Multisensory Stimulation and Priming (MuSSAP) in 4-10 Months Old Infants with a Unilateral Brain Lesion: A Pilot Randomised Clinical Trial.

Aim: To explore the effect of an Early Intensive-Upper Limb intervention (EI-UL) compared to EI-UL with integrated Multisensory Stimulation And Priming (MuSSAP) training on improving manual ability in infants with a unilateral brain lesion. Method: A pilot randomised clinical trial with pre- and postintervention and follow-up measurements (T0, T1, and T2) was conducted. Sixteen infants with a unilateral brain lesion (corrected age is 4-10 months) received home-based intervention with video coaching. Eight infants received EI-UL and eight infants received EI-UL with integrated MuSSAP training. Primary outcome was the Hand Assessment for Infants (HAI) score. Additionally, effects were explored on initiation of goal-directed movements in both groups and on attention in the EI-UL with integrated MuSSAP training group. Results: No significant group differences in HAI scores were found. Overall, HAI 'Affected hand score' increased between T0 and T1 (p = 0.001, Cohen's d = 1.04) and between T0 and T2 (p < 0.001, Cohen's d = 1.28); and the HAI 'Both Hands Measure' increased between T0 and T1 (p < 0.001, Cohen's d = 1.72) and between T0 and T2 (p < 0.001, Cohen's d = 1.81). At the start of the intervention, six infants (three in both groups) did not demonstrate initiation of goal-directed contralesional upper limb movements. During the intervention one infant receiving EI-UL and all three infants receiving EI-UL with integrated MuSSAP training started to initiate goal-directed movements. Conclusion: The results suggest manual ability of infants with unilateral brain lesion improved with both interventions. We hypothesize that the integrated MuSSAP training may facilitate attention and initiation of contralesional upper limb goal-directed movements. This trial is registered with NCT05533476).

Personalized tDCS for Focal Epilepsy-A Narrative Review: A Data-Driven Workflow Based on Imaging and EEG Data.

Conventional transcranial electric stimulation(tES) using standard anatomical positions for the electrodes and standard stimulation currents is frequently not sufficiently selective in targeting and reaching specific brain locations, leading to suboptimal application of electric fields. Recent advancements in in vivo electric field characterization may enable clinical researchers to derive better relationships between the electric field strength and the clinical results. Subject-specific electric field simulations could lead to improved electrode placement and more efficient treatments. Through this narrative review, we present a processing workflow to personalize tES for focal epilepsy, for which there is a clear cortical target to stimulate. The workflow utilizes clinical imaging and electroencephalography data and enables us to relate the simulated fields to clinical outcomes. We review and analyze the relevant literature for the processing steps in the workflow, which are the following: tissue segmentation, source localization, and stimulation optimization. In addition, we identify shortcomings and ongoing trends with regard to, for example, segmentation quality and tissue conductivity measurements. The presented processing steps result in personalized tES based on metrics like focality and field strength, which allow for correlation with clinical outcomes.

An immersive virtual reality game to train spatial attention orientation after stroke: A feasibility study.

Immersive virtual reality (IVR) may boost neglect recovery, as it can provide an engaging experience in a 3D environment. We designed an IVR rehabilitation game for neglect patients using the Oculus Rift. Multisensory cues were presented in the neglected visual field in a patient-tailored way. We acquired pilot data in 15 neurologically healthy controls and 7 stroke patients. First, we compared cybersickness before and after VR exposure. Second, we assessed the user experience through a questionnaire. Third, we tested whether neglect symptoms corresponded between the VR game and a computerized cancelation task. Fourth, we evaluated the effect of the multisensory cueing on target discrimination. Last, we tested two algorithms to tailor the game to the characteristics of the neglected visual field. Cybersickness significantly reduced after VR exposure in six stroke patients and was low in healthy controls. Patients rated the user experience neutral to positive. In addition, neglect symptoms were consistent between a computerized cancelation and VR rehabilitation task. The multisensory cue positively affected target discrimination in the game and we successfully presented sensory stimulation to the neglected visual field in a patient-tailored way. Our results show that it is promising to use gamified patient-tailored immersive VR for neglect rehabilitation.

The Use of the Term Virtual Reality in Post-Stroke Rehabilitation: A Scoping Review and Commentary.

