Neuroimaging Analysis of Visual Motion

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 300-300
Author(s):  
M Osaka ◽  
N Osaka ◽  
S Koyama ◽  
R Kakigi
Keyword(s):  
Magnetic Field ◽  
Goodness Of Fit ◽  
Visual Motion ◽  
Human Subjects ◽  
Projection System ◽  
Research Systems ◽  
Cambridge Research ◽  
Stationary Frame ◽  
Dot Motion ◽  
The Right

The evoked magnetic field (magnetoencephalogram: MEG) was measured in human subjects observing random-dot motion. 600 random dots generated with VSG2/3 (Cambridge Research Systems) moved at about 10 deg s−1 (either in the 45° or the 135° direction). The motion frame (5 s) was followed by a stationary frame on a screen (projected from Barcodata 3100 projection system) subtending a visual angle of about 20 deg × 20 deg. Six subjects observed the motion frame presented in the left visual field. The magnetic evoked field (80 averagings) was measured from 37 points over occipital, temporal, and parietal areas (Magnes SQUID biomagnetometer, BTi) of the right brain hemisphere. Dipole estimates based on equal magnetic field contours (190 ms after motion frame onset with value of goodness of fit greater than 0.95) and MRI image fitting (sagittal, coronal, and axial view) for each subject suggest that the main loci subserving motion perception lie in the surrounding region over occipital, temporal, and parietal junction areas in the human brain close to area MT.

Visually Evoked Magnetic Field Induced by Ring Motion Aftereffect

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 301-301
Author(s):  
N Osaka ◽  
M Osaka ◽  
S Koyama ◽  
R Kakigi
Keyword(s):  
Magnetic Field ◽  
Goodness Of Fit ◽  
Visual Motion ◽  
Motion Aftereffect ◽  
Adaptation Period ◽  
Luminance Profile ◽  
The Subject ◽  
The Right ◽  
Clear Increase ◽  
Good Agreement

Motion aftereffect (MAE) is a negative aftereffect caused by prolonged viewing of visual motion: after gazing at a moving grating for a while, a stationary image will appear to move in the opposite direction (Ashida and Osaka, 1995 Vision Research35 1825). Evoked magnetic field (magnetoencephalogram: MEG) was measured when a human subject observing ring MAE in which concentric circles appear to contract continuously after viewing continuously expanding rings. The diameter of the stimulus was 20 deg with fixation point in the centre. The magnetic evoked field (80 averagings at a latency of 190 ms) was measured from 37 points over the occipital and parietal areas (Magnes SQUID biomagnetometer, BTi) while the subject was observing stationary rings after an adaptation period of 2 s at low spatial frequency (4 cycles deg−1, 4 Hz). The luminance profile was sinusoidally changed across rings. MRI image fitting (sagittal, coronal, and axial view) for each of four subjects, and dipole estimates obtained for equal magnetic field contours (with value of goodness of fit greater than 0.98) from the right brain hemisphere suggest that the main loci subserving MAE lie in the surrounding region over the lateral occipitotemporal areas in the human brain, close to area MT. This is in good agreement with another study with fMRI-based MAE measures [Tootell et al, 1995 Nature (London)375 139] in which a clear increase in activity in these areas was observed when subjects viewed MAE.

Visually induced cross-axis postsaccadic eye drift

1993 ◽  
Vol 69 (4) ◽  
pp. 1031-1043 ◽  
Author(s):  
Z. Kapoula ◽  
D. A. Robinson ◽  
L. M. Optican
Keyword(s):  
Magnetic Field ◽  
Human Subjects ◽  
Vertical Component ◽  
Field Method ◽  
Full Field ◽  
Vertical Saccades ◽  
Before And After ◽  
Cross Axis ◽  
The Right ◽  
Random Dot Pattern

