Execution Of Motor Activities Research Articles

Wireless vibrotactile wireless optical device for motor activity assistance motor activities

This article describes the research that leads to the development of a wireless optical device capable of generating vibrotactile mechanical stimuli at different points on the skin and at desired frequencies by means of sixteen actuators contained in a portable bracelet designed for any extremity of the human body. This prototype allows control over each actuator used as a stimulation point, actuated independently by wirelessly transmitted commands to a rechargeable stand-alone control system in the bracelet. Usability tests were carried out, with respect to tactile perception, which proved the correct functioning of the device. In perspective, the development, after a variety of validation tests with a large sample of patients with and without neuropathy, aims at creating a database to be used as set point values in front of these patients with the expectation that the system will also be used in patients with movement deficits, and employing tactile perception as a psychomotor stimulant in the execution of motor activities.

Studying the functional connectivity of the primary motor cortex with the binarized cross recurrence plot: The influence of Parkinson's disease.

Two new recurrence plot methods (the binary recurrence plot and binary cross recurrence plot) were introduced here to study the long-term dynamic of the primary motor cortex and its interaction with the primary somatosensory cortex, the anterior motor thalamus of the basal ganglia motor loop and the precuneous nucleus of the default mode network. These recurrence plot methods: 1. identify short-term transient interactions; 2. identify long-lasting delayed interactions that are common in complex systems; 3. work with non-stationary blood oxygen level dependent (BOLD) data; 4. may study the relationship of centers with non-linear functional interactions; 5 may compare different experimental groups performing different tasks. These methods were applied to BOLD time-series obtained in 20 control subjects and 20 Parkinson´s patients during the execution of motor activity and body posture tasks (task-block design). The binary recurrence plot showed the task-block BOLD response normally observed in the primary motor cortex with functional magnetic resonance imaging methods, but also shorter and longer BOLD-fluctuations than the task-block and which provided information about the long-term dynamic of this center. The binary cross recurrence plot showed short-lasting and long-lasting functional interactions between the primary motor cortex and the primary somatosensory cortex, anterior motor thalamus and precuneous nucleus, interactions which changed with the resting and motor tasks. Most of the interactions found in healthy controls were disrupted in Parkinson’s patients, and may be at the basis of some of the motor disorders and side-effects of dopaminergic drugs commonly observed in these patients.

EEG Synchronization-Parameters in Patients With Subcortical Arteriosclerotic Encephalopathy and Gait Disorder.

Subcortical arteriosclerotic encephalopathy (SAE) is characterized by extensive white matter lesions in the MRI. Clinical symptoms are cognitive impairment, ranging from mild deficits to vascular dementia, impaired executive functioning, and gait disorders. In the EEG of SAE patients with vascular dementia, the lower frequencies are increased. However, it is unclear whether EEG changes also exist in SAE patients with gait disorders but without vascular dementia. The authors analyzed the EEGs of 50 nondemented patients with SAE and gait disorders and 50 healthy controls applying pointwise transinformation as a measure of synchronization. Hundred seconds of waking EEG that appeared unaltered in visual analysis were sufficient to prove changes in synchronization. The authors found a decrease in the mean level of synchronization, combined with an elongation of synchronization time in all examined brain areas. These effects correlated slightly with the extent of subcortical lesions. Changes in EEG synchronization in patients with SAE and gait disorders seem to occur independently of cognitive function. The causal relationship of the changes in EEG synchronization and gait disorders remains to be clarified. The results of this study might point to a decrease in coupling efficiency in these patients, with the increase in synchronization duration as a possible compensatory mechanism. Because a time-efficient signal transmission particularly during gait execution is crucial, reduced efficiency might contribute to an impairment of postural stabilization. The study results might indicate a neuronal network for planning and execution of motor activity and particularly gait, extending from the frontal over the central to the parietal cortex.

How does looking the other way portray executive dysfunction in frontotemporal degeneration?

In Heilman and Valenstein's1 widely used text, Clinical Neuropsychology , standing alone among the chapters dedicated to neurobehavioral syndromes (aphasia, agnosia, apraxia) is one entitled “The frontal lobes.” This label subsumes executive cognitive functions, comportment, and the control and execution of motor activity, which includes both somatomotor and oculomotor systems. The oculomotor control system for saccades mediates reflexive responses influenced by the superior colliculus and volitional movements controlled by the frontal eye fields (FEF).2 As initially reported over 30 years ago, the antisaccade task assesses a central feature of executive control, the ability to inhibit an automatic or prepotent response to a novel visual stimulus.3 Test performance involves 2 separate tasks: 1) suppressing a reflex prosaccade toward a novel visual stimulus presented on one side, and 2) diverting gaze in the opposite direction by executing a volitional antisaccade.4 A number of variations of this basic paradigm have been developed to evaluate neuropsychological processes such as visual attention, spatial memory, working memory, motivation, and decision-making across a variety of neurologic and psychiatric disorders.5

