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PubMed1994

Perseverative dysgraphia: a selective disorder in writing double letters.

Models of writing processes postulate that abstract graphemic representations contain information about letter doubling independent of letter identity. We describe a patient, R.T., who made perseverative errors only in handwriting geminate letters, [e.g.: "CORTECCIA" (cortex)-->"CORTECCCIA"]. Perseveration was specific to orthography. To explain R.T.'s errors, we argue that after the selection of the correct graphic motor programs, the geminate feature induced a perseverative graphic behaviour. This form of dysgraphia supports the notion that graphemic representations contain specific information about letter doubling.

Agraphia↗
PubMed1990

Quantification of tremor with a digitizing tablet.

Handwriting and drawing are commonly employed in the clinical assessment of tremor. These tasks have been quantified heretofore by subjective rating schemes, which are incapable of providing precise measures of the amplitude and frequency of tremor. A commercially-available digitizing tablet and personal computer can be interfaced so as to reliably record any pathologic tremor that is induced by writing or drawing. Numerical differentiation and spectral analysis can be used to conveniently quantify the amplitude and frequency of tremor. However, digitizing tablets lack sufficient sensitivity to measure physiologic tremor.

Handwriting↗
PubMed1982

Trajectory determines movement dynamics.

The relation between figural and kimematic aspects of movement was studied in handwriting and drawing. It was found that, throughout the movement, the tangential velocity. V is proportional to the radius of curvature r of the trajectory: V= kr, or, equivalently, that the angular velocity is constant: dalpha(t)/dt = K. However, the constant k generally takes several distinct values during the movement, the changes being abrupt. These changes suggest a clear segmentation of the movement into units of action which overlap but do not coincide with the figural units as defined by the discontinuities of the movement (cuspids, points of inflection). This organisational principle holds even when movements are mechanically constrained or are executed under strict visuo-motor guidance. Moreover, the segmentation of a given trajectory is invariant with respect to the total duration of the movement. A tentative interpretation of the principle is proposed which results from the assumption that the actual movement is produced as a continuous approximation to an intended movement, and that the well known relationship between movement speed and extent in rectilinear trajectories (Fitts' law) also applies to such continuous approximation.

Biomechanical Phenomena↗
PubMedDate not supplied

The psychodynamics of the presidential assassin and an examination of the theme/graphic variables of his threatening correspondence.

Many document examiners recognize the importance of an individuals 'state of mind' and its effect on handwriting but historically have steered clear of working closely with psychiatrists, linguists, or psychologists in understanding the interaction of nervous impulses and motor responses on the final handwritten product. In an attempt to better understand and evaluate those fears and motivational influences which should exist within the writings of the mentally disturbed in his threatening correspondence, research was conducted to ascertain whether there are consistently reappearing delusional value systems/hostilities which characterize the writings of the paranoid schizophrenic assassin subject. The results of this preliminary investigation revealed substantial evidence to suggest that most U.S. assassins have been psychotic at the time they attempted to kill their victims and that the most frequently rendered diagnosis was 'paranoid schizophrenia'. It was also reported that many of the assassin subjects had either sent threatening correspondence to their victims prior to the assassination attempt or had recanted the justifiable nature of their 'heroic deed' in letters or personal diaries which were recovered shortly after the assault. It is also apparent that over the years, the Secret Service has investigated a number of threatening letter writers who were later diagnosed as suffering from some sort of schizophrenic reaction and characterized as 'potentially dangerous' to the President. Most of the insight to be gained from an examination of what researchers have discovered regarding those unique graphic traits found in 'schizophrenic writing' can be gleaned from those published papers contributed by graphologists/document examiners and that offered by the behavioral science/medical community in the form of psychiatrists, neurologists, psychologists and psycholinguists. The results of bonafide scientific and forensic literature research strongly suggest that the threatening writings of the paranoid schizophrenic and/or potential assassin will probably reveal distinctive graphic 'abnormalities' which are found to act in combination with certain combinations of reoccurring delusional value systems, frustrations, and hostilities.

