of EEG activity there was the increase of power spectrum of theta activity in the central and frontal parts of both cerebral hemispheres, so it was associated with the cortical-hippocampal interactions to achieve a successful biofeedback.

A Pilot Study Using Mindfulness-Guided-Relaxation & Biofeedback To Alleviate Stress In A Group

The following study investigated the efficacy of a mindfulness intervention to reduce staff stress at a university in Melbourne that was undergoing a restructure and relocation. Using mindfulness guided-relaxation that incorporated positive emotions, controlled breathing and biofeedback monitors, 13 university staff recorded their sympathetic and parasympathetic activity over a four week period. They also supplied qualitative reflections of their experience. After one session of guided-relaxation and biofeedback there were significant increases in parasympathetic activity. For those people that continued practicing guided-relaxation by listening to a digital recording of the session, these gains continued to increase.

EMG and kinematic responses to unexpected slips after slip training in virtual reality

The objective of the study was to design a virtual reality (VR) training to induce perturbation in older adults similar to a slip and examine the effect of the training on kinematic and muscular responses in older adults. Twenty-four older adults were involved in a laboratory study and randomly assigned to two groups (VR training and control). Both groups went through three sessions including baseline slip, training, and transfer of training on slippery surface. The training group experienced 12 simulated slips using a visual perturbation induced by tilting a VR scene while walking on the treadmill and the control group completed normal walking during the training session. Kinematic, kinetic, and electromyography data were collected during all the sessions. Results demonstrated the proactive adjustments such as increased trunk flexion at heel contact after training. Reactive adjustments included reduced time to peak activations of knee flexors, reduced knee coactivation, reduced time to trunk flexion, and reduced trunk angular velocity after training. In conclusion, the study findings indicate that the VR training was able to generate a perturbation in older adults that evoked recovery reactions and such motor skill can be transferred to the actual slip trials.

Love withdrawal predicts electrocortical responses to emotional faces with performance feedback: a follow-up and extension

BACKGROUND

Parental use of love withdrawal is thought to affect children's later psychological functioning because it creates a link between children's performance and relational consequences. In addition, recent studies have begun to show that experiences of love withdrawal also relate to the neural processing of socio-emotional information relevant to a performance-relational consequence link, and can moderate effects of oxytocin on social information processing and behavior. The current study follows-up on our previous results by attempting to confirm and extend previous findings indicating that experiences of maternal love withdrawal are related to electrocortical responses to emotional faces presented with performance feedback.

RESULTS

More maternal love withdrawal was related to enhanced early processing of facial feedback stimuli (reflected in more positive VPP amplitudes, and confirming previous findings). However, attentional engagement with and processing of the stimuli at a later stage were diminished in those reporting higher maternal love withdrawal (reflected in less positive LPP amplitudes, and diverging from previous findings).

CONCLUSIONS

Maternal love withdrawal affects the processing of emotional faces presented with performance feedback differently in different stages of neural processing.

[Biofeedback: a new method for the prevention of amputations in patients with diabetes]

Lower limb amputations in patients with diabetes are still a huge public health problem. Despite of our knowledge and advanced technical tools, the incidence of amputations and they relapses remain very high and inacceptable. A key role in primary and secondary prevention of amputations is the foot off-loading. We dispose different off-loading devices and techniques which are efficient on short term. However, knowledge about its long term efficacy is missing. In this article, we review different methods of foot off-loading. We also describe a new method for diabetic foot off-loading based on the biofeedback technique we recently developed.

[Comparison of electroencephalogram changes at cardiovascular training in adolescents of subpolar and polar northern territories]

The features of the electroencephalogram (EEG) at the heart rate variability single biofeedback session in adolescents aged 15-17 years living in the subpolar and polar northern regions were determined. In adolescents of the subpolar region identified shaped age EEG pattern. We have established higher diencephalic and subcortical brain structures activity manifested in the elevated theta-activity levels and the diffuse photic driving reactions in adolescents of the polar region than in adolescents of subpolar region. In the dynamics of the biofeedback sessions in both regions there were identified groups of persons with both increased alpha-activity spectral power and decreased of it. After biofeedback sessions in adolescents of polar region more prolonged increase of alpha-activity, more pronounced reduction of theta-activity and the photic driving reactions were revealed. Changes in EEG patterns are most characteristic of the right brain hemisphere involving the frontal brain areas.

[A feedback method in clinical practice]

The authors reviewed a history of development of a feedback method, its physiological basis, essence, methodological aspects of its practical application and factors related to its effectiveness. This method may be used in studies of basic functional disorders, syndromes and diseases. Perspectives of its using in restorative and preventive health care are considered.

