Biomedical subjects

Regine K Lange

Publications and source records attributed to Regine K Lange.

3 recordsLinked to original sources

PubMed2006

Motor learning in man: a review of functional and clinical studies.

This chapter reviews results of clinical and functional imaging studies which investigated the time-course of cortical and subcortical activation during the acquisition of motor a skill. During the early phases of learning by trial and error, activation in prefrontal areas, especially in the dorsolateral prefrontal cortex, is has been reported. The role of these areas is presumably related to explicit working memory and the establishment of a novel association between visual cues and motor commands. Furthermore, motor associated areas of the right hemisphere and distributed cerebellar areas reveal strong activation during the early motor learning. Activation in superior-posterior parietal cortex presumably arises from visuospatial processes, while sensory feedback is coded in the anterior-inferior parietal cortex and the neocerebellar structures. With practice, motor associated areas of the left-hemisphere reveal increased activity. This shift to the left hemisphere has been observed regardless of the hand used during training, indicating a left-hemispheric dominance in the storage of visuomotor skills. Concerning frontal areas, learned actions of sequential character are represented in the caudal part of the supplementary motor area (SMA proper), whereas the lateral premotor cortex appears to be responsible for the coding of the association between visuo-spatial information and motor commands. Functional imaging studies which investigated the activation patterns of motor learning under implicit conditions identified for the first, a motor circuit which includes lateral premotor cortex and SMA proper of the left hemisphere and primary motor cortex, for the second, a cognitive loop which consists of basal ganglia structures of the right hemisphere. Finally, activity patterns of intermanual transfer are discussed. After right-handed training, activity in motor associated areas maintains during performance of the mirror version, but is increased during the performance of the original-oriented version with the left hand. In contrary, increased activity during the mirror reversed action, but not during the original-oriented performance of the untrained right hand is observed after left-handed training. These results indicate the transfer of acquired right-handed information which reflects the mirror symmetry of the body, whereas spatial information is mainly transferred after left-handed training. Taken together, a combined approach of clinical lesion studies and functional imaging is a promising tool for identifying the cerebral regions involved in the process of motor learning and provides insight into the mechanisms underlying the generalisation of actions.

Brain↗

PubMed2005

Coordinate processing during the left-to-right hand transfer investigated by EEG.

Information about visuomotor tasks is coded in extrinsic, object-centered and intrinsic, body-related coordinates. For the reproduction of a trained task in mirror orientation with the opposite untrained hand, acquired extrinsic coordinates must be transformed. In contrast, intrinsic coordinates have to be modified during the execution of the originally oriented task. As shown recently, processes of coordinate transformations during the right-to-left hand transfer are associated with movement preparation and occur preferentially in the left hemisphere. Here, movement-related potentials, EEG power, and EEG coherence were recorded during the repetition of a drawing task previously trained by the nondominant left hand (Learned-task) and its execution in original and mirror orientation by the right hand (Normal- and Mirror-task). To identify EEG correlates of coordinate processing during intermanual transfer rather than effects due to the use of the right versus left hand, only those EEG data were analyzed which differed between the Normal- and Mirror-tasks. Whereas the Normal-task did not differ from the Learned-task in any of these predefined EEG parameters, beta coherence increased in the Mirror-task in the period ranging from 1 to 2 s after movement onset. These increases were especially prominent between hemispheres but were also observed symmetrically in the parieto-frontal electrode pairs of both hemispheres. Behavioral data revealed that the performance in the Learned- and both transfer tasks improved after left-hand training. Results of the present study indicate that coordinate transformation during the left-to-right hand transfer occurs in the phase of movement execution and affects predominantly extrinsic coordinates. Intrinsic coordinates are presumably mainly used in their original form. The modification of extrinsic coordinates is accompanied by increased information flow between both hemispheres; thereby inter-hemispheric connections--as mediated via the corpus callosum--seem to play a central role.

Adult↗

PubMed2004

EEG correlates of coordinate processing during intermanual transfer.

Goal-directed movements require mapping of target information to patterns of muscular activation. While visually acquired information about targets is initially encoded in extrinsic, object-centered coordinates, muscular activation patterns are encoded in intrinsic, body-related coordinates. Intermanual transfer of movements previously learned with one hand is accomplished by the recall of unmodified extrinsic coordinates if the task is performed in original orientation. Intrinsic coordinates are retrieved in case of mirror-reversed orientation. In contrast, learned extrinsic coordinates are modified during the mirror movement and intrinsic coordinates during the originally oriented task. To investigate the neural processes of recall and modification, electroencephalogram (EEG) recording was employed during the performance of a figure drawing task previously trained with the right hand in humans. The figure was reproduced with the right hand (Learned-task) and with the left hand in original (Normal-task) and mirror orientations (Mirror-task). Prior to movement onset, beta-power and alpha- and beta-coherence decreased during the Normal-task as compared with the Learned-task. Negative amplitudes over fronto-central sites during the Normal-task exceeded amplitudes manifested during the Learned-task. In comparison to the Learned-task, coherences between fronto-parietal sites increased during the Mirror-task. Results indicate that intrinsic coordinates are processed during the pre-movement period. During the Normal-task, modification of intrinsic coordinates was revealed by cerebral activation. Decreased coherences appeared to reflect suppressed inter-regional information flow associated with utilization of intrinsic coordinates. During the Mirror-task, modification of extrinsic coordinates induced activation of cortical networks.

Adult↗