Distinct neural processes of bodily awareness in crossed fingers illusion

The tactile reassignment process supports the flexible and dynamic changes of body schema in various situations such as those involving tool use. Here, we show that there exist two distinct neural processes in the dynamical reassignment process. One process is involved in identifying the body part where the tactile stimuli are applied, whereas the other is involved in the assignment of the tactile stimuli in the external space including one's body. These processes, combined together, would facilitate the quick and appropriate acquisition of information from the environment, resulting in the speedy spatial perception and execution of motor activities. In addition, we show that the body posture affects the accuracy of tactile localization in the crossed fingers illusion.

Dipyridamole Promotes Changes in Calbindin-D28k and Tyrosine Hydroxylase Expression in Neonatal Rats

Background: Perinatal hypoxia alters the concentration of many neurochemicals in the brain, including adenosine, and promotes central nervous system (CNS) disorders in human infants such as periventricular leukomalacia or encephalopathy. Objective: Using the postnatal rat as a model of perinatal human development, we examined the effects of sustained increases in brain adenosine on CNS regions thought to be involved with both planning and execution of motor activity. Methods: To simulate hypoxia-induced changes in adenosine, Sprague-Dawley rats were injected twice daily from postnatal day (P) 3 to P14, with the adenosine uptake inhibitor dipyridamole (DIP) or the A₁ adenosine receptor agonist N⁶-cyclopentyladenosine (CPA). Vehicle-injected animals served as controls. Immunohistochemical and morphological analyses were then performed to examine the expression of calbindin D-28k (CB) and the thickness of the external granule cell layer (eGL) in the cerebellum. Additionally tyrosine hydroxylase (TH) expression in the caudate putamen and ventricular size were also examined. Results: In the cerebellum, both DIP and CPA reduced the number of CB-positive Purkinje cells as well as decreased the thickness of the eGL compared to vehicle. In the caudate putamen we found that DIP but not CPA decreased TH expression when compared to vehicle. Neither agent significantly altered ventricular size when compared to vehicle. Conclusions: These observations suggest that elevations in brain adenosine, which can occur following hypoxia, leads to both neurochemical and cellular changes in regions of the brain which control the planning and execution of motor activity. Thus, therapeutic strategies that target brain regions most sensitive to adenosine may prevent or control at least some of the CNS damage observed following perinatal hypoxia.

Surface Laplacian based Single Channel Activity (SCA) in control subjects and stroke patients

Event Abstract Back to Event Surface Laplacian based Single Channel Activity (SCA) in control subjects and stroke patients K. Fulop1*, Vegso B1, Cs Szekrenyesi1, T. Magos1, M. Dombovari1, Gy Kozmann1 and Z. Nagy1 1 Universtity of Pannonia, Department of Electrical Engineering and Information Systems, Faculty of Information Technology, Hungary Aim: Sequential activity of cortical areas is responsible for preparation and execution of motor activity. High power 128 channels EEG with its 0.5 msec temporal resolution promises an appropriate technique to study brain function in a "mesoscopic" level. Methods: Visually guided left- and right-hand finger tapping experiments are carried out in an electrically shielded room on right handed subjects using a 128+9 channels EEG device at 2048Hz sampling rate. The tapping is performed at a predefined pace with 10 seconds inter-tap interval, 32 tapping epochs are selected for processing. Power line noise removal is followed by band-passing the signal to 1-400Hz, leaving the selected 3072 sample (1500ms) data epoch clean. A 500ms pre-tapping interval is selected as baseline phase, 500-500ms before and after tapping intervals are considered for further processing. The 128 scalp electrodes are grouped by anatomical relevance to the task. Two dimensional discrete Surface Laplacian calculations allow for estimation of radial cortical surface current density (SCD), which is averaged over the 32 selected tapping epochs. Threshold values are calculated from the baseline interval to determine radial current density limits of activation (Single Channel Activity - SCA). The activation level of the anatomically defined regions were characterised by the accumulated SCD values. Results: Age related increase of activated SCA was documented in control subjects. In young age group the relevant motor and premotor activity was moderate compared to the elderly control subjects. Immediately following stroke the relevant activity was poorly detectable while in the course of rehabilitation the typical motor and premotor activity has returned. Conclusion: We developed a new Surface Laplacian based technology (SCA) [1] capable of characterizing task related activation of motor and premotor cortex and following the post-stroke repair phenomenon. The technique also proved to be a useful tool for assessing lateralization. Acknowledgments: Granted by NeuroMath Action BM0601, OTKA K69240, NTP OM00191/2008 AALAMSRK.