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PubMedDate not supplied

Dynamics of the temporal parameters of sensorimotor reactions as a function of movement type in man.

An investigation consisting of two series was carried out on nine healthy male subjects, age 20-24 years. In the first series, a warning signal and then four symbols which required a simple or a complex reaction were presented sequentially on a display screen. In the second series, asterisks were presented instead of the symbols. The sequence of reactions was performed from memory. The results of the investigations made possible the identification of two specific features: a significant decrease in RT in the series of reaction from memory, and a successive decrease in RT with a decrease in the number of the remaining signals in the block of signals. In the first series, the RT decreased successively by 35-40 msec, and in the second, by 16-20 msec. It is hypothesized that the difference in RT between the series characterizes the time of analysis of one signal, and the difference, on the other hand, in the RT within the limits of a single block in the second series characterizes the time for the retrieval from memory of the motor program.

Adult↗
PubMed1980

Amplitude of responses to perturbation in primate sensorimotor cortex as a function of task.

1. Monkeys learned to maintain hand position against a range of background forces. Short-latency responses to passive wrist extension or flexion were recorded from units in areas 4, 3, 1, and 2. Response amplitude was studied as a function of background force direction (extension or flexion). 2. For 40% of the precentral and postcentral responses, response amplitude depended on constant force direction. For these dependent responses, amplitude with background force in one direction averaged 2.8 times amplitude with background force in the opposite direction. 3. Units for which background activity varied with constant force direction were designated task related. Dependent responses from area 4 task-related units were usually larger when background activity was greater and when background force direction matched the direction of the passive movement. 4. Dependent responses from area 4 task-related units occurred significantly later than nondependent responses from the same units. 5. Since most area 4 task-related activity was explicable as a result of peripheral input via the same oligosynaptic path mediating area 4 responses to passive movements (32), the present findings imply that area 4-task-related activity may result in large part from centrally mediated change in the access of short-latency peripheral input to area 4 units. 6. The dependence of responses from non-task-related area 4 units and from non-task-related and task-related postcentral units showed no dominant correlation with background activity or with background force direction. Their dependence appeared to require no explanation other than a change in peripheral input with change in background force direction.

Animals↗
PubMed1997

Cerebral vascular malformations adjacent to sensorimotor and visual cortex. Functional magnetic resonance imaging studies before and after therapeutic intervention.

BACKGROUND AND PURPOSE: It is not known how cerebral vascular malformations affect the function of the surrounding brain. Functional magnetic resonance imaging (fMRI) can provide information about normal functional neuroanatomy and its alteration by vascular lesions and therapeutic intervention. METHODS: We performed fMRI studies in 24 patients harboring vascular malformations adjacent to primary somatosensory, motor, and visual cortex. The fMRI studies consisted of the acquisition of an image time series coupled with functional activation of motor, sensory, or visual cortex in both hemispheres. Activated voxels were identified using frequency domain analyses, and their number and anatomic location were compared between the affected and unaffected hemispheres. RESULTS: Every patient capable of performing the desired task showed functional activation. Eight patients without neurological deficits showed a symmetrical pattern of activation between the hemispheres. Each had a vascular malformation located one or more gyri from the functional region imaged. Three patients showed hemispheric symmetry in the location of activated cortex but with a marked asymmetry in the number of activated voxels. Each harbored vascular malformations located within one gyrus of the functional region and showed either subtle or no neurological deficit. Eleven patients showed hemispheric asymmetry in the location of activated cortex. In 6, the anatomic displacement appeared to be due to a mass effect of the lesion. In 5, the activation occurred at a different anatomic locale, and the patients exhibited gross neurological deficit in the respective function. Posttherapeutic changes in functional activation reflected elimination of the mass effect or recovery of clinical function. CONCLUSIONS: Systematic fMRI studies are possible in patients with vascular malformations in brain regions adjacent to primary somatosensory, motor, and visual cortex. Displacement of the activated region and hemispheric asymmetry in the number of activated voxels in the functional regions appear to reflect the anatomic and physiological impact of the vascular malformation. Changes in fMRI findings after intervention reflect the consequences of therapy and parallel clinical recovery.

