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The current study employed a within-participant design to analyze the effects of head movements in three conditions (i.e., head nodding, head shaking, and no head movements) during positive (motivational) self-talk among 22 male cyclists. After the self-talk and head-movements task, physical performance (i.e., anaerobic power) was assessed using a Wingate Test for each experimental condition. Each cyclist participated individually on three separate days, completing one of the three experimental conditions each day. We hypothesized and found that the head-nodding condition resulted in greater physical performance (i.e., mean and peak power) than the no-head-movements condition. This is the first time that head nodding has been shown to improve physical performance compared with no head movements during encouraging and self-assuring self-talk. Relevantly, these findings emphasize the importance of focusing on athletes' nonverbal behavior (e.g., head movements) when engaging in positive (motivational) self-talk to perform better. [ABSTRACT FROM AUTHOR]

Most studies of developing visual attention are conducted using screen-based tasks in which infants move their eyes to select where to look. However, real-world visual exploration entails active movements of both eyes and head to bring relevant areas in view. Thus, relatively little is known about how infants coordinate their eyes and heads to structure their visual experiences. Infants were tested every 3 months from 9 to 24 months while they played with their caregiver and three toys while sitting in a highchair at a table. Infants wore a head-mounted eye tracker that measured eye movement toward each of the visual targets (caregiver's face and toys) and how targets were oriented within the head-centered field of view (FOV). With age, infants increasingly aligned novel toys in the center of their head-centered FOV at the expense of their caregiver's face. Both faces and toys were better centered in view during longer looking events, suggesting that infants of all ages aligned their eyes and head to sustain attention. The bias in infants' head-centered FOV could not be accounted for by manual action: Held toys were more poorly centered compared with non-held toys. We discuss developmental factors-attentional, motoric, cognitive, and social-that may explain why infants increasingly adopted biased viewpoints with age.

Head movement plays a vital role in auditory processing by contributing to spatial awareness and the ability to identify and locate sound sources. Here we investigate head-orienting behaviors using a dual-task experimental paradigm to measure: (a) localization of a speech source; and (b) detection of meaningful speech (numbers), within a complex acoustic background. Ten younger adults with normal hearing and 20 older adults with mild-to-severe sensorineural hearing loss were evaluated in the free field on two headmovement conditions: (1) head fixed to the front and (2) head moving to a source location; and two context conditions: (1) with audio only or (2) with audio plus visual cues. Head-tracking analyses quantified the target location relative to head location, as well as the peak velocity during head movements. Evaluation of head-orienting behaviors revealed that both groups tended to undershoot the auditory target for targets beyond 60° in azimuth. Listeners with hearing loss had higher head-turn errors than the normal-hearing listeners, even when a visual location cue was provided. Digit detection accuracy was better for the normal-hearing than hearing-loss groups, with a main effect of signal-to-noise ratio (SNR). When performing the dual-task paradigm in the most difficult listening environments, participants consistently demonstrated a wait-and-listen head-movement strategy, characterized by a short pause during which they maintained their head orientation and gathered information before orienting to the target location. [ABSTRACT FROM AUTHOR]

Moving through a dynamic world, humans need to intermittently stabilize gaze targets on their retina to process visual information. Overt attention being thus split into discrete intervals, the automatic detection of such fixation events is paramount to downstream analysis in many eye-tracking studies. Standard algorithms tackle this challenge in the limiting case of little to no head motion. In this static scenario, which is approximately realized for most remote eye-tracking systems, it amounts to detecting periods of relative eye stillness. In contrast, head-mounted eye trackers allow for experiments with subjects moving naturally in everyday environments. Detecting fixations in these dynamic scenarios is more challenging, since gaze-stabilizing eye movements need to be reliably distinguished from non-fixational gaze shifts. Here, we propose several strategies for enhancing existing algorithms developed for fixation detection in the static case to allow for robust fixation detection in dynamic real-world scenarios recorded with head-mounted eye trackers. Specifically, we consider (i) an optic-flow-based compensation stage explicitly accounting for stabilizing eye movements during head motion, (ii) an adaptive adjustment of algorithm sensitivity according to head-motion intensity, and (iii) a coherent tuning of all algorithm parameters. Introducing a new hand-labeled dataset, recorded with the Pupil Invisible glasses by Pupil Labs, we investigate their individual contributions. The dataset comprises both static and dynamic scenarios and is made publicly available. We show that a combination of all proposed strategies improves standard thresholding algorithms and outperforms previous approaches to fixation detection in head-mounted eye tracking. [ABSTRACT FROM AUTHOR]

We explored how body movements influence illusory body motion intensity and their association with motion sickness. Twelve individuals who were seated in the back of a passenger car, performed a visual task and were subjected to continuous rotations followed by driving in a straight line. The body movements during and immediately after rotation were categorized as follows: (A) upright posture; (B) leaning the body in the yaw direction towards the rotation center, returning the yaw angle to zero upon transitioning to straight line travel, and tilting in the roll condition and gradually returning to upright; and (C) tilting in roll conditions towards the centripetal direction during rotation and becoming upright upon transitioning to straight line travel. In experiment-1, after spanning half a lap, participants reported the intensity of the illusory motion experienced during straight line travel immediately after rotation. In experiment-2, after travelling up to eight laps, the participants reported the symptom level of motion sickness experienced during two straight sections per lap using the MIsery SCale (MISC). Experiment-1 revealed that condition (C) had significantly larger illusions than Conditions (A) and (B). Experiment-2 revealed that motion sickness progressed significantly more in Condition (C) than in Condition (A). A significant positive correlation was found between the observed MISC and the illusion strength. Our findings suggest that body movements during and immediately after continuous rotation have a significant impact on the illusion strength. Additionally, illusory motion could serve as an indicator of impending motion sickness. [ABSTRACT FROM AUTHOR]

Seemingly simple behaviors such as swatting a mosquito or glancing at a signpost involve the precise coordination of multiple body parts. Neural control of coordinated movements is widely thought to entail transforming a desired overall displacement into displacements for each body part. Here we reveal a different logic implemented in the mouse gaze system. Stimulating superior colliculus (SC) elicits head movements with stereotyped displacements but eye movements with stereotyped endpoints. This is achieved by individual SC neurons whose branched axons innervate modules in medulla and pons that drive head movements with stereotyped displacements and eye movements with stereotyped endpoints, respectively. Thus, single neurons specify a mixture of endpoints and displacements for different body parts, not overall displacement, with displacements for different body parts computed at distinct anatomical stages. Our study establishes an approach for unraveling motor hierarchies and identifies a logic for coordinating movements and the resulting pose.

