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At least 613 records · Page 34Linked to original sources
PubMed1997

Adaptive Fourier modeling for quantification of tremor.

A new computational method for quantification of tremor, the weighted frequency Fourier linear combiner (WFLC), is presented. This technique rapidly determines the frequency and amplitude of tremor by adjusting its filter weights according to a gradient search method. It provides continual tracking of frequency and amplitude modulations over the course of a test. By quantifying time-varying characteristics, the WFLC assists in correctly interpreting the results of spectral analysis, particularly for recordings exhibiting multiple spectral peaks. It therefore supplements spectral analysis, providing a more accurate picture of tremor than spectral analysis alone. The method has been incorporated into a desktop tremor measurement system to provide clinically useful analysis of tremor recorded during handwriting and drawing using a digitizing tablet. Simulated data clearly demonstrate tracking of variations in frequency and amplitude. Clinical recordings then show specific examples of quantification of time-varying aspects of tremor.

Algorithms↗
PubMed2000

Dissociation of writing processes: functional magnetic resonance imaging during writing of Japanese ideographic characters.

Dissociation between copying letters and writing to dictation has been reported in the clinical neuropsychological literature. Functional magnetic resonance imaging (fMRI) was conducted in normal volunteers to detect the neurofunctional differences between 'copying Kanji', the Japanese ideographic characters, and 'writing Kanji corresponding to phonological information'. Four tasks were conducted: the copying-Kanji task, the writing-Kanji-corresponding-to-phonogram task, the Kanji-grapheme-puzzle task, and the control task. The right superior parietal lobule was extensively activated during the copying-Kanji task (a model of the copying letters process) and the Kanji-grapheme-puzzle task. These observations suggested that this area was involved in referring the visual stimuli closely related to the ongoing handwriting movements. On the other hand, Broca's area, which is crucial for language production, was extensively activated during the writing-Kanji-corresponding-to-phonogram task (a model of the writing-to-dictation process). The Kanji-grapheme-puzzle task activated the bilateral border portions between the inferior parietal lobule and the occipital lobe, the left premotor area, and the bilateral supplementary motor area (SMA). Since the Kanji-grapheme-puzzle task involved manipulospatial characteristics, these results suggested cooperation between visuospatial and motor executive functions, which may be extensively utilized in demanding visual language processing. The neurofunctional difference between 'copying Kanji' and 'writing Kanji corresponding to phonogram' was efficiently demonstrated by this fMRI experiment.

Adult↗
PubMed2003

Visual presentation of single letters activates a premotor area involved in writing.

In the present fMRI study, we addressed the question as to whether motor-perceptual interactions might be involved in reading. Recognizing the letters encountered when reading is generally assumed to be a purely visual process, yet because we know how to write, we also possess a sensorimotor representation of the letters. Does simply viewing a letter suffice to activate the corresponding motor representation? To answer this question, we asked right-handed subjects first to look at and then to copy single letters or pseudoletters. We established that the visual presentation of letters activated a part of the left premotor cortex (BA6) that was also activated when the letters were being written by the subjects. This premotor zone resembles Exner's area, which is thought to contain the motor programs necessary for producing letters. Visually presented pseudoletters, which had never been written before by the subjects, did not activate this region. These results indicate that the writing motor processes are implicitly evoked when passively observing letters. The cerebral representation of letters is therefore presumably not strictly visual, but based on a multicomponent neural network built up while learning concomitantly to read and write. One of the components might be a sensorimotor one associated with handwriting. This finding shows the existence of close functional relations between the reading and writing processes, and suggests that our reading abilities might be somehow dependent on the way we write.

Adult↗
PubMed2003

Acquired epileptic dysgraphia: a longitudinal study.

A male presenting with benign partial epilepsy with rolandic spikes from the age of 7 years was evaluated at age 11 years for worsening of his epilepsy associated with a specific regression of graphomotor skills. A longitudinal study over nearly 2 years showed an improvement in handwriting to an almost normal level under modified antiepileptic therapy. A detailed analysis with a computer-monitored graphics table showed at first a rapid improvement of skills followed by protracted slower progress. We argue that the initial rapid recovery of skills was directly linked to the improvement of his epilepsy. The slower late acquisition of motor programmes that had never been fully established was due to long-standing interference by his epilepsy. The specificity of the deficit within the graphomotor system and its possible neurobiological basis are also discussed. The analytical method and approach used in a single patient might provide an example for other patients in whom epilepsy can interfere in the acquisition, progress, and maintenance of new skills and can be responsible for selective deficits.

Aging↗
PubMed1982

Speech dominance, handedness and electro-convulsions.

