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PubMed1996

Selective drawing disorders after right subcortical stroke: a neuropsychological premorbid and follow-up case study.

We report the case of a patient affected by a subcortical lesion of the right non-dominant hemisphere, and demonstrate that he had selective constructional disorders by comparing his post-stroke performances with those assessed 18 months before the stroke. A detailed analysis was made of the visuospatial, perceptual, representational and executive competences involved in drawing tasks at one, two and six months post-stroke. Neuropsychological follow-up revealed the progressive recovery of all visuospatial abilities. This study provides some interpretative elements for constructional disorders and, in particular, for the closing-in phenomenon observed only during the subacute phase.

Aged↗
PubMed1982

[Course studies of spontaneous speech and graphic achievements in 175 aphasics].

In 175 aphasic patients with agraphia the course of the expressive oral and graphic performances was compared. Spontaneous speech and writing and the writing of dictated words and sentences were investigated and evaluated. In addition, several peculiarities of this syndrome were examined. The investigations showed that the relationship between the expressive oral and graphic performances changes in the course of improvement depending on the type of aphasia. In the first period of testing no difference was found in the performances of patients with total aphasia and motor-amnesic aphasia; in the group of mixed aphasics and sensory-amnesic aphasics, however, the oral performance predominated the writing. Investigations at later periods showed that in the cases of total aphasia the improvement of the oral performance was better whereas in the cases of motor-amnesic and sensory-amnesic aphasia the graphic performance was more improved.

Agraphia↗
PubMed1991

Psychiatric aspects of writer's cramp.

Although its aetiopathogenesis is still unknown, writer's cramp is meanwhile regarded essentially an organically induced disorder. However, as shown by this interdisciplinary study, psychodynamic factors should not be neglected. Special attention should be given to the patients' experience of the syndrome and secondary psychoreactive processes.

Achievement↗
PubMed1992

Dysgraphia and selective impairment of the graphemic buffer.

We report the linguistic analysis of a case of pure dysgraphia whose features suggest a selective deficit of the graphemic buffer. We discuss the neuropsychological pattern in the light of theoretical models of the cognitive processes considered to underlie writing skills.

Aged↗
PubMed2006

Psychomotor performance and sequence planning in anorexia nervosa before and after weight restoration.

BACKGROUND: In the study of psychomotor performance in anorexia nervosa (AN), motor control has not been studied extensively. The present study explores sequence planning in a sample of AN patients. METHOD: A group of 26 female restricting AN inpatients, aged 14 to 25, was compared with 24 healthy women matched for age and educational level. During the performance of a simple copying task, in which movement planning, but not working capacity, was challenged, the ease with which generally favored graphic production rules could be applied was manipulated. Computerized recordings of the drawing movements allowed detailed analyses of reaction and movement times and of drawing sequences. Fifteen patients were retested after weight restoration, as were 15 controls. RESULTS: Copying patterns that normally elicit a conflict between preferred graphic production rules induced significantly less slowing in the reaction times of the anorexia nervosa patients than in the controls, both before and after weight restoration. There were no group differences as regards the consistency with which the implicit production rules were applied. DISCUSSION: AN patients seem to show a fast response style combined with good sequence planning capacity.

Adaptation, Psychological↗
PubMed2004

"Proprioceptive signature" of cursive writing in humans: a multi-population coding.