Head movement plays a vital role in auditory processing by contributing to spatial awareness and the ability to identify and locate sound sources. Here we investigate head-orienting behaviors using a dual-task experimental paradigm to measure: (a) localization of a speech source; and (b) detection of meaningful speech (numbers), within a complex acoustic background. Ten younger adults with normal hearing and 20 older adults with mild-to-severe sensorineural hearing loss were evaluated in the free field on two head-movement conditions: (1) head fixed to the front and (2) head moving to a source location; and two context conditions: (1) with audio only or (2) with audio plus visual cues. Head-tracking analyses quantified the target location relative to head location, as well as the peak velocity during head movements. Evaluation of head-orienting behaviors revealed that both groups tended to undershoot the auditory target for targets beyond 60° in azimuth. Listeners with hearing loss had higher head-turn errors than the normal-hearing listeners, even when a visual location cue was provided. Digit detection accuracy was better for the normal-hearing than hearing-loss groups, with a main effect of signal-to-noise ratio (SNR). When performing the dual-task paradigm in the most difficult listening environments, participants consistently demonstrated a wait-and-listen head-movement strategy, characterized by a short pause during which they maintained their head orientation and gathered information before orienting to the target location.

Abstract In natural environments, head movements are required to search for objects outside the field of view (FoV). Here we investigate the power of a salient target in an extended visual search array to facilitate faster detection once this item comes into the FoV by a head movement. We conducted two virtual reality experiments using spatially clustered sets of stimuli to observe target detection and head and eye movements during visual search. Participants completed search tasks with three conditions: (1) target in the initial FoV, (2) head movement needed to bring the target into the FoV, (3) same as condition 2 but the periphery was initially hidden and appeared after the head movement had brought the location of the target set into the FoV. We measured search time until participants found a more salient (O) or less salient (T) target among distractors (L). On average O’s were found faster than T’s. Gaze analysis showed that saliency facilitation occurred due to the target guiding the search only if it was within the initial FoV. When targets required a head movement to enter the FoV, participants followed the same search strategy as in trials without a visible target in the periphery. Moreover, faster search times for salient targets were only caused by the time required to find the target once the target set was reached. This suggests that the effect of stimulus saliency differs between visual search on fixed displays and when we are actively searching through an extended visual field.

With increasing automation in the rail sector, the train driver’s task changes from full control to a supervisory position. This bears the risk of monotony and subsequent changes in visual attention, possibly for the worse. Similar to concepts in car driving, one solution for this could be driver state monitoring with triggered interventions in case of declining task attention. Previous research on train drivers’ visual attention has used eye tracking. In contrast, head tracking is easier to realize within the train driver cabin. This study set out to test whether head tracking is a feasible alternative to eye tracking and can provide similar findings. Based on previous eye-tracking research, we compared differences in head movements in automated vs. manual driving, and for different levels of driving speed and driving experience. We conducted a study with 25 active train drivers in a high-fidelity train simulator. Statistical analyses revealed no significant difference in the vertical head movements between automation levels. There was a significant difference in the horizontal head movements, with train drivers looking more to the right for manual driving. We found no significant influence of driving speed and experience on head movements. Safety implications and the feasibility of head tracking as an alternative to eye tracking are discussed.

In natural environments, head movements are required to search for objects outside the field of view (FoV). Here we investigate the power of a salient target in an extended visual search array to facilitate faster detection once this item comes into the FoV by a head movement. We conducted two virtual reality experiments using spatially clustered sets of stimuli to observe target detection and head and eye movements during visual search. Participants completed search tasks with three conditions: (1) target in the initial FoV, (2) head movement needed to bring the target into the FoV, (3) same as condition 2 but the periphery was initially hidden and appeared after the head movement had brought the location of the target set into the FoV. We measured search time until participants found a more salient (O) or less salient (T) target among distractors (L). On average O's were found faster than T's. Gaze analysis showed that saliency facilitation occurred due to the target guiding the search only if it was within the initial FoV. When targets required a head movement to enter the FoV, participants followed the same search strategy as in trials without a visible target in the periphery. Moreover, faster search times for salient targets were only caused by the time required to find the target once the target set was reached. This suggests that the effect of stimulus saliency differs between visual search on fixed displays and when we are actively searching through an extended visual field. [ABSTRACT FROM AUTHOR]

Altered head range of motion (RoM) and head repositioning accuracy (HRA) are commonly reported in neck pain. However, the quality of motion (QoM) is currently not easy to assess clinically. This study investigated the agreement of head rotation recordings using a 3D camera system compared to a commercially available inertial measurement unit (MOTI). Thirty participants, mean age 26.5 years old (SD 4.4), partook in this study. Participants wore a Headband with MOTI and markers for 3D motion capture analysis during head rotations. The two systems recorded active head RoM in rotation, HRA, and QoM. Agreement of RoM, HRA and QoM data was compared between the two systems using Interclass correlation coefficients (ICC; 2.1) and Bland-Altman plots. Good to excellent agreement between the two systems was seen for RoM (ICC: 0.998), HRA (0.75–0.88) and QoM (ICC: 0.911–0.913). The Bland-Altman plots revealed a systemic offset where the MOTI device measured higher values for RoM (mean bias: −0.56 ± 0.65°), HRA (mean bias: 0.48 ± 0.76°) and QoM (mean bias: −16.9 ± 51.6 A.U.). The present study found that the MOTI device can accurately measure RoM, HRA and QoM during head rotation. MOTI may be preferred over a 3D camera system for clinical use. [ABSTRACT FROM AUTHOR]

Objective: We aimed to evaluate eye and head movements, which are objective parameters in ADHD. Method: While the children were watching the course video task, which included the relevant (teacher and smart board) and irrelevant (any regions outside the relevant area) areas of interest, their eye movements were evaluated through eye tracking, and video recordings were made simultaneous. Head position estimation was made using through video recordings. The proportion of total fixation duration on areas of interest (PFDAOI) and saccade count, amplitude, velocity for eye movements, number of total head movements and angular change of head movement in x - y - z axes for head movements were compared. Results: Children with ADHD had lower PFDAOI on the relevant area, and had more saccade and head movements The angular change of head movement in the x-axis was higher in the ADHD group. Conclusion: In the assessment of ADHD, the eye and head movements may be particulary useful. [ABSTRACT FROM AUTHOR]

With increasing automation in the rail sector, the train driver's task changes from full control to a supervisory position. This bears the risk of monotony and subsequent changes in visual attention, possibly for the worse. Similar to concepts in car driving, one solution for this could be driver state monitoring with triggered interventions in case of declining task attention. Previous research on train drivers' visual attention has used eye tracking. In contrast, head tracking is easier to realize within the train driver cabin. This study set out to test whether head tracking is a feasible alternative to eye tracking and can provide similar findings. Based on previous eye-tracking research, we compared differences in head movements in automated vs. manual driving, and for different levels of driving speed and driving experience. We conducted a study with 25 active train drivers in a high-fidelity train simulator. Statistical analyses revealed no significant difference in the vertical head movements between automation levels. There was a significant difference in the horizontal head movements, with train drivers looking more to the right for manual driving. We found no significant influence of driving speed and experience on head movements. Safety implications and the feasibility of head tracking as an alternative to eye tracking are discussed. [ABSTRACT FROM AUTHOR]