Virtual reality (VR) offers many opportunities for post-stroke rehabilitation. However, "VR" can refer to several types of computer-based rehabilitation systems. Since these systems may impact the feasibility and the efficacy of VR interventions, consistent terminology is important. In this study, we aimed to optimize the terminology for VR-based post-stroke rehabilitation by assessing whether and how review papers on this topic defined VR and what types of mixed reality systems were discussed. In addition, this review can inspire the use of consistent terminology for other researchers working with VR. We assessed the use of the term VR in review papers on post-stroke rehabilitation extracted from Scopus, Web of Science and PubMed. We also developed a taxonomy distinguishing 16 mixed reality systems based on three factors: immersive versus semi-immersive displays, the way in which real and virtual information is mixed, and the main input device. 64% of the included review papers (N = 121) explicitly defined VR and 33% of them described different subtypes of VR, with immersive and non-immersive VR as the most common distinction. The most frequently discussed input devices were motion-capture cameras and handheld devices, while regular 2D monitors were the most frequently mentioned output devices. Our analysis revealed that reviews on post-stroke VR rehabilitation did not or only broadly defined "VR" and did not focus on a specific system. Since the efficacy and feasibility of rehabilitation may depend on the specific system, we propose a new data-driven taxonomy to distinguish different systems, which is expected to facilitate communication amongst researchers and clinicians working with virtual reality.

Dynamics of a Mutual Inhibition Circuit between Pyramidal Neurons Compared to Human Perceptual Competition.

Neural competition plays an essential role in active selection processes of noisy and ambiguous input signals, and it is assumed to underlie emergent properties of brain functioning, such as perceptual organization and decision-making. Despite ample theoretical research on neural competition, experimental tools to allow neurophysiological investigation of competing neurons have not been available. We developed a "hybrid" system where real-life neurons and a computer-simulated neural circuit interacted. It enabled us to construct a mutual inhibition circuit between two real-life pyramidal neurons. We then asked what dynamics this minimal unit of neural competition exhibits and compared them with the known behavioral-level dynamics of neural competition. We found that the pair of neurons shows bistability when activated simultaneously by current injections. The addition of modeled synaptic noise and changes in the activation strength showed that the dynamics of the circuit are strikingly similar to the known properties of bistable visual perception: The distribution of dominance durations showed a right-skewed shape, and the changes of the activation strengths caused changes in dominance, dominance durations, and reversal rates as stated in the well-known empirical laws of bistable perception known as Levelt's propositions.SIGNIFICANCE STATEMENT Visual perception emerges as the result of neural systems actively organizing visual signals that involves selection processes of competing neurons. While the neural competition, realized by a "mutual inhibition" circuit has been examined in many theoretical studies, its properties have not been investigated in real neurons. We have developed a "hybrid" system where two real-life pyramidal neurons in a mouse brain slice interact through a computer-simulated mutual inhibition circuit. We found that simultaneous activation of the neurons leads to bistable activity. We investigated the effect of noise and the effect of changes in the activation strength on the dynamics. We observed that the pair of neurons exhibit dynamics strikingly similar to the known properties of bistable visual perception.

Intracranial Recordings Reveal Unique Shape and Timing of Responses in Human Visual Cortex during Illusory Visual Events.

During binocular rivalry, perception spontaneously changes without any alteration to the visual stimulus. What neural events bring about this illusion that a constant stimulus is changing? We recorded from intracranial electrodes placed on the occipital and posterior temporal cortex of two patients with epilepsy while they experienced illusory changes of a face-house binocular-rivalry stimulus or observed a control stimulus that physically changed. We performed within-patient comparisons of broadband high-frequency responses, focusing on single epochs recorded along the ventral processing stream. We found transient face- and house-selective responses localized to the same electrodes for illusory and physical changes, but the temporal characteristics of these responses markedly differed. In comparison with physical changes, responses to illusory changes were longer lasting, in particular exhibiting a characteristic slow rise. Furthermore, the temporal order of responses across the visual hierarchy was reversed for illusory as compared to physical changes: for illusory changes, higher order fusiform and parahippocampal regions responded before lower order occipital regions. Our tentative interpretation of these findings is that two stages underlie the initiation of illusory changes: a destabilization stage in which activity associated with the impending change gradually accumulates across the visual hierarchy, ultimately graduating in a top-down cascade of activity that may stabilize the new perceptual interpretation of the stimulus.

Age-dependency in binocular rivalry is reflected by exclusive percepts, not mixed percepts.