Adolescent↗
PubMed2004

Identification of authorship using lateral palm print--a new concept.

Identification of individual by signature examination could be improved by the lateral palm print examination. By the use of new technique discussed by the author in this paper, the forensic expert can find out very useful information about the writer of writings even without going into the depth of questioned document/signature examination and without the formal or informal handwriting exemplars. The document expert with little more knowledge of the palm print can identify whether the signature is done by hand/leg/anything else, whether the author is right handed or left handed, the approximate age of the author, whether the signature is genuine or forged. Such information of author would be very much useful in elimination of the list of suspects of anonymous letters. In order to fix the authorship, standard and disputed lateral palm prints can be examined either with photographic superimposition technique or with the statistical study of the outline of the lateral palm print or with the standard method as implied in fingerprint examination. The evidential value of such lateral palm print can be placed at par with the finger prints in the court of law and could be placed right on the top of all other scientific evidences.

Adolescent↗
PubMed2003

Developmental coordination impairments in adulthood.

The aim of this study was to extend the understanding of Developmental Coordination Disorder (DCD) into adulthood. We recruited 19 adults aged between 18 and 65 who had received diagnoses of DCD or dyspraxia or who self-reported as having motor impairments consistent with a history of DCD, together with age- and gender-matched controls. Participants were given tests of manual dexterity, handwriting, construction, obstacle avoidance, dynamic balance, static balance, dual task performance, ball skills, reaction time, movement time and sequencing. As a group, adults with DCD performed more poorly than controls across all tasks. Slowness and variability of movement was a pervasive feature of their performance and many individuals had considerable problems with sequencing and with dual task performance. A discriminant function analysis conducted using six performance measures correctly classified participants as car drivers or non-drivers. Adults do retain motor difficulties and these can exclude them from important activities of daily living.

Adolescent↗
PubMed2006

Advances in graphonomics: studies on fine motor control, its development and disorders.

During the past 20 years graphonomic research has become a major contributor to the understanding of human movement science. Graphonomic research investigates the relationship between the planning and generation of fine motor tasks, in particular, handwriting and drawing. Scientists in this field are at the forefront of using new paradigms to investigate human movement. The 16 articles in this special issue of Human Movement Science show that the field of graphonomics makes an important contribution to the understanding of fine motor control, motor development, and movement disorders. Topics discussed include writer's cramp, multiple sclerosis, Parkinson's disease, schizophrenia, drug-induced parkinsonism, dopamine depletion, dysgraphia, motor development, developmental coordination disorder, caffeine, alertness, arousal, sleep deprivation, visual feedback transformation and suppression, eye-hand coordination, pen grip, pen pressure, movement fluency, bimanual interference, dominant versus non-dominant hand, tracing, freehand drawing, spiral drawing, reading, typewriting, and automatic segmentation.

Handwriting↗
PubMed2006

Testosterone improves motor function in Parkinson's disease.

In Parkinson's disease (PD) there is increasing evidence that sex steroids such as estradiol and testosterone modulate, either as a positive or negative effect, the clinical expression of a variety of movement disorders involving the nigrostriatum. Testosterone deficiency is common in the older male population and has an increased prevalence in parkinsonian patients. Testosterone therapy has been shown to improve the non-motor symptoms of PD but evidence for a direct effect of testosterone on motor symptoms is lacking. This case report demonstrates a significant improvement in the resting tremor and fine motor control after testosterone administration in a parkinsonian patient with testosterone deficiency (1 nmol/L). Motor symptom change was shown by serial assessment of the patient's handwriting, self-reporting using the Unified Parkinson's Disease Rating Scale and measurement of resting tremor amplitude by an accelerometer. The improvement in motor symptoms correlated with serum testosterone levels. The use of testosterone replacement in those men with decreased levels may improve the motor symptoms as well as increase general wellbeing.

Aged, 80 and over↗
PubMed2006

Prism adaptation improves spatial dysgraphia following right brain damage.