The goal of the present study was to investigate the firing behavior of populations of muscle spindle afferents in all the muscles acting on the ankle while this joint was being subjected to "writing-like" movements. First it was proposed to determine whether the ensemble of muscle spindles give rise to a unique, specific, and reproducible feedback information characterizing each letter, number or short word. Secondly, we analyzed how the proprioceptive feedback on the whole encodes the spatial and temporal characteristics of writing movements using the "vector population model". The unitary activity of 51 primary and secondary muscle spindle afferents was recorded in the tibial and common peroneal nerves at the level of the popliteal fossea, using the microneurographic method. The units recorded from belonged to the tibialis anterior, the extensor digitorum longus, the extensor hallucis longus, the peroneus lateralis, the gastrocnemius-soleus and the tibialis posterior muscles. The "writing-like" movements were randomly imposed at a "natural" velocity via a computer-controlled machine in a two-dimensional space. In general, muscle spindle afferents from any of the six muscles responded according to the tuning properties of the parent muscle, i.e. increasing their discharge rate during the phases where the direction of movement was within the preferred sensory sector of the parent muscle. The whole trajectory of the writing movements was coded in turn by the activity of Ia afferents arising from all the muscles acting on the joint. Both single afferent responses and population responses were found to be highly specific and reproducible with each graphic sign. The complex multi-muscle afferent pattern involved, with its timing and distribution in the muscle space, seems to constitute a true "proprioceptive signature" for each graphic symbol. The ensemble of muscle spindle afferents were therefore found to encode the instantaneous direction and velocity of writing movements remarkably accurately. It was concluded that the proprioceptive feedback from all the muscles with which the moving joint is equipped provides the CNS with highly specific information that might contribute to a graphic sign identification process.

Action Potentials↗
PubMed2000

Proprioceptive population coding of two-dimensional limb movements in humans: II. Muscle-spindle feedback during "drawing-like" movements.

It was proposed to study the proprioceptive sensory coding of movement trajectories during the performance of two-dimensional "drawing-like" movements imposed on the tip of the foot. For this purpose, the activity of the muscle-spindle afferents from the Extensor digitorum longus, Tibialis anterior, Extensor hallucis longus, and Peroneus lateralis muscles was recorded from the lateral peroneal nerve using the microneurographic technique. The drawing movements, describing geometrical shapes such as squares, triangles, ellipses, and circles, were imposed at a constant velocity in both the clockwise and counterclockwise directions. A total number of 44 muscle-spindle afferents were tested, 36 of which were identified as primary and eight as secondary afferents. Whatever the shape of the imposed foot movement, the primary endings from one muscle never discharged throughout the whole trajectory (on average, they discharged for only 49.2% of the length of the trajectory), whereas all the secondary endings discharged for most part of the drawing trajectories (average: 84.8%). The relationship between afferent discharge rate and direction could be described with a cosine-shaped tuning function. The peak of this function corresponded to the preferred sensory direction of the receptor-bearing muscles. The whole path of a given geometrical drawing movement was found to be coded in turn by each of the primary afferents originating from each of the muscles successively stretched. The contribution of each population of muscle afferents from each ankle muscle was represented by a "population vector", whose orientation was the preferred direction of the muscle under consideration and whose length was the mean instantaneous frequency of the afferent population. The "sum vector" corresponding to the sum of all these weighted "population vectors" was found to point in the instantaneous direction of the drawing trajectory, i.e., the tangent to the trajectory. These findings suggest that trajectory information is already encoded at the peripheral level on the basis of the integrated inputs provided by sets of receptors belonging to all the muscles acting on a given joint.

Adult↗
PubMed1999

Proprioceptive control of multijoint movement: unimanual circle drawing.

The present experiments addressed whether proprioception is used by the central nervous system (CNS) to control the spatial and temporal characteristics of unimanual circle drawing. Circle drawing is a multijoint movement, in which the muscles crossing the elbow and the shoulder are sequentially activated. The spatial and temporal characteristics of circle drawing depend on the precise coordination of these sequential activation patterns, and proprioception is ideally suited to support this coordination. Blindfolded human subjects produced a counterclockwise circular drawing motion (diameter = 16 cm) with the dominant arm at a repetition rate of 1/s. In some trials, 60-70 Hz vibration was applied to the tendons of the biceps brachii and/or the anterior deltoid. Spatial parameters measured from hand-movement data included the x- and y-axis diameters, circularity, and drift of the hand in the workspace. Vibration of either the biceps brachii or the anterior deltoid caused subjects to draw circles with decreased diameter, with changes in circularity, and with a systematic drift of the hand. These distortions to circle drawing by tendon vibration demonstrate that the CNS uses proprioceptive information to accomplish the spatial characteristics of this motor task. Simultaneous vibration of both muscles produced a drift that exceeded the individual vibration effects, which suggests that the CNS combined proprioceptive information related to elbow and shoulder rotation to control the movement of the hand. The temporal characteristics of circle drawing were quantified from joint angle data. While vibration did not significantly influence the relative phase between elbow and shoulder rotation, the variability of the phase relationship increased significantly, which suggests that proprioception contributes to phase stabilization. During circle drawing, elbow flexion-extension movements were produced with limited activation of the biceps. Nevertheless, biceps vibration distorted the circle metrics, suggesting that a muscle's significance as a sensory transducer is independent of its activity level.

