scholarly journals Internal Model of Gravity for Hand Interception: Parametric Adaptation to Zero-Gravity Visual Targets on Earth

2005 ◽  
Vol 94 (2) ◽  
pp. 1346-1357 ◽  
Author(s):  
Myrka Zago ◽  
Francesco Lacquaniti
Keyword(s):  
Internal Model ◽  
Visual Target ◽  
Neural Mechanism ◽  
Visual Environment ◽  
Zero Gravity ◽  
Vestibular Cortex ◽  
Central Processing ◽  
Virtual Target ◽  
Subcortical Regions ◽  
Central Processing Time

Internal model is a neural mechanism that mimics the dynamics of an object for sensory motor or cognitive functions. Recent research focuses on the issue of whether multiple internal models are learned and switched to cope with a variety of conditions, or single general models are adapted by tuning the parameters. Here we addressed this issue by investigating how the manual interception of a moving target changes with changes of the visual environment. In our paradigm, a virtual target moves vertically downward on a screen with different laws of motion. Subjects are asked to punch a hidden ball that arrives in synchrony with the visual target. By using several different protocols, we systematically found that subjects do not develop a new internal model appropriate for constant speed targets, but they use the default gravity model and reduce the central processing time. The results imply that adaptation to zero-gravity targets involves a compression of temporal processing through the cortical and subcortical regions interconnected with the vestibular cortex, which has previously been shown to be the site of storage of the internal model of gravity.

scholarly journals Impact of obesity on central processing time rather than overall reaction time in young adult men

2019 ◽  
Vol 24 (6) ◽  
pp. 1051-1061 ◽  
Author(s):  
Mohammad Narimani ◽  
Samad Esmaeilzadeh ◽  
Arto J. Pesola ◽  
Liane B. Azevedo ◽  
Akbar Moradi ◽  
...  
Keyword(s):  
Reaction Time ◽  
Young Adult ◽  
Processing Time ◽  
Central Processing ◽  
Adult Men ◽  
Central Processing Time

Effect of Variations in Sensory Feedback on Performance in a Virtual Reaching Task

2005 ◽  
Vol 14 (4) ◽  
pp. 450-462 ◽  
Author(s):  
Paula J. Durlach ◽  
Jennifer Fowlkes ◽  
Christopher J. Metevier
Keyword(s):  
Auditory Feedback ◽  
Sensory Feedback ◽  
Visual Target ◽  
Tactile Feedback ◽  
Sensory Cues ◽  
Reaching Task ◽  
Sense Of Presence ◽  
Phenomenological Experience ◽  
Virtual Target ◽  
Visual Realism

An experiment was conducted to investigate whether manipulation of the sensory cues provided in a virtual-reality context would affect performance of a reaching task and its associated phenomenology. Performance was measured by speed (the time taken to reach out and touch a virtually presented visual target) and accuracy (the distance of the fingertip from the center of the virtual target). Phenomenological experience was measured via questionnaires. The cues manipulated were the visual realism of the virtual hand (fidelity), whether the virtual fingertip was seen to penetrate the virtual target or not (constraint), and whether the feedback given on contact with the virtual target was tactile or auditory (feedback). We found that better hand fidelity speeded movement, increased presence, and reduced disorientation. In contrast, the constraint manipulation affected touch accuracy and disorientation. Tactile feedback enhanced the sense of presence and reduced disorientation, compared with auditory feedback.

Timing and Torque Involvement in the Organisation of a Rapid Forearm Flexion

1983 ◽  
Vol 35 (2) ◽  
pp. 323-331 ◽  
Author(s):  
D. M. Baba ◽  
R. G. Marteniuk
Keyword(s):  
Movement Time ◽  
Reaction Times ◽  
Motor Reaction ◽  
Movement Execution ◽  
Total Moment ◽  
Central Processing ◽  
Fast Movement ◽  
Time Required ◽  
Timing Requirement ◽  
Central Processing Time

The study was designed to determine whether the magnitude of force and the timing of force are response parameters involved in the organisation of a rapid forearm flexion to a target. The magnitude of torque and the timing of torque were manipulated independently through manipulations of the total moment of inertia and movement time, and the effect of these manipulations on premotor and motor reaction times was observed. Planned comparison analyses revealed that premotor and motor reaction times increased when a movement, which required the same magnitude of torque as in a fast movement, was performed slower. However, premotor and motor reaction times were not affected when movements were performed at the same speed, but differed with respect to the magnitude of torque required. These results indicate that a different timing requirement in the forthcoming movement is associated with a corresponding change in the amount of central processing time required. Therefore, the timing of torque appears to be a parameter of the movement that is organised in advance of movement execution. However, a change in the specification for the magnitude of torque does not affect the amount of time needed to organise the movement.

scholarly journals Sensory convergence in the parieto-insular vestibular cortex

2014 ◽  
Vol 111 (12) ◽  
pp. 2445-2464 ◽  
Author(s):  
Michael E. Shinder ◽  
Shawn D. Newlands
Keyword(s):  
Visual Target ◽  
Rhesus Macaques ◽  
Insular Cortex ◽  
Object Motion ◽  
Visual Object ◽  
Vestibular Cortex ◽  
Combined Movements ◽  
Sensory Convergence ◽  
The Central Nervous System ◽  
The Individual

