scholarly journals Reward modulates behaviour and neural responses in motor cortex during action observation

2019 ◽  
Author(s):  
Andreea Loredana Cretu ◽  
Rea Lehner ◽  
Rafael Polania ◽  
Nicole Wenderoth
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Response Times ◽  
Contextual Information ◽  
Action Observation ◽  
Neural Responses ◽  
Motor Resonance ◽  
Neural Representations ◽  
Attentional Engagement ◽  
Physiological Outcomes

AbstractTranscranial magnetic stimulation (TMS) studies demonstrated that observing the actions of other individuals leads to action-specific facilitation of primary motor cortex (M1) (i.e., “motor resonance”). Motor resonance is modulated by contextual information accompanying others’ actions, however, it is currently unknown whether action value influences behavioural and physiological outcomes during action observation in humans. Here we tested whether response times (RT) and muscle-specific changes of M1 excitability are modulated by the value an observer assigns to the action executed by another agent and whether this effect can be distinguished from attentional engagement. We show that observing highly-valued actions leads to a significant decrease in RT variability and a significant strengthening of action-specific neural representations in M1. This “sharpening” of behavioural and neural responses was observed over and beyond a control task requiring similar attentional engagement but did not include any rewards. Our finding that reward influences action specific representations in human M1 even if no motor response is required is new, suggesting that reward influences the transformation of action stimuli from the perceptual to the motor domain. We suggest that premotor areas are important for mediating the observed effect, most likely by optimizing grasp-specific PMv-M1 interactions which cause muscular facilitation patterns in M1 to be more distinct for rewarded actions.

scholarly journals Uncertainty in contextual and kinematic cues jointly modulates motor resonance in primary motor cortex

2019 ◽  
Vol 121 (4) ◽  
pp. 1451-1464 ◽  
Author(s):  
Andreea Loredana Cretu ◽  
Kathy Ruddy ◽  
Maria Germann ◽  
Nicole Wenderoth
Keyword(s):  
Motor Cortex ◽  
Neural Activity ◽  
Primary Motor Cortex ◽  
Contextual Information ◽  
Action Observation ◽  
Motor Resonance ◽  
Movement Kinematics ◽  
Corticomotor Excitability ◽  
Movement Observation ◽  
Motor Representations

Contextual information accompanying others’ actions modulates “motor resonance”, i.e., neural activity within motor areas that is elicited by movement observation. One possibility is that we weigh and combine such information in a Bayesian manner according to their relative uncertainty. Therefore, contextual information becomes particularly useful when others’ actions are difficult to discriminate. It is unclear, however, whether this uncertainty modulates the neural activity in primary motor cortex (M1) during movement observation. Here, we applied single-pulse transcranial magnetic stimulation (TMS) while subjects watched different grasping actions. We operationalized motor resonance as grip-specific modulation of corticomotor excitability measured in the index (FDI) versus the little finger abductor (ADM). We experimentally modulated either the availability of kinematic information ( experiment 1) or the reliability of contextual cues ( experiment 2). Our results indicate that even in the absence of movement kinematics, reliable contextual information is enough to trigger significant muscle-specific corticomotor excitability changes in M1, which are strongest when both kinematics and contextual information are available. These findings suggest that bottom-up mechanisms that activate motor representations as a function of the observed kinematics and top-down mechanisms that activate motor representations associated with arbitrary cues converge in M1. NEW & NOTEWORTHY Our study reveals new neurophysiological insights in support of the Bayesian account of action observation by showing that “motor resonance”, i.e., neural activity evoked by observing others’ actions, incorporates the uncertainty related to both contextual (prior beliefs) and kinematic (sensory evidence) cues. Notably, we show that muscle-specific modulation of M1 is strongest when context and movement kinematics are available, and it can be elicited even in the absence of movement kinematics.

scholarly journals Uncertainty in contextual and kinematic cues jointly modulate motor resonance in primary motor cortex

2018 ◽  
Author(s):  
Andreea Loredana Cretu ◽  
Kathy Ruddy ◽  
Maria Germann ◽  
Nicole Wenderoth
Keyword(s):  
Motor Cortex ◽  
Neural Activity ◽  
Primary Motor Cortex ◽  
Contextual Information ◽  
Single Pulse ◽  
Contextual Cues ◽  
Motor Resonance ◽  
Corticomotor Excitability ◽  
Movement Observation ◽  
Motor Representations

