Horizontal Head Movements Research Articles

Cross-Country Ski Skating Style Sub-Technique Detection and Skiing Characteristic Analysis on Snow Using High-Precision GNSS.

A comprehensive analysis of cross-country skiing races is a pivotal step in establishing effective training objectives and tactical strategies. This study aimed to develop a method of classifying sub-techniques and analyzing skiing characteristics during cross-country skiing skating style timed races on snow using high-precision kinematic GNSS devices. The study involved attaching GNSS devices to the heads of two athletes during skating style timed races on cross-country ski courses. These devices provided precise positional data and recorded vertical and horizontal head movements and velocity over ground (VOG). Based on these data, sub-techniques were classified by defining waveform patterns for G2, G3, G4, and G6P (G6 with poling action). The validity of the classification was verified by comparing the GNSS data with video analysis, a process that yielded classification accuracies ranging from 95.0% to 98.8% for G2, G3, G4, and G6P. Notably, G4 emerged as the fastest technique, with sub-technique selection varying among skiers and being influenced by skiing velocity and course inclination. The study's findings have practical implications for athletes and coaches as they demonstrate that high-precision kinematic GNSS devices can accurately classify sub-techniques and detect skiing characteristics during skating style cross-country skiing races, thereby providing valuable insights for training and strategy development.

Gaze and behavioural metrics in the refractive correction of presbyopia.

To investigate gaze and behavioural metrics at different viewing distances with multifocal contact lenses (MFCLs), single vision contact lenses (SVCLs) and progressive addition lenses (PALs). Fifteen presbyopic contact lens wearers participated over five separate study visits. At each visit, participants were randomly assigned to wear one of five refractive corrections: habitual PAL spectacles, delefilcon A (Alcon Inc.) MFCLs and three separate pairs of delefilcon A single vision lenses worn as distance, intermediate and near corrections. Participants wore a Pupil Core headset to record eye and head movements while performing three visual tasks: reading, visual search and scene observation. Data were investigated using linear regression and post-hoc testing. Parameters of interest included gaze (fixation duration, head movement) and behavioural (reading speed, reading accuracy, visual search time) metrics. Reading speed in SVCLs was significantly faster than in MFCLs and PAL spectacles (F = 16.3, p < 0.0001). Refractive correction worn did not influence visual search times (F = 0.16, p = 0.85). Fixation duration was significantly affected by the type of visual task (F = 60.2, p < 0.001), and an interaction effect was observed between viewing distance and refractive correction (F = 4.3, p = 0.002). There was significantly more horizontal and vertical head movement (F = 3.2, p = 0.01 and F = 3.3, p = 0.01, respectively) during visual search tasks when wearing PAL spectacles compared to SVCLsor MFCLs. This work showed that the type of refractive correction affects behavioural metrics such as reading speed and gaze behaviour by affecting horizontal and vertical head movements. The findings of this study suggest that under certain conditions, wearers of MFCLs make fewer head movements compared to PAL spectacles. Gaze behaviour metrics offer a new approach to compare and understand contact lens and spectacle performance, with potential applications including peripheral optical designs for myopia management.

Automated Detection of Train Drivers’ Head Movements: A Proof-of-Concept Study

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.

Real-time ultrasound-guided thoracentesis simulation using an optical see-through head-mounted display: a proof-of-concept study.

This study aimed to examine the feasibility and potential benefits of an optical see-through head-mounted display (OST-HMD) during real-time ultrasound-guided thoracentesis simulations. Six physicians performed a thoracentesis simulation using an OST-HMD and a wireless image transmission system. The time required, puncture needle visibility, pleural fluid collection success rate, and head movement during the procedure using a smart glass equipped with an inertial measurement unit were all recorded and compared with and without the HMD. Study participants successfully extracted effusions in all procedures. The use of OST-HMD did not significantly affect the time of the procedure, but notably decreased the horizontal and vertical head movements during the procedure. The study demonstrated the feasibility of using an OST-HMD in a simulated real-time ultrasound-guided thoracentesis procedure and showed the potential of HMD in thoracentesis to improve ergonomics and accuracy. Further research is necessary to confirm these findings.

Changes in gait performances during walking with head movements in older adults with chronic neck pain.