There are several factors for vehicle accidents during driving such as drivers' negligence, drowsiness, and fatigue. These accidents can be avoided, if drivers are warned in time. Moreover, recent developments in computer vision and artificial intelligence (AI) have helped to monitor drivers and alert them in case they are not concentrating on driving. The AI techniques can extract relevant features from expressions of driver's face, such as eye closure, yawning, and head movements to infer the level of sleepiness. In addition, they can acquire biological signals from the driver's body, and indications from the vehicle behavior. This paper provides a comprehensive review of the detection techniques of drowsiness and fatigue of drivers using machine learning (ML) and deep learning (DL). The current techniques for this application are classified into four categories: image- or video-based analysis during the driving, biological signal analysis for drivers, vehicle movement analysis, and hybrid techniques. A review of supervised techniques is presented for detecting fatigue and drowsiness on different datasets, with a comparison of the various techniques in terms of pros and cons. Results are presented in terms of accuracy of detection for each technique. The results are discussed according to the recent problems and challenges in this field. The paper also highlights the applicability and reliability of the different techniques. Furthermore, some suggestions are presented for the future work in the field of driver drowsiness detection (DDD). [ABSTRACT FROM AUTHOR]

Introduction: Benign recurrent vertigo (BRV), Menière's disease (MD), and vestibular migraine (VM) show many similarities with regard to the course of vertigo attacks and clinical features. In this paper, we elaborate on the decreasing frequency of vertigo attacks observed in a previous study from our group by exploring changes in the duration and trigger factors of vertigo attacks in patients with BRV, MD, or VM. Methods: For this 3-year prospective cohort study in our tertiary referral center we recruited patients with a confirmed diagnosis of BRV, MD, or VM by a neurologist and otorhinolaryngologist in our center in 2015–2016. A study-specific questionnaire was used to assess the usual duration of vertigo attacks and their potential triggers every 6 months. Main outcome measures were changes in duration and trigger factors of vertigo attacks in the subgroups of patients with persisting attacks, which were analyzed using repeated measures logistic regression models. Results: 121 patients were included (BRV: n = 44; MD: n = 43; VM: n = 34) of whom 117 completed the 3-year follow-up period and 57 (48.7%) kept reporting vertigo attacks at one more follow-up measurements. None of the diagnosis groups showed statistically significant shortening of attack duration at the subsequent annual follow-up measurements compared to baseline. At baseline, stress and fatigue being reported as triggers for attacks differed significantly between the three groups (stress: BRV 40.9%, MD 62.8%, VM 76.5%, p = 0.005; fatigue: BRV 31.0%, MD 48.8%, VM 68.8%, p = 0.003). In the VM group, a consistent reduction of stress and fatigue as triggers was observed up until the 24- and the 30-month follow-up measurements, respectively, with odds ratios (ORs) ranging from 0.15 to 0.33 (all p < 0.05). In the MD group, a consistent reduction of head movements as trigger was observed from the 24-month measurement onward (ORs ranging from 0.07 to 0.11, all p < 0.05). Conclusion: Our study showed no reduction in vertigo attack duration over time in patients with BRV, MD, and VM who remain to have vertigo attacks. In VM and MD patients with persisting vertigo attacks stress, fatigue and head movements became less predominant triggers for vertigo attacks. [ABSTRACT FROM AUTHOR]

Head movements of insects play a vital role in diverse locomotory behaviors including flying and walking. Because insect eyes move minimally within their sockets, their head movements are essential to reduce visual blur and maintain a stable gaze. As in most vertebrates, gaze stabilization behavior in insects requires the integration of both visual and mechanosensory feedback by the neck motor neurons. Although visual feedback is derived from the optic flow over the retina of their compound eyes, mechanosensory feedback is derived from their organs of balance, similar to the vestibular system in vertebrates. In Diptera, vestibular feedback is derived from the halteres—modified hindwings that evolved into mechanosensory organs—and is integrated with visual feedback to actuate compensatory head movements. However, non‐Dipteran insects, including Lepidoptera, lack halteres. In these insects, vestibular feedback is obtained from the antennal Johnston's organs but it is not well‐understood how it integrates with visual feedback during head movements. Indeed, although head movements are well‐studied in flies, the underlying motor apparatus in non‐Dipteran taxa has received relatively less attention. As a first step toward understanding compensatory head movements in the Oleander hawkmoth Daphnis nerii, we image the anatomy and architecture of their neck joint sclerites and muscles using X‐ray microtomography, and the associated motor neurons using fluorescent dye fills and confocal microscopy. Based on these morphological data, we propose testable hypotheses about the putative function of specific neck muscles during head movements, which can shed light on their role in neck movements and gaze stabilization. [ABSTRACT FROM AUTHOR]

There is a discrepancy between the hearing test results in patients with single-sided deafness (SSD) and their reported outcome measures. This is probably due to the presence of two elements in everyday situations: noise and head movements. We developed a stereo-audiometric test in noise with free head movements to evaluate movements and auditory performance in monaural and binaural conditions in normal hearing volunteers with one occluded ear. Tests were performed in the binaural condition (BIN), with the left ear (LEO) or the right ear occluded (REO). The signal was emitted by one of the seven speakers, placed every 30° in a semicircle, and the noise (cocktail party) by all speakers. Subjects turned their head freely to obtain the most comfortable listening position, then repeated 10 sentences in this position. In monaural conditions, the sums of rotations (head rotations for an optimal hearing position in degrees, random signal azimuth, 1 to 15 signal ad lib signal presentations) were higher (LEO 255 ± 212°, REO 308 ± 208° versus BIN 74 ± 76, p < 0.001, ANOVA) than those in the BIN condition and the discrimination score (out of 10) was lower than that in the BIN condition (LEO 5 ± 1, REO 7 ± 1 versus BIN 8 ± 1, respectively p < 0.001 and p < 0.05 ANOVA). In the monaural condition, total rotation and discrimination in noise were negatively correlated with difficulty (Pearson r = −0.68, p < 0.01 and −0.51, p < 0.05, respectively). Subjects' behaviors were different in optimizing their hearing in noise via head rotation. The evaluation of head movements seems to be a significant parameter in predicting the difficulty of monaural hearing in noisy environments. [ABSTRACT FROM AUTHOR]