Visuo-manual adaptation to prisms produces a long-lasting improvement of visuo-spatial neglect. Improvement is also observed in tasks that do not involve visuo-manual component and that can all be consider to rely on a rightward (ipsilesional) orienting bias. Here, we report positive effects of prism adaptation on spatial dysgraphia, in a neglect patient following right brain damage. A long-lasting improvement concerned the right-page preference reflecting the ipsilesional bias but also the sloping lines and the broken lines reflecting visuo-constructive disorders in handwriting. Moreover, a transient improvement was also evidenced for the graphic errors. These results reinforce the idea that the process of prism adaptation may activate brain functions related to multisensory integration and higher spatial representations and show a generalization at a functional level. Prism adaptation therefore appears as useful tool in the theoretical attempt to identify the underlying 'core' mechanisms of the neglect syndrome.

Adaptation, Physiological↗
PubMed2004

The role of cutaneous sensation in the motor function of the hand.

We studied the effect of abolishing cutaneous sensation (by infiltrating local anaesthetic around the median nerve at the wrist) on the ability of 10 healthy volunteers (a) to maintain a submaximal isometric pinch-grip force for 30 s without visual feedback, and (b) to perform a fine finger-manipulation 'handwriting' task. Blocking cutaneous sensation had no effect on ability to maintain pinch force, suggesting that muscle afferents have the major role in force-control feedback. However, a near-linear fall in force, present with or without block (mean slope=-1.3+/-0.2% s(-1)), which cannot be attributed to motor fatigue, reveals a shortcoming of the afferent feedback system. Blocking cutaneous sensation did impair ability to perform the more demanding writing task, as judged by an 18+/-6% increase in the length of the path between target points, a 22+/-9% increase in the duration of the movement and a 63+/-24% in 'normalised averaged rectified jerk', an averaged time-derivative of acceleration (all significantly nonzero, P < 0.04). These experiments demonstrate the relative importance of muscular and cutaneous afferent feedback on two aspects of hand performance, and provide a way to quantify the deficit resulting from the lack of cutaneous sensation.

Electromyography↗
PubMed2006

Responsiveness of impairments and disabilities in Parkinson's disease.

The objective of this study is to evaluate the responsiveness of items of the Activities of Daily Living (ADL) and Motor section of the Unified Parkinson's Disease Rating Scale (UPDRS) in patients with Parkinson's Disease (PD). A standardized Response Mean (SRM) per item was calculated using data of four trials (n=376) that randomised patients with early PD to dopamine agonist (DA) monotherapy or placebo. In the ADL section, the SRMs ranged from -0.04 (no effect) to -0.50 (moderate effect). Hand functions were the most responsive ADL items with 'handwriting' showing the largest response. Self-assessed symptoms were the least responsive. In the Motor section, SRMs ranged from -0.09 to -0.60 with bradykinesia items showing the largest response, especially the item 'finger taps'. The tremor items showed the smallest response, however, rest tremor arms was much more responsive than rest tremor of the head and legs or postural tremor. SRMs in the placebo group ranged from 0.08 to -0.21 in the ADL section and from 0.03 to -0.35 in the Motor section. ADL and motor items have comparable and mostly small effect sizes. The most responsive items are in the ADL section hand functions and in the Motor section bradykinesia items. A more responsive ADL section would omit the self-assessed symptoms and the Motor section would retain only rest tremor arms of the tremor items.

Activities of Daily Living↗
PubMed2006

Writer's cramp: restoration of striatal D2-binding after successful biofeedback-based sensorimotor training.

INTRODUCTION: Previous studies of writer's cramp have detected cerebral sensorimotor abnormalities in this disorder and, more specifically, a reduced striatal D2-binding as assessed by [(123)I]IBZM SPECT. However, empirical data were lacking about the influence of effective biofeedback-based sensorimotor training on D2 receptor binding. METHODS: To determine whether there is a restoration of D2-binding after successful sensorimotor treatment, pre- and posttreatment SPECTs were compared in five patients with writer's cramp and correlated with improvement in handwriting. RESULTS: After treatment, the clinical and electromyographic picture appeared substantially improved connected with a significant increase in D2-binding to nearly normal levels similar to normative data in age/sex-matched healthy subjects. CONCLUSION: The current study supported the view that writer's cramp results from a plastic adaptation of a rectifiable nigrostriatal dopaminergic system and that effective sensorimotor training leads to increased efficacy of striatal dopaminergic transmission.