Chronic neck pain (CNP) can lead to altered gait which is worse when combined with head movement. Gait parameters for indicating speed and symmetry have not been thoroughly investigated in older adults with CNP. This study aimed to compare gait performance in term of speed and symmetry in older adults with and without CNP during walking with head movement. Fifty young older adults, consisting of 36 healthy controls without neck pain (OLDs) and 14 older adults with CNP, participated in the study. Participants completed the Neck Disability Index and Activities-specific Balance Confidence Scale. The 10-Meter Walk Test (10MWT) was used to assess gait performance. Participants were instructed to walk at preferred speed under three different head movement patterns: no head movement (NM), horizontal head movement (HM), and vertical head movement (VM). The Inertial Measurement Unit was used to capture gait performance, and its software was used to analyze gait variables; gait speed, Locomotor Rehabilitation Index (LRI), gait asymmetry index, Phase Coordination Index (PCI). The CNP group reported moderate neck pain with mild disability in activities of daily living, and less balance confidence than the OLD group (p < 0.05). The CNP group showed significantly slower gait speed and lower LRI during walking with both the HM and VM (p < 0.05), which corresponded to lower stride length and cadence. The gait asymmetry index in the CNP group was significantly higher than the OLD group during walking with VM (p < 0.05), whereas the PCI was significantly higher than the OLD group during walking with both HM and VM (p < 0.05). Chronic neck pain affects both speed and symmetry when walking with head movement. Gait parameters in this study could be implemented to identify changes in speed and symmetry of gait in older adults with CNP who have mild disability and high physical functioning.

Reliability, validity and normal ranges of the Zur Balance Scale for detecting mild postural control differences: introducing the modified, short version mZBS.

Balance is achieved through interactions between the vestibular, somatosensory, and visual systems. There are several clinical tests to measure postural stability. However, most of them do not assess postural stability with head movements, which is the main function of the vestibular system, and those that do, require the use of sizeable, expensive equipment. Therefore, an applicable, easy-to-perform test that challenges the function of the visual, somatosensory and vestibular systems, using head movements, is needed. The Zur Balance Scale (ZBS) contains ten conditions, which are a combination of surfaces (floor or Styrofoam with subject standing on its width in Romberg position or its length in tandem position), stances (Romberg or tandem), tasks (no head movement with eyes open or closed and horizontal or vertical head movements with eyes open). The purpose of this study was to determine the validity, inter- and intra-examiner reliability, and normal performance values of the ZBS among individuals 29-70-years of age and to introduce the modified version: the mZBS, using kinetic measurements. Healthy participants ages 29-70 years were evaluated for inter- and intra-tester reliability (n = 65), kinetic measurements on a force plate, and validity compared to the modified clinical test of sensory interaction and balance (mCTSIB) (n = 44) and characterization of normal values (n = 251). Zur Balance Scale head movements, duration of each condition (up to 10 s) and the total ZBS score agreed across examiners (ICC > 0.8). Normal ZBS scores were negatively correlated with age (r = -0.34; P < 0.0001). Older subjects (60-70 years) had a median score of 95.5 compared with younger subjects, where medians ranged from 97.6 to 98.9. Kinetic parameters showed positive correlations between ZBS and the mCTSIB scores, with the highest correlation between the five Romberg tasks (modified ZBS). Zur Balance Scale is a valid and reliable test. Its advantages include using head movements and the ability to detect minimal differences in postural control, even in healthy populations. Kinetic evaluation of the ZBS enables the use of a modified, shorter version of the ZBS (mZBS).

Is vigilance a personality trait? Plasticity is key alongside some contextual consistency.

Animals regularly scan their environment for predators and to monitor conspecifics. However, individuals in a group seem to differ in their vigilance linked to age, sex or state with recent links made to personality. The aims of the study were to investigate whether a) individuals differ consistently in their vigilance, b) vigilance is linked to other personality traits and c) other factors affect vigilance in the colour polymorphic Gouldian finch. Birds were tested in same (red-headed or black-headed) or mixed head colour morph same sex pairs in four contexts (novel environment, familiar environment, two changed environments). Vigilance was measured as horizontal head movements. Vigilance showed contextual consistency but no long-term temporal consistency over a year. Head movements were only weakly linked to other personality traits indicative of a risk-reward trade-off with more explorative individuals being less vigilant. Vigilance was highly plastic across situations and affected by group composition. Mixed head colour morph pairs made more head movements, potentially linked to higher social vigilance. Results indicate that vigilance is a highly plastic trait affected by personality rather than a personality trait on its own, which allows adapting vigilance to different situations.

