scholarly journals The neural correlates of learned motor acuity

2014 ◽  
Vol 112 (4) ◽  
pp. 971-980 ◽  
Author(s):  
Lior Shmuelof ◽  
Juemin Yang ◽  
Brian Caffo ◽  
Pietro Mazzoni ◽  
John W. Krakauer
Keyword(s):  
Signal To Noise Ratio ◽  
Movement Time ◽  
Motor Task ◽  
Neural Correlates ◽  
Skill Learning ◽  
Movement Variability ◽  
Cortical Areas ◽  
Magnetic Resonance Brain Imaging ◽  
Speed Accuracy ◽  
Potential Confound

We recently defined a component of motor skill learning as “motor acuity,” quantified as a shift in the speed-accuracy trade-off function for a task. These shifts are primarily driven by reductions in movement variability. To determine the neural correlates of improvement in motor acuity, we devised a motor task compatible with magnetic resonance brain imaging that required subjects to make finely controlled wrist movements under visual guidance. Subjects were imaged on day 1 and day 5 while they performed this task and were trained outside the scanner on intervening days 2, 3, and 4. The potential confound of performance changes between days 1 and 5 was avoided by constraining movement time to a fixed duration. After training, subjects showed a marked increase in success rate and a reduction in trial-by-trial variability for the trained task but not for an untrained control task, without changes in mean trajectory. The decrease in variability for the trained task was associated with increased activation in contralateral primary motor and premotor cortical areas and in ipsilateral cerebellum. A global nonlocalizing multivariate analysis confirmed that learning was associated with increased overall brain activation. We suggest that motor acuity is acquired through increases in the number of neurons recruited in contralateral motor cortical areas and in ipsilateral cerebellum, which could reflect increased signal-to-noise ratio in motor output and improved state estimation for feedback corrections, respectively.

scholarly journals Complex motor task associated with non-linear BOLD responses in cerebro-cortical areas and cerebellum

2015 ◽  
Vol 221 (5) ◽  
pp. 2443-2458 ◽  
Author(s):  
Adnan A. S. Alahmadi ◽  
Rebecca S. Samson ◽  
David Gasston ◽  
Matteo Pardini ◽  
Karl J. Friston ◽  
...  
Keyword(s):  
Motor Task ◽  
Cortical Areas ◽  
Bold Responses ◽  
Non Linear ◽  
Complex Motor

Abstract T P123: Non-invasive Brain Stimulation for Motor Function of Chronic Stroke Patients

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Eunhee Park ◽  
Tae Gun Kwon ◽  
Won Hyuk Chang ◽  
Yun-Hee Kim
Keyword(s):  
Motor Function ◽  
Brain Stimulation ◽  
Movement Time ◽  
Motor Task ◽  
Chronic Stroke ◽  
Stroke Patients ◽  
Dual Mode ◽  
Simultaneous Application ◽  
Corticomotor Excitability ◽  
Cathodal Tdcs

Objective: The purpose of this study was to investigate the effect of dual-mode noninvasive brain stimulation (NBS) by combining transcranial direct current stimulation (tDCS) over the unaffected primary motor cortex (uM1) and high-frequency repetitive transcranial magnetic stimulation (rTMS) over the affected M1 (aM1) on motor functions and corticomotor excitability in chronic stroke patients. Methods: Seventeen chronic stroke patients (12 men; mean age 58.7 years; 12 infarctions and 5 hemorrhages) participated in this double blinded random-order crossover study. All participants received three randomly arranged, dual-mode stimulations with 24 hours of washout period; Condition 1, simultaneous application of 10 Hz rTMS over the aM1 and cathodal tDCS over the uM1; Condition 2, simultaneous application of 10 Hz rTMS over the M1a and anodal tDCS over the uM1; Condition 3, 10 Hz rTMS over the aM1 and sham tDCS over the uM1. Corticomotor excitability using motor evoked potential (MEP) amplitude and hand motor functions using the sequential motor task were assessed before and after stimulation. Results: MEP amplitude was significantly increased after condition 1 and 3, respectively (p<0.05). The changes of MEP amplitude were significantly higher in condition 1 than condition 2 (p<0.05). In sequential motor task, the movement time was significantly decreased after condition 1 and 3, respectively (p<0.05). The change of movement time was significantly larger in condition 1 than the other conditions (p<0.05). Conclusions: Simultaneous stimulation of cathodal tDCS over the uM1 produced enhancement of 10 Hz rTMS effect over the aM1 in patients with stroke. These results suggest the dual-mode NBS as a method of enhancing motor function probably by inducing interhemispheric interaction of bilateral primary motor cortices in chronic stroke patients (Supported by the National Research Foundation of Korea grant (No.2011-0016960) and a KOSEF grant (M10644000022-06N4400-02210)).

