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https://www.readbyqxmd.com/read/27919100/viewpoint-oscillation-improves-the-perception-of-distance-travelled-based-on-optic-flow
#1
Martin Bossard, Cédric Goulon, Daniel R Mestre
When static observers are presented with a visual simulation of forward self-motion, they generally misestimate distance travelled relative to a previously seen distant target: It has been suggested that this finding can be accounted for by a "leaky path integration" model. In the present study, using a similar experimental procedure, this result was confirmed. It was also established that combining the translational optical flow with simulated head oscillations (similar to those during natural walking) improved the subjects' perception of the distance travelled in comparison with a purely translational flow...
December 1, 2016: Journal of Vision
https://www.readbyqxmd.com/read/27915367/the-virtual-reality-head-mounted-display-oculus-rift-induces-motion-sickness-and-is-sexist-in-its-effects
#2
Justin Munafo, Meg Diedrick, Thomas A Stoffregen
Anecdotal reports suggest that motion sickness may occur among users of contemporary, consumer-oriented head-mounted display systems and that women may be at greater risk. We evaluated the nauseogenic properties of one such system, the Oculus Rift. The head-mounted unit included motion sensors that were sensitive to users' head movements, such that head movements could be used as control inputs to the device. In two experiments, seated participants played one of two virtual reality games for up to 15 min. In Experiment 1, 22% of participants reported motion sickness, and the difference in incidence between men and women was not significant...
December 3, 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/27895619/a-functional-magnetic-resonance-imaging-study-of-head-movements-in-cervical-dystonia
#3
Cecília N Prudente, Randall Stilla, Shivangi Singh, Cathrin Buetefisch, Marian Evatt, Stewart A Factor, Alan Freeman, Xiaoping Philip Hu, Ellen J Hess, K Sathian, H A Jinnah
Cervical dystonia (CD) is a neurological disorder characterized by abnormal movements and postures of the head. The brain regions responsible for these abnormal movements are not well understood, because most imaging techniques for assessing regional brain activity cannot be used when the head is moving. Recently, we mapped brain activation in healthy individuals using functional magnetic resonance imaging during isometric head rotation, when muscle contractions occur without actual head movements. In the current study, we used the same methods to explore the neural substrates for head movements in subjects with CD who had predominantly rotational abnormalities (torticollis)...
2016: Frontiers in Neurology
https://www.readbyqxmd.com/read/27871096/responses-and-injuries-to-pmhs-in-side-facing-and-oblique-seats-in-horizontal-longitudinal-sled-tests-per-faa-emergency-landing-conditions
#4
John R Humm, Narayan Yoganandan, Frank A Pintar, Richard L DeWeese, David M Moorcroft, Amanda M Taylor, Brian Peterson
The objective of the present exploratory study is to understand occupant responses in oblique and side-facing seats in the aviation environment, which are increasingly installed in modern aircrafts. Sled tests were conducted using intact Post Mortem Human Surrogates (PMHS) seated in custom seats approximating standard aircraft geometry. End conditions were selected to represent candidate aviation seat and restraint configurations. Three-dimensional head center-of-gravity linear accelerations, head angular velocities, and linear accelerations of the T1, T6, and T12 spinous processes, and sacrum were obtained...
November 2016: Stapp Car Crash Journal
https://www.readbyqxmd.com/read/27869148/motor-noise-is-rich-signal-in-autism-research-and-pharmacological-treatments
#5
E B Torres, K Denisova
The human body is in constant motion, from every breath that we take, to every visibly purposeful action that we perform. Remaining completely still on command is a major achievement as involuntary fluctuations in our motions are difficult to keep under control. Here we examine the noise-to-signal ratio of micro-movements present in time-series of head motions extracted from resting-state functional magnetic resonance imaging scans in 1048 participants. These included individuals with autism spectrum disorders (ASD) and healthy-controls in shared data from the Autism Brain Imaging Data Exchange (ABIDE) and the Attention-Deficit Hyperactivity Disorder (ADHD-200) databases...