Dynamic visual acuity test findings of migraine patients: Observational case-control study

ObjectiveTo evaluate computerized dynamic visual acuity (DVA) test findings among patients with migraine and to determine whether self-motion sensitivity and visually induced migraine symptoms that are seen in migraine patients can be explained by DVA results. MethodsTwenty migraine patients and twenty control subjects were evaluated with DVA test during rapid horizontal (left and right) and vertical (up and down) head movements. The subjects were asked to quickly recognize the direction of the Landolt-C optotype on the monitor while moving their heads. Test began with the largest optotype and progressively decreased in size by 0.1 logMAR until the subject could no answer correctly state the orientation of the optotype. DVA test scores of migraine group and control group were compared. ResultsPatient with migraine had significant DVA loss as compared with control subjects in four positions (left DVA, right DVA, up DVA, down DVA respectively p < 0.001, <0.001 = 0.001 and <0.001). ConclusionMigraine patients were found to have abnormal DVA scores mediated vestibular-ocular reflex. These abnormal DVA findings can explain the pathophysiology of head motion hypersensitivity and visual motion sensitivity that encountered by migraine patients.

Application of digital practice to improve head movement, visual perception and activities of daily living for subacute stroke patients with unilateral spatial neglect: Preliminary results of a single-blinded, randomized controlled trial.

Background:Virtual reality (VR) based digital practice is an attractive way to provide a patient engagement, motivation and adaptable environment for stroke rehabilitation. However, clinical evidence of efficacy with VR-based digital practice is very limited. In this study, we investigated the effects of VR-based digital practice program on unilateral spatial neglect (USN) rehabilitation in patients with subacute stroke.Methods:Twenty-four subacute stroke patients with USN were enrolled and randomly assigned to digital practice group (n = 12) and control group (n = 12). Patients in digital practice group received training programs with VR-based applications with leap motion environment. Control group received conventional USN specific training programs. All patients were underwent 4 week practice program (3 sessions/week, a half-hour/session). We analyzed training effects before and after training by assessing the line bisection test, Catherine Bergego Scale, modified Barthel index, Motor-Free Visual Perception Test Vertical Version (MVPT-V), and horizontal head movements (rotation degree and velocity during the VR-based applications), and compared the results between the two groups.Results:Compared to control group, digital practice group showed significantly greater improvements in the line bisection test (P = .020), and visual perceptual tasks (MVPT-V, responded more on left visual task, P = .024; correctly respond more on both left and right visual tasks, P = .024 and P = .014, respectively; and faster response time, P = .014). Additionally, horizontal head movement of rotation degree and velocity during the VR based practice in the digital practice group were significantly increased more than control group (P = .007 and P = .001, respectively).Conclusions:VR-based digital practice program might be an affordable approach for visual perception and head movement recovery for subacute stroke patients with USN.

Spontaneous visual exploration during locomotion in patients with phobic postural vertigo