This paper discusses methods for assessing speech dominance in cases for unilateral ECT. The use of formal laterality tests has been strongly advocated in the literature, but is seldom adopted in clinical practice. Assessment of handwriting type (left/right, inverted/non-inverted) has been put forward as an alternative, but is not valid. Consideration of handedness alone is the most common practice, but is of little value. From current evidence on the relation of handedness to speech dominance, the paper evaluates the likely outcomes of always administering right-sided ECT, and of giving formal tests to left-handers only.

Dominance, Cerebral↗
PubMed1992

A comparison of the diagnoses of a graphologist with results of psychological tests. 1941.

A class of twenty-four students who had previously been given intelligence, interest, and personality tests wrote to a newspaper graphologist for vocational guidance, their university connection being disguised and the requests being staggered over a period of more than one week. The vocational recommendations and the diagnoses of personality traits were then compared with the test scores. It was found that: 1. Assuming that a certain minimum intelligence is necessary for a given occupation, the occupations recommended by the graphologist showed no more than a change relationship with the recommendations which a psychologist would have made on the basis of intelligence tests. 2. Assuming that a certain pattern of interests is desirable for adjustment in an occupation, the occupation recommended by the graphologist were quite different from those which a psychologist would have recommended on the basis of an interest inventory, certain unsuitable occupations being recommended with more than chance frequency by the graphologist. 3. The graphologist's estimates of the students' personality traits showed no more than a chance agreement with those made by a psychologist on the basis of personality inventories in the case of four traits, and in the case of the two others were worse than change, again revealing a constant error. 4. There was reason for ascribing these constant errors to a belief in the existence of opportunities in certain areas rather than to poor diagnosis alone, and to the use of clues to personality traits not intrinsic in handwriting. 5. It was pointed out that, with certain graphological principles gaining acceptance in scientific circles, it is still important to check the activities of persons who claim to use these newer principles.

Adult↗
PubMed2006

Written spelling to dictation: Sound-to-spelling regularity affects both writing latencies and durations.

The authors examined the effect of sound-to-spelling regularity on written spelling latencies and writing durations in a dictation task in which participants had to write each target word 3 times in succession. The authors found that irregular words (i.e., those containing low-probability phoneme-to-grapheme mappings) were slower both to initially produce and to execute in writing than were regular words. The regularity effect was found both when participants could and could not see their writing (Experiments 1 and 2) and was larger for low- than for high-frequency words (Experiment 3). These results suggest that central processing of the conflict generated by lexically specific and assembled spelling information for irregular words is not entirely resolved when the more peripheral processes controlling handwriting begin.

Adolescent↗
PubMed2005

[Kinematic movement analyses and their application in psychiatry].

There is a long tradition to develop valid instruments for the exact assessment of psycho-motor dysfunctions in psychiatry. However, progress is hampered by the complexity of emotionally driven movements in psychiatric patients. Methods used up to now either remains unspecific due to only qualitative measurements or focus on the neurophysiological aspects too much. Thus, the results accomplished so far are only very general unspecific concerning different groups of psychiatric patients. In this paper, two own methods are presented which are aimed to avoid the two poles above mentioned. Kinematic analyses of facial expressions as well as handwriting movements provide quantitative and quite specific informations about psycho-motor dysfunctions of psychiatric patients and the effects of psychotropic substances. Thus, these methods are well suitable for relating them to other neurobiological parameters in order to contribute to the pathophysiological understanding of psycho-motor symptoms in psychiatric patients.

Antipsychotic Agents↗
PubMed1987

[Origin of mirror writing in children].

In left-handedness it is not the right hemisphere which usually dominates, as previously assumed but rather the left, as recent studies show. The development of right- and left-handedness is considered here in the light of the findings of Eccles, who substantiated the hypothesis of a relationship between the brain and a consciousness which is to be seen as basically independent of this organ. Right- and left-handedness are engendered by the interplay between consciousness and certain liasion areas in the brain. When the subject's will dictates a movement, consciousness exercises a strong influence on the impulse pattern of the modules. In genetically conditioned left-handedness it is not primarily motoric, but rather neuronal factors which are responsible for the reversal in the direction of writing and mirror-image script. Left-handed children who produce mirror-handwriting can be retrained to write normally by exercises and by assimilating conscious experience.

Aged↗
PubMed1988

Null hypothesis disrespect in neuropsychology: dangers of alpha and beta errors.