Some aspects of decision-making are known to decline with normal aging. One of the known perceptual decision-making processes which is vastly studied is binocular rivalry. It is well-established that the older the person, the slower the perceptual dynamics. However, the underlying neurobiological cause is unknown. So, to understand how age affects visual decision-making, we investigated age-related changes in perception during binocular rivalry. In binocular rivalry, the image presented to one eye competes for perceptual dominance with the image presented to the other eye. Perception during binocular rivalry consists of alternations between exclusive percepts. However, frequently, mixed percepts with combinations of the two monocular images occur. The mixed percepts reflect a transition from the percept of one eye to the other but frequently the transitions do not complete the full cycle and the previous exclusive percept becomes dominant again. The transitional idiosyncrasy of mixed percepts has not been studied systematically in different age groups. Previously, we have found evidence for adaptation and noise, and not inhibition, as underlying neural factors that are related to age-dependent perceptual decisions. Based on those conclusions, we predict that mixed percepts/inhibitory interactions should not change with aging. Therefore, in an old and a young age group, we studied binocular rivalry dynamics considering both exclusive and mixed percepts by using two paradigms: percept-choice and percept-switch. We found a decrease in perceptual alternation Probability for older adults, although the rate of mixed percepts did not differ significantly compared to younger adults. Interestingly, the mixed percepts play a very similar transitional idiosyncrasy in our different age groups. Further analyses suggest that differences in synaptic depression, gain modulation at the input level, and/or slower execution of motor commands are not the determining factors to explain these findings. We then argue that changes in perceptual decisions at an older age are the result of changes in neural adaptation and noise.

A randomized cross-over study on the blood pressure lowering effect of the combined passive head-up and -down movement with Device-Guided slow breathing.

Purpose: Baroreflex emerges as a therapeutic target of hypertension. We investigated blood pressure (BP) lowering effect of the combined passive head-up and -down movement with device-guided slow breathing in untreated mild hypertension or high-normal BP. Methods: In a randomized, cross-over trial, untreated subjects with an ambulatory systolic/diastolic BP of 125-140/80-90 mmHg and a clinic BP of 130-150/80-90 mmHg were randomized to intervention treatment with head movement and slow breathing or sham control, and then crossed over. Both treatments consisted of 1-week preparation, 2-week treatment, and 1-week recovery. During the 2-week treatment, subjects were treated for a session of 20 min/day. BP, pulse rate and respiration were measured before and after each treatment session. Ambulatory BP monitoring was performed at baseline and the end of the 2-week treatments' period, and home BP monitoring in the morning and evening for the whole 8-week follow-up period. Results: 14 subjects completed the study. The intervention treatment, compared to control, reduced respiration rate by -2.1 breaths/min (95% CI -2.9 to -1.2, p = .0001), but not clinic BP and pulse rate (p ≥ .67). The intervention treatment, compared to control, significantly reduced nighttime systolic/diastolic blood pressure by -5.63/-3.82 mm Hg (p ≤ .01) but not 24-h or daytime ambulatory blood pressure (p ≥ .69). Home BP decreased with the intervention treatment, but the between-treatment difference was not statistically significant (p ≥ .27). Conclusions: The combined head movement with slow breathing did not influence 24-h BP, but reduced nighttime BP in untreated mild hypertension or high-normal BP.

Children's perception of visual and auditory ambiguity and its link to executive functions and creativity.

The phenomenon of perceptual bistability provides insights into aspects of perceptual processing not normally accessible to everyday experience. However, most experiments have been conducted in adults, and it is not clear to what extent key aspects of perceptual switching change through development. The current research examined the ability of 6-, 8-, and 10-year-old children (N = 66) to switch between competing percepts of ambiguous visual and auditory stimuli and links between switching rate, executive functions, and creativity. The numbers of switches participants reported in two visual tasks (ambiguous figure and ambiguous structure from motion) and two auditory tasks (verbal transformation and auditory streaming) were measured in three 60-s blocks. In addition, inhibitory control was measured with a Stroop task, set shifting was measured with a verbal fluency task, and creativity was measured with a divergent thinking task. The numbers of perceptual switches increased in all four tasks from 6 to 10 years of age but differed across tasks in that they were higher in the verbal transformation and ambigous structure-from-motion tasks than in the ambigous figure and auditory streaming tasks for all age groups. Although perceptual switching rates differed across tasks, there were predictive relationships between switching rates in some tasks. However, little evidence for the influence of central processes on perceptual switching was found. Overall, the results support the notion that perceptual switching is largely modality and task specific and that this property is already evident when perceptual switching emerges.

Acceptance of immersive head-mounted virtual reality in older adults.