November 21, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27814855/older-adult-alexander-technique-practitioners-walk-differently-than-healthy-age-matched-controls
#6
Kate A Hamel, Christopher Ross, Brooke Schultz, Matthew O'Neill, David I Anderson
The Alexander Technique (AT) seeks to eliminate harmful patterns of tension that interfere with the control of posture and movement and in doing so, it may serve as a viable intervention method for increasing gait efficacy in older adults. The purpose of this study was to compare the comfortable pace gait kinematics of older AT practitioners with those of healthy, age-matched controls. Participants were six licensed AT practitioners and seven healthy age-matched controls between the ages of 61-76. During the stance phase, AT participants exhibited significantly greater ankle stance range of motion (ROM) and plantar flexion at toe off, as well as lower ROM of the trunk and head compared to controls...
October 2016: Journal of Bodywork and Movement Therapies
https://www.readbyqxmd.com/read/27811303/developmental-changes-in-head-movement-kinematics-during-swimming-in-xenopus-laevis-tadpoles
#7
Sara Hänzi, Hans Straka
During the post-embryonic developmental growth of animals, a number of physiological parameters such as locomotor performance, dynamics and behavioural repertoire are adjusted to match the requirements determined by changes in body size, proportions and shape. Moreover, changes in movement parameters also cause changes in the dynamics of self-generated sensory stimuli, to which motion-detecting sensory systems have to adapt. Here, we examined head movements and swimming kinematics of Xenopus laevis tadpoles with a body length of 10 to 45 mm (developmental stage 46 to 54) and compared these parameters to fictive swimming, recorded as ventral root activity in semi-intact in-vitro preparations...
November 3, 2016: Journal of Experimental Biology
https://www.readbyqxmd.com/read/27781442/synchronization-of-multi-agent-systems-with-metric-topological-interactions
#8
Lin Wang, Guanrong Chen
A hybrid multi-agent systems model integrating the advantages of both metric interaction and topological interaction rules, called the metric-topological model, is developed. This model describes planar motions of mobile agents, where each agent can interact with all the agents within a circle of a constant radius, and can furthermore interact with some distant agents to reach a pre-assigned number of neighbors, if needed. Some sufficient conditions imposed only on system parameters and agent initial states are presented, which ensure achieving synchronization of the whole group of agents...
September 2016: Chaos
https://www.readbyqxmd.com/read/27751941/sources-and-implications-of-whole-brain-fmri-signals-in-humans
#9
Jonathan D Power, Mark Plitt, Timothy O Laumann, Alex Martin
Whole-brain fMRI signals are a subject of intense interest: variance in the global fMRI signal (the spatial mean of all signals in the brain) indexes subject arousal, and psychiatric conditions such as schizophrenia and autism have been characterized by differences in the global fMRI signal. Further, vigorous debates exist on whether global signals ought to be removed from fMRI data. However, surprisingly little research has focused on the empirical properties of whole-brain fMRI signals. Here we map the spatial and temporal properties of the global signal, individually, in 1000+ fMRI scans...
October 14, 2016: NeuroImage
https://www.readbyqxmd.com/read/27705769/myosin-induced-gliding-patterns-at-varied-mgatp-unveil-a-dynamic-actin-filament
#10
Elina Bengtsson, Malin Persson, Mohammad A Rahman, Saroj Kumar, Hideyo Takatsuki, Alf Månsson
Actin filaments have key roles in cell motility but are generally claimed to be passive interaction partners in actin-myosin-based motion generation. Here, we present evidence against this static view based on an altered myosin-induced actin filament gliding pattern in an in vitro motility assay at varied [MgATP]. The statistics that characterize the degree of meandering of the actin filament paths suggest that for [MgATP] ≥ 0.25 mM, the flexural rigidity of heavy meromyosin (HMM)-propelled actin filaments is similar (without phalloidin) or slightly lower (with phalloidin) than that of HMM-free filaments observed in solution without surface tethering...