ABSTRACTContextual information accompanying others’ actions modulates “motor resonance”, i.e. neural activity within motor areas that is elicited by movement observation. One possibility is that we weight and combine such information in a Bayesian manner according to their relative uncertainty. Therefore, contextual information becomes particularly useful when others’ actions are ambiguous. It is unclear, however, whether this uncertainty modulates the neural activity in primary motor cortex (M1) during movement observation. Here we applied single-pulse transcranial magnetic stimulation (TMS) while subjects watched different grasping actions. We operationalized motor resonance as grip specific modulation of corticomotor excitability measured in the index (FDI) versus the little finger abductor (ADM). We experimentally modulated either the availability of kinematic information (Exp. 1) or the reliability of contextual cues (Exp. 2). Our results indicate that even in the absence of movement kinematics, reliable contextual information is enough to trigger significant muscle-specific corticomotor excitability changes in M1 (p<.0001) which are strongest when both kinematics and contextual information are available (p<.005). These findings suggest that bottom-up mechanisms that activate motor representations as a function of the observed kinematics, and top-down mechanisms which activate motor representations associated with arbitrary cues converge in M1 in a statistically optimal manner.

scholarly journals Implicit visual sensitivity towards slim versus overweight bodies modulates motor resonance in the primary motor cortex: A tDCS study

2020 ◽  
Author(s):  
Stergios Makris ◽  
Valentina Cazzato
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Action Observation ◽  
Video Clip ◽  
Normal Weight ◽  
Visual Sensitivity ◽  
Motor Resonance ◽  
Action Observation Network ◽  
Cathodal Tdcs ◽  
Overweight Group

AbstractMotor resonance (MR) can be influenced by individual differences and similarity in the physical appearance between the actor and observer. Recently, we reported that action simulation is modulated by an implicit visual sensitivity towards normal-weight compared with overweight bodies. Furthermore, recent research has suggested the existence of an action observation network responsible for MR, with limited evidence whether the primary motor cortex (M1) is part of this. We expanded our previous findings with regards to the role of an implicit normal-weight-body preference in the MR mechanism. At the same time, we tested the functional relevance of M1 to MR, by using a transcranial direct current stimulation (tDCS) protocol. Seventeen normal-weight and 17 overweight participants were asked to observe normal-weight or overweight actors reaching and grasping a light or heavy cube, and then, at the end of each video-clip to indicate the correct cube weight. Before the task, all participants received 15 min of sham or cathodal tDCS over the left M1. Measures of anti-fat attitudes were also collected. During sham tDCS, all participants were better in simulating the actions performed by normal-weight compared with overweight models. Surprisingly, cathodal tDCS selectively improved the ability in the overweight group to simulate actions performed by the overweight models. This effect was not associated with scores of fat phobic attitudes or implicit anti-fat bias. Our findings are discussed in the context of relevance of M1 to MR and its social modulation by anti-fat attitudes.

scholarly journals Muscle-specific modulation of indirect inputs to primary motor cortex during action observation

2020 ◽  
Vol 238 (7-8) ◽  
pp. 1735-1744 ◽  
Author(s):  
Andreea Loredana Cretu ◽  
Kathy L. Ruddy ◽  
Alain Post ◽  
Nicole Wenderoth
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Action Observation

Characterization of Torque-Related Activity in Primary Motor Cortex During a Multijoint Postural Task

2007 ◽  
Vol 97 (4) ◽  
pp. 2887-2899 ◽  
Author(s):  
Troy M. Herter ◽  
Isaac Kurtzer ◽  
D. William Cabel ◽  
Kirk A. Haunts ◽  
Stephen H. Scott
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Bimodal Distribution ◽  
Joint Torque ◽  
Neural Responses ◽  
Joint Activities ◽  
Baseline Activity ◽  
Arm Muscles ◽  
Postural Task

