W. Hulstijn

Programming in handwriting: Reaction time and movement time as a function of sequence length

Abstract In order to test whether the model developed by Sternberg et al. (1978b) on the programming of speech and typewriting movements also holds for handwriting, three experiments were conducted in which four trained subjects each wrote a few letters in a simple reaction paradigm. In experiment 1, one to four letters had to be written in each of three conditions: normal, large and with the addition of extra strokes. In experiment 2, digits were used, written either in the normal way or according to a novel movement pattern. In experiment 3, the letters formed words or nonsense strings. In all three experiments a linear increase of reaction time with sequence length was found, the slope of which rapidly decreased with practice, however. The time to write a letter did not increase with sequence length. The variables of experiments 2 and 3 had large effects on movement times but no effect on reaction times. A parallel processing model is suggested in which only the first unit is completely preprogrammed before the go signal and in which succeeding elements are programmed during the execution of preceding ones.

Motor-skill learning in Alzheimer's disease: a review with an eye to the clinical practice

Since elderly people suffering from dementia want to go on living independently for as long as possible, they need to be able to maintain familiar and learn new practical skills. Although explicit or declarative learning methods are mostly used to train new skills, it is hypothesized that implicit or procedural techniques may be more effective in this population. The present review discusses 23 experimental studies on implicit motor-skill learning in patients with Alzheimer’s disease (AD). All studies found intact implicit motor-learning capacities. Subsequently, it is elaborated how these intact learning abilities can be exploited in the patients’ rehabilitation with respect to the variables ‘practice’ and ‘feedback.’ Recommendations for future research are provided, and it is concluded that if training programs are adjusted to specific needs and abilities, older people with AD are well able to (re)learn practical motor skills, which may enhance their autonomy.

Speech motor dynamics in stuttering

ion not obvious from the actions of the individual articula-

The coordination of reaching and grasping in spastic hemiparesis

Abstract The kinematics and intrinsic dynamics of reaching and grasping movements in six subjects with spastic hemiparesis were studied. Movements were performed with both hands together as well as with each hand in isolation, and two target widths were used. As expected, large manual asymmetries existed in unimanual task performance. These asymmetries were more pronounced for grasping than for reaching, which was a consequence of the fact that in grasping the impaired hand stayed longer at zero velocity before lifting the object. This implies difficulties coordinating the more distal movement component (hand and fingers). In addition, the impaired hand attained the movement goal with a (1) decreased angular range of motion of the joints and (2) an increased trunk involvement. With respect to the intrinsic dynamics, intra- and inter-limb coupling was studied by evaluating cross-correlations of position–time functions joint pairs. In effector space the displacement of the wrist and ipsilateral shoulder were correlated, and in joint-angle space the elbow extension–shoulder flexion angle pair and the elbow extension–shoulder elevation angle pair were analysed. It was found that despite tight couplings between the different pairs, the couping strengths for the impaired limb were consistently lower. This was caused by fragmentation of the movement, mainly due to a large shoulder involvement at the start of the movement concurrent with little or no elbow extension. It is concluded that fragmentation of the movement, operationalised by the value of the cross-correlation between joint pairs is an essential variable by which the level of recovery of function can be captured. It was further shown that the unimpaired hand `mimicked the impaired hand on a number of movement characteristics under bimanual responding. The impaired hand did not change its style of movement organisation among uni- and bimanual movement responding. It is argued that the apparent stability of the impaired hand can only be sustained at the cost of a decreased flexibility. Finally, inter-limb coupling, assessed by means of cross-correlations of the tangential velocity profiles of both hands, was shown to be high during the course of movement.

Bimanual movement coordination in spastic hemiparesis

A Fitts task was used to examine whether the large movement asymmetry in subjects with spastic hemiparesis can be reduced or eliminated when both limbs are required to perform functionally equivalent tasks. Furthermore, it was determined whether any such benefit was expressed as mutual accommodation, or whether one hand “slaves” the other. Finally, the effect of increased task constraints on the magnitude of the asymmetry was considered. A group of ten students served as controls. Subjects had to grasp small balls and subsequently place them into holes. As expected, large total response time differences were present between the hands of the hemiparetic subjects in the unimanual conditions. However, 92% of the difference between hands was eliminated in the bimanual conditions. It is argued that the observed temporal invariance, or time locking, between hands in the bimanual conditions might be facilitated through the activity of bilateral controls exerted from each hemisphere and neural crosstalk at different levels of the central nervous system. Still, an asymmetric tendency remained in the bimanual conditions: a tendency existed for the impaired hand to reach the “target” later in time compared with the dominant hand. This tendency was enlarged as the asymmetry in task demands for the two limbs increased.

Handwriting Development in Grade 2 and Grade 3 Primary School Children with Normal, At Risk, or Dysgraphic Characteristics.

