Gowrishankar Ganesh

• PhD
• Senior Researcher at French National Centre for Scientific Research

Motor contagions refer to implicit effects induced by the observation of actions made by others on one’s own actions. A plethora of studies conducted over the last two decades have demonstrated that both observed and predicted actions can induce various kinds of motor contagions in a human observer. However, motor contagions have always been invest...

The haptic sense is an important mode of communication during physical interactions, and it is known to enable humans to estimate key features of their partner's behavior. It is proposed that such estimations are based upon the exchange of information mediated by the interaction forces, resulting in role distribution and coordination between partne...

Physical interaction can enhance motor learning, but it remains unclear what type of interaction is best suited to increasing the active effort put into a task, which should improve learning. Here, we used the same interactive tracking task with different instructions to induce three training conditions: competition, collaboration, and self-improve...

Motor contagions refer to implicit effects in one's actions induced by the observation of actions made by others. A plethora of studies over the last two decades have exhibited that observed, as well as predicted, actions can induce various kinds of motor contagions in a human observer. However, motor contagion has always been investigated in regar...

Even if we cannot control them, or when we receive no tactile or proprioceptive feedback from them, limbs attached to our bodies can still provide indirect proprioceptive and haptic stimulations to the body parts they are attached to simply due to the physical connections. In this study we investigated whether such indirect movement and haptic feed...

To interact with machines, from computers to cars, we need to monitor multiple sensory stimuli, and respond to them with specific motor actions. It has been shown that our ability to react to a sensory stimulus is dependent on both the stimulus modality, as well as the spatial compatibility of the stimulus and the required response. However, the co...

Many everyday tasks, like walking down a street, require us to dual task to also avoid collisions of our swinging arms with other pedestrians. The collision avoidance is possible with ease because humans attend to all our (embodied) limbs. But how does the level of embodiment affect attention distribution, and consequently task performance in dual...

Human tool use prowess distinguishes us from other animals. In many scenarios, a human is able to recognize objects seen for the first time as potential tools for a task and use them without requiring any learning. Here we propose a framework to enable similar abilities in robots. We first characterized human tools to identify a special category of...

Can our brain perceive a sense of ownership towards an independent supernumerary limb; one that can be moved independently of any other limb and provides its own independent movement feedback? Following the rubber-hand illusion experiment, a plethora of studies have shown that the human representation of “self” is very plastic. But previous studies...

Can our brain perceive a sense of ownership towards an independent supernumerary limb; one that can be moved independently of any other limb and provides its own independent movement feedback? Following the rubber-hand illusion experiment, a plethora of studies have shown that the human representation of 'self' is very plastic. But previous studies...

A significant problem in brain-computer interface (BCI) research is decoding - obtaining required information from very weak noisy electroencephalograph signals and extracting considerable information from limited data. Traditional intention decoding methods, which obtain information from induced or spontaneous brain activity, have shortcomings in...

To develop a more reliable brain-computer interface (BCI) for patients in the completely locked-in state (CLIS), here we propose a Pavlovian conditioning paradigm using galvanic vestibular stimulation (GVS), which can induce a strong sensation of equilibrium distortion in individuals. We hypothesized that associating two different sensations caused...

Humans have the amazing ability to learn the dynamics of the body and environment to develop motor skills. Traditional motor studies using arm reaching paradigms have viewed this ability as the process of ‘internal model adaptation’. However, the behaviors have not been fully explored in the case when reaches fail to attain the intended target. Her...

Cyber space enables us to “share” bodies whose movements are a consequence of movements by several individuals. But whether and how our motor behavior is affected during body sharing remains unclear. Here we examined this issue in arm reaching performed by a shared avatar, whose movement was generated by averaging the movements of two participants....

Humans have the amazing ability to learn the dynamics of the body and environment to develop motor skills. Traditional motor studies using arm reaching paradigms have viewed this ability as the process of internal model adaptation. However, the behaviors have not been fully explored in the case when reaches fail to attain the intended target. Here...