The present study examined neural activity in the shoulder/elbow region of primary motor cortex (M1) during a whole-limb postural task. By selectively imposing torques at the shoulder, elbow, or both joints we addressed how neurons represent changes in torque at a single joint, multiple joints, and their interrelation. We observed that similar proportions of neurons reflected changes in torque at the shoulder, elbow, and both joints and these neurons were highly intermingled across the cortical surface. Most torque-related neurons were reciprocally excited and inhibited (relative to their unloaded baseline activity) by opposing flexor and extensor torques at a single joint. Although coexcitation/coinhibition was occasionally observed at a single joint, it was rarely observed at both joints. A second analysis assessed the relationship between single-joint and multijoint activity. In contrast to our previous observations, we found that neither linear nor vector summation of single-joint activities could capture the breadth of neural responses to multijoint torques. Finally, we studied the neurons' directional tuning across all the torque conditions, i.e., in joint-torque space. Our population of M1 neurons exhibited a strong bimodal distribution of preferred-torque directions (PTDs) that was biased toward shoulder-extensor/elbow-flexor (whole-limb flexor) and shoulder-flexor/elbow-extensor (whole-limb extensor) torques. Notably, we recently observed a similar bimodal distribution of PTDs in a sample of proximal arm muscles. This observation illustrates the intimate relationship between M1 and the motor periphery.

scholarly journals Noise-Correlation Is Modulated by Reward Expectation in the Primary Motor Cortex Bilaterally During Manual and Observational Tasks in Primates

2020 ◽  
Vol 14 ◽  
Author(s):  
Brittany Moore ◽  
Sheng Khang ◽  
Joseph Thachil Francis
Keyword(s):  
Motor Cortex ◽  
Firing Rate ◽  
Primary Motor Cortex ◽  
Action Observation ◽  
Noise Correlation ◽  
Information Channel ◽  
Qualitative Response ◽  
Computer Interfaces ◽  
Single Target ◽  
Target Center

Reward modulation is represented in the motor cortex (M1) and could be used to implement more accurate decoding models to improve brain-computer interfaces (BCIs; Zhao et al., 2018). Analyzing trial-to-trial noise-correlations between neural units in the presence of rewarding (R) and non-rewarding (NR) stimuli adds to our understanding of cortical network dynamics. We utilized Pearson’s correlation coefficient to measure shared variability between simultaneously recorded units (32–112) and found significantly higher noise-correlation and positive correlation between the populations’ signal- and noise-correlation during NR trials as compared to R trials. This pattern is evident in data from two non-human primates (NHPs) during single-target center out reaching tasks, both manual and action observation versions. We conducted a mean matched noise-correlation analysis to decouple known interactions between event-triggered firing rate changes and neural correlations. Isolated reward discriminatory units demonstrated stronger correlational changes than units unresponsive to reward firing rate modulation, however, the qualitative response was similar, indicating correlational changes within the network as a whole can serve as another information channel to be exploited by BCIs that track the underlying cortical state, such as reward expectation, or attentional modulation. Reward expectation and attention in return can be utilized with reinforcement learning (RL) towards autonomous BCI updating.

scholarly journals The Activation of the Mirror Neuron System during Action Observation and Action Execution with Mirror Visual Feedback in Stroke: A Systematic Review

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Jack J. Q. Zhang ◽  
Kenneth N. K. Fong ◽  
Nandana Welage ◽  
Karen P. Y. Liu
Keyword(s):  
Motor Cortex ◽  
Visual Feedback ◽  
Primary Motor Cortex ◽  
Mirror Neuron System ◽  
Action Observation ◽  
Mirror Neuron ◽  
Action Execution ◽  
Neuron System ◽  
Mu Suppression ◽  
Mirror Visual Feedback

Objective. To evaluate the concurrent and training effects of action observation (AO) and action execution with mirror visual feedback (MVF) on the activation of the mirror neuron system (MNS) and its relationship with the activation of the motor cortex in stroke individuals. Methods. A literature search using CINAHL, PubMed, PsycINFO, Medline, Web of Science, and SCOPUS to find relevant studies was performed. Results. A total of 19 articles were included. Two functional magnetic resonance imaging (fMRI) studies reported that MVF could activate the ipsilesional primary motor cortex as well as the MNS in stroke individuals, whereas two other fMRI studies found that the MNS was not activated by MVF in stroke individuals. Two clinical trials reported that long-term action execution with MVF induced a shift of activation toward the ipsilesional hemisphere. Five fMRI studies showed that AO activated the MNS, of which, three found the activation of movement-related areas. Five electroencephalography (EEG) studies demonstrated that AO or MVF enhanced mu suppression over the sensorimotor cortex. Conclusions. MVF may contribute to stroke recovery by revising the interhemispheric imbalance caused by stroke due to the activation of the MNS. AO may also promote motor relearning in stroke individuals by activating the MNS and motor cortex.

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