Background: The head plays an important role in the postural control. Chewing co‐activates jaw and neck muscles leading to coordinated jaw and head‐neck movements. Therefore, to examine effect of masticatory movements on head and trunk sways, and sitting and foot pressure distributions during mastication is helpful in the attempt to understand the interrelationship between stomatognathic function and posture control system in the sitting position. Objectives: The purpose of this study was to test the hypothesis in healthy subjects that masticatory movements affect head and trunk sways and sitting and foot pressure distributions during sitting position. Methods: A total of 30 healthy male subjects with an average age of 25.3 years (range, 22–32 years) were evaluated. The CONFORMat™ and MatScan™ system were used to analyse changes in sitting pressure distribution center of sitting pressure (COSP) and changes in foot pressure distribution center of foot pressure (COFP), respectively, and the three‐dimensional motion analysis system was used to analyse changes in head and trunk postures while subjects remained sitting position with rest position, centric occlusion and chewing. The total trajectory length of COSP/COFP, COSP/COFP area, and head and trunk sway values were compared between the three conditions to evaluate whether masticatory movement affected the stability of head and trunk sways and sitting and foot pressure distributions. Results: Total trajectory length of COSP and COSP area during chewing were significantly shorter and smaller respectively than it was in rest position and centric occlusion (p ⟨.016). Head sway value during chewing was significantly larger than it was in rest position and centric occlusion (p ⟨.016). Conclusion: Masticatory movements affect sitting pressure distribution and head movements during sitting position. [ABSTRACT FROM AUTHOR]

Blast exposure can injure brain by multiple mechanisms, and injury attributable to direct effects of the blast wave itself have been difficult to distinguish from that caused by rapid head displacement and other secondary processes. To resolve this issue, we used a rat model of blast exposure in which head movement was either strictly prevented or permitted in the lateral plane. Blast was found to produce axonal injury even with strict prevention of head movement. This axonal injury was restricted to the cerebellum, with the exception of injury in visual tracts secondary to ocular trauma. The cerebellar axonal injury was increased in rats in which blast-induced head movement was permitted, but the pattern of injury was unchanged. These findings support the contentions that blast per se, independent of head movement, is sufficient to induce axonal injury, and that axons in cerebellar white matter are particularly vulnerable to direct blast-induced injury.

Background and Purpose: Use of unilateral cochlear implant (UCI) is associated with limited spatial hearing skills. Evidence that training these abilities in UCI user is possible remains limited. In this study, we assessed whether a Spatial training based on hand-reaching to sounds performed in virtual reality improves spatial hearing abilities in UCI users Methods: Using a crossover randomized clinical trial, we compared the effects of a Spatial training protocol with those of a Non-Spatial control training. We tested 17 UCI users in a head-pointing to sound task and in an audio-visual attention orienting task, before and after each training.
Study is recorded in clinicaltrials.gov (NCT04183348). Results: During the Spatial VR training, sound localization errors in azimuth decreased. Moreover, when comparing head-pointing to sounds before vs. after training, localization errors decreased after the Spatial more than the control training. No training effects emerged in the audio-visual attention orienting task. Conclusions: Our results showed that sound localization in UCI users improves during a Spatial training, with benefits that extend also to a non-trained sound localization task (generalization). These findings have potentials for novel rehabilitation procedures in clinical contexts. [ABSTRACT FROM AUTHOR]

KEY POINTS: Sensory systems are adapted to the statistical structure of natural stimuli, thereby optimizing neural coding. Head motion during natural activities is first sensed and then processed by central vestibulo-motor pathways to influence subsequent behaviour, thereby establishing a feedback loop. To investigate the role of this vestibular feedback on the statistical structure of the head movements, we compared head movements in patients with unilateral vestibular loss and healthy controls. We show that the loss of vestibular feedback substantially alters the statistical structure of head motion for activities that require rapid online feedback control and predict this change by modelling the effects of increased movement variability. Our findings suggest that, following peripheral vestibular loss, changes in the reliability of the sensory input to central pathways impact the statistical structure of head motion during voluntary behaviours. ABSTRACT: It is widely believed that sensory systems are adapted to optimize neural coding of their natural stimuli. Recent evidence suggests that this is the case for the vestibular system, which senses head movement and contributes to essential functions ranging from the most automatic reflexes to voluntary motor control. During everyday behaviours, head motion is sensed by the vestibular system. In turn, this sensory feedback influences subsequent behaviour, raising the questions of whether and how real-time feedback provided by the vestibular system alters the statistical structure of head movements. We predicted that a reduction in vestibular feedback would alter head movement statistics, particularly for tasks reliant on rapid vestibular feedback. To test this proposal, we recorded six-dimensional head motion in patients with variable degrees of unilateral vestibular loss during standard balance and gait tasks, as well as dynamic self-paced activities. While distributions of linear accelerations and rotational velocities were comparable for patients and age-matched healthy controls, comparison of power spectra revealed significant differences during more dynamic and challenging activities. Specifically, consistent with our prediction, head movement power spectra were significantly altered in patients during two tasks that required rapid online vestibular feedback: active repetitive jumping and walking on foam. Using computational methods, we analysed concurrently measured torso motion and identified increases in head-torso movement variability. Taken together, our results demonstrate that vestibular loss significantly alters head movement statistics and further suggest that increased variability and impaired feedback to internal models required for accurate motor control contribute to the observed changes.

How are eyes and head adapted to meet the demands of visual exploration in different tasks and environments? In two studies, we measured the horizontal movements of the eyes (using mobile eye tracking in Studies 1 and 2) and the head (using inertial sensors in Study 2) while participants completed a walking task and a search and retrieval task in a large, outdoor environment. We found that the spread of visual exploration was greater while searching compared with walking, and this was primarily driven by increased movement of the head as opposed to the eyes. The contributions of the head to gaze shifts of different eccentricities was greater when searching compared to when walking. Findings are discussed with respect to understanding visual exploration as a motor action with multiple degrees of freedom.

The vestibular system broadcasts head-movement-related signals to sensory areas throughout the brain, including visual cortex. These signals are crucial for the brain's ability to assess whether motion of the visual scene results from the animal's head movements. However, how head movements affect visual cortical circuits remains poorly understood. Here, we discover that ambient luminance profoundly transforms how mouse primary visual cortex (V1) processes head movements. While in darkness, head movements result in overall suppression of neuronal activity; in ambient light, the same head movements trigger excitation across all cortical layers. This light-dependent switch in how V1 processes head movements is controlled by somatostatin-expressing (SOM) inhibitory neurons, which are excited by head movements in dark, but not in light. This study thus reveals a light-dependent switch in the response of V1 to head movements and identifies a circuit in which SOM cells are key integrators of vestibular and luminance signals.

Visual motion information plays an important role in the control of movements in sports. Skilled ball players are thought to acquire accurate visual information by using an effective visual search strategy with eye and head movements. However, differences in catching ability and gaze movements due to sports experience and expertise have not been clarified. Therefore, the purpose of this study was to determine the characteristics of gaze strategies based on eye and head movements during a ball-catching task in athlete and novice groups. Participants were softball and tennis players and college students who were not experienced in ball sports (novice). They performed a one-handed catching task using a tennis ball-shooting machine, which was placed at 9 m in front of the participants, and two conditions were set depending on the height of the ball trajectory (high and low conditions). Their head and eye velocities were detected using a gyroscope and electrooculography (EOG) during the task. Our results showed that the upward head velocity and the downward eye velocity were lower in the softball group than in the tennis and novice groups. When the head was pitched upward, the downward eye velocity was induced from the vestibulo-ocular reflex (VOR) during ball catching. Therefore, it is suggested that skilled ball players have relatively stable head and eye movements, which may lead to an effective gaze strategy. An advantage of the stationary gaze in the softball group could be to acquire visual information about the surroundings other than the ball.