1. It has been previously shown that, if a visual pattern is transiently moved just after every saccade, it is possible to induce horizontal, postsaccadic, ocular drift after horizontal saccades that persists in the dark. In this study we show that horizontal ocular drift can also be created after vertical saccades. Five human subjects viewed binocularly the interior of a full-field hemisphere filled with a random-dot pattern. They were encouraged to make frequent vertical saccades. During training, eye movements were recorded by the electrooculogram. A computer detected the end of every saccade and immediately moved the pattern to the left after up saccades and right after down saccades. The motion was exponential, its amplitude was 25% of the vertical component of the antecedent saccade, its time constant was 50 ms. Before and after 2-3 h of training, movements of both eyes were measured by the eye-coil/magnetic-field method while subjects were instructed to make vertical saccades in the dark, in the presence of the movable adapting pattern, and between stationary targets for calibration. 2. After training (approximately 20,000 saccades) all subjects developed a zero-latency, exponential ocular drift to the left after up saccades and to the right after down saccades. The amplitude of the horizontal drift, expressed as a percentage of the vertical component of the preceding saccade, was 2.7% in the dark. This rose to 10.2% in the presence of the movable adapting stimulus. The latter rise is not due to visual following systems but to a zero-latency increase in initial drift velocity. 3. The horizontal drifts were usually unequal between the two eyes, indicating the presence of disconjugate movements. We measured intrasaccadic disconjugate horizontal movements of all subjects. In agreement with studies by others of saccades in the light, we measured a divergence during up saccades (1.3 degrees) and a convergence for down (0.4 degrees), but in this case for spontaneous saccades in the dark. After training, these values increased for saccades in the dark but decreased in the light in the presence of the adapting stimulus. These changes were largely idiosyncratic and statistically significant in only a few subjects. 4. The cross-axis postsaccadic drifts were separated into their conjugate and disconjugate components. The disconjugate components were small and idiosyncratic, and the means were small for saccades in the dark. The only consistent trend was in the presence of the adapting stimulus where up saccades were often followed by convergence.(ABSTRACT TRUNCATED AT 400 WORDS)

Extrapolation of Visual Motion for Manual Interception

2008 ◽  
Vol 99 (6) ◽  
pp. 2956-2967 ◽  
Author(s):  
John F. Soechting ◽  
Martha Flanders
Keyword(s):  
Visual Motion ◽  
Human Subjects ◽  
Hand Movement ◽  
Target Motion ◽  
Target Color ◽  
Local Motion ◽  
Initial Direction ◽  
Time Required ◽  
Starting Location ◽  
The Right

A frequent goal of hand movement is to touch a moving target or to make contact with a stationary object that is in motion relative to the moving head and body. This process requires a prediction of the target's motion, since the initial direction of the hand movement anticipates target motion. This experiment was designed to define the visual motion parameters that are incorporated in this prediction of target motion. On seeing a go signal (a change in target color), human subjects slid the right index finger along a touch-sensitive computer monitor to intercept a target moving along an unseen circular or oval path. The analysis focused on the initial direction of the interception movement, which was found to be influenced by the time required to intercept the target and the target's distance from the finger's starting location. Initial direction also depended on the curvature of the target's trajectory in a manner that suggested that this parameter was underestimated during the process of extrapolation. The pattern of smooth pursuit eye movements suggests that the extrapolation of visual target motion was based on local motion cues around the time of the onset of hand movement, rather than on a cognitive synthesis of the target's pattern of motion.

scholarly journals Null Effect of Transcranial Static Magnetic Field Stimulation over the Dorsolateral Prefrontal Cortex on Behavioral Performance in a Go/NoGo Task

2021 ◽  
Vol 11 (4) ◽  
pp. 483
Author(s):  
Tatsunori Watanabe ◽  
Nami Kubo ◽  
Xiaoxiao Chen ◽  
Keisuke Yunoki ◽  
Takuya Matsumoto ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Prefrontal Cortex ◽  
Inhibitory Control ◽  
Static Magnetic Field ◽  
Dorsolateral Prefrontal Cortex ◽  
Cortical Excitability ◽  
Control Function ◽  
Field Stimulation ◽  
Dorsolateral Prefrontal ◽  
The Right

The purpose of this pilot study was to investigate whether transcranial static magnetic field stimulation (tSMS), which can modulate cortical excitability, would influence inhibitory control function when applied over the dorsolateral prefrontal cortex (DLPFC). Young healthy adults (n = 8, mean age ± SD = 24.4 ± 4.1, six females) received the following stimulations for 30 min on different days: (1) tSMS over the left DLPFC, (2) tSMS over the right DLPFC, and (3) sham stimulation over either the left or right DLPFC. The participants performed a Go/NoGo task before, immediately after, and 10 min after the stimulation. They were instructed to extend the right wrist in response to target stimuli. We recorded the electromyogram from the right wrist extensor muscles and analyzed erroneous responses (false alarm and missed target detection) and reaction times. As a result, 50% of the participants made erroneous responses, and there were five erroneous responses in total (0.003%). A series of statistical analyses revealed that tSMS did not affect the reaction time. These preliminary findings suggest the possibility that tSMS over the DLPFC is incapable of modulating inhibitory control and/or that the cognitive load imposed in this study was insufficient to detect the effect.