BackgroundEarlier studies on stance and gait with posturographic and EMG-recordings and automatic gait analysis in patients with phobic postural vertigo (PPV) or visual height intolerance (vHI) revealed similar patterns of body stiffening with muscle co-contraction and a slow, cautious gait. Visual exploration in vHI patients was characterized by a freezing of gaze-in-space when standing and reduced horizontal eye and head movements during locomotion.ObjectiveBased on the findings in vHI patients, the current study was performed with a focus on visual control of locomotion in patients with PPV while walking along a crowded hospital hallway.MethodsTwelve patients with PPV and eleven controls were recruited. Participants wore a mobile infrared video eye-tracking system that continuously measured eye-in-head movements in the horizontal and vertical planes and head orientation and motion in the yaw, pitch, and roll planes. Visual exploration behavior of participants was recorded at the individually preferred speed for a total walking distance of 200 m. Gaze-in-space directions were determined by combining eye-in-head and head-in-space orientation. Walking speeds were calculated based on the trial duration and the total distance traversed. Participants were asked to rate their feelings of discomfort during the walk on a 4-point numeric rating scale. The examiners rated the crowdedness of the hospital hallway on a 4-point numeric rating scale.ResultsThe major results of visual exploration behavior in patients with PPV in comparison to healthy controls were: eye and head positions were directed more downward in the vertical plane towards the ground ahead with increased frequency of large amplitude vertical orientation movements towards the destination, the end of the ground straight ahead. The self-adjusted speed of locomotion was significantly lower in PPV. Particularly those patients that reported high levels of discomfort exhibited a specific visual exploration of their horizontal surroundings. The durations of fixating targets in the visual surroundings were significantly shorter as compared to controls.ConclusionGaze control of locomotion in patients with PPV is characterized by a preferred deviation of gaze more downward and by horizontal explorations for suitable auxiliary means for potential postural support in order to prevent impending falls. These eye movements have shorter durations of fixation as compared to healthy controls and patients with vHI. Finally, the pathological alterations in eye–head coordination during locomotion correlate with a higher level of discomfort and anxiety about falling.

Nodding and shaking of the head as simulated approach and avoidance responses

Our recent study within the embodiment perspective showed that the evaluation of true and false information activates the simulation of vertical and horizontal head movements involved in nodding and shaking of the head (Moretti & Greco, 2018). This result was found in an explicit evaluation task where motion detection software was deployed to enable participants to assess a series of objectively true or false statements by moving them with the head vertically and horizontally on a computer screen, under conditions of compatibility and incompatibility between simulated and performed action. This study replicated that experiment, but with subjective statements about liked and disliked food, in both explicit and implicit evaluation tasks. Two experiments, plus one control experiment, were devised to test the presence of a motor-affective compatibility effect (vertical-liked; horizontal-disliked) and whether the motor-semantic compatibility found with objective statements (vertical-true; horizontal-false) could be a sub-effect of a more general and automatic association (vertical-accepted; horizontal-refused). As expected, response times were shorter when statements about liked foods and disliked foods were moved vertically and horizontally respectively by making head movements, even when participants were not explicitly required to evaluate them. In contrast, the truth compatibility effect only occurred in the explicit evaluation task. Overall results support the idea that head-nodding and shaking are simulated approach-avoidance responses. Different aspects of the meaning of these gestures and the practical implications of the study for cognitive and social research are discussed.

Robustness analysis of decoding SSVEPs in humans with head movements using a moving visual flicker

Objective. The emergence of mobile electroencephalogram (EEG) platforms have expanded the use cases of brain–computer interfaces (BCIs) from laboratory-oriented experiments to our daily life. In challenging situations where humans’ natural behaviors such as head movements are unrestrained, various artifacts could deteriorate the performance of BCI applications. This paper explored the effect of muscular artifacts generated by participants’ head movements on the signal characteristics and classification performance of steady-state visual evoked potentials (SSVEPs). Approach. A moving visual flicker was employed to induce not only SSVEPs but also horizontal and vertical head movements at controlled speeds, leading to acquiring EEG signals with intensity-manipulated muscular artifacts. To properly induce neck muscular activities, a laser light was attached to participants’ heads to give visual feedback; the laser light indicates the direction of the head independently from eye movements. The visual stimulus was also modulated by four distinct frequencies (10, 11, 12, and 13 Hz). The amplitude and signal-to-noise ratio (SNR) were estimated to quantify the effects of head movements on the signal characteristics of the elicited SSVEPs. The frequency identification accuracy was also estimated by using well-established decoding algorithms including calibration-free and fully-calibrated approaches. Main results. The amplitude and SNR of SSVEPs tended to deteriorate when the participants moved their heads, and this tendency was significantly stronger in the vertical head movements than in the horizontal movements. The frequency identification accuracy also deteriorated in proportion to the speed of head movements. Importantly, the accuracy was significantly higher than its chance-level regardless of the level of artifact contamination and algorithms. Significance. The results suggested the feasibility of decoding SSVEPs in humans freely moving their head directions, facilitating the real-world applications of mobile BCIs.