October 4, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27629710/distinct-fmri-responses-to-self-induced-versus-stimulus-motion-during-free-viewing-in-the-macaque
#11
Brian E Russ, Takaaki Kaneko, Kadharbatcha S Saleem, Rebecca A Berman, David A Leopold
UNLABELLED: Visual motion responses in the brain are shaped by two distinct sources: the physical movement of objects in the environment and motion resulting from one's own actions. The latter source, termed visual reafference, stems from movements of the head and body, and in primates from the frequent saccadic eye movements that mark natural vision. To study the relative contribution of reafferent and stimulus motion during natural vision, we measured fMRI activity in the brains of two macaques as they freely viewed >50 hours of naturalistic video footage depicting dynamic social interactions...
September 14, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27591489/adaptations-to-walking-on-an-uneven-terrain-for-individuals-with-and-without-developmental-coordination-disorder
#12
J Gentle, A L Barnett, K Wilmut
Given the importance of walking in everyday life, understanding why this is challenging for some populations is particularly important. Studies focusing on gait patterns of individuals with Developmental Coordination Disorder (DCD) have shown that whilst increased variability is characteristic of walking patterns for this group, differences in spatio-temporal gait variables seem only to arise when task demands increase. However, these differences occur under rather artificial conditions, for example using a treadmill...
October 2016: Human Movement Science
https://www.readbyqxmd.com/read/27586485/human-field-of-regard-field-of-view-and-attention-bias
#13
Woncheol Jang, Joon-Ho Shin, Mingyu Kim, Kwanguk Kenny Kim
BACKGROUND AND OBJECTIVE: Human field of regard (FOR) is an important concept that should be considered along with field of view (FOV) for people with/without handicaps, but previous studies have neglected this aspect of human perception. In the current study, we suggest and test a new virtual reality (VR) software with which to evaluate individual's detection abilities in the human FOR. METHODS: We conducted measurements of human FOV, FOR, and FOR with visual cue (FOR-cue), and we evaluated healthy adults' responses in a first experiment...
October 2016: Computer Methods and Programs in Biomedicine
https://www.readbyqxmd.com/read/27581452/galvanic-vestibular-stimulation-cellular-substrates-and-response-patterns-of-neurons-in-the-vestibulo-ocular-network
#14
Kathrin D Gensberger, Anna-Kristin Kaufmann, Haike Dietrich, Francisco Branoner, Roberto Banchi, Boris P Chagnaud, Hans Straka
UNLABELLED: Galvanic vestibular stimulation (GVS) uses modulated currents to evoke neuronal activity in vestibular endorgans in the absence of head motion. GVS is typically used for a characterization of vestibular pathologies; for studies on the vestibular influence of gaze, posture, and locomotion; and for deciphering the sensory-motor transformation underlying these behaviors. At variance with the widespread use of this method, basic aspects such as the activated cellular substrate at the sensory periphery or the comparability to motion-induced neuronal activity patterns are still disputed...
August 31, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27580091/a-space-variant-model-for-motion-interpretation-across-the-visual-field
#15
Manuela Chessa, Guido Maiello, Peter J Bex, Fabio Solari
We implement a neural model for the estimation of the focus of radial motion (FRM) at different retinal locations and assess the model by comparing its results with respect to the precision with which human observers can estimate the FRM in naturalistic motion stimuli. The model describes the deep hierarchy of the first stages of the dorsal visual pathway and is space variant, since it takes into account the retino-cortical transformation of the primate visual system through log-polar mapping. The log-polar transform of the retinal image is the input to the cortical motion-estimation stage, where optic flow is computed by a three-layer neural population...