Adolescent↗
PubMed2004

Functional neuroanatomy of the sensorimotor control of singing.

Reviews of the songbird vocal control system frequently begin by describing the forebrain nuclei and pathways that form anterior and posterior circuits involved in song learning and song production, respectively. They then describe extratelencephalic projections upon the brainstem respiratory-vocal system in a manner suggesting, quite erroneously, that this system is itself well understood. One aim of this chapter is to demonstrate how limited is our understanding of that system. I begin with an overview of the neural network for the motor control of song production, with a particular emphasis on brainstem structures, including the tracheosyringeal motor nucleus (XIIts), which innervates the syrinx, and nucleus retroambigualis (RAm), which projects upon XIIts and upon spinal motor neurons innervating expiratory muscles. I describe the sources of afferent projections to XIIts and RAm and discuss their probable role in coordinating the bilateral activity of respiratory and syringeal muscles during singing. I then consider the routes by which sensory feedback, which could arise from numerous structures involved in singing, might access the song system to guide song learning, maintain accurate song production, and inform the song system of the requirements for air. I describe possible routes of access of auditory feedback, which is known to be necessary for song learning and maintenance, and identify potential sites of interaction with somatosensory and visceral feedback that could arise from the syrinx, the lungs and air sacs, and the upper vocal tract, including the jaw. I conclude that the incorporation of brainstem-based respiratory-vocal variables is likely to be a necessary next step in the construction of more sophisticated models of the control of vocalization.

Animals↗
PubMed1999

Sensorimotor performance as a function of eye dominance and handedness.

Performance on a speeded target striking task was significantly associated with eye dominance and handedness for a sample of 30 subjects. They showed the expected higher performance with the dominant hand but also showed an effect of eye of input. Highest performance was obtained with binocular viewing, next best used the dominant eye, and poorest performance the nondominant eye. Effects were additive with no interaction between hand and eye dominance.

Adult↗
PubMed1994

[Functional analysis of the sensorimotor processes in the brain as a methodological and methodical basis for the theory and practice of referent bioadaptation].

Stimulus programs and their reproduction by the examinees are compared. This makes up the system of logic regularities, reflecting characteristics of voluntary movement control. The authors ground their investigations on the principle of estimating dynamics of intracyclic components in electromyographic equivalent of reproductive tapping synergy considered as a sample of voluntary movement combining neurophysiological, psychophysiological and biomechanical components.

Adaptation, Physiological↗
PubMed1993

Differential cyclic AMP dependence of facilitation at Aplysia sensorimotor synapses as a function of prior stimulation: augmentation versus restoration of transmitter release.

Synaptic facilitation at sensory-to-motor neuron synapses in Aplysia is a mechanism contributing to a simple form of learning called behavioral sensitization. Previous work has shown that facilitation is mediated in part by the neurotransmitter 5-HT acting through cAMP to broaden presynaptic action potentials and thus increase transmitter release from the sensory neuron terminals. Other studies have indicated that 5-HT causes facilitation by more than one mechanism, depending on whether the synapse has first been depressed by prior stimulation. The present study examines the involvement of cAMP in facilitation at depressed synapses by utilizing the adenylyl cyclase activator 7 beta-desacetyl-7 beta-[gamma-(N-methylpiperazino)-butyryl] forskolin (7B-forskolin) and 5-HT separately and in combination. Facilitation at relatively rested synapses can be mimicked with application of 7B-forskolin, whereas transmission at synapses that have been subjected to repeated stimulation is not affected. The forskolin derivative by itself increases cAMP levels in sensory neurons and potentiates 5-HT-induced stimulation of cAMP 2-10-fold. Nonetheless, joint application of 7B-forskolin and 5-HT at submaximal concentrations to depressed synapses causes the same amount of facilitation as 5-HT alone. This finding implies that facilitation by 5-HT at repeatedly stimulated synapses is not mediated by cAMP alone. In addition, facilitation by 7B-forskolin at relatively rested synapses can occur without prolongation of action potentials, suggesting that cAMP can act in more than one way to enhance transmission. Taken together with earlier findings, the present results suggest that at least three distinct processes participate in facilitation by 5-HT.

Action Potentials↗
PubMed1992

The relationship between disability and memory dysfunction in multiple sclerosis.