Immersive virtual reality has become increasingly popular to improve the assessment and treatment of health problems. This rising popularity is likely to be facilitated by the availability of affordable headsets that deliver high quality immersive experiences. As many health problems are more prevalent in older adults, who are less technology experienced, it is important to know whether they are willing to use immersive virtual reality. In this study, we assessed the initial attitude towards head-mounted immersive virtual reality in 76 older adults who had never used virtual reality before. Furthermore, we assessed changes in attitude as well as self-reported cybersickness after a first exposure to immersive virtual reality relative to exposure to time-lapse videos. Attitudes towards immersive virtual reality changed from neutral to positive after a first exposure to immersive virtual reality, but not after exposure to time-lapse videos. Moreover, self-reported cybersickness was minimal and had no association with exposure to immersive virtual reality. These results imply that the contribution of VR applications to health in older adults will neither be hindered by negative attitudes nor by cybersickness.

Changes in low-level neural properties underlie age-dependent visual decision making.

Aging typically slows down cognitive processes, specifically those related to perceptual decisions. However, the neurobiological mechanisms underlying these age-associated changes are still elusive. To address this, we studied the effect of aging on both perceptual and binocular rivalry in various presentation conditions. Two age groups of participants reported their spontaneous percept switches during continuous presentation and percept choices during intermittent presentation. We find no significant age effect on the mean and cumulative frequencies of percept switch durations under continuous presentation. However, the data show a significant age effect on coefficient of variation, ratio of standard deviation to mean of percept durations. Our results also reveal that the alternation rate for percept choices significantly declines at an older age under intermittent presentation. The latter effect is even more pronounced at shorter inter-stimulus durations. These results together with the predictions of existing neural models for bistable perception imply that age-dependency of visual perceptual decisions is caused by shifts in neural adaptation and noise, not by a change in inhibition strength. Thus, variation in the low-level neural properties, adaptation and noise, cause age-dependent properties in visual perceptual decisions.

Similar but separate systems underlie perceptual bistability in vision and audition.

The dynamics of perceptual bistability, the phenomenon in which perception switches between different interpretations of an unchanging stimulus, are characterised by very similar properties across a wide range of qualitatively different paradigms. This suggests that perceptual switching may be triggered by some common source. However, it is also possible that perceptual switching may arise from a distributed system, whose components vary according to the specifics of the perceptual experiences involved. Here we used a visual and an auditory task to determine whether individuals show cross-modal commonalities in perceptual switching. We found that individual perceptual switching rates were significantly correlated across modalities. We then asked whether perceptual switching arises from some central (modality-) task-independent process or from a more distributed task-specific system. We found that a log-normal distribution best explained the distribution of perceptual phases in both modalities, suggestive of a combined set of independent processes causing perceptual switching. Modality- and/or task-dependent differences in these distributions, and lack of correlation with the modality-independent central factors tested (ego-resiliency, creativity, and executive function), also point towards perceptual switching arising from a distributed system of similar but independent processes.

Acute alerting effects of light: A systematic literature review.

Periodic, well timed exposure to light is important for our health and wellbeing. Light, in particular in the blue part of the spectrum, is thought to affect alertness both indirectly, by modifying circadian rhythms, and directly, giving rise to acute effects. We performed a systematic review of empirical studies on direct, acute effects of light on alertness to evaluate the reliability of these effects. In total, we identified 68 studies in which either light intensity, spectral distribution, or both were manipulated, and evaluated the effects on behavioral measures of alertness, either subjectively or measured in reaction time performance tasks. The results show that increasing the intensity of polychromatic white light has been found to increase subjective ratings of alertness in a majority of studies, though a substantial proportion of studies failed to find significant effects, possibly due to small sample sizes or high baseline light intensities. The effect of the color temperature of white light on subjective alertness is less clear. Some studies found increased alertness with higher color temperatures, but other studies reported no detrimental effects of filtering out the short wavelengths from the spectrum. Similarly, studies that used monochromatic light exposure showed no systematic pattern for the effects of blue light compared to longer wavelengths. Far fewer studies investigated the effects of light intensity or spectrum on alertness as measured with reaction time tasks and of those, very few reported significant effects. In general, the small sample sizes used in studies on acute alerting effects of light make it difficult to draw definitive conclusions and better powered studies are needed, especially studies that allow for the construction of dose-response curves.

50 Years of Stereoblindness: Reconciliation of a Continuum of Disparity Detectors With Blindness for Disparity in Near or Far Depth.