The effects of head rotation exercise on postural balance, muscle strength, and gait in older women

ABSTRACTThis study aimed to evaluate the effects of resistive exercise (RE) with head rotation exercise (RE+HRE) on postural balance, lower limb muscle strength, and gait in older women. This study was conducted from December 7, 2015 to January 29, 2016 in Seoul, South Korea. Forty older women were recruited at welfare center and randomly allocated to RE+HRE (n = 20) or RE (n = 20) groups. The RE+HRE group performed RE+HRE for 60 min twice per week for 6 weeks, using an elastic band with variable resistance along the length. The HRE included horizontal or vertical head movement during the exercise. The RE group performed RE in a similar manner, but without head movements. The outcome measures were static postural balance (one-leg stance test, functional reach test, and postural sway), dynamic postural balance (timed up and go test, four square step test, and Mini-balance evaluation systems test), lower limb muscle strength (sit-to-stand test), and temporal gait parameters. In the RE+HRE group, all variables were significantly improved compared to baseline (p < .05), and postural balance and gait were significantly improved compared to those in the RE group (p < .05). These findings suggest that RE+HRE can improve dynamic postural balance, gait speed, and cadence in older women.

Discharge properties of morphologically identified vestibular neurons recorded during horizontal eye movements in the goldfish.

Computational capability and connectivity are key elements for understanding how central vestibular neurons contribute to gaze-stabilizing eye movements during self-motion. In the well-characterized and segmentally distributed hindbrain oculomotor network of goldfish, we determined afferent and efferent connections along with discharge patterns of descending octaval nucleus (DO) neurons during different eye motions. Based on activity correlated with horizontal eye and head movements, DO neurons were categorized into two complementary groups that either increased discharge during both contraversive (type II) eye (e) and ipsiversive (type I) head (h) movements (eIIhI) or vice versa (eIhII). Matching time courses of slow-phase eye velocity and corresponding firing rates during prolonged visual and head rotation suggested direct causality in generating extraocular motor commands. The axons of the dominant eIIhI subgroup projected either ipsi- or contralaterally and terminated in the abducens nucleus, Area II, and Area I with additional recurrent collaterals of ipsilaterally projecting neurons within the parent nucleus. Distinct feedforward commissural pathways between bilateral DO neurons likely contribute to the generation of eye velocity signals in eIhII cells. The shared contribution of DO and Area II neurons to eye velocity storage likely represents an ancestral condition in goldfish that is clearly at variance with the task separation between mammalian medial vestibular and prepositus hypoglossi neurons. This difference in signal processing between fish and mammals might correlate with a larger repertoire of visuo-vestibular-driven eye movements in the latter species that potentially required a shift in sensitivity and connectivity within the hindbrain-cerebello-oculomotor network. NEW & NOTEWORTHY We describe the structure and function of neurons within the goldfish descending octaval nucleus. Our findings indicate that eye and head velocity signals are processed by vestibular and Area II velocity storage integrator circuitries whereas the velocity-to-position Area I neural integrator generates eye position solely. This ancestral condition differs from that of mammals, in which vestibular neurons generally lack eye position signals that are processed and stored within the nucleus prepositus hypoglossi.

Dynamic visual acuity in benign paroxysmal positional vertigo

Background: Head motions cause transient vertigo in patients with benign paroxysmal positional vertigo (BPPV) and may reduce visual ability. Objectives: The aim is to investigate the clinical utility of dynamic visual acuity (DVA) test in those patients. Material and methods: Thirty patients, 11 with lateral canal BPPV (6 geotropic and 5 ageotropic), and 19 with posterior canal BPPV, were evaluated with DVA test during rapid horizontal (left and right) and vertical (up and down) head movements. Patients were asked to identify the direction of the letter C, ranging from 1.0 to 0.0 logMAR, while moving their heads. The orientation of the optotype was randomly changed by a computer-generated program. Ten subjects were served as control. Data were analyzed with a one-way ANOVA. p Value <.01 was considered significant. Results: Patients with LC and PC BPPV had significant DVA loss as compared with control subjects (p < .01). However, no significant difference was found in vDVA between patients with LC and PC BPPV, or in hDVA between ipsilesional and contralesional head rotation in patients with LC or PC BPPV (LC: p = .755, PC: p = .765). Conclusions: Patients with BPPV may have impaired visual acuity, particularly during acute onset condition. Present study indicated that DVA test was not helpful for differentiation of the pathologic and normal ears.