scholarly journals Differential Recordings of Local Field Potential:A Genuine Tool to Quantify Functional Connectivity

2018 ◽  
Author(s):  
Meyer Gabriel ◽  
Caponcy Julien ◽  
Paul A. Salin ◽  
Comte Jean-Christophe
Keyword(s):  
Functional Connectivity ◽  
Local Field ◽  
Signal To Noise Ratio ◽  
Field Potential ◽  
Low Frequency ◽  
Large Area ◽  
Signal To Noise ◽  
Cortical Areas ◽  
Electrophysiological Method ◽  
Local Field Potential Lfp

AbstractLocal field potential (LFP) recording is a very useful electrophysiological method to study brain processes. However, this method is criticized for recording low frequency activity in a large area of extracellular space potentially contaminated by distal activity. Here, we theoretically and experimentally compare ground-referenced (RR) with differential recordings (DR). We analyze electrical activity in the rat cortex with these two methods. Compared with RR, DR reveals the importance of local phasic oscillatory activities and their coherence between cortical areas. Finally, we show that DR provides a more faithful assessment of functional connectivity caused by an increase in the signal to noise ratio, and of the delay in the propagation of information between two cortical structures.

scholarly journals Olfaction Modulates Early Neural Responses to Matching Visual Objects

2015 ◽  
Vol 27 (4) ◽  
pp. 832-841 ◽  
Author(s):  
Amanda K. Robinson ◽  
Judith Reinhard ◽  
Jason B. Mattingley
Keyword(s):  
Neural Activity ◽  
Visual Processing ◽  
Sensory Information ◽  
Neural Correlates ◽  
Neural Responses ◽  
Visual Objects ◽  
Cortical Areas ◽  
Early Visual Processing ◽  
Considerable Research ◽  
Matter Concentration

Sensory information is initially registered within anatomically and functionally segregated brain networks but is also integrated across modalities in higher cortical areas. Although considerable research has focused on uncovering the neural correlates of multisensory integration for the modalities of vision, audition, and touch, much less attention has been devoted to understanding interactions between vision and olfaction in humans. In this study, we asked how odors affect neural activity evoked by images of familiar visual objects associated with characteristic smells. We employed scalp-recorded EEG to measure visual ERPs evoked by briefly presented pictures of familiar objects, such as an orange, mint leaves, or a rose. During presentation of each visual stimulus, participants inhaled either a matching odor, a nonmatching odor, or plain air. The N1 component of the visual ERP was significantly enhanced for matching odors in women, but not in men. This is consistent with evidence that women are superior in detecting, discriminating, and identifying odors and that they have a higher gray matter concentration in olfactory areas of the OFC. We conclude that early visual processing is influenced by olfactory cues because of associations between odors and the objects that emit them, and that these associations are stronger in women than in men.

scholarly journals Effects of Multiple Sessions of Cathodal Priming and Anodal HD-tDCS on Visuo Motor Task Plateau Learning and Retention