Adult↗
PubMed1998

Elderly subjects are impaired in spatial coordination in fine motor control.

Elderly and young control subjects performed back-and-forth handwriting movements in various orientations, therefore varying the coordination demands. Elderly subjects showed higher normalized jerk and straightness scores than the young subjects. However, jerk scores were independent of the coordination demands in either group. In contrast, the straightness scores were highly dependent on stroke orientation for the elderly, but they remained constant across orientations for the young controls. Moreover, group differences in stroke size and stroke duration were not significant, and orientation effects were unrelated. It is suggested that the orientation-dependent straightness scores in the elderly may result from unequal timing or improper scaling of muscle forces. These data suggest that aging deteriorates the spatial coordination of finger and wrist movements, but not accelerative force control.

Adult↗
PubMed1998

The 2/3 power law: when and why?

This paper presents the origin of some reported observations, which links the kinematics of handwriting with a movement trajectory, best known as the 2/3 power law. Using computer simulations, it is shown that the vectorial delta-lognormal model recently proposed to describe 2D movements can successfully simulate these phenomena. Although the power law has been found to be a good predictor in many experimental conditions, a few experiments have shown that the law does not apply to all graphic movements. Using the vectorial delta-lognormal model, the conditions under which a 2/3 power relationship can be observed are presented and the reasons why it does not seem to be verified for more general handwritten patterns are highlighted.

Biomechanical Phenomena↗
PubMed1978

Differential finger movements and hand preference.

In an attempt to replicate a study by Kimura and Vanderwolf (1970), normal left-handed and right-handed subjects were asked to flex a single finger or pairs of fingers at the middle joint. Both hands were found to be equally proficient at this task and no differences between right- and left-handers were found. When left-handers were divided into inverters and non-inverters according to hand-writing posture, a left hand superiority was a found for the right-handed and the left-inverted subjects, while the left-non-inverters showed a right hand superiority. Paired finger flexion was found to be more useful in discriminating between the handedness groups. These findings support the idea that the neural mechanism for hand preference is not based on an asymmetry in the control of fine movement. They also support the theory that two separate groups of left-handers exist, and the they can be differentiated by their handwriting postures.

Adolescent↗
PubMed1982

Left visual field superiority in a letter-naming task for both left- and right-handers.

Subjects identified on the basis of sex, handedness, and handwriting posture performed a letter-naming task. Single letters were shown briefly in the left or right visual field and the subject was required to name the letter as quickly as possible. Both left- and right-handers had shorter response latencies when the stimulus was presented in the left visual field. Response latency decreased across trials, however, the decrement was largest to right visual field stimuli. In addition, males produced significantly faster reaction than did females.

Discrimination Learning↗
PubMed2002

When writing 0 (zero) is easier than writing O (o): a neuropsychological case study of agraphia.

Though a few case studies reported a dissociation between intact writing of Arabic and impaired writing of alphabetical script, a detailed experimental analysis of such a dissociation is still lacking. We report a follow-up study of a patient with a parieto-occipital lesion who is affected by severe peripheral agraphia for letters, but not for Arabic digits. While letters in writing to dictation are frequently illegible, distorted, or consist in meaningless strokes, Arabic digits are well-formed and fluently produced. In a series of tasks, including copying of letters with tachistoscopic presentation and handwriting on a digitizing tablet, several processing levels are assessed in order to localize JS' functional writing impairment and to determine different processing routes for letters and for numbers. Overall, the results of the experimental investigation suggest a notation specific deficit in the activation of graphomotor patterns for letters, but not for digits. The study thus adds evidence to the so far reported dissociations between Arabic and alphabetical scripts.

Aged↗