Accuracy of seizure semiology obtained from first-time seizure witnesses

BackgroundLittle is known of how accurately a first-time seizure witness can provide reliable details of a semiology. Our goal was to determine how accurately first-time seizure witnesses could identify key elements of an epileptic event that would aid the clinician in diagnosing a seizure.MethodsA total of 172 participants over 17 years of age, with a mean (sd) of 33.12 (13.2) years and 49.4% female, composed of two groups of community dwelling volunteers, were shown two different seizure videos; one with a focal seizure that generalized (GSV), and the other with a partial seizure that did not generalize (PSV). Participants were first asked about what they thought was the event that had occurred. They then went through a history-taking scenario by an assessor using a battery of pre-determined questions about involvement of major regions: the head, eyes, mouth, upper limbs, lower limbs, or change in consciousness. Further details were then sought about direction of movement in the eyes, upper and lower limbs, the side of limb movements and the type of movements in the upper and lower limbs. Analysis was with descriptive statistics and logistic regression.ResultsOne hundred twenty-two (71.4%) identified the events as seizure or epilepsy. The accuracy of identifying major areas of involvement ranged from 60 to 89.5%. Horizontal head movements were significantly more recognized in the PSV, while involvement of the eyes, lateralization of arm movement, type of left arm movement, leg involvement, and lateralization of leg movement were significantly more recognized in the GSV. Those shown the GSV were more likely to recognize the event as "seizure" or "epilepsy" than those shown the PSV; 78 (84.8%) vs 44 (55.7%), (OR 0.22, p < 0.0001). Younger age was also associated with correct recognition (OR 0.96, P 0.049). False positive responses ranged from 2.5 to 32.5%.ConclusionFirst-time witnesses can identify important elements more than by chance alone, and are more likely to associate generalized semiologies with seizures or epilepsy than partial semiologies. However, clinicians still need to navigate the witness’s account carefully for additional information since routine questioning could result in a misleading false positive answer.

Head-eye movement of collegiate baseball batters during fastball hitting.

Successful baseball hitting involves a combination of highly trained perceptual skills and forceful bat swing motions. The purpose of the present study was to quantify the horizontal movement of the head and eyes while baseball batters hit a fastball to clarify a visual strategy for this highly trained interceptive task. Six collegiate baseball players hit a fastball that was launched from a pitching machine. The ball speed was 31.9 m·s-1 for the Slow Ball Task and 40.3 m·s-1 for the Fast Ball Task. Horizontal head movements were analysed using images that were captured by two high-speed video cameras. The Horizontal eye movement was recorded with electrooculography. The angular speed of the horizontal head and eye movements during hitting were divided into four time periods (I-40 = 21–40% of total ball-flight, I-60 = 41–60% of total ball-flight, I-80 = 61–80% of total ball-flight, I-100 = 81–100% of total ball-flight) and analysed using analysis of variance and a Tukey post-hoc multiple-comparison. In the Slow Ball Task, the horizontal angular velocity of the head during I-80 was significantly faster than that during I-40 (p < 0.05). In the Fast Ball Task, the horizontal angular velocity of the head during I-80 was significantly faster than that during I-40 and I-60 (p < 0.05). These results indicated that the tracking motion of the head became faster as the launched ball came close to the batters, but there was no change in the angular tracking motion of the eyes. Therefore, rapid eye movement may not be suitable to accurately estimate the ball’s future location during fastball hitting based on the eye-centered coordinates. Our findings suggest that conventional vision training with a wide range of saccadic or smooth-pursuit eye movements does not reflect the characteristics of tracking strategies during baseball hitting.

Truth is in the head. A nod and shake compatibility effect

Studies from the embodiment perspective on language processing have shown facilitation or interference effects depending on the compatibility between verbal contents, concrete or abstract, and the motion of various parts of the body. The aim of the present study was to test whether such compatibility effects can be found when a higher cognitive process like truth evaluation is accomplished with head movements. Since nodding is a vertical head gesture typically performed with positive and affirmative responses, and shaking is a horizontal head gesture associated with negative and dissenting contents, faster response times can be expected when true information is evaluated by making a vertical head movement and false information by making a horizontal head movement.Three experiments were designed in order to test this motor compatibility effect. In the first experiment a series of very simple sentences were asked to be evaluated as true or false by dragging them vertically and horizontally with the head. It resulted that truth-value was assessed faster when it was compatible with the direction of the head movement, compared to when it was incompatible. In the second experiment participants were asked to evaluate the same sentences as the first experiment but by moving them with the mouse. In the third experiment, a non-evaluative classification task was given, where sentences concerning animals or objects were to be dragged by vertical and horizontal head movements. In the second and third experiment no compatibility effect was observed. Overall results support the hypothesis of an embodiment effect between the abstract processing of truth evaluation and the direction of the two head movements of nodding and shaking. Cultural aspects, cognitive implications, and the limits of these findings are discussed.

ABroAD: A Machine Learning Based Approach to Detect Broadband NIRS Artefacts.

Artefacts are a common and unwanted aspect of any measurement process, especially in a clinical environment, with multiple causes such as environmental changes or motion. In near-infrared spectroscopy (NIRS), there are several existing methods that can be used to identify and remove artefacts to improve the quality of collected data.We have developed a novel Automatic Broadband Artefact Detection (ABroAD) process, using machine learning methods alongside broadband NIRS data to detect common measurement artefacts using the broadband intensity spectrum. Data were collected from eight subjects, using a broadband NIRS monitoring over the frontal lobe with two sensors. Six different artificial artefacts – vertical head movement, horizontal head movement, frowning, pressure, ambient light, torch light – were simulated using movement and light changes on eight subjects in a block test design. It was possible to identify both light artefacts to a good degree, as well as pressure artefacts. This is promising and, by expanding this work to larger datasets, it may be possible to create and train a machine learning pipeline to automate the detection of various artefacts, making the analysis of collected data more reliable.

Vestibulo-ocular reflex deficits with medial longitudinal fasciculus lesions

The medial longitudinal fasciculus (MLF) is the final common pathway for all conjugate adducting horizontal eye movements, as well as for the vertical-torsional vestibulo-ocular reflex (VOR). MLF lesion causes adduction paresis of ipsilesional (adducting) eye with dissociated nystagmus of contralesional (abducting) eye-the well-known clinical syndrome of internuclear ophthalmoplegia (INO). We measured the VOR stimulation and also any catch-up saccades, from individual semicircular canal (SCC) evoked by the head impulse test (HIT), using head and binocular 3-dimensional scleral search coils in 27 multiple sclerosis (MS) patients, 8 with unilateral, 19 with bilateral INO. In unilateral INO, VOR gain (normal >0.90) from ipsilesional lateral SCC stimulation was 0.48 for the adducting eye and 0.81 for the abducting eye; 0.61 from contralesional anterior SCC stimulation and only 0.29 from contralesional posterior SCC stimulation. In bilateral INO, there were VOR gain deficits from all six SCCs: lateral SCC gains were asymmetrically reduced to 0.45 in the adducting eye and 0.66 in the abducting eye; anterior SCC gain was 0.48 and posterior SCC gain was only 0.19. Horizontal VOR versional dysconjugacy between adducting and abducting eyes at 0.66 was less severe than horizontal catch-up saccade versional dysconjugacy (0.44); normal >0.80. Unexpected partial preservation of horizontal VOR with greater catch-up saccade impairment from the adducting than abducting eye suggests that the ascending tract of Deiters(ATD), an extra-MLF pathway, also mediates the horizontal VOR, but not adducting horizontal saccades. Vertical VOR deficits will produce vertical oscillopsia with any vertical head movement and measurement of the vertical VOR could help with the diagnosis and quantitative evaluation of MLF lesions in suspected MS. Horizontal VOR deficits and catch-up saccade versional dysconjugacy in INO will cause gaze instability and horizontal oscillopsia during active horizontal head movements.