January 1, 2016: Journal of Vision
https://www.readbyqxmd.com/read/27537702/sensitivity-and-bias-in-the-discrimination-of-two-dimensional-and-three-dimensional-motion-direction
#16
Emily A Cooper, Marcus van Ginkel, Bas Rokers
Sensory systems are faced with an essentially infinite number of possible environmental events but have limited processing resources. Posed with this challenge, it makes sense to allocate these resources to prioritize the discrimination of events with the most behavioral relevance. Here, we asked if such relevance is reflected in the processing and perception of motion. We compared human performance on a rapid motion direction discrimination task, including monocular and binocular viewing. In particular, we determined sensitivity and bias for a binocular motion-in-depth (three-dimensional; 3D) stimulus and for its constituent monocular (two-dimensional; 2D) signals over a broad range of speeds...
August 1, 2016: Journal of Vision
https://www.readbyqxmd.com/read/27518212/application-of-virtual-reality-head-mounted-display-for-investigation-of-movement-a-novel-effect-of-orientation-of-attention
#17
Brendan Quinlivan, John S Butler, Ines Beiser, Laura Williams, Eavan McGovern, Sean O'Riordan, Michael Hutchinson, Richard B Reilly
OBJECTIVE: To date human kinematics research has relied on video processing, motion capture and magnetic search coil data acquisition techniques. However, the use of head mounted display virtual reality systems, as a novel research tool, could facilitate novel studies into human movement and movement disorders. These systems have the unique ability of presenting immersive 3D stimulus while also allowing participants to make ecologically valid movement-based responses. APPROACH: We employed one such system (Oculus Rift DK2) in this study to present visual stimulus and acquire head-turn data from a cohort of 40 healthy adults...
October 2016: Journal of Neural Engineering
https://www.readbyqxmd.com/read/27511627/age-related-differences-in-autism-the-case-of-white-matter-microstructure
#18
P Cédric M P Koolschijn, Matthan W A Caan, Jalmar Teeuw, Sílvia D Olabarriaga, Hilde M Geurts
Autism spectrum disorder (ASD) is typified as a brain connectivity disorder in which white matter abnormalities are already present early on in life. However, it is unknown if and to which extent these abnormalities are hard-wired in (older) adults with ASD and how this interacts with age-related white matter changes as observed in typical aging. The aim of this first cross-sectional study in mid- and late-aged adults with ASD was to characterize white matter microstructure and its relationship with age. We utilized diffusion tensor imaging with head motion control in 48 adults with ASD and 48 age-matched controls (30-74 years), who also completed a Flanker task...
August 11, 2016: Human Brain Mapping
https://www.readbyqxmd.com/read/27511012/3d-visual-response-properties-of-mstd-emerge-from-an-efficient-sparse-population-code
#19
Michael Beyeler, Nikil Dutt, Jeffrey L Krichmar
UNLABELLED: Neurons in the dorsal subregion of the medial superior temporal (MSTd) area of the macaque respond to large, complex patterns of retinal flow, implying a role in the analysis of self-motion. Some neurons are selective for the expanding radial motion that occurs as an observer moves through the environment ("heading"), and computational models can account for this finding. However, ample evidence suggests that MSTd neurons exhibit a continuum of visual response selectivity to large-field motion stimuli...
August 10, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27501052/convergence-of-visual-and-whisker-responses-in-the-primary-somatosensory-thalamus-ventral-posterior-medial-region-of-the-mouse
#20
Annette E Allen, Christopher A Procyk, Timothy M Brown, Robert J Lucas
Sensory signals reach the cortex via sense-specific thalamic nuclei. Here we report that neurons in the primary sensory thalamus of the mouse vibrissal system (the ventral posterior medial region; VPM) can be excited by visual as well as whisker stimuli. Using extracellular electrophysiological recordings from anaesthetized mice we first show that simple light steps can excite a subset of VPM neurons. We then test the ability of the VPM to respond to spatial patterns and show that many units are excited by visual motion in a direction selective manner...
August 8, 2016: Journal of Physiology
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