Eurhinodelphinids are a family of extremely long-snouted dolphins that once was widespread across the North Atlantic realm, but so far has not been recorded from the epicontinental Paratethys Sea. Here, we describe a new specimen of Xiphiacetus cristatus, including the cranium, left ear bones and a partial mandible, from the Middle Miocene (Badenian) of Austria. Our new fossil is the first record of this species outside the North Atlantic proper, and the first unequivocal record of eurhinodelphinids from the Paratethys. Its presence suggests a local invasion via the Mediterranean, and corroborates the persistence of an active marine gateway between the Mediterranean and the Central Paratethys throughout the Middle Miocene. Measurements of the bony labyrinth reveal that X. cristatus likely employed narrow-band high-frequency echolocation, making eurhinodelphinids only the second extinct odontocete family with this trait. Marked non-orthogonality of the semicircular canals suggests that X. cristatus was unsuited to rapid head movements, and thus more likely a benthic forager than a snap feeder. [ABSTRACT FROM AUTHOR]

The present study investigates the statistics and spectral content of natural vestibular stimuli experienced by healthy human subjects during three unconstrained activities. More specifically, we assessed how the characteristics of vestibular inputs are altered during the operation of a complex human-machine interface (a flight in a helicopter simulator) compared with more ecological tasks, namely a walk in an office space and a seated visual exploration task. As previously reported, we found that the power spectra of vestibular stimuli experienced during self-navigation could be modeled by two power laws but noted a potential effect of task intensity on the transition frequency between the two fits. In contrast, both tasks that required a seated position had power spectra that were better described by an inverted U shape in all planes of motion. Taken together, our results suggest that 1) walking elicits stereotyped vestibular inputs whose power spectra can be modeled by two power laws that intersect at a task intensity-dependent frequency; 2) body posture induces changes in the frequency content of vestibular information; 3) pilots tend to operate their aircraft in a way that does not generate highly nonecological vestibular stimuli; and 4) nevertheless, human-machine interfaces used as a means of manual navigation still impose some unnatural, contextual constraints on their operators. [ABSTRACT FROM AUTHOR]

Many wheelchair users experience disabilities in stabilising and positioning of the head. For these users, adequate head support is required. Although several types of head supports are available, further development of these systems is needed to improve functionality and quality of life, especially for the group of severely challenged users. For this group, user needs have not been clearly established. In this article, we provide an overview of the state-of-the-art in wheelchair mounted head supports and associated scientific evidence in order to identify requirements for the next generation of head support systems. A scoping review was performed including scientific literature (PubMed/Scopus), patents (Espacenet/Google Scholar) and commercial information. Types of head support and important system characteristics for future head support systems were proposed from consultations with wheelchair users (n = 3), occupational therapists (n = 3) and an expert panel. Forty scientific papers, 90 patents and 80 descriptions of commercial devices were included in the scoping review. The identified head support systems were categorised per head support type. Only limited scientific clinical evidence with respect to the effectiveness of existing head support systems was found. From the user and expert consultations, a need was identified for personalised head support systems that intuitively combine changes in sitting and head position with continuous optimal support of the head to accommodate severely challenged users. This study presents the state-of-the-art in head support systems. Additionally, several important system characteristics are introduced that provide guidance for the development and improvement of head supports. Especially for the group of severely challenged wheelchair users, current head support systems require further development to improve their users' quality of life. The desired system characteristics which are discussed in this review are an important step in the definition of requirements for the next generation of head supports. [ABSTRACT FROM AUTHOR]

Serotonergic hallucinogens such as lysergic acid diethylamide (LSD) induce head twitches in rodents via 5-HT2A receptor activation. The goal of the present investigation was to determine whether a correlation exists between the potency of hallucinogens in the mouse head-twitch response (HTR) paradigm and their reported potencies in other species, specifically rats and humans. Dose-response experiments were conducted with phenylalkylamine and tryptamine hallucinogens in C57BL/6J mice, enlarging the available pool of HTR potency data to 41 total compounds. For agents where human data are available (n = 36), a strong positive correlation (r = 0.9448) was found between HTR potencies in mice and reported hallucinogenic potencies in humans. HTR potencies were also found to be correlated with published drug discrimination ED50 values for substitution in rats trained with either LSD (r = 0.9484, n = 16) or 2,5-dimethoxy-4-methylamphetamine (r = 0.9564, n = 21). All three of these behavioral effects (HTR in mice, hallucinogen discriminative stimulus effects in rats, and psychedelic effects in humans) have been linked to 5-HT2A receptor activation. We present evidence that hallucinogens induce these three effects with remarkably consistent potencies. In addition to having high construct validity, the HTR assay also appears to show significant predictive validity, confirming its translational relevance for predicting subjective potency of hallucinogens in humans. These findings support the use of the HTR paradigm as a preclinical model of hallucinogen psychopharmacology and in structure-activity relationship studies of hallucinogens. Future investigations with a larger number of test agents will evaluate whether the HTR assay can be used to predict the hallucinogenic potency of 5-HT2A agonists in humans. "This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

Head motion represents one of the greatest technical obstacles in magnetic resonance imaging (MRI) of the human brain. Accurate detection of artifacts induced by head motion requires precise estimation of movement. However, head motion estimates may be corrupted by artifacts due to magnetic main field fluctuations generated by body motion. In the current report, we examine head motion estimation in multiband resting state functional connectivity MRI (rs-fcMRI) data from the Adolescent Brain and Cognitive Development (ABCD) Study and comparison 'single-shot' datasets. We show that respirations contaminate movement estimates in functional MRI and that respiration generates apparent head motion not associated with functional MRI quality reductions. We have developed a novel approach using a band-stop filter that accurately removes these respiratory effects from motion estimates. Subsequently, we demonstrate that utilizing a band-stop filter improves post-processing fMRI data quality. Lastly, we demonstrate the real-time implementation of motion estimate filtering in our FIRMM (Framewise Integrated Real-Time MRI Monitoring) software package.

Hallucinogens induce the head-twitch response (HTR), a rapid reciprocal head movement, in mice. Although head twitches are usually identified by direct observation, they can also be assessed using a head-mounted magnet and a magnetometer. Procedures have been developed to automate the analysis of magnetometer recordings by detecting events that match the frequency, duration, and amplitude of the HTR. However, there is considerable variability in the features of head twitches, and behaviors such as jumping have similar characteristics, reducing the reliability of these methods. We have developed an automated method that can detect head twitches unambiguously, without relying on features in the amplitude-time domain. To detect the behavior, events are transformed into a visual representation in the time-frequency domain (a scalogram), deep features are extracted using the pretrained convolutional neural network (CNN) ResNet-50, and then the images are classified using a Support Vector Machine (SVM) algorithm. These procedures were used to analyze recordings from 237 mice containing 11,312 HTR. After transformation to scalograms, the multistage CNN-SVM approach detected 11,244 (99.4%) of the HTR. The procedures were insensitive to other behaviors, including jumping and seizures. Deep learning based on scalograms can be used to automate HTR detection with robust sensitivity and reliability.