The wide variation in prevalence of dysgraphic handwriting (5-33%) is of clinical importance, because poor handwriting has been identified as one of the most common reasons for referring school-age children to occupational therapy or physiotherapy, and is included as an criterion for the diagnosis of Developmental Coordination Disorder. This study aimed to map the development and improvement in handwriting during the early grades to differentiate between temporary and consistent dysgraphic handwriting. In this longitudinal and cross-sectional study, children in grade 2 (age 7-8 years, n=169) and grade 3 (8-9 years, n=70) took handwriting (Concise Assessment Method for Childrens Handwriting; acronym BHK) and visuomotor integration (BeeryVMI) screening tests twice within one school year. Dysgraphia decreased strongly from 37% to 17% in grade 2 and diminished further to a low and stable rate of 6% in grade 3. Stability in handwriting quality only occurred in the children whose scores were within the normal range. The at risk and dysgraphic children continued to show significant and substantial improvement during grades 2 and 3. BeeryVMI was inappropriate as a screening instrument for handwriting problems. It was concluded that handwriting must be consistently dysgraphic before making any decisions about a diagnosis of dysgraphia or referral for therapy.

Stuttering and anxiety: The difference between stutterers and nonstutterers in verbal apprehension and physiologic arousal during the anticipation of speech and non-speech tasks

Abstract To test if stressful anticipation of speech situations is a factor in eliciting stuttering behavior, the difference between 24 stutterers and 24 nonstutterers in verbal apprehension and physiologic activity was studied before and during speech tasks (reading and conversation), and nonspeech tasks (motor and intelligence task). Results indicate that the difference between stutterers and nonstutterers mainly were restricted to anxiety ratings assessed after each task. Heart rate, vasomotor responses, and electrodermal activity recorded before and during speech tasks were higher compared with the physiologic activity before and during nonspeech tasks but, unexpectedly, this was also the case for nonstutterers. It is concluded that stuttering is not elicited by anxiety.

Action monitoring and depressive symptom reduction in major depressive disorder.

INTRODUCTIONnAction monitoring has been reported to be disturbed in Major Depressive Disorder (MDD). Well-known markers for this action monitoring process are the error negativity/error-related negativity (Ne/ERN) and error positivity (Pe), both event-related potentials (ERP) generated in the anterior cingulate cortex. This study aims to explore the impact of symptom severity reduction on the Ne/ERN and Pe in MDD.nnnMETHODSnBehavioural and ERP measurements were obtained in 15 MDD patients during performance on a speeded flankers task during the early stages of a depressive episode and compared with those recorded after 7 weeks of treatment. The same schedule was used in 15 healthy controls.nnnRESULTSnWhereas overall Ne/ERN and Pe peak amplitudes did not improve from sessions 1 to 2 in the patients, positive correlations emerged between between-session changes in symptom severity and Ne/ERN amplitudes. No such correlations were observed for the Pe. ERP amplitudes in the controls also remained unchanged between both sessions. Significant group differences were observed between MDD patients and controls for the Pe, but not for the Ne/ERN.nnnCONCLUSIONSnWhereas a clear association was observed between the level of symptom reduction and the level of improvement in Ne/ERN amplitudes in a MDD sample, no overall Ne/ERN enhancements were observed during symptom remission. Subsequent research is needed to further investigate the possible impact of depressive symptom reduction on the action monitoring in MDD. Several factors that might explain the absence of Ne/ERN group differences between patients and healthy controls in the current sample will also be discussed.

Recent Developments in Speech Motor Research into Stuttering

This paper discusses recent speech motor research into stuttering within the framework of a speech production model. There seems to be no support for the claim that stutterers differ from nonstutterers in assembling motor plans for speech. However, physiological data suggest that stutterers may at least have different ways of initiating and controlling speech movements. It is hypothesized that stuttering may be the result of a deficiency in speech motor skill. Furthermore, objections to the use of stuttering frequency as a severity index are formulated and future developments in the assessment of speech motor behavior in stuttering are described.

Modulation of memory and visuospatial processes by biperiden and rivastigmine in elderly healthy subjects

RationaleThe central cholinergic system is implicated in cognitive functioning. The dysfunction of this system is expressed in many diseases like Alzheimers disease, dementia of Lewy body, Parkinsons disease and vascular dementia. In recent animal studies, it was found that selective cholinergic modulation affects visuospatial processes even more than memory function.ObjectiveIn the current study, we tried to replicate those findings. In order to investigate the acute effects of cholinergic drugs on memory and visuospatial functions, a selective anticholinergic drug, biperiden, was compared to a selective acetylcholinesterase-inhibiting drug, rivastigmine, in healthy elderly subjects.MethodsA double-blind, placebo-controlled, randomised, cross-over study was performed in 16 healthy, elderly volunteers (eight men, eight women; mean age 66.1, SD 4.46 years). All subjects received biperiden (2xa0mg), rivastigmine (3xa0mg) and placebo with an interval of 7 days between them. Testing took place 1xa0h after drug intake (which was around Tmax for both drugs). Subjects were presented with tests for episodic memory (wordlist and picture memory), working memory tasks (N-back, symbol recall) and motor learning (maze task, pursuit rotor). Visuospatial abilities were assessed by tests with high visual scanning components (tangled lines and Symbol Digit Substitution Test).ResultsEpisodic memory was impaired by biperiden. Rivastigmine impaired recognition parts of the episodic memory performance. Working memory was non-significantly impaired by biperiden and not affected by rivastigmine. Motor learning as well as visuospatial processes were impaired by biperiden and improved by rivastigmine.ConclusionsThese results implicate acetylcholine as a modulator not only of memory but also of visuospatial abilities.