Consolidation of the postural set during voluntary intermittent light finger contact as a function of hand dominance

Light fingertip contact with an earth-fixed referent decreases body sway. In a previous study Johannsen et al. (2014) demonstrated longer return-to-baseline of body sway for intermittent contacts of more than 2 seconds duration. This indicates that sway reduction with light tactile contact involves postural control strategies independent of the availability of tactile feedback and may depend on the intention to control body sway with light touch feedback. In the present study, we investigated the effect of hand dominance on post-contact return-to-baseline to probe for potential inter-hemispheric differences in the utilization of light finger contact for sway control. Twelve healthy, right-handed young adults stood in normal bipedal stance with eyes closed on a force plate with an earth-fixed referent directly in front. Acoustic signals instructed onset and removal of intermittent light touch. We found that return-to-baseline of sway following longer contact durations is affected by hand dominance with the dominant hand resulting in a slower return to No-contact levels of sway. Our results indicate that the light touch postural set is more persistent and might need longer to disengage when established with the dominant hand or takes longer to consolidate when established with the non-dominant hand

Serving performance in a suprapostural visual signal detection task: context-dependent and direction-specific control of body sway with fingertip light touch

Keeping gaze fixed on a target during visual smooth pursuit or touch light during fingertip contact while standing may resemble the goals of a suprapostural task with the implicit demands to minimize self-imposed sensorimotor variability. To test whether the principle of a suprapostural task generalizes to more complex sensorimotor stimulus-response mappings, we investigated how the control of body sway is influenced by an implicit feedback coupling (IFC) between the variability of touch forces at the contact point and perceptual difficulty, that is vertical jitter of a horizontally oscillating Landolt-C, in a visual signal detection task (VSDT). Mediolateral (ML) body sway of ten young healthy adults was assessed in four IFC conditions: (1) LT with independent jitter (LT-IJ), (2) LT with jitter depending on LT contact force (LT-CF), (3) LT with jitter depending on body sway (LT-BS), and (4) no contact with jitter depending on body sway (NT-BS). We assumed that the postural control system would be responsive to IFC and therefore reduce body sway in both IFC conditions. Resulting mediolateral body sway differed between the IFC conditions. Reduced sway was found in LT-CF and LT-BS compared to LT-IJ and in LT-BS compared to NT-BS. Our results demonstrate that processes controlling body sway can reduce postural variability below a variability level achieved by LT augmentation of body sway-related feedback alone. Both direct (LT-CF) and indirect (LT-BS) IFC involvement of fingertip contact minimized sway, which implies that no hierarchy existed for whole body sway or precision of fingertip contact (integration of both control processes) or that they can be reversed flexibly (one facilitating the other) if it serves the implicit goal of reduced perceptual noise and enhanced performance within the context of our suprapostural VSDT

Neuroplasticity of Ipsilateral Cortical Motor Representations, Training Effects and Role in Stroke Recovery

This thesis examines the contribution of the ipsilateral hemisphere to motor control with the aim of evaluating the potential of the contralesional hemisphere to contribute to motor recovery after stroke. Predictive algorithms based on neurobiological principles emphasize integrity of the ipsilesional corticospinal tract as the strongest prognostic indicator of good motor recovery. In contrast, extensive lesions placing reliance on alternative contralesional ipsilateral motor pathways are associated with poor recovery. Within the predictive algorithms are elements of motor control that rely on contributions from ipsilateral motor pathways, suggesting that balanced, parallel contralesional contributions can be beneficial. Current therapeutic approaches have focussed on the maladaptive potential of the contralesional hemisphere and sought to inhibit its activity with neuromodulation. Using Transcranial Magnetic Stimulation I seek examples of beneficial plasticity in ipsilateral cortical motor representations of expert performers, who have accumulated vast amounts of deliberate practise training skilled bilateral activation of muscles habitually under ipsilateral control. I demonstrate that ipsilateral cortical motor representations reorganize in response to training to acquisition of skilled motor performance. Features of this reorganization are compatible with evidence suggesting ipsilateral importance in synergy representations, controlled through corticoreticulopropriospinal pathways. I demonstrate that ipsilateral plasticity can associate positively with motor recovery after stroke. Features of plastic change in ipsilateral cortical representations are shown in response to robotic training of chronic stroke patients. These findings have implications for the individualization of motor rehabilitation after stroke, and prompt reappraisal of the approach to therapeutic intervention in the chronic phase of stroke

Emergence of Cortical Activity Patterns as Infants Develop Functional Motor Skills.

Despite the careful examination of the developmental changes in overt behavior and the underlying muscle activity and joint movement patterns, there is very little empirical evidence on how the brain and its link to behavior evolves during the first year of life. The dynamic systems approach and theory of neuronal group selection provides a framework that hypothesizes the development of the CNS early in life. However, the direct examination of the changes in brain activation that underlie the development of functional motor control in infants have yet to be determined or tested. The goal of my dissertation was to use functional near-infrared spectroscopy (fNIRS) to document the changes in brain activation patterns as infants acquired functional motor skills. My studies show that fNIRS is a viable and useful tool to examine brain activity in the context of infant movements. My findings demonstrate that as the behavioral and motor outcomes improve, the underlying neural activation patterns emerge. When functional motor skills are unstable and not fully functional, larger areas of the broad brain regions are recruited. As the skills become more reliable and functional, the brain activation patterns become refined and show an increase in strength of activity. The results from the studies in my dissertation take an important first step of describing the typical neural patterns that emerge with functional motor skills early in life. This work will help future studies build the body of empirical evidence that will improve our knowledge regarding the developing link between brain development and behavior. Finally, these studies provide foundational knowledge to better understand the atypical development of the CNS in those with disabilities.PhDKinesiologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133452/1/ryonish_1.pd

