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CNS Neuroscience & Therapeutics Feb 2022Parkinson's (PD) is a common degenerative disease of the central nervous system. It affects more than 6 million individuals worldwide. The typical clinical...
INTRODUCTION
Parkinson's (PD) is a common degenerative disease of the central nervous system. It affects more than 6 million individuals worldwide. The typical clinical manifestations include static tremor, slow movement, and unstable posture. However, the correlation between head tremor and the severity of PD remains unclear.
METHODS
In the current study, 18 patients and 18 healthy subjects were recruited to undergo a phonation test. Noldus facereader 7.0 software was used to analyze the range of head trembling between the two groups.
RESULTS
The data revealed that patients with PD had significant differences in the x-, y-, and z-axis of head movement with respect to the specific pronunciation syllables compared with the normal group. Moreover, the head movement of the patients with PD was positively correlated with the severity of the disease in the single, double, and multiple syllable tests. In the phonetic test, the head displacement of patients with PD was significantly greater than that of healthy individuals, and the displacement range was positively correlated with the severity of the disease.
CONCLUSION
These pieces of evidence suggested that the measurement of head displacement assists the early diagnosis and severity of the disease.
Topics: Aged; Aged, 80 and over; Female; Head Movements; Humans; Male; Middle Aged; Parkinson Disease; Patient Acuity; Tremor
PubMed: 34758102
DOI: 10.1111/cns.13753 -
Sensors (Basel, Switzerland) May 2021Psychotherapists, who use their communicative skills to assist people, review their dialogue practices and improve their skills from their experiences. However,...
Psychotherapists, who use their communicative skills to assist people, review their dialogue practices and improve their skills from their experiences. However, technology has not been fully exploited for this purpose. In this study, we analyze the use of head movements during actual psychotherapeutic dialogues between two participants-therapist and client-using video recordings and head-mounted accelerometers. Accelerometers have been utilized in the mental health domain but not for analyzing mental health related communications. We examined the relationship between the state of the interaction and temporally varying head nod and movement patterns in psychological counseling sessions. Head nods were manually annotated and the head movements were measured using accelerometers. Head nod counts were analyzed based on annotations taken from video data. We conducted cross-correlation analysis of the head movements of the two participants using the accelerometer data. The results of two case studies suggest that upward and downward head nod count patterns may reflect stage transitions in counseling dialogues and that peaks of head movement synchrony may be related to emphasis in the interaction.
Topics: Accelerometry; Communication; Head; Head Movements; Movement; Video Recording
PubMed: 34063286
DOI: 10.3390/s21093162 -
Optometry and Vision Science : Official... Jan 2022Stereothresholds increase in the presence of disconjugate image motion, whether this motion results from vergence errors that occur during active head movements or is...
SIGNIFICANCE
Stereothresholds increase in the presence of disconjugate image motion, whether this motion results from vergence errors that occur during active head movements or is imposed externally.
PURPOSE
During rapid voluntary oscillations of the head, vergence eye position has been reported to vary with a peak-to-peak amplitude of about 0.5°-a considerably greater amplitude than when the head is still. Concurrently, stereopsis was reported to be unaffected by voluntary head motion. In the present study, we measured stereothresholds during voluntary side-to-side head movements and during imposed disconjugate image motion with the head stationary, to simulate that produced during active head movement.
METHODS
Stereothresholds were measured for a pair of 30-arcmin bright vertical lines presented on an oscilloscope and viewed through a custom mirror haploscope. Data were obtained from four normal observers during voluntary side-to-side head movements at temporal frequencies up to 1.5 Hz and also while the head remained still. In addition, stereothresholds were measured with the head stationary when opposite rotations of the galvanometer-driven mirrors in each channel of the haploscope created disconjugate image motion to simulate vergence variability during active head movement.
RESULTS
During head motion, average stereothresholds increased from about 10 to about 14 arcsec. With imposed disconjugate image motion, stereothresholds rose systematically to about 35 arcsec when the peak-to-peak motion amplitude was 0.5°. Stereothresholds depend primarily on the amplitude of imposed motion and only marginally on variations of the disjunctive-motion wave form.
CONCLUSIONS
Stereothresholds are elevated modestly during active head movements. The results obtained with imposed disjunctive image motion are consistent with a previously proposal that stereothresholds vary according to the unsigned, time-averaged deviation of the stereotarget from the plane of the horopter.