Adolescent↗
PubMed1999

Proprioceptive control of multijoint movement: bimanual circle drawing.

Proprioception is used by the central nervous system (CNS) in the control of the spatial and temporal characteristics of single joint and multiple joint movement. The present study addressed the role of proprioception in the control of bilateral cyclical movements of the limbs. Normal blindfolded human subjects drew circles simultaneously and symmetrically with the two arms (16 cm diameter, 1 /s) upon two digitizing tablets. In selected trials, vibration (60-70 Hz) was applied to the tendon of the biceps and/or anterior deltoid muscles of the dominant arm to distort the proprioceptive information from muscle spindle afferents. One goal of this study was to identify whether tendon vibration influenced the spatial characteristics of circles drawn by the vibrated, dominant arm and the non-vibrated, non-dominant arm. A second goal was to determine the effect of vibration on the temporal coupling between the two arms during circle drawing. The results revealed that tendon vibration affected the spatial characteristics of circles drawn by the vibrated arm in a manner similar to that previously found for unilateral circle drawing. During bimanual circle drawing, vibration had only a minimal effect on the spatial characteristics of the non-vibrated, non-dominant arm. Temporal interlimb coupling was quantified by the relative phasing between the arms. Without tendon vibration, the dominant arm led the non-dominant arm. Vibration of the dominant arm increased the average phase lead. In a first control experiment, vibration of the non-dominant arm decreased the phase lead of the dominant arm, or even reversed it to a non-dominant arm phase lead. In a second control experiment, the subjects performed the bimanual circle-drawing task with vision of only the vibrated arm, in which case there was no spatial distortion of the circles drawn by the vibrated arm, but the phase relation between the two arms was still shifted as if vision were completely unavailable. It was concluded that, in bimanual movements such as these, the spatial and temporal characteristics of movement are controlled independently. Whereas the spatial characteristics of hand movement seem to be controlled unilaterally, the temporal characteristics of interlimb coupling appear to be controlled by proprioceptive information from both limbs, possibly by a proprioceptive triggering mechanism.

Adult↗
PubMed1998

Basal ganglia arteriovenous malformation presenting as "writer's cramp".

A 12-year-old girl with a 3-year history of writer's cramp in association with a basal ganglia arteriovenous malformation (AVM) is reported. The lesion was localized to the left globus pallidus and putamen, extending to the adjacent white matter of the frontal lobe. Our experience confirms a common anatomical basis of symptomatic focal dystonia: disruption of the pathways within and adjacent to these structures. Appropriate imaging should be carried out in patients with unexplained movement disorders.

Basal Ganglia↗
PubMed1999

Primary central nervous system lymphoma presenting with a parkinsonian syndrome of pure akinesia.

The incidence of primary central nervous system lymphoma (PCNSL), once a rare tumour, has risen significantly in both immunocompetent and immunosuppressed patients. Although infiltration of the basal ganglia is not uncommon in PCNSL, extrapyramidal movement disorders are generally not recognised as a mode of clinical presentation of this type of cerebral tumour. We present the unusual case of a 75-year-old man who developed a parkinsonian syndrome of "pure akinesia" due to autopsy-confirmed PCNSL primarily involving the globus pallidus bilaterally. Parkinsonism due to bilateral pallidal lesions is known but rare, and such cases help in the understanding of basal ganglia function with regard to akinesia and freezing.