Controlling the emotional heart: heart rate biofeedback improves cardiac control during emotional reactions

When regulating negative emotional reactions, one goal is to reduce physiological reactions. However, not all regulation strategies succeed in doing that. We tested whether heart rate biofeedback helped participants reduce physiological reactions in response to negative and neutral pictures. When viewing neutral pictures, participants could regulate their heart rate whether the heart rate feedback was real or not. In contrast, when viewing negative pictures, participants could regulate heart rate only when feedback was real. Ratings of task success paralleled heart rate. Participants' general level of anxiety, emotion awareness, or cognitive emotion regulation strategies did not influence the results. Our findings show that accurate online heart rate biofeedback provides an efficient way to down-regulate autonomic physiological reactions when encountering negative stimuli.

Guest editorial: Introduction to the special issue on modern control for computer games

A typical gaming scenario, as developed in the past 20 years, involves a player interacting with a game using a specialized input device, such as a joystic, a mouse, a keyboard, etc. Recent technological advances and new sensors (for example, low cost commodity depth cameras) have enabled the introduction of more elaborated approaches in which the player is now able to interact with the game using his body pose, facial expressions, actions, and even his physiological signals. A new era of games has already started, employing computer vision techniques, brain-computer interfaces systems, haptic and wearable devices. The future lies in games that will be intelligent enough not only to extract the player's commands provided by his speech and gestures but also his behavioral cues, as well as his/her emotional states, and adjust their game plot accordingly in order to ensure more realistic and satisfactory gameplay experience. This special issue on modern control for computer games discusses several interdisciplinary factors that influence a user's input to a game, something directly linked to the gaming experience. These include, but are not limited to, the following: behavioral affective gaming, user satisfaction and perception, motion capture and scene modeling, and complete software frameworks that address several challenges risen in such scenarios.

Fusing visual and behavioral cues for modeling user experience in games

Estimating affective and cognitive states in conditions of rich human-computer interaction, such as in games, is a field of growing academic and commercial interest. Entertainment and serious games can benefit from recent advances in the field as, having access to predictors of the current state of the player (or learner) can provide useful information for feeding adaptation mechanisms that aim to maximize engagement or learning effects. In this paper, we introduce a large data corpus derived from 58 participants that play the popular Super Mario Bros platform game and attempt to create accurate models of player experience for this game genre. Within the view of the current research, features extracted both from player gameplay behavior and game levels, and player visual characteristics have been used as potential indicators of reported affect expressed as pairwise preferences between different game sessions. Using neuroevolutionary preference learning and automatic feature selection, highly accurate models of reported engagement, frustration, and challenge are constructed (model accuracies reach 91%, 92%, and 88% for engagement, frustration, and challenge, respectively). As a step further, the derived player experience models can be used to personalize the game level to desired levels of engagement, frustration, and challenge as game content is mapped to player experience through the behavioral and expressivity patterns of each player.

Adaptive Inverse optimal neuromuscular electrical stimulation

Neuromuscular electrical stimulation (NMES) is a prescribed treatment for various neuromuscular disorders, where an electrical stimulus is provided to elicit a muscle contraction. Barriers to the development of NMES controllers exist because the muscle response to an electrical stimulation is nonlinear and the muscle model is uncertain. Efforts in this paper focus on the development of an adaptive inverse optimal NMES controller. The controller yields desired limb trajectory tracking while simultaneously minimizing a cost functional that is positive in the error states and stimulation input. The development of this framework allows tradeoffs to be made between tracking performance and control effort by putting different penalties on error states and control input, depending on the clinical goal or functional task. The controller is examined through a Lyapunov-based analysis. Experiments on able-bodied individuals are provided to demonstrate the performance of the developed controller.

Identification of the feedforward component in manual control with predictable target signals

In the manual control of a dynamic system, the human controller (HC) often follows a visible and predictable reference path. Compared with a purely feedback control strategy, performance can be improved by making use of this knowledge of the reference. The operator could effectively introduce feedforward control in conjunction with a feedback path to compensate for errors, as hypothesized in literature. However, feedforward behavior has never been identified from experimental data, nor have the hypothesized models been validated. This paper investigates human control behavior in pursuit tracking of a predictable reference signal while being perturbed by a quasi-random multisine disturbance signal. An experiment was done in which the relative strength of the target and disturbance signals were systematically varied. The anticipated changes in control behavior were studied by means of an ARX model analysis and by fitting three parametric HC models: two different feedback models and a combined feedforward and feedback model. The ARX analysis shows that the experiment participants employed control action on both the error and the target signal. The control action on the target was similar to the inverse of the system dynamics. Model fits show that this behavior can be modeled best by the combined feedforward and feedback model.