2020 ◽  
Vol 10 (11) ◽  
pp. 875 ◽  
Author(s):  
Pierre Besson ◽  
Makii Muthalib ◽  
Christophe De Vassoigne ◽  
Jonh Rothwell ◽  
Stephane Perrey
Keyword(s):  
Motor Learning ◽  
Motor Task ◽  
Controlled Study ◽  
Anodal Tdcs ◽  
Retention Performance ◽  
Baseline Training ◽  
Double Blind ◽  
Trade Off ◽  
The Impact ◽  
Speed Accuracy

A single session of priming cathodal transcranial direct current stimulation (tDCS) prior to anodal tDCS (c-a-tDCS) allows cumulative effects on motor learning and retention. However, the impact of multiple sessions of c-a-tDCS priming on learning and retention remains unclear. Here, we tested whether multiple sessions of c-a-tDCS (over 3 consecutive days) applied over the left sensorimotor cortex can further enhance motor learning and retention of an already learned visuo-motor task as compared to anodal tDCS (a-tDCS) or sham. In a between group and randomized double-blind sham-controlled study design, 25 participants separated in 3 independent groups underwent 2 days of baseline training without tDCS followed by 3-days of training with both online and offline tDCS, and two retention tests (1 and 14 days later). Each training block consisted of five trials of a 60 s circular-tracing task intersected by 60 s rest, and performance was assessed in terms of speed–accuracy trade-off represented notably by an index of performance (IP). The main findings of this exploratory study were that multiple sessions of c-a-tDCS significantly further enhanced IP above baseline training levels over the 3 training days that were maintained over the 2 retention days, but these learning and retention performance changes were not significantly different from the sham group. Subtle differences in the changes in speed–accuracy trade-off (components of IP) between c-a-tDCS (maintenance of accuracy over increasing speed) and a-tDCS (increasing speed over maintenance of accuracy) provide preliminary insights to a mechanistic modulation of motor performance with priming and polarity of tDCS.

scholarly journals High variability impairs motor learning regardless of whether it affects task performance

2018 ◽  
Vol 119 (1) ◽  
pp. 39-48 ◽  
Author(s):  
Marco Cardis ◽  
Maura Casadio ◽  
Rajiv Ranganathan
Keyword(s):  
Motor Learning ◽  
Task Performance ◽  
Null Space ◽  
Motor Task ◽  
Task Space ◽  
Movement Variability ◽  
Motor Variability ◽  
Different Dimensions ◽  
Left And Right

Motor variability plays an important role in motor learning, although the exact mechanisms of how variability affects learning are not well understood. Recent evidence suggests that motor variability may have different effects on learning in redundant tasks, depending on whether it is present in the task space (where it affects task performance) or in the null space (where it has no effect on task performance). We examined the effect of directly introducing null and task space variability using a manipulandum during the learning of a motor task. Participants learned a bimanual shuffleboard task for 2 days, where their goal was to slide a virtual puck as close as possible toward a target. Critically, the distance traveled by the puck was determined by the sum of the left- and right-hand velocities, which meant that there was redundancy in the task. Participants were divided into five groups, based on both the dimension in which the variability was introduced and the amount of variability that was introduced during training. Results showed that although all groups were able to reduce error with practice, learning was affected more by the amount of variability introduced rather than the dimension in which variability was introduced. Specifically, groups with higher movement variability during practice showed larger errors at the end of practice compared with groups that had low variability during learning. These results suggest that although introducing variability can increase exploration of new solutions, this may adversely affect the ability to retain the learned solution.NEW & NOTEWORTHY We examined the role of introducing variability during motor learning in a redundant task. The presence of redundancy allows variability to be introduced in different dimensions: the task space (where it affects task performance) or the null space (where it does not affect task performance). We found that introducing variability affected learning adversely, but the amount of variability was more critical than the dimension in which variability was introduced.

scholarly journals Somatosensory changes associated with motor skill learning

2020 ◽  
Vol 123 (3) ◽  
pp. 1052-1062 ◽  
Author(s):  
Jasmine L. Mirdamadi ◽  
Hannah J. Block
Keyword(s):  
Motor Cortex ◽  
Motor Skill ◽  
Motor Adaptation ◽  
Short Latency ◽  
Skill Learning ◽  
Motor Skill Learning ◽  
Short Latency Afferent Inhibition ◽  
Afferent Inhibition ◽  
Speed Accuracy ◽  
Somatosensory Function