Whitman Richards (1932-2016) discovered some 50 years ago that about 30% of observers from the normal population exhibit stereoblindness: the disability to process binocular disparities in either far or near depth. We review the literature on stereoblindness entailing two insights. First, contemporary scholars in stereopsis undervalue the comprehension that disparity processing studies require precise assessments of observers' stereoblindness. We argue that this frequently leads to suboptimal interpretations. Second, there is still an open conundrum: How can the established finding that disparity is processed by a continuum of detectors be reconciled with the disability of many observers to process a whole class of far or near disparities? We propose, based upon integration of literature, that an asymmetry between far and near disparity detection at birth-being present for a variety of reasons-can suppress the typical formation of binocular correlation during the critical period for the development of stereopsis early in life, thereby disabling a whole class of far or near disparities.

Continuous Flash Suppression: Stimulus Fractionation rather than Integration.

Recent studies using continuous flash suppression suggest that invisible stimuli are processed as integrated, semantic entities. We challenge the viability of this account, given recent findings on the neural basis of interocular suppression and replication failures of high-profile CFS studies. We conclude that CFS reveals stimulus fractionation in visual cortex.

Visual suppression at the offset of binocular rivalry.

Various paradigms can make visual stimuli disappear from awareness, but they often involve stimuli that are either relatively weak, competing with other salient inputs, and/or presented for a prolonged period of time. Here we explore a phenomenon that involves controlled perceptual disappearance of a peripheral visual stimulus without these limitations. It occurs when one eye's stimulus is abruptly removed during a binocular rivalry situation. This manipulation renders the remaining stimulus, which is still being presented to the other eye, invisible for up to several seconds. Our results suggest that this perceptual disappearance depends on a visual offset-transient that promotes dominance of the eye in which it occurs regardless of whether the eye is dominant or suppressed at the moment of the transient event. Using computational modeling, we demonstrate that standard rivalry mechanisms of interocular inhibition can indeed be complemented by a hypothesized transient-driven gating mechanism to explain the phenomenon. In essence, such a system suggests that visual awareness is dominated by the eye that receives transients and "sticks with" this eye-based dominance for some time in the absence of further transient events. We refer to this phenomenon as the "disrupted rivalry effect" and suggest that it is a potentially powerful paradigm for the study of cortical suppression mechanisms and the neural correlates of visual awareness.

The relation of trait and state mindfulness with satisfaction and physical activity: A cross-sectional study in 305 Dutch participants.

Previous research has shown that satisfaction mediates the relationship of state mindfulness (i.e. during physical activity) with physical activity. This study aimed to replicate this finding and to explore the role of trait mindfulness with a cross-sectional design. In all, 305 participants completed measures on trait and state mindfulness, satisfaction with physical activity, and physical activity. Mediation analyses were used. Satisfaction mediated the effect of state mindfulness on physical activity. Trait mindfulness related to physical activity via an indirect path, namely through two consecutive mediators, first state mindfulness and then satisfaction. Our results suggest that to enhance satisfaction, both state and trait mindfulness should be considered.

Gamification in Physical Therapy: More Than Using Games.

The implementation of computer games in physical therapy is motivated by characteristics such as attractiveness, motivation, and engagement, but these do not guarantee the intended therapeutic effect of the interventions. Yet, these characteristics are important variables in physical therapy interventions because they involve reward-related dopaminergic systems in the brain that are known to facilitate learning through long-term potentiation of neural connections. In this perspective we propose a way to apply game design approaches to therapy development by "designing" therapy sessions in such a way as to trigger physical and cognitive behavioral patterns required for treatment and neurological recovery. We also advocate that improving game knowledge among therapists and improving communication between therapists and game designers may lead to a novel avenue in designing applied games with specific therapeutic input, thereby making gamification in therapy a realistic and promising future that may optimize clinical practice.

"Smooth operator": Music modulates the perceived creaminess, sweetness, and bitterness of chocolate.

There has been a recent growth of interest in determining whether sound (specifically music and soundscapes) can enhance not only the basic taste attributes associated with food and beverage items (such as sweetness, bitterness, sourness, etc.), but also other important components of the tasting experience, such as, for instance, crunchiness, creaminess, and/or carbonation. In the present study, participants evaluated the perceived creaminess of chocolate. Two contrasting soundtracks were produced with such texture-correspondences in mind, and validated by means of a pre-test. The participants tasted the same chocolate twice (without knowing that the chocolates were identical), each time listening to one of the soundtracks. The 'creamy' soundtrack enhanced the perceived creaminess and sweetness of the chocolates, as compared to the ratings given while listening to the 'rough' soundtrack. Moreover, while the participants preferred the creamy soundtrack, this difference did not appear to affect their overall enjoyment of the chocolates. Interestingly, and in contrast with previous similar studies, these results demonstrate that in certain cases, sounds can have a perceptual effect on gustatory food attributes without necessarily altering the hedonic experience.