Biomedical subjects

C A Hauert

Publications and source records attributed to C A Hauert.

8 recordsLinked to original sources

PubMed2001

Alpha band power changes in unimanual and bimanual sequential movements, and during motor transitions.

OBJECTIVE: To investigate the cortical activation during execution of unimanual and bimanual synchronous and asynchronous finger sequences, as well as during transitions between those sequences. METHODS: Task-related power (TRPow) analysis of multichannel surface EEG was used to examine the regional oscillatory brain activity in the lower (7.8-9.8 Hz) and upper (10.8-11.8 Hz) alpha band. Unimanual to bimanual, bimanual to unimanual, and unimanual to unimanual transitions, prompted by visual cues, were studied in 10 right handed subjects. RESULTS: (1) Execution of unimanual and bimanual movements was accompanied by a bilateral activation over the central regions. (2) The 7.8-9.8 Hz TRPow decrease was more prominent for left and bimanual movements, suggesting sensitivity of the lower alpha band to task difficulty. (3) No difference in alpha oscillatory activity was found between bimanual synchronous and asynchronous sequences. (4) Transitions between motor sequences were invariably accompanied by a mesioparietal TRPow decrease in the lower alpha band. (5) This mesioparietal activation was contingent to the change of motor program, and could not be accounted for by the change of visual cue, or related attentional processes. CONCLUSION: The 7.8-9.8 Hz mesioparietal activation most likely reflects a posterior parietal motor command initiating transition between motor programs.

Adult↗

PubMed2000

Visually induced activity in human frontal motor areas during simple visuomotor performance.

Visuomotor tasks elicit neuronal activity in primate motor areas at relatively short latencies. Although this early activity embodies features of visual responses (short latency, stimulus-dependency), its sensory nature has been questioned. We investigated neural correlates of visuomotor performance in human motor areas using scalp and intracranial event-related potential measures. A simple visuomanual reaction-time task evoked early potentials at 133-145 ms post-stimulus which occurred much earlier than the motor potentials of the same region. The amplitude of the early potentials covaried with stimulus location and was independent of parameters of the motor response. Because of their timing, stimulus-dependency and characteristics of our behavioral task, the early potentials are suggested to reflect neuronal responses of sensory nature rather than processing related to pure motor aspects of the task.

Adult↗

PubMed2000

Sequential pointing in children and adults.

The development of visuomotor control in sequential pointing was investigated in 6- to 10-year-old children and in adults. In 3 experiments we manipulated task difficulty by changing the number, the size, and the spacing of the targets in the sequences. In Experiment 4, only 1 movement was required; we varied independently the distance between targets and the distance of the starting point from the participant's body. Children's temporal and spatial parameters of the motor sequences showed large age-dependent trends, but did not reach the adult values. Comparison of performance across levels of difficulty and ages suggests that motor development is not a uniform fine-tuning of stable strategies. Instead, we argue that each stage of development is best characterized by the set of strategic components potentially available at that stage, and by the (age-dependent) rules for the selection of components in a given context.

Adult↗

PubMed1999

Evidence for interhemispheric motor-level transfer in a simple reaction time task: an EEG study.

Simple visuomanual reaction time tasks require interhemispheric communication when stimuli are presented in the hemifield opposite the responding hand. Although confirmed in many studies, it is still a matter of debate when, at what functional level and at what site this interhemispheric transfer takes place. To address these questions, we recorded event-related potentials (ERPs) in 12 healthy subjects performing such a task and analyzed the data using techniques based on topographic ERP map characteristics. A method which has proved useful for associating ERP map configurations of different time periods with functional states of the brain was supplemented by a source localization procedure. The results suggest that transfer occurs late in time, on a functional motor level and at frontal sites, at least for left-to-right interhemispheric direction of transfer.

Adult↗

PubMed1996

Visuo-manual aiming movements in 6- to 10-year-Old children: evidence for an asymmetric and asynchronous development of information processes.

Sixty children from 6 to 10 years old participated in an open-loop visuo-manual aiming task (Experiment 1). They were asked to point as fast and accurately as possible toward lateralized visual targets. Responses were wrist flexion-extension movements. Results showed non-monotonic changes with age of constant error, reaction time, and movement time. Constant error for targets presented in the right visual field increased between 6 and 8 years and decreased afterward. Reaction time and movement time decreased with age except at 8 years where they tended to increase. The same subjects participated in two control tasks. One task was designed to test the spatial localization of the lateralized visual targets (Experiment 2). Results showed that subjects localized very accurately the targets at all ages. The second control task was designed to test simple reaction time to the same visual stimuli used in the previous tasks (Experiment 3). Results indicate that reaction time decreased linearly with age when no spatial processing is required for the production of the response. The results of the three experiments showed different developmental functions according to the processes involved in each task. Moreover, they suggest that the conversion from visual to motor coordinates undergo a qualitative change at 8 years of age, and that the prevailing process of this conversion is located in the left cerebral hemisphere.

Age Factors↗

PubMed1993

Effects of lexicality and trigram frequency on handwriting production in children and adults.

Recent studies of handwriting have shown that linguistic variables, such as phonology or lexicality, influence various aspects of the production of letter sequences. Following a previous experiment, in which a facilitation effect of words over pseudowords has been documented both in children and in adults, an experiment is reported concerning the effect of lexicality and of trigram frequency on handwriting production at different levels of handwriting mastery. In this experiment, 8- to 12-year-old children and adults were asked to write words, pseudowords ending with a frequent trigram, and pseudowords ending with a nonfrequent trigram. Results show that in adults there is a facilitation effect of words over pseudowords and of frequent trigrams over nonfrequent trigrams. In children, no clear effect of lexicality or trigram frequency could be observed. Developmental trends show that major changes in children's handwriting occur between 8 and 10 years, whereas only minor modifications are observed between 10 and 12 years.

Adult↗

PubMed1986

The relationship between motor function and cognition in the developmental perspective.

The relationships between motor functions and cognitive functions in the normal human subject are discussed from three points of view: a priori analysis of the operations involved in the production and control of movement; synchronic experimental data; diachronic experimental data. This evidence is adduced in support of the view that motor function is a cognitive function, a view that runs strongly counter to the concepts at present dominating the domain of motor behavior research. According to the current concepts motor function is almost independent of cognition, except in so far as concerns the ideational aspects preceding motor performance and defining the most general logical characteristics of movement. The theoretical and methodological interest of taking the developmental perspective into account in the study of motor function is emphasized.

Adult↗

PubMed1983

Motor strategies in lifting movements: a comparison of adult and child performance.

The experiment compares the performances of children six to nine years old and adults in a simple, monoarticular lifting task. Overt behaviors, as described by the kinematic features of the movement, do not differ qualitatively in the two groups. The patterns of motor commands, as expressed by the electromyographic recordings, are however strikingly different. Adults plan the movement with a careful balance between agonist muscle activity and passive, viscoelastic forces, whereas children use both agonist and antagonist active forces. It is argued that the motor strategy adopted by adults depends upon an internal representation of the properties of the motor system and of the size/weight covariation in natural objects, and that this representation is not yet fully developed at nine years of age.

Journal Article↗