Aged↗
PubMed2001

Thalamic stimulation for primary writing tremor.

We report a patient with primary writing tremor whose tremor was treated with thalamic stimulation. He had undergone trials of multiple oral medications with no benefit for his tremor. An electrode lead was implanted in the thalamic nucleus ventralis intermedius with nearly complete control of his tremor and no postoperative complications. We conclude that nucleus ventralis intermedius thalamic stimulation is safe and effective for primary writing tremor.

Electric Stimulation Therapy↗
PubMed2003

Perceiving while acting: action affects perception.

In two experiments we studied how motor responses affect stimulus encoding when stimuli and responses are functionally unrelated and merely overlap in time. Such R-S effects across S-R assignments have been reported by Schubö, Aschersleben, and Prinz (2001), who found that stimulus encoding was affected by concurrent response execution in the sense of a contrast (i.e., emphasizing differences). The present study aimed at elucidating the mechanisms underlying this effect. Experiment 1 studied the time course of the R-S effect. Contrast was only obtained for short intertrial intervals (ITIs). With long ITIs contrast turned into assimilation (i.e., emphasizing similarities). Experiment 2 excluded an interpretation of the assimilation effect in terms of motor repetition. Our findings support the notion of a shared representational domain for perception and action control, and suggest that contrast between stimulus and response codes emerges when two S-R assignments compete with each other in perception. When perceptual competition is over, assimilation emerges in memory.

Adult↗
PubMed2006

Analysis of a Chinese phonetic compound database: implications for orthographic processing.

The complexity of Chinese orthography has hindered the progress of research in Chinese to the same level of sophistication of that in alphabetic languages such as English. Also, there has been no publicly available resource concerning the decomposition of Chinese characters, which is essential in any attempt to model the cognitive processes of Chinese character recognition. Here we report our construction and analysis of a Chinese lexical database containing the most frequent phonetic compounds decomposed into semantic and phonetic radicals according to Chinese etymology. Each radical was further decomposed into basic stroke patterns according to a Chinese transcription system, Cangjie (Chu, 1979 Laboratory of chu Bong-Foo Retrieved August 25, 2004, from http://www.cbflabs.com/). Other information such as pronunciation and character frequency were also incorporated. We examine the distribution of different types of character, the information skew in phonetic compounds, the relations between subcharacter orthographic units and the pronunciation of the entire character, and the processing implications of these phenomena in terms of universal psycholinguistic principles.

Databases as Topic↗
PubMed2005

The corpus callosum, interhemisphere interactions, and the function of the right hemisphere of the brain.

A complex clinical-neuropsychological study was performed by the Luriya method before and after surgery in 36 patients with arteriovenous malformations (AVM) of the corpus callosum. The symptoms of local lesions to the various parts of the corpus callosum are described. Symptoms of partial lesioning of the corpus callosum were found to be modality-specific, though only relatively. The symptoms of dyscopia or dysgraphia could appear in isolation fro each other. Combined lesions of the medial parts of the brain (cingulate cortex, frontal lobes) and the corpus callosum significantly increased the level of dysfunction of these medial parts. Patients with lesions to the anterior parts of the corpus callosum showed symptoms of frontal lobe dysfunction. Lesions to the corpus callosum led to dysfunction of the right hemisphere in the spheres of emotion, perception, and spatial activity. Previous studies have demonstrated that the right hemisphere integrates impulses from both sides of the space and is the first zone involved in activity, performing its initial stages. The author believes that this synthetic activity of the right hemisphere, with tight connections with the "conscious" left hemisphere, is required for the formation of the overall conceptualization of both individual objects and particular types of activity. From this point of view, it is the right hemisphere that can, in a sense, be regarded as dominant, rather than the left hemisphere.

Adolescent↗