To understand why there are so many inconsistencies and contradictory findings among hemispheric-asymmetry studies, data were analyzed from a large study of 300 left-handers. These data included information on familial sinistrality (FS), handwriting posture (HPO), a measure of cognitive performance, and five measures of hemispheric specialization. Using computer simulation methodology, 40 independent samples of 36 to 65 subjects each were drawn randomly with replacement. The sample data were analyzed and the results compared to those of the parent "population." Often, the samples poorly reflected the parent "population," and some procedures substantially inflated error rates. These procedures are discussed and specific guidelines suggested. These results are also discussed in the broader context of the necessity for investigators in neuropsychology to differentiate between the statistical and clinical significance of research findings; and to develop a more positive attitude toward the design, execution, and publication of replication studies.

Adult↗
PubMed2004

Influence of motor disorders on the visual perception of human movements in a case of peripheral dysgraphia.

We report the case of a 71 year-old female patient (DC) with a left parietal lesion resulting in a peripheral dysgraphia essentially characterized by difficulties in letter sequences writing. The aim of our experiments was to analyze the influence of motor difficulties on the visual perception of both writing and reaching movements. Results showed a strong link between motor and perceptual performance. For reaching movements, performances in both production and perception tasks conform to the motor principles identified in healthy subjects (Fitts' law and motor anticipation). By contrast, for handwriting movements, DC's productions do not follow the motor principles usually observed in normal subjects (isochrony principle, motor anticipation) and in perception the same results were observed. The motor references used by DC in the visual perception of writing movement were not the laws of movement but rather her own way of writing. Taken together these data strongly suggest that motor competences is involved in the visual perception of human movements. They are discussed in the general framework of the simulation theory.

Aged↗
PubMed1995

Primary writing tremor.

Primary writing tremor (PWT) is considered to be a type of task-specific tremor in which tremor predominantly occurs and interferes with handwriting. We describe the clinical and neurophysiological features of 21 patients (20 male and one female) with PWT. Mean age at tremor onset was 50.1 years. A family history of PWT was obtained from seven patients. Ten patients obtained benefit from drug treatment (mainly propranalol or primidone) and seven responded to alcohol. The writing speeds of the patients (mean +/- SEM: 73.1 +/- 6.6 letters per minute) when using their preferred hand were significantly reduced (Student's t test: P < 0.001) compared with those of healthy control subjects (mean +/- SEM: 127.7 +/- 6.4). Surface polymyography performed during writing showed 4.1-7.3 Hz rhythmic activity predominantly in the intrinsic hand and forearm muscles. Alternating, extensor activation alone, skipping from alternating to extensor activation, and co-contracting EMG patterns were recorded from the flexor and extensor muscles of the forearm. There was no evidence for excessive 'overflow' of this rhythmic EMG activity, as similar activity was detected in comparable muscle groups of healthy control subjects. Accelerometry confirmed that the frequency of PWT ranged from 4.1-7.3 Hz (median 5.5 Hz) and that normal subjects wrote with a 4.0-7.7 Hz oscillation (median 4.6 Hz). Forearm reciprocal inhibition was normal in PWT (n = 13), and thus patients with PWT can be distinguished from those with writer's cramp in whom decreased presynaptic inhibition has been found. Patients were sub-classified as having either type A (n = 11) or B (n = 10) PWT depending on whether tremor appeared during writing (type A: task induced tremor) or whilst writing and adopting the hand position used in writing (type B: positionally sensitive tremor). However, the only differences between these two groups were that a co-contracting EMG pattern and tremor induced by tendon taps to the volar aspect of the wrist were present in type B but not type A cases.

Adult↗
PubMed2001

Dynamic organization of the somatosensory cortex induced by motor activity.

Intensive and long-lasting experience of altered sensory input induces permanent changes in the functional organization of the somatosensory cortex. In addition, an increasing body of evidence suggests the existence of dynamic, short-term and task-dependent adaptation of representational maps within somatosensory cortex. It is hypothesized that somatosensory maps can, not only, be acquired within a short period of time, but might also be set up during periods of training related to specific tasks and subsequently activated dynamically upon performance of that particular task. In order to test this hypothesis we studied the functional organization of somatosensory cortex for a heavily overlearned and frequently performed task for which no new acquisition of a sensory map had to be assumed. To this end, the functional organization of somatosensory cortex for handwriting was compared with the organization during rest in healthy humans. Functional organization of the somatosensory cortex was assessed using non-invasive, neuromagnetic source imaging based on tactile stimulation of the thumb (D1) and little finger (D5) during writing and rest. In different blocks, subjects wrote with their right, dominant and their left hand, respectively. During writing, D1 and D5 of the writing hand were stimulated. To test the reliability of our results all measurements were repeated after 1 week. It was found that amplitudes of somatosensory evoked magnetic fields with latencies of 45 ms were reduced during writing compared with rest. This finding is in accordance with the sensorimotor gating effect. Using source localization we could show that cortical representations of D1 and D5 are more distant during writing with either hand compared with rest. Our data suggest that somatosensory cortical maps undergo rapid modulation depending on task-specific involvement of sensory processing in daily-life overlearned movements. As it is unlikely that a new sensory map is always acquired when a frequently used task such as writing is performed, we suggest that somatosensory cortex switches between different, concurrently pre-existing maps depending on actual requirements. Task-dependent activation of pre-existing maps might be a powerful mechanism to optimize stimulus processing.