Virtual reality (VR) is increasingly used in gaming, training, and health-related applications. However, the level of immersion and presence generated by VR can significantly influence the user and the achievement of desired outcomes. Therefore, methods to assess levels of immersion and presence need to be established. In this paper, we investigate the vestibulo-ocular reflex (VOR) and saccadic eye movements in multiple subjects exposed to VR to determine if VR triggers these responses as in real life. Using an HTC VIVE Pro Eye headset and Tobii Pro Lab software, we record head and eye movements in response to a 3D video of a roller coaster ride. Our results show that critical scenes in the video triggered VOR and saccadic eye movements in most subjects, indicating a strong correlation between VOR and saccadic eye movements during VR immersion. These findings may have implications for the study of human behavior and suggest the use of eye movement measures as feedback mechanisms during VR experiences.

Abstract Background Balance stabilization exercises are often prescribed to facilitate compensation in individuals with vestibular schwannoma (VS). However, both the assessment and prescription of these exercises are reliant on clinical observations and expert opinion rather than on quantitative evidence. The aim of this study was to quantify head motion kinematics in individuals with vestibular loss while they performed commonly prescribed balance stability exercises. Methods Using inertial measurement units, head movements of individuals with vestibular schwannoma were measured before and after surgical deafferentation and compared with age-matched controls. Results We found that individuals with vestibular schwannoma experienced more variable head motion compared to healthy controls both pre- and postoperatively, particularly in absence of visual input, but that there was little difference between preoperative and postoperative kinematic measurements for our vestibular schwannoma group. We further found correlations between head motion kinematic measures during balance exercises, performed in the absence of visual input, and multiple clinical measurements for preoperative VS subjects. Subjects with higher head motion variability also had worse DVA scores, moved more slowly during the Timed up and Go and gait speed tests, and had lower scores on the functional gait assessment. In contrast, we did not find strong correlations between clinical measures and postoperative head kinematics for the same VS subjects. Conclusions Our data suggest that further development of such metrics based on the quantification of head motion has merit for the assessment and prescription of balance exercises, as demonstrated by the calculation of a “kinematic score” for identifying the most informative balance exercise (i.e., “Standing on foam eyes closed”).

Electroencephalography (EEG) is widely used in clinical applications and basic research. Dry EEG opened the application area to new fields like self-application during gaming and neurofeedback. While recording, the signals are always affected by artefacts. Manual detection of bad channels is the gold standard in both gel-based and dry EEG but is timeconsuming. We propose a simple and robust method for automatic bad channel detection in EEG. Our method is based on the iterative calculation of standard deviations for each channel. Statistical measures of these standard deviations serve as indications for bad channel detection. We compare the new method to the results obtained from the manually identified bad channels for EEG recordings. We analysed EEG signals during resting state with eyes closed and datasets with head movement. The results showed an accuracy of 99.69 % for both gel-based and dry EEG for resting state EEG. The accuracy of our new method is 99.38 % for datasets with the head movement for both setups. There was no significant difference between the manual gold standard of bad channel identification and our iterative standard deviation method. Therefore, the proposed iterative standard deviation method can be used for bad channel detection in resting state and movement EEG recordings.

Unilateral hearing loss (UHL) leads to an alteration of binaural cues resulting in a significant increment of spatial errors in the horizontal plane. In this study, nineteen patients with UHL were recruited and randomized in a cross-over design into two groups; a first group (n = 9) that received spatial audiovisual training in the first session and a non-spatial audiovisual training in the second session (2 to 4 weeks after the first session). A second group (n = 10) received the same training in the opposite order (non-spatial and then spatial). A sound localization test using head-pointing (LOCATEST) was completed prior to and following each training session. The results showed a significant decrease in head-pointing localization errors after spatial training for group 1 (24.85° ± 15.8° vs. 16.17° ± 11.28°; p < 0.001). The number of head movements during the spatial training for the 19 participants did not change (p = 0.79); nonetheless, the hand-pointing errors and reaction times significantly decreased at the end of the spatial training (p < 0.001). This study suggests that audiovisual spatial training can improve and induce spatial adaptation to a monaural deficit through the optimization of effective head movements. Virtual reality systems are relevant tools that can be used in clinics to develop training programs for patients with hearing impairments. [ABSTRACT FROM AUTHOR]

BackgroundOral administration of magnesium and boron might have a beneficial effect on headshaking behavior in horses.ObjectiveEvaluate the effects of oral magnesium alone or in combination with boron on headshaking behavior in affected horses.AnimalsTwelve geldings (6 healthy controls and 6 affected).MethodsProspective randomized controlled dietary trial over 42 days in 12 horses (6 horses diagnosed with trigeminal-mediated headshaking and 6 unaffected healthy controls). All horses received a hay diet and were randomized into 3 treatment groups: pelleted feed combination (PF), pelleted feed combination with magnesium (M), and pelleted feed combination with magnesium-boron (MB) with a week washout of hay only between treatments. Headshaking behavior and biochemical blood variables were assessed at baseline (hay only) and then after each week of supplementation.ResultsAll 3 diet interventions increased blood ionized and total magnesium. Groups M and MB further increased Mg2+ when compared to PF. Horses receiving treatments had a significant reduction in headshaking behavior, as measured by incidence rate ratio (IRR), when compared to unsupplemented hay diet (44% for PF, IRR, 0.558; CI, 0.44, 0.72; P

In recent years, rigid analogs of phenylalkylamine hallucinogens have appeared as recreational drugs. Examples include 2-(8-bromo-2,3,6,7-tetrahydrobenzo[1,2-b:4,5-b']difuran-4-yl)ethan-1-amine (2C-B-FLY) and 1-(8-bromobenzo[1,2-b;4,5-b']difuran-4-yl)-2-aminopropane (Bromo-DragonFLY, DOB-DFLY). Although some rigid compounds such as DOB-DFLY reportedly have higher potency than their non-rigid counterparts, it is not clear whether the same is true for 2C-B-FLY and other tetrahydrobenzodifurans. In the present study, the head twitch response (HTR), a 5-HT2A receptor-mediated behavior induced by serotonergic hallucinogens, was used to assess the effects of 2,5-dimethoxy-4-bromoamphetamine (DOB) and its α-desmethyl homologue 2,5-dimethoxy-4-bromophenethylamine (2C-B), as well as their benzodifuranyl and tetrahydrobenzodifuranyl analogs, in C57BL/6J mice. DOB (ED50 = 0.75 μmol/kg) and 2C-B (ED50 = 2.43 μmol/kg) induced the HTR. The benzodifurans DOB-DFLY (ED50 = 0.20 μmol/kg) and 2C-B-DFLY (ED50 = 1.07 μmol/kg) had significantly higher potency than DOB and 2C-B, respectively. The tetrahydrobenzodifurans DOB-FLY (ED50 = 0.67 μmol/kg) and 2C-B-FLY (ED50 = 1.79 μmol/kg), by contrast, were approximately equipotent with their non-rigid counterparts. Three novel tetrahydrobenzodifurans (2C-I-FLY, 2C-E-FLY and 2C-EF-FLY) were also active in the HTR assay but had relatively low potency. In summary, the in vivo potency of 2,5-dimethoxyphenylalkylamines is enhanced when the 2- and 5-methoxy groups are incorporated into aromatic furan rings, whereas potency is not altered if the methoxy groups are incorporated into dihydrofuran rings. The potency relationships for these compounds in mice closely parallel the human hallucinogenic data. The high potency of DOB-DFLY is probably linked to the presence of two structural features (a benzodifuran nucleus and an α-methyl group) known to enhance the potency of phenylalkylamine hallucinogens.