Trial-and-error motor adaptation has been linked to somatosensory plasticity and shifts in proprioception (limb position sense). The role of sensory processing in motor skill learning is less understood. Unlike adaptation, skill learning involves the acquisition of new movement patterns in the absence of perturbation, with performance limited by the speed-accuracy trade-off. We investigated somatosensory changes during motor skill learning at the behavioral and neurophysiological levels. Twenty-eight healthy young adults practiced a maze-tracing task, guiding a robotic manipulandum through an irregular two-dimensional track featuring several abrupt turns. Practice occurred on days 1 and 2. Skill was assessed before practice on day 1 and again on day 3, with learning indicated by a shift in the speed-accuracy function between these assessments. Proprioceptive function was quantified with a passive two-alternative forced-choice task. In a subset of 15 participants, we measured short-latency afferent inhibition (SAI) to index somatosensory projections to motor cortex. We found that motor practice enhanced the speed-accuracy skill function ( F4,108 = 32.15, P < 0.001) and was associated with improved proprioceptive sensitivity at retention ( t22 = 24.75, P = 0.0031). Furthermore, SAI increased after training ( F1,14 = 5.41, P = 0.036). Interestingly, individuals with larger increases in SAI, reflecting enhanced somatosensory afference to motor cortex, demonstrated larger improvements in motor skill learning. These findings suggest that SAI may be an important functional mechanism for some aspect of motor skill learning. Further research is needed to test what parameters (task complexity, practice time, etc.) are specifically linked to somatosensory function. NEW & NOTEWORTHY Somatosensory processing has been implicated in motor adaptation, where performance recovers from a perturbation such as a force field. We investigated somatosensory function during motor skill learning, where a new motor pattern is acquired in the absence of perturbation. After skill practice, we found changes in proprioception and short-latency afferent inhibition (SAI), signifying somatosensory change at both the behavioral and neurophysiological levels. SAI may be an important functional mechanism by which individuals learn motor skills.

Actions Speak Louder Than Functions: The Importance of Manipulability and Action in Tool Representation

2003 ◽  
Vol 15 (1) ◽  
pp. 30-46 ◽  
Author(s):  
Marion L. Kellenbach ◽  
Matthew Brett ◽  
Karalyn Patterson
Keyword(s):  
Premotor Cortex ◽  
Neural Correlates ◽  
Middle Temporal Gyrus ◽  
Intraparietal Sulcus ◽  
Object Representations ◽  
Traffic Light ◽  
Retrieval Task ◽  
Middle Temporal ◽  
Cortical Areas ◽  
Action Knowledge

PET was used to investigate the neural correlates of action knowledge in object representations, particularly the left lateralized network of activations previously implicated in the processing of tools and their associated actions: ventral premotor cortex (VPMCx), posterior middle temporal gyrus (PMTG), and intraparietal sulcus (IPS). Judgments were made about the actions and functions associated with manipulable man-made objects (e.g., hammer); this enabled us to measure activations in response to both explicit and implicit retrieval of knowledge about actions associated with manipulable tools. Function judgments were also made about nonmanipulable artifacts (e.g., traffic light) providing a direct comparison for manipulable objects. Although neither the left VPMCx nor the left PMTG were selective for tool stimuli (nonmanipulable objects also activated these areas relative to a visual control condition), both regions responded more strongly to manipulable objects, suggesting a role for these cortical areas in the processing of knowledge associated with tools. Furthermore, these activations were insensitive to retrieval task, suggesting that visually presented tools automatically recruit both left VPMCx and left PMTG in response to action features that are inherent in tool representations. In contrast, the IPS showed clear selectivity for explicit retrieval of action information about manipulable objects. No regions of cortex were more activated by function relative to action judgments about artifacts. These results are consistent with the brain's preferential responsiveness to how we interact with objects, rather than what they are used for.

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