Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 14566446

Task-dependent motor learning.

Isaac Kurtzer·Paul DiZio·James Lackner
View original source ↗Export metadata ↓

Abstract

We examined whether task-dependent modulation was evident in a motor learning paradigm. Subjects performed reaching movements before, during, and after exposure to a novel force perturbation while adopting either a spatial goal, "continue towards the target", or an effort goal, "keep your effort profile the same". Before the perturbation, the hand trajectories were moderately straight and accurate regardless of the task. However, during and immediately after the perturbation, the reaches exhibited unambiguous task-dependent differences in both the initial and terminal periods of the reach. With the spatial goal, subjects showed terminal compensations to the force-induced displacements indicative of feedback control. In addition, feedforward control was evident in the smaller path deviations with continued exposure and the initial path aftereffects when the perturbation was removed. In contrast, when adopting an effort goal, subjects showed large and chronically deviated endpoints from the perturbation indicating an absence of feedback compensation. They also showed no feedforward adaptation during repeated exposure or visible aftereffects when the perturbation was removed. Therefore, both feedforward and feedback control mechanisms show task-dependent modulation in a motor learning paradigm.

Explore related subjects

Adaptation, PhysiologicalAdultFeedbackHumansLearningMaleMotor ActivityMovementPsychomotor PerformanceSpace PerceptionJournal ArticleResearch Support, U.S. Gov't, Non-P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Isaac Kurtzer, Paul DiZio, James Lackner. 2003-09-16. Task-dependent motor learning.. https://doi.org/10.1007/s00221-003-1632-0

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2025

Genome sequencing and population genetics provide insights into local adaptation of Opisthopappus species on cliff environments of Taihang Mountains.

Local adaptation represents a pivotal theme in evolutionary biology. The Opisthopappus genus, comprising Opisthopappus longilobus and O. taihangensis, thrives on the cliffs of the Taihang Mountains. During their evolutionary history, two species are hypothesized to have locally adapted to their cliff habitats. In the present study, we employed a combined approach of whole-genome sequencing of O. taihangensis and population genomic analysis from both species to gain deeper insights into their patterns of local adaptation. Our results revealed that the expansive genome of O. taihangensis (3010.18 Mb), a consequence of a whole-genome duplication (WGD) event, coupled with a high proportion of repetitive sequences (82.70%), was postulated as one of its adaptive strategies. A clear differentiation between O. taihangensis and O. longilobus was observed, with the two species diverging approximately 17.57 million years ago (Mya), with O. longilobus serving as the ancestor. Since their divergence, limited gene flow was observed between the two species. Post-divergence, the effective population sizes of both species expanded, yet underwent a dramatic reduction at approximately 0.07 Mya. Furthermore, a total of 798 adaptive genes were identified, of which 207 overlapped with expanded genes, and eight genes were found to be under positive selection. These genes primarily regulated the growth and development of both species via pathways such as oxidation-reduction and ubiquitin-proteasome, enabling them to withstand climate changes. These findings provide profound insights into the local adaptation of Opisthopappus species to the cliff environments and offer valuable clues for further exploring the local adaptation among various cliff-dwelling organisms.

Adaptation, Physiological↗
PubMed2015

Variation in Drosophila melanogaster central metabolic genes appears driven by natural selection both within and between populations.

In this report, we examine the hypothesis that the drivers of latitudinal selection observed in the eastern US Drosophila melanogaster populations are reiterated within seasons in a temperate orchard population in Pennsylvania, USA. Specifically, we ask whether alleles that are apparently favoured in northern populations are also favoured early in the spring, and decrease in frequency from the spring to autumn with the population expansion. We use SNP data collected for 46 metabolic genes and 128 SNPs representing the central metabolic pathway and examine for the aggregate SNP allele frequencies whether the association of allele change with latitude and that with increasing days of spring-autumn season are reversed. Testing by random permutation, we observe a highly significant negative correlation between these associations that is consistent with this expectation. This correlation is stronger when we confine our analysis to only those alleles that show significant latitudinal changes. This pattern is not caused by association with chromosomal inversions. When data are resampled using SNPs for amino acid change the relationship is not significant but is supported when SNPs associated with cis-expression are only considered. Our results suggest that climate factors driving latitudinal molecular variation in a metabolic pathway are related to those operating on a seasonal level within populations.

Adaptation, Physiological↗
PubMed2006

Reading embossed capital letters: an fMRI study in blind and sighted individuals.

Reading Braille activates visual cortex in blind people [Burton et al., J Neurophysiol 2002;87:589-611; Sadato et al., Nature 1996;380:526-528; Sadato et al., Brain 1998;121:1213-1229]. Because learning Braille requires extensive training, we had sighted and blind people read raised block capital letters to determine whether all groups engage visual cortex similarly when reading by touch. Letters were passively rubbed across the right index finger at 30 mm/s using an MR-compatible drum stimulator. Age-matched sighted, early blind (lost sight 0-5 years), and late blind (lost sight >5.5 years) volunteers performed three tasks: stating an identified letter, stating a verb containing an identified letter, and feeling a moving smooth surface. Responses were voiced immediately after the drum stopped moving across the fingertip. All groups showed increased activity in visual areas V1 and V2 during both letter identification tasks. Blind compared to sighted participants showed greater activation increases predominantly in the parafoveal-peripheral portions of visuotopic areas and posterior parts of BA 20 and 37. Sighted participants showed suppressed activity in most of the same areas except for small positive responses bilaterally in V1, left V5/MT+, and bilaterally in BA 37/20. Blind individuals showed suppression of the language areas in the frontal cortex, while sighted individuals showed slight positive responses. Early blind showed a more extensive distribution of activity in superior temporal sulcal multisensory areas. These results show cross-modal reorganization of visual cortex and altered response dynamics in nonvisual areas that plausibly reflect mechanisms for adaptive plasticity in blindness.

Adaptation, Physiological↗