Background: Early differences in sensorimotor functioning have been documented in young autistic children and infants who are later diagnosed with autism. Previous research has demonstrated that autistic toddlers exhibit more frequent head movement when viewing dynamic audiovisual stimuli, compared to neurotypical toddlers. To further explore this behavioral characteristic, in this study, computer vision (CV) analysis was used to measure several aspects of head movement dynamics of autistic and neurotypical toddlers while they watched a set of brief movies with social and nonsocial content presented on a tablet. Methods: Data were collected from 457 toddlers, 17–36 months old, during their well‐child visit to four pediatric primary care clinics. Forty‐one toddlers were subsequently diagnosed with autism. An application (app) displayed several brief movies on a tablet, and the toddlers watched these movies while sitting on their caregiver's lap. The front‐facing camera in the tablet recorded the toddlers' behavioral responses. CV was used to measure the participants' head movement rate, movement acceleration, and complexity using multiscale entropy. Results: Autistic toddlers exhibited significantly higher rate, acceleration, and complexity in their head movements while watching the movies compared to neurotypical toddlers, regardless of the type of movie content (social vs. nonsocial). The combined features of head movement acceleration and complexity reliably distinguished the autistic and neurotypical toddlers. Conclusions: Autistic toddlers exhibit differences in their head movement dynamics when viewing audiovisual stimuli. Higher complexity of their head movements suggests that their movements were less predictable and less stable compared to neurotypical toddlers. CV offers a scalable means of detecting subtle differences in head movement dynamics, which may be helpful in identifying early behaviors associated with autism and providing insight into the nature of sensorimotor differences associated with autism. [ABSTRACT FROM AUTHOR]

Background: Balance stabilization exercises are often prescribed to facilitate compensation in individuals with vestibular schwannoma (VS). However, both the assessment and prescription of these exercises are reliant on clinical observations and expert opinion rather than on quantitative evidence. The aim of this study was to quantify head motion kinematics in individuals with vestibular loss while they performed commonly prescribed balance stability exercises.Methods: Using inertial measurement units, head movements of individuals with vestibular schwannoma were measured before and after surgical deafferentation and compared with age-matched controls.Results: We found that individuals with vestibular schwannoma experienced more variable head motion compared to healthy controls both pre- and postoperatively, particularly in absence of visual input, but that there was little difference between preoperative and postoperative kinematic measurements for our vestibular schwannoma group. We further found correlations between head motion kinematic measures during balance exercises, performed in the absence of visual input, and multiple clinical measurements for preoperative VS subjects. Subjects with higher head motion variability also had worse DVA scores, moved more slowly during the Timed up and Go and gait speed tests, and had lower scores on the functional gait assessment. In contrast, we did not find strong correlations between clinical measures and postoperative head kinematics for the same VS subjects.Conclusions: Our data suggest that further development of such metrics based on the quantification of head motion has merit for the assessment and prescription of balance exercises, as demonstrated by the calculation of a "kinematic score" for identifying the most informative balance exercise (i.e., "Standing on foam eyes closed"). [ABSTRACT FROM AUTHOR]

In everyday life, sound localization entails more than just the extraction and processing of auditory cues. When determining sound position in three dimensions, the brain also considers the available visual information (e.g., visual cues to sound position) and resolves perceptual ambiguities through active listening behavior (e.g., spontaneous head movements while listening). Here, we examined to what extent spontaneous head movements improve sound localization in 3D—azimuth, elevation, and depth—by comparing static vs. active listening postures. To this aim, we developed a novel approach to sound localization based on sounds delivered in the environment, brought into alignment thanks to a VR system. Our system proved effective for the delivery of sounds at predetermined and repeatable positions in 3D space, without imposing a physically constrained posture, and with minimal training. In addition, it allowed measuring participant behavior (hand, head and eye position) in real time. We report that active listening improved 3D sound localization, primarily by ameliorating accuracy and variability of responses in azimuth and elevation. The more participants made spontaneous head movements, the better was their 3D sound localization performance. Thus, we provide proof of concept of a novel approach to the study of spatial hearing, with potentials for clinical and industrial applications. [ABSTRACT FROM AUTHOR]

Abstract Background Neck pain is one of the most common musculoskeletal disorders encountered by healthcare providers. A precise assessment of functional deficits, including sensorimotor control impairment, is regarded necessary for tailored exercise programmes. Sensorimotor control can be measured by kinematic characteristics, such as velocity, acceleration, smoothness, and temporal measures, or by assessing movement accuracy. This systematic review aims to identify movement tasks and distinct outcome variables used to measure kinematics and movement accuracy in patients with neck pain and present their results in comparison to asymptomatic controls. Methods Electronic searches were conducted in MEDLINE, PEDro, Cochrane Library and CINAHL databases from inception to August 2020. Risk of bias of included studies was assessed. Movement tasks and specific outcome parameters used were collated. The level of evidence for potential group differences in each outcome variable between patients with neck pain and controls was evaluated. Results Twenty-seven studies examining head kinematics and movement accuracy during head-aiming, functional and unconstrained movement tasks of the head were included. Average Risk of Bias of included studies was moderate. In total, 23 different outcome variables were assessed. A strong level of evidence for an increased movement time and for an increased number of errors during head aiming tasks was found. Moderate evidence was found in traumatic neck pain for a decreased mean velocity, peak acceleration, and reaction time, and for point deviation and time on target during head aiming tasks. Moderate evidence was found for decreased acceleration during unconstrained movements, too. Results on the remaining movement task and outcome variables showed only limited, very limited or even conflicting level of evidence for patients with neck pain to differ from controls. Conclusions Sensorimotor control in NP in the way of kinematic and movement accuracy characteristics of head motion was examined in head aiming, functional or unconstrained movement tasks. The results from this review indicate that for some characteristics that describe sensorimotor control, patients with NP differ from healthy controls. Systematic review registration PROSPERO registration number: CRD42020139083.