STUDIES ON HABITUATION TO COLD PAIN

1966 ◽  
Vol 44 (2) ◽  
pp. 287-293 ◽  
Author(s):  
Jacques LeBlanc ◽  
Pierre Potvin
Keyword(s):  
Cold Water ◽  
Mental Arithmetic ◽  
Blood Pressure Response ◽  
Human Subjects ◽  
Cold Pain ◽  
Left Hand ◽  
Water Test ◽  
The Difference ◽  
The Right ◽  
Habituation To Cold

It was possible to produce habituation to cold in a group of human subjects by immersing the left hand in cold water for [Formula: see text] minutes twice a day for 19 days. The right hand did not adapt. Another group of subjects was exposed similarly with the difference that an anxiety test (mental arithmetic test) was always given simultaneously with the cold-water test. In this second group the original blood pressure response, i.e. for the first day, was greater than in the first group because of the cumulative effects of the two tests. After 19 days definite evidence was obtained for adaptation to these two tests administered together. However, when these tests were given separately to the second group, no adaptation was evident; adaptation occurred only to both tests given simultaneously. These results indicate that no adaptation develops to cold per se if the subjects are distracted from cold discomfort. It was also found that adaptation of one hand to cold water not only failed to induce adaptation in the opposite hand but even reinforced responses of the unadapted hand. These findings suggest a participation of the central nervous system in adaptation to cold pain, and tend to minimize the importance of local peripheral changes.

scholarly journals The Right Hemisphere Planum Temporale Supports Enhanced Visual Motion Detection Ability in Deaf People: Evidence from Cortical Thickness

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Martha M. Shiell ◽  
François Champoux ◽  
Robert J. Zatorre
Keyword(s):  
Cortical Thickness ◽  
Motion Detection ◽  
Visual Motion ◽  
Right Hemisphere ◽  
Deaf People ◽  
Planum Temporale ◽  
Detection Thresholds ◽  
Temporal Area ◽  
The Right ◽  
Visual Motion Detection

After sensory loss, the deprived cortex can reorganize to process information from the remaining modalities, a phenomenon known as cross-modal reorganization. In blind people this cross-modal processing supports compensatory behavioural enhancements in the nondeprived modalities. Deaf people also show some compensatory visual enhancements, but a direct relationship between these abilities and cross-modally reorganized auditory cortex has only been established in an animal model, the congenitally deaf cat, and not in humans. Using T1-weighted magnetic resonance imaging, we measured cortical thickness in the planum temporale, Heschl’s gyrus and sulcus, the middle temporal area MT+, and the calcarine sulcus, in early-deaf persons. We tested for a correlation between this measure and visual motion detection thresholds, a visual function where deaf people show enhancements as compared to hearing. We found that the cortical thickness of a region in the right hemisphere planum temporale, typically an auditory region, was greater in deaf individuals with better visual motion detection thresholds. This same region has previously been implicated in functional imaging studies as important for functional reorganization. The structure-behaviour correlation observed here demonstrates this area’s involvement in compensatory vision and indicates an anatomical correlate, increased cortical thickness, of cross-modal plasticity.

scholarly journals Intersectoral approaches and integrated services in achieving the right to health for refugees upon resettlement: a scoping review protocol

BMJ Open ◽  
2017 ◽  
Vol 7 (8) ◽  
pp. e016638 ◽  
Author(s):  
Dena Javadi ◽  
Etienne V Langlois ◽  
Shirley Ho ◽  
Peter Friberg ◽  
Göran Tomson
Keyword(s):  
Scoping Review ◽  
Human Subjects ◽  
Grey Literature ◽  
Open Science ◽  
Right To Health ◽  
Refugee Health ◽  
International Standards ◽  
Vulnerable Groups ◽  
Physical And Mental Health ◽  
The Right

IntroductionGlobal insecurity and climate change are exacerbating the need for improved management of refugee resettlement services. International standards hold states responsible for the protection of the right of non-citizens to an adequate standard of physical and mental health while recognising the importance of social determinants of health. However, programmes to protect refugees’ right to health often lack coordination and monitoring. This paper describes the protocol for a scoping review to explore barriers and facilitators to the integration of health services for refugees; the content, process and actors involved in protecting refugee health; and the extent to which intersectoral approaches are leveraged to protect refugees’ right to health on resettlement, especially for vulnerable groups such as women and children.Methods and analysisPeer-reviewed (through four databases including MEDLINE, Web of Science, Global Health and PsycINFO) and grey literature were searched to identify programmes and interventions designed to promote refugee health in receiving countries. Two reviewers will screen articles and abstract data. Two frameworks for integration and intersectoral action will be applied to understand how and why certain approaches work while others do not and to identify the actors involved in achieving success at different levels of integration as defined by these frameworks.Ethics and disseminationFindings from the scoping review will be shared in relevant conferences and meetings. A brief will be created with lessons learnt from successful programmes to inform decision making in design of refugee programmes and services. Ethical approval is not required as human subjects are not involved.Trial registration numberRegistered on Open Science Framework athttps://osf.io/gt9ck/.