The long term success of a human-robot interaction will depend on how comfortable and safe a human feels with it. But which feature of a robot’s movement determines human comfort? To address this question, here we considered four different models of human discomfort. We then designed an empirical human-robot co-worker task that enables us to both,...

Object handovers between humans are common in our daily life but the mechanisms underlying handovers are still largely unclear. A good understanding of these mechanisms is important not only for a better understanding of human social behaviors, but also for the prospect of an automatized society in which machines will need to perform similar object...

Sensory feedback is the fundamental driving force behind motor control and learning. However, the technology for low-cost and efficient sensory feedback remains a big challenge during stroke rehabilitation, and for prosthetic designs. Here we show that a low-cost accelerometer mounted on the finger can provide accurate decoding of many daily life m...

The first systematic collaboration between cognitive scientists and sports psychologists considers the mind–body relationship from the perspective of athletic skill and sports practice. This landmark work is the first systematic collaboration between cognitive scientists and sports psychologists that considers the mind–body relationship from the pe...

Does the presence of a robot co-worker influence the performance of humans around it? Studies of motor contagions during human-robot interactions have examined either how the observation of a robot affects a human’s movement velocity, or how it affects the human’s movement variance, but never both together. Performance however, has to be measured c...

All participants regression fits in the robot indus co-worker condition. Examples of linear regression fits obtained between the participant’s htp change between the together and alone conditions (ordinates), as a function of co-worker’s htps (abscissa). Like in S3 to S5 Figs, we observed no effect in the participants in the robot indus co-worker c...

All participants regression fits in the robot covered co-worker condition. Examples of linear regression fits obtained between the participant’s htp change between the together and alone conditions (ordinates), as a function of co-worker’s htps (abscissa). Note that there is no trend in slopes across participant –the slopes were in fact observed to...

All participants regression fits in the human covered co-worker condition. Examples of linear regression fits obtained between the participant’s htp change between the together and alone conditions (ordinates), as a function of co-worker’s htps (abscissa). Like in S3 Fig, the slopes were observed to be zero across participants (Fig 6), indicating t...

All participants regression fits in the robot non-biol co-worker condition. Examples of linear regression fits obtained between the participant’s htp change between the together and alone conditions (ordinates), as a function of co-worker’s htps (abscissa). The plots again show that the participant’s htps were not affected in the robot non-biol co-...

The video of our experiment explaining task protocol and data analysis is available here. https://goo.gl/9rqv4G. (MP4)

All participants regression fits in the robot co-worker condition. Examples of linear regression fits obtained between the participant’s htp change between the together and alone conditions (ordinates), as a function of co-worker’s htps (abscissa). Note that most participant plots show a positive slope indicating that the robot co-worker’s performa...

All participants regression fits in the human co-worker condition. Examples of linear regression fits obtained between the participant’s htp change between the together and alone conditions (ordinates), as a function of co-worker’s htps (abscissa). The positive slopes show that the human co-worker’s performance htp (hence frequency) influenced the...

Motor contagions refer to implicit effects on one's actions induced by observed actions. Motor contagions are believed to be induced simply by action observation and cause an observer's action to become similar to the action observed. In contrast, here we report a new motor contagion that is induced only when the observation is accompanied by predi...

Humans can skilfully use tools and interact with the environment by adapting their movement trajectory, contact force, and impedance. Motivated by the human versatility, we develop here a robot controller that concurrently adapts feedforward force, impedance, and reference trajectory when interacting with an unknown environment. In particular, the...

We propose a new methodology for decoding movement intentions of humans. This methodology is motivated by the well-documented ability of the brain to predict sensory outcomes of self-generated and imagined actions using so-called forward models. We propose to subliminally stimulate the sensory modality corresponding to a user’s intended movement, a...

This corrects the article DOI: 10.1038/ncomms5524.

Author summary Humans are talented at coordinating movements with one another through a multitude of objects such as a hard table or a soft mattress. Depending on the softness of the object, the force we perceive from the partner can be strong enough to sense directional cues, or could be too weak to understand the partner’s