Face-to-face meetings on a conference table are a frequent form of communication. The short-range exposure risk of aerosol disease transmission is high in the scenario of susceptible facing the infectious person over the table. We propose a mitigation methodology using the air curtain to reduce direct exposure to virus-laden aerosols. A numerical model was validated with experimental data to simulate the dispersion of aerosols. A dynamic mesh was adopted to consider the head movement of a 3D thermal manikin model. Results show that nodding head increase the potential risk by 74 % compared to motionless. Subsequently, for a single air curtain, placing it in the middle of the table is more effective in preventing risks than on the sides. For double air curtains, increasing the distance between them has a greater risk reduction effect than a shorter distance. Increasing the air velocity or width is more effective than increasing the number of air curtains. A moderate velocity (1 m s−1) works well to reduce the risk of nasal breathing. A higher velocity (2 m s−1) is needed for the coughing scenario. For similar indoor environments, the air curtains on the table can offer active precautions without changing the current ventilation system. [Display omitted] ● A mitigation methodology using the air curtains is developed considering head movements. ● Nodding head increases the short-ranged risk by 74.0 % compared to motionless. ● Central placement of single air curtain provides the greatest protection than on the sides. ● Improving the air velocity to 2 m s−1 is required for coughing scenarios. ● Increased room-scaled exposure due to air curtains is negligible compared to short-ranged exposure. [ABSTRACT FROM AUTHOR]

Animals invest in costly vigilance to detect threats. Joining groups reduces these costs, which can be further reduced in mixed-species assemblages. In colour-polymorphic species, morphs often experience different predation pressure and vary in a variety of traits. However, little is known about differences in vigilance or how group composition affects vigilance. The aim was to investigate whether higher conspicuousness increased vigilance and whether vigilance was reduced in mixed-morph groups like in mixed-species assemblages. I tested vigilance in the colour-polymorphic Gouldian Finch (Chloebia gouldiae). Same sex pairs of different age and of either pure (red-red or black-black) or mixed head colour were exposed to three contexts (familiar, changed and novel environment) and head movements were recorded. All birds reduced the frequency of head movements with increasing novelty, indicating different vigilance strategies (switching from a searching to a tracking strategy) depending on the situation. While vigilance did not differ between morphs, morph composition mattered. Black-headed pairs made fewer head movements than mixed-head colour pairs. Results indicated that conspicuousness did not affect vigilance, possibly due to existing adaptations to reduce predation risk. However, whenever red-headed birds were involved, vigilance increased either because of higher group conspicuousness or prevalence of aggression.

Background: Neck pain is one of the most common musculoskeletal disorders encountered by healthcare providers. A precise assessment of functional deficits, including sensorimotor control impairment, is regarded necessary for tailored exercise programmes. Sensorimotor control can be measured by kinematic characteristics, such as velocity, acceleration, smoothness, and temporal measures, or by assessing movement accuracy. This systematic review aims to identify movement tasks and distinct outcome variables used to measure kinematics and movement accuracy in patients with neck pain and present their results in comparison to asymptomatic controls. Methods: Electronic searches were conducted in MEDLINE, PEDro, Cochrane Library and CINAHL databases from inception to August 2020. Risk of bias of included studies was assessed. Movement tasks and specific outcome parameters used were collated. The level of evidence for potential group differences in each outcome variable between patients with neck pain and controls was evaluated. Results: Twenty-seven studies examining head kinematics and movement accuracy during head-aiming, functional and unconstrained movement tasks of the head were included. Average Risk of Bias of included studies was moderate. In total, 23 different outcome variables were assessed. A strong level of evidence for an increased movement time in idiopathic neck pain, and for an increased number of errors during head aiming tasks in both idiopathic and traumatic neck pain was found. Moderate evidence was found in traumatic neck pain for a decreased mean velocity, and peak acceleration, and for an increased reaction time, further for a decreased time on target and increased point deviation during head aiming tasks. Moderate evidence was found for decreased acceleration during unconstrained movements, too. Results on the remaining movement task and outcome variables showed only limited, very limited or even conflicting level of evidence for patients with neck pain to differ from controls. Conclusions: Sensorimotor control in NP in the way of kinematic and movement accuracy characteristics of head motion was examined in head aiming, functional or unconstrained movement tasks. The results from this review indicate that for some characteristics that describe sensorimotor control, patients with NP differ from healthy controls. Systematic review registration: PROSPERO registration number: CRD42020139083. [ABSTRACT FROM AUTHOR]

Moving the head while a sound is playing improves its localization in human listeners, in children and adults, with or without hearing problems. It remains to be ascertained if this benefit can also extend to aging adults with hearing-loss, a population in which spatial hearing difficulties are often documented and intervention solutions are scant. Here we examined performance of elderly adults (61-82 years old) with symmetrical or asymmetrical age-related hearing-loss, while they localized sounds with their head fixed or free to move. Using motion-tracking in combination with free-field sound delivery in visual virtual reality, we tested participants in two auditory spatial tasks: front-back discrimination and 3D sound localization in front space. Front-back discrimination was easier for participants with symmetrical compared to asymmetrical hearing-loss, yet both groups reduced their front-back errors when head-movements were allowed. In 3D sound localization, free head-movements reduced errors in the horizontal dimension and in a composite measure that computed errors in 3D space. Errors in 3D space improved for participants with asymmetrical hearing-impairment when the head was free to move. These preliminary findings extend to aging adults with hearing-loss the literature on the advantage of head-movements on sound localization, and suggest that the disparity of auditory cues at the two ears can modulate this benefit. These results point to the possibility of taking advantage of self-regulation strategies and active behavior when promoting spatial hearing skills. [ABSTRACT FROM AUTHOR]

In a realistic steady-state visual evoked potential (SSVEP) based braincomputer interface (BCI) application like driving a car or controlling a quadrotor, observing the surrounding environment while simultaneously gazing at the stimulus is necessary. This kind of application inevitably could cause head movements and variation of the accompanying gaze fixation point, which might affect the SSVEP and BCI's performance. However, few papers studied the effects of head movements and gaze fixation switch on SSVEP response, and the corresponding BCI performance. This study aimed to explore these effects by designing a new ball tracking paradigm in a virtual reality (VR) environment with two different moving tasks, i.e., the following and free moving tasks, and three moving patterns, pitch, yaw, and static. Sixteen subjects were recruited to conduct a BCI VR experiment. The offline data analysis showed that head moving patterns [F(2, 30) = 9.369, p = 0.001, effect size = 0.384] resulted in significantly different BCI decoding performance but the moving tasks had no effect on the results [F(1, 15) = 3.484, p = 0.082, effect size = 0.188]. Besides, the canonical correlation analysis (CCA) and filter bank canonical correlation analysis (FBCCA) accuracy were better than the PSDA and MEC methods in all of the conditions. These results implied that head movement could significantly affect the SSVEP performance but it was possible to switch gaze fixation to interact with the surroundings in a realistic BCI application. [ABSTRACT FROM AUTHOR]