Dinámica Cerebral. La actividad cerebral en función de las condiciones dinámicas de la excitabilidad nerviosa. Tomo segundo

This book can be cited as: Gonzalo J. (1945/2010/2022), "Dinámica Cerebral", Tomo segundo, Consejo Superior de investigaciones Cientificas, Madrid 1945, in: "Dinámica Cerebral" facsimile edition, Gonzalo I. (Ed), Red Temática en Tecnologías de Computación Artificial/Natural, Universidad de Santiago de Compostela 2010 (Open Access http://dspace.usc.es/handle/10347/4341). "Brain Dynamics" Volume 2, Gonzalo I. (Ed and English translation), Madrid 2022 (Open Access in this web page).This volume is the English translation of Volume 2 of the book "Dinámica Cerebral" written in Spanish by Justo Gonzalo Rodríguez-Leal (Barcelona 1910 – Madrid 1986), first published in 1950. The volume, devoted to tactile functions, is the continuation of Volume 1 (on general aspects and visual functions, English translation Open Access in https:/eprints.ucm.es/id/eprint/63730/) to which it refers continuously. A facsimile Spanish edition includindg Vol. 1, 2 and supplements was published by the Red Temática en Tecnologías de Computación Artificial/Natural (RTNAC) and the University of Santiago de Compostela in 2010, and whose on-line Open-Access version (http://dspace.usc.es/handle/10347/4341 ) maintains a significant rate of visits since its publication. The author, after specialization in neurology and brain pathology in Austria and Germany (1933-35) developed a research on the human cerebral cortex. The interest of the research described here lies, as in Volume 1, in the fact that it is surprisingly of current interest, apart from its undoubted historical interest. Some aspects were ahead of discoveries that were made later. It is remarkable that some of the phenomena exposed are still unknown and that the proposed functional dynamic unit of the cortex is closely related to current trends in the study of the brain. This volume deals with tactile functions and further elaborates on concepts introduced in Volume 1. The tactile phenomenology in cases of central syndrome is described. This syndrome, already studied in Volume 1, is the result of a unilateral lesion in an association area in the left parieto-occipital cortex, equidistant from the visual, tactile and auditory primary areas. It consists of a multisensory alteration (visual, tactile, auditory) although the lesion does not involve specific areas, all functions being affected, from simple excitability to more complex functions, bilaterally and symmetrically. In particular, the striking phenomenon in which the visual image is tilted or nearly inverted (see Vol. 1), is now extended to the phenomenon of localization of stimuli in the tactile system. Inversion in tactile space is studied in detail in cases of central syndrome, being generalized to all sensory systems of a spatial nature, once confirmed in the auditory system. Similarly to what happens in vision, the tactile phenomena in the mentioned syndrome have a dynamic character since the disorders vary with the intensity of the stimulus and with the facilitation by other stimulus. The phenomenon of facilitation by muscular effort is particularly noticeable. The greater the deficit in brain excitability (due to the lesion), the greater the effect of facilitation. In the process of tactile localization of a stimulus, up to five phases are distinguished, from simple sensation to specific localization (passing through inversion), as stimulation increases. This process is described as a spiral development of the organization of the sensory field (tactile and also visual). As in vision, a continuity is found between the various functions that appear according to physiological requirements. Likewise, a continuity is established between sensory functions and gnosis, both being based on the same physiological laws. The schema function is studied in detail and considered in diverse degree according to the somatic model, postural model and praxis model. In addition to the patients directly studied by the author, a reference case is also the famous Schneider patient of Goldstein and Gelb studied in 1918 and 1919, which deserves publications even at present, and which the author interpreted under the central syndrome. This syndrome is also related to Gerstmann's syndrome. In subsequent research, the author found 35 cases that also fit the central syndrome. In a later publication (English translation, Open Access in https://eprints.ucm.es/id/eprint/30931/ ) the author exposed a model based on functional gradients through the cortex, according to which, its specificity is distributed in a continuous gradation, and in agreement with a continuous transition between the central syndrome and other cortical syndromes. The author continued to develop a functional brain model applying the principle of similarity of a dynamic system to the central syndrome, the latter being understood as a change of scale in nervous excitability with respect to a normal individual. This concept was already introduced in the preceding Vol. 1 and also in this Vol. 2. A preface introduces some aspects of this research, its author and his subsequent research.Depto. de ÓpticaFac. de Ciencias FísicasFALSEunpu

EEG coherence between the verbal-analytical region (T3) and the motor-planning region (Fz) increases under stress in explicit motor learners but not implicit motor learners

This journal supplement contains abstracts of NASPSPA 2010Free Communications - Verbal and Poster: Motor Learning and Controlpublished_or_final_versionThe Annual Conference of the North American Society for the Psychology of Sport and Physical Activity (NASPSPA 2010), Tucson, AZ., 10-12 June 2010. In Journal of Sport and Exercise Psychology, 2010, v. 32 suppl., p. S13

Attention and time constraints in performing and learning a table tennis forehand shot

This is a section on p. S95 of article 'Verbal and Poster: Motor Development, Motor Learning and Control, and Sport and Exercise Psychology' in Journal of Sport and Exercise Psychology, 2010, v.32, p.S36-S237published_or_final_versio