We examined the relationship between memory impairment and functional disability in multiple sclerosis. Tests of memory, sensorimotor ability, and functional capacity were administered to fifty-six subjects with chronic-progressive or remitting-relapsing MS. Sensorimotor impairment, functional disability, and chronicity predicted impairment on various measures of memory acquisition, while age and type of diagnosis did not. After accounting for the effects of initial acquisition, delayed-recall performance was weakly-associated with disability. We suggest that: (1) Functional disability is associated with memory loss in MS; (2) MS-forgetting is caused by defective acquisition, rather by a deficit in consolidation or storage; (3) Level of disease activity, rather than type of MS diagnosis, determines the degree of memory impairment; and (4) MS disability needs to be evaluated multidimensionally, to account for both neurologic and functional impairment.

Activities of Daily Living↗
PubMedDate not supplied

The relationships among sensorimotor components, fine motor skill, and functional performance in preschool children.

OBJECTIVES: This correlational study investigated the relationships among sensorimotor components, standardized measures of fine motor skill, and functional performance in self-care, mobility, and social interaction. It also examined which sensorimotor components and fine motor skills were predictors of functional performance. METHOD: Thirty preschool children with motor delays were evaluated with tests of in-hand manipulation, tactile defensiveness, stereognosis, grasping strength, and fine motor skill. Parents of the subjects were interviewed with the Pediatric Evaluation of Disabilities Inventory. Correlational and regression analyses were computed. RESULTS: Significant correlations were found among sensorimotor components and discrete fine motor skills as measured on standardized observational tests. Few correlations emerged between foundational components of fine motor skill and functional performance in self-care, mobility, and social function. CONCLUSION: Lack of significant relationships among the variables, all of which were aspects of functional performance might be due to the difference between judgment-based and observational evaluation, the influence of the environmental context on the child's performance, and the influence of cultural values on the opportunities afforded to the child.

Child↗
PubMed2005

Blood oxygenation level dependent contrast resting state networks are relevant to functional activity in the neocortical sensorimotor system.

The relevance of correlations between blood oxygenation level dependent (BOLD) signal changes across the brain acquired at rest (resting state networks, or RSN) to functional networks was tested using two quantitative criteria: (1) the localisation of major RSN correlation clusters and the task-related maxima defined in BOLD fMRI signal changes from the same subjects; and (2) the relative hemispheric lateralisation (LI) of BOLD fMRI signal changes in sensorimotor cortex. RSN were defined on the basis of signal changes correlated with that of a "seed" voxel in the primary sensorimotor cortex. We found a generally close spatial correspondence between clusters of correlated BOLD signal change in RSN and activation maxima associated with hand movement. Conventional BOLD fMRI during active hand movement showed the expected wide variation in relative hemispheric lateralisation of LI for sensorimotor cortex across the subjects. There was a good correlation between LIs for the active hand movement task and the RSN (r=0.74, p<0.001). The RSN thus define anatomically relevant regions of motor cortex and change with functionally relevant variations in hemispheric lateralisation of sensorimotor cortical interactions with hand movement.

Adult↗
PubMed1998

A prospective approach to correct for inter-image head rotation in fMRI.

Global head motion occurring between successive image acquisitions during a functional MRI time series can corrupt the signal of physiologic brain activation, potentially invalidating interpretation of the final activation map from that particular fMRI time series. By approximating the head as a rigid body, multiaxial global head motion can be decomposed into orthogonal linear and rotational components. This paper describes a method using orbital navigator echoes to provide prospective correction for both through-plane and in-plane inter-image head rotation in functional MRI. The dynamic detection and correction of rotation can be performed in <100 ms. Phantom experiments demonstrate accurate correction of rotational motion over a range of +/-0.36 degrees to +/-12 degrees. Imaging studies in volunteers document the feasibility of real-time prospective correction of rotational motion in vivo. Using a modified receiver operating characteristic method, motion-corrected functional MRI sensorimotor studies incorporating deliberate head rotations are shown to be superior to functional MRI time series acquired under similar conditions but without motion correction.

Artifacts↗
PubMedDate not supplied

The effects of sensorimotor-based intervention versus therapeutic practice on improving handwriting performance in 6- to 11-year-old children.