Adult↗
PubMed1976

Electromyographic feedback to improve ankle dorsiflexion, wrist extension, and hand grasp.

Electromyographic feedback was used to train a patient with hemiplegia in the functional use of the muscles of his right upper and lower limbs. The patient trained with the therapist over a period of two and one-half months, engaging in exercises for ankle dorsiflexion, wrist extension, and hand grasp twice a week for one to one and one-half hours. Feedback was recorded with surface electrodes placed over the extensor surface of the forearm and the tibialis anterior; the electromyographic activity was displayed on a meter. After training, muscle control proved functional for walking, handwriting, and daily self-care activities.

Ankle↗
PubMed2005

Noisy text categorization.

This work presents categorization experiments performed over noisy texts. By noisy, we mean any text obtained through an extraction process (affected by errors) from media other than digital texts (e.g., transcriptions of speech recordings extracted with a recognition system). The performance of a categorization system over the clean and noisy (Word Error Rate between approximately 10 and approximately 50 percent) versions of the same documents is compared. The noisy texts are obtained through handwriting recognition and simulation of optical character recognition. The results show that the performance loss is acceptable for Recall values up to 60-70 percent depending on the noise sources. New measures of the extraction process performance, allowing a better explanation of the categorization results, are proposed.

Algorithms↗
PubMed2005

A parallel-line detection algorithm based on HMM decoding.

The detection of groups of parallel lines is important in applications such as form processing and text (handwriting) extraction from rule lined paper. These tasks can be very challenging in degraded documents where the lines are severely broken. In this paper, we propose a novel model-based method which incorporates high-level context to detect these lines. After preprocessing (such as skew correction and text filtering), we use trained Hidden Markov Models (HMM) to locate the optimal positions of all lines simultaneously on the horizontal or vertical projection profiles, based on the Viterbi decoding. The algorithm is trainable so it can be easily adapted to different application scenarios. The experiments conducted on known form processing and rule line detection show our method is robust, and achieves better results than other widely used line detection methods.

Algorithms↗
PubMed1981

Serum phenytoin concentration and clinical response in patients with epilepsy.

1 Patients with poorly controlled epilepsy were cautiously transferred from multiple drug therapy to treatment with phenytoin sodium alone. One patient suffered more severe seizures and the initial treatment was restarted. The remainder showed no deterioration. 2 The daily dose of phenytoin was then increased by a small increment at intervals of 2 or more months. The serum phenytoin concentration (total and free) was measured regularly and response was assessed by records of seizure frequency and tests of speech, handwriting, short-term memory and coordination. 3 Patients (n = 11) with partial seizures showed no consistent improvement with increased phenytoin concentration within the range 15 mg/l (60 mumol/l) to the individual threshold for intoxication, greater than or equal to 35 mg/l (140 mumol/l). Patients (n = 4) with generalized seizures however were consistently improved at higher concentrations. 4 Tolerance to phenytoin varied, the threshold for symptomatic intoxication ranging from 35-60 mg/l (140-240 mumol/l) total and 2.7-5.2 mg/l (10.8-20.8 mumol/l) free. Ataxia was the commonest symptom and in some cases this was manifest by worsening of performance on the test of coordination (pursuit rotor). Even at lower phenytoin concentrations the patients performed less well on this test than control subjects. Other tests of performance showed no evidence of impairment at higher phenytoin concentrations. 5 The same daily dose of phenytoin tended to give higher serum drug concentrations after intoxication than before.

Adolescent↗
PubMed1983

Qualitative changes in dynamic tripod grip between seven and 14 years of age.

The dynamic tripod grip during handwriting was examined among seven- to 14-year-old children. Four components were measured: (a) degree of index-finger flexion; (b) degree of forearm pronation/supination; (c) number of fingers used on the pencil shaft; and (d) thumb and forefinger opposition. Developmental trends were identified for measures (a) and (b), suggesting refinement of the dynamic tripod grip with age.

Adolescent↗