Topics: Depth Perception; Eye Movements; Head; Head Movements; Humans; Motion Perception
PubMed: 34882606
DOI: 10.1097/OPX.0000000000001831 -
Journal of Neurophysiology Jul 2020Conventional explanations of the vestibulo-ocular reflex (VOR) and eye and head movements are revisited by considering two alternative frameworks addressing the question... (Review)
Review
Conventional explanations of the vestibulo-ocular reflex (VOR) and eye and head movements are revisited by considering two alternative frameworks addressing the question of how the brain controls motor actions. Traditionally, biomechanical and/or computational frameworks reflect the views of several prominent scholars of the past, including Helmholtz and von Holst, who assumed that the brain directly specifies the desired motor outcome and uses efference copy to influence perception. However, empirical studies resulting in the theory of referent control of action and perception (an extension of the equilibrium-point hypothesis) revealed that direct specification of motor outcome is inconsistent with nonlinear properties of motoneurons and with the physical principle that the brain can control motor actions only indirectly, by changing or maintaining the values of neurophysiological parameters that influence, but can remain independent of, biomechanical variables. Some parameters are used to shift the origin (referent) points of spatial frames of reference (FRs) or system of coordinates in which motor actions emerge without being predetermined. Parameters are adjusted until the emergent motor actions meet the task demands. Several physiological parameters and spatial FRs have been identified, supporting the notion of indirect, referent control of movements. Instead of integration of velocity-dependent signals, position-dimensional referent signals underlying head motion can likely be transmitted to motoneurons of extraocular muscles. This would produce compensatory eye movement preventing shifts in gaze during head rotation, even after bilateral destruction of the labyrinths. The referent control framework symbolizes a shift in the paradigm for the understanding of VOR and eye and head movement production.
Topics: Eye Movements; Head Movements; Humans; Motor Activity; Motor Neurons; Oculomotor Muscles; Reflex, Vestibulo-Ocular; Superior Colliculi
PubMed: 32490708
DOI: 10.1152/jn.00076.2020 -
Scientific Reports Mar 2022Smoothness (i.e. non-intermittency) of movement is a clinically important property of the voluntary movement with accuracy and proper speed. Resting head position and...
Smoothness (i.e. non-intermittency) of movement is a clinically important property of the voluntary movement with accuracy and proper speed. Resting head position and head voluntary movements are impaired in cervical dystonia. The current work aims to evaluate if the smoothness of voluntary head rotations is reduced in this disease. Twenty-six cervical dystonia patients and 26 controls completed rightward and leftward head rotations. Patients' movements were differentiated into "towards-dystonia" (rotation accentuated the torticollis) and "away-dystonia". Smoothness was quantified by the angular jerk and arc length of the spectrum of angular speed (i.e. SPARC, arbitrary units). Movement amplitude (mean, 95% CI) on the horizontal plane was larger in controls (63.8°, 58.3°-69.2°) than patients when moving towards-dystonia (52.8°, 46.3°-59.4°; P = 0.006). Controls' movements (49.4°/s, 41.9-56.9°/s) were faster than movements towards-dystonia (31.6°/s, 25.2-37.9°/s; P < 0.001) and away-dystonia (29.2°/s, 22.9-35.5°/s; P < 0.001). After taking into account the different amplitude and speed, SPARC-derived (but not jerk-derived) indices showed reduced smoothness in patients rotating away-dystonia (1.48, 1.35-1.61) compared to controls (1.88, 1.72-2.03; P < 0.001). Poor smoothness is a motor disturbance independent of movement amplitude and speed in cervical dystonia. Therefore, it should be assessed when evaluating this disease, its progression, and treatments.
Topics: Dystonic Disorders; Head Movements; Humans; Torticollis
PubMed: 35332258
DOI: 10.1038/s41598-022-09149-1 -
PloS One 2023One approach to studying the recognition of scenes and objects relies on the comparison of eye movement patterns during encoding and recognition. Past studies typically...
One approach to studying the recognition of scenes and objects relies on the comparison of eye movement patterns during encoding and recognition. Past studies typically analyzed the perception of flat stimuli of limited extent presented on a computer monitor that did not require head movements. In contrast, participants in the present study saw omnidirectional panoramic scenes through an immersive 3D virtual reality viewer, and they could move their head freely to inspect different parts of the visual scenes. This allowed us to examine how unconstrained observers use their head and eyes to encode and recognize visual scenes. By studying head and eye movement within a fully immersive environment, and applying cross-recurrence analysis, we found that eye movements are strongly influenced by the content of the visual environment, as are head movements-though to a much lesser degree. Moreover, we found that the head and eyes are linked, with the head supporting, and by and large mirroring the movements of the eyes, consistent with the notion that the head operates to support the acquisition of visual information by the eyes.
Topics: Humans; Head Movements; Eye Movements; Recognition, Psychology; Virtual Reality; Photic Stimulation
PubMed: 36800398
DOI: 10.1371/journal.pone.0282030 -
Journal of Neurophysiology Sep 2021On average, we redirect our gaze with a frequency at about 3 Hz. In real life, gaze shifts consist of eye and head movements. Much research has focused on how the...
On average, we redirect our gaze with a frequency at about 3 Hz. In real life, gaze shifts consist of eye and head movements. Much research has focused on how the accuracy of eye movements is monitored and calibrated. By contrast, little is known about how head movements remain accurate. I wondered whether serial dependencies between artificially induced errors in head movement targeting and the immediately following head movement might recalibrate movement accuracy. I also asked whether head movement targeting errors would influence visual localization. To this end, participants wore a head-mounted display and performed head movements to targets, which were displaced as soon as the start of the head movement was detected. I found that target displacements influenced head movement amplitudes in the same trial, indicating that participants could adjust their movement online to reach the new target location. However, I also found serial dependencies between the target displacement in trial -1 and head movements amplitudes in the following trial . I did not find serial dependencies between target displacements and visuomotor localization. The results reveal that serial dependencies recalibrate head-movement accuracy. Head movements are recalibrated by serial dependencies by errors between consecutive trials. Head movements are subject to a regression of the average target location.