OBJECTIVE: The aim of this study was to investigate the effects of two interventions (sensorimotor and therapeutic practice) on handwriting and selected sensorimotor components in elementary-age children. METHOD: Thirty-eight children 6 to 11 years of age with handwriting dysfunction but no identified educational need were randomly assigned to one of the two intervention groups or a control group. Intervention groups met four times per week over 5 weeks. Handwriting was measured pre- and postintervention using the Test of Handwriting Skills. Visual perception (motor-reduced), visual-motor integration, proprioception, and in-hand manipulation were also measured. RESULTS: Children receiving therapeutic practice moderately improved handwriting whereas children receiving sensorimotor intervention declined in handwriting performance. The control group did not change significantly. Sensorimotor impairment was noted at pretest in three or four components and selected sensorimotor component function improved with intervention. CONCLUSION: Therapeutic practice was more effective than sensorimotor-based intervention at improving handwriting performance. Children who received sensorimotor intervention improved in some sensorimotor components but also experienced a clinically meaningful decline in handwriting performance.

Child↗
PubMed1991

Functional anatomy of human hand sensorimotor cortex from spatiotemporal analysis of electrocorticography.

We measured chronic electrocorticography (ECoG) of sensorimotor cortex during contralateral median nerve stimulation in 6 patients with partial seizures evaluated for surgery. We analyzed the spatiotemporal structure of the somatosensory evoked response (SER) using multiple source modeling to investigate functional anatomy of its neuronal sources. Two dipole sources in postcentral gyrus explained the large majority of the first 60 msec of the SER, indicating a subregion of hand somatosensory cortex generating this activity. The source locations agreed with normal functional anatomy from cortical stimulations, intraoperative photographs, and postoperative neurological examinations after focal excisions. The time patterns of both sources were biphasic like the previously described N20-P30 and P25-N35 peaks. The spatiotemporal patterns of both sources overlapped. Spatiotemporal analysis with multiple dipole sources appears useful to determine the number, locations, and spatiotemporal field patterns of cortical regions active during peripheral somatosensory stimulation and reveals simplicity in the macroscopic functional anatomy of dynamic human sensorimotor cortex.

Adolescent↗
PubMed1994

[Functional cerebral neuro-imaging at 1.5 Tesla. The results of visual, sensorimotor and auditory stimulations].

Functional activation of the cerebral cortex can be observed with a standard 1.5 Tesla MRI magnet. We used a repeated FLASH 2D one-section sequence with a long echo (TE = 60 ms) and a small passing band. Modification of regional cerebral oxygenation due to neurone activation seems to be the main source of contrast. Sensorimotor stimulation was effected by an unusual mobilization of the fingers. Visual stimulation was performed by intermittent lightings at a frequency of 8 Hz. Auditory stimulation relied on listening to speech sounds. Signal increases were localized on the cerebral cortex with precise anatomico-functional correlation. Using a clinical 1.5 Tesla magnet requires an adequate treatment of data. Thus, stimulated cerebral activity can be portrayed by MRI therapy opening a new way for anatomico-functional cerebral studies.

Acoustic Stimulation↗
PubMed1992

Biochemical and behavioral effects of a sensorimotor cortex injury in rats pretreated with the noradrenergic neurotoxin DSP-4.

The role of the noradrenergic (NE) system in recovery of motor function after sensorimotor cortex (SMCX) injury was investigated. After training on a beam-walking task to assess changes in motor function, animals were given DSP-4 or saline and tested for 2 weeks; both groups then received unilateral SMCX suction ablations. Animals that received DSP-4 were significantly retarded in motor recovery compared with the saline group. At 24 days after injury (after motor recovery), the animals' deficits were significantly reinstated with NE-blocking drugs. DSP-4 significantly depressed NE levels in the hippocampus and cerebellum. A Timm histochemical analysis revealed glutamatergic sprouting in the hippocampus of animals that were pretreated with DSP-4, which suggests the possibility that similar glutamatergic plasticity in other pathways may occur and that excitotoxicity might also play a role after the DSP-4 induced NE deafferentation.

Adrenergic Agents↗