scholarly journals On hypergeometric generalized negative binomial distribution

2002 ◽  
Vol 29 (12) ◽  
pp. 727-736 ◽  
Author(s):  
M. E. Ghitany ◽  
S. A. Al-Awadhi ◽  
S. L. Kalla
Keyword(s):  
Recurrence Relation ◽  
Negative Binomial Distribution ◽  
Binomial Distribution ◽  
Field Data ◽  
Goodness Of Fit ◽  
Negative Binomial ◽  
Generalized Negative Binomial Distribution ◽  
The Right ◽  
Three Term Recurrence Relation

It is shown that the hypergeometric generalized negative binomial distribution has moments of all positive orders, is overdispersed, skewed to the right, and leptokurtic. Also, a three-term recurrence relation for computing probabilities from the considered distribution is given. Application of the distribution to entomological field data is given and its goodness-of-fit is demonstrated.

Foveal Attention Modulates Responses to Peripheral Stimuli

2000 ◽  
Vol 83 (4) ◽  
pp. 2443-2452 ◽  
Author(s):  
Simo Vanni ◽  
Kimmo Uutela
Keyword(s):  
Visual Field ◽  
Target Location ◽  
Peripheral Vision ◽  
Human Subjects ◽  
Stimulus Onset ◽  
Visual Object ◽  
Frontal Eye Field ◽  
L1 Norm ◽  
Luminance Stimulus ◽  
The Right

When attending to a visual object, peripheral stimuli must be monitored for appropriate redirection of attention and gaze. Earlier work has revealed precentral and posterior parietal activation when attention has been directed to peripheral vision. We wanted to find out whether similar cortical areas are active when stimuli are presented in nonattended regions of the visual field. The timing and distribution of neuromagnetic responses to a peripheral luminance stimulus were studied in human subjects with and without attention to fixation. Cortical current distribution was analyzed with a minimum L1-norm estimate. Attention enhanced responses 100–160 ms after the stimulus onset in the right precentral cortex, close to the known location of the right frontal eye field. In subjects whose right precentral region was not distinctly active before 160 ms, focused attention commonly enhanced right inferior parietal responses between 180 and 240 ms, whereas in the subjects with clear earlier precentral response no parietal enhancement was detected. In control studies both attended and nonattended stimuli in the peripheral visual field evoked the right precentral response, whereas during auditory attention the visual stimuli failed to evoke such response. These results show that during focused visual attention the right precentral cortex is sensitive to stimuli in all parts of the visual field. A rapid response suggests bypassing of elaborate analysis of stimulus features, possibly to encode target location for a saccade or redirection of attention. In addition, load for frontal and parietal nodi of the attentional network seem to vary between individuals.

An appropriate biomechanical model of seated human subjects exposed to whole-body vibration

2021 ◽  
pp. 146441932110394
Author(s):  
Raj Desai ◽  
Anirban Guha ◽  
Pasumarthy Seshu
Keyword(s):  
Degrees Of Freedom ◽  
Human Subjects ◽  
Computational Cost ◽  
Biomechanical Model ◽  
Whole Body ◽  
Body Parts ◽  
Lumped Parameter ◽  
Long Duration ◽  
The One ◽  
The Right

Long duration automobile-induced vibration is the cause of many ailments to humans. Predicting and mitigating these vibrations through seat requires a good model of seated human body. A good model is the one that strikes the right balance between modelling difficulty and simulation results accuracy. Increasing the number of body parts which have been separately modelled and increasing the number of ways these parts are connected to each other increase the number of degrees of freedom of the entire model. A number of such models have been reported in the literature. These range from simple lumped parameter models with limited accuracy to advanced models with high computational cost. However, a systematic comparison of these models has not been reported till date. This work creates eight such models ranging from 8 to 26 degrees of freedom and tries to identify the model which strikes the right balance between modelling complexity and results accuracy. A comparison of the models’ prediction with experimental data published in the literature allows the identification of a 12 degree of freedom backrest supported model as optimum for modelling complexity and prediction accuracy.

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