Vestibular signals are pervasive throughout the central nervous system, including the cortex, where they likely play different roles than they do in the better studied brainstem. Little is known about the parieto-insular vestibular cortex (PIVC), an area of the cortex with prominent vestibular inputs. Neural activity was recorded in the PIVC of rhesus macaques during combinations of head, body, and visual target rotations. Activity of many PIVC neurons was correlated with the motion of the head in space (vestibular), the twist of the neck (proprioceptive), and the motion of a visual target, but was not associated with eye movement. PIVC neurons responded most commonly to more than one stimulus, and responses to combined movements could often be approximated by a combination of the individual sensitivities to head, neck, and target motion. The pattern of visual, vestibular, and somatic sensitivities on PIVC neurons displayed a continuous range, with some cells strongly responding to one or two of the stimulus modalities while other cells responded to any type of motion equivalently. The PIVC contains multisensory convergence of self-motion cues with external visual object motion information, such that neurons do not represent a specific transformation of any one sensory input. Instead, the PIVC neuron population may define the movement of head, body, and external visual objects in space and relative to one another. This comparison of self and external movement is consistent with insular cortex functions related to monitoring and explains many disparate findings of previous studies.

scholarly journals An internal model of a moving visual target in the lateral cerebellum

2009 ◽  
Vol 587 (2) ◽  
pp. 429-442 ◽  
Author(s):  
Nadia L. Cerminara ◽  
Richard Apps ◽  
Dilwyn E. Marple-Horvat
Keyword(s):  
Internal Model ◽  
Visual Target

Major Gene Locus of Spearman's General Factor of Intelligence

1982 ◽  
Vol 50 (1) ◽  
pp. 48-50 ◽  
Author(s):  
Volkmar Weiss
Keyword(s):  
Major Gene ◽  
Appreciable Amount ◽  
General Factor ◽  
Mendelian Segregation ◽  
Central Processing ◽  
The Mean ◽  
True Scores ◽  
Central Processing Time ◽  
Mendelian Analysis

The reigning biometrical paradigm asserts that continuous variation implies the determination of intelligence by many genes with small effects. However, if an appreciable amount of the variability of a continuous trait is due to Mendelian segregation at a single locus, we may speak of the major locus for that trait. In such a case the distributions between the genotypic classes show considerable overlap, caused by error of measurement and environmental influences. As confirmed by Mendelian analysis, Spearman's general factor is the result of genotypes with discrete true scores of central processing time, the heterozygotes being exactly in the mean of the differences of the means of homozygotes.

scholarly journals Watching the Effects of Gravity. Vestibular Cortex and the Neural Representation of “Visual” Gravity

2021 ◽  
Vol 15 ◽  
Author(s):  
Sergio Delle Monache ◽  
Iole Indovina ◽  
Myrka Zago ◽  
Elena Daprati ◽  
Francesco Lacquaniti ◽  
...  
Keyword(s):  
Internal Model ◽  
Internal Representation ◽  
Neural Representation ◽  
Visual Signals ◽  
Otolith Organs ◽  
Viewing Distance ◽  
Vestibular Cortex ◽  
Sensory Signals ◽  
Visual Areas ◽  
Gravity Effects

Gravity is a physical constraint all terrestrial species have adapted to through evolution. Indeed, gravity effects are taken into account in many forms of interaction with the environment, from the seemingly simple task of maintaining balance to the complex motor skills performed by athletes and dancers. Graviceptors, primarily located in the vestibular otolith organs, feed the Central Nervous System with information related to the gravity acceleration vector. This information is integrated with signals from semicircular canals, vision, and proprioception in an ensemble of interconnected brain areas, including the vestibular nuclei, cerebellum, thalamus, insula, retroinsula, parietal operculum, and temporo-parietal junction, in the so-called vestibular network. Classical views consider this stage of multisensory integration as instrumental to sort out conflicting and/or ambiguous information from the incoming sensory signals. However, there is compelling evidence that it also contributes to an internal representation of gravity effects based on prior experience with the environment. This a priori knowledge could be engaged by various types of information, including sensory signals like the visual ones, which lack a direct correspondence with physical gravity. Indeed, the retinal accelerations elicited by gravitational motion in a visual scene are not invariant, but scale with viewing distance. Moreover, the “visual” gravity vector may not be aligned with physical gravity, as when we watch a scene on a tilted monitor or in weightlessness. This review will discuss experimental evidence from behavioral, neuroimaging (connectomics, fMRI, TMS), and patients’ studies, supporting the idea that the internal model estimating the effects of gravity on visual objects is constructed by transforming the vestibular estimates of physical gravity, which are computed in the brainstem and cerebellum, into internalized estimates of virtual gravity, stored in the vestibular cortex. The integration of the internal model of gravity with visual and non-visual signals would take place at multiple levels in the cortex and might involve recurrent connections between early visual areas engaged in the analysis of spatio-temporal features of the visual stimuli and higher visual areas in temporo-parietal-insular regions.

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