Topics: Adult; Eye Movements; Female; Head Movements; Humans; Male; Psychomotor Performance; Sensorimotor Cortex; Visual Perception
PubMed: 34259049
DOI: 10.1152/jn.00231.2021 -
Journal of Vision Mar 2021Motion perception is a critical function of the visual system. In a three-dimensional environment, multiple sensory cues carry information about an object's motion...
Motion perception is a critical function of the visual system. In a three-dimensional environment, multiple sensory cues carry information about an object's motion trajectory. Previous work has quantified the contribution of binocular motion cues, such as interocular velocity differences and changing disparities over time, as well as monocular motion cues, such as size and density changes. However, even when these cues are presented in concert, observers will systematically misreport the direction of motion-in-depth. Although in the majority of laboratory experiments head position is held fixed using a chin or head rest, an observer's head position is subject to involuntary small movements under real-world viewing conditions. Here, we considered the potential impact of such "head jitter" on motion-in-depth perception. We presented visual stimuli in a head-mounted virtual reality device that facilitated low latency head tracking and asked observers to judge 3D object motion. We found performance improved when we updated the visual display consistent with the small changes in head position. When we disrupted or delayed head movement-contingent updating of the visual display, the proportion of motion-in-depth misreports again increased, reflected in both a reduction in sensitivity and an increase in bias. Our findings identify a critical function of head jitter in visual motion perception, which has been obscured in most (head-fixed and non-head jitter contingent) laboratory experiments.
Topics: Cues; Depth Perception; Head Movements; Humans; Imaging, Three-Dimensional; Motion Perception; Virtual Reality; Vision, Binocular
PubMed: 33687429
DOI: 10.1167/jov.21.3.12 -
Tracking and Classification of Head Movement for Augmentative and Alternative Communication Systems.Sensors (Basel, Switzerland) Jan 2022The use of assistive technologies can mitigate or reduce the challenges faced by individuals with motor disabilities to use computer systems. However, those who feature...
The use of assistive technologies can mitigate or reduce the challenges faced by individuals with motor disabilities to use computer systems. However, those who feature severe involuntary movements often have fewer options at hand. This work describes an application that can recognize the user's head using a conventional webcam, track its motion, model the desired functional movement, and recognize it to enable the use of a virtual keyboard. The proposed classifier features a flexible structure and may be personalized for different user need. Experimental results obtained with participants with no neurological disorders have shown that classifiers based on Hidden Markov Models provided similar or better performance than a classifier based on position threshold. However, motion segmentation and interpretation modules were sensitive to involuntary movements featured by participants with cerebral palsy that took part in the study.
Topics: Cerebral Palsy; Communication; Head Movements; Humans; Movement; Self-Help Devices; User-Computer Interface
PubMed: 35062395
DOI: 10.3390/s22020435 -
Aerospace Medicine and Human Performance Feb 2022Head tracking movements are common in interceptive tasks. The benefits of these movements are unclear. The purpose of this study was to compare coincidence anticipation...
Head tracking movements are common in interceptive tasks. The benefits of these movements are unclear. The purpose of this study was to compare coincidence anticipation timing (CAT) responses for a simulated approaching object when the eyes were used in tracking the object and when the head was used in tracking the object. A total of 29 subjects participated. A Bassin Anticipation Timer consisting of a track of sequentially illuminated lights was used to simulate an approaching object at velocities of 223 cm · s to 894 cm · s. Each velocity was used 10 times under 2 conditions. In one condition, subjects were told to turn the eyes with the stimulus. In the other condition, subjects viewed the stimulus through apertures and were told to turn the head with the stimulus. Subjects pushed a button to coincide with illumination of the final light on the track. Signed CAT errors, unsigned CAT errors, and variable CAT errors were compared between the head movement (HM) and eye movement (EM) conditions. No significant differences were noted for the signed errors (mean signed error at 894 cm · s; 10.3 ± 75.4 ms (HM), -16.1 ± 51.0 ms (EM). However, the unsigned and variable errors were significantly larger at some stimulus velocities in the head movement condition [mean unsigned error at 894 cm · s: 82.6.0 ± 45.9 ms (HM), 59.0 ± 22.4 ms (EM); mean variable error at 894 cm · s; 78.0 ± 37.8 ms (HM), 49.2 ± 17.1ms (EM)]. Head movement did not result in improved CAT performance compared to eye movements. Further work will be required to determine whether these results are generalizable to situations where head tracking is required but apertures are not worn.
Topics: Eye Movements; Eye-Tracking Technology; Head Movements; Psychomotor Performance
PubMed: 35105424
DOI: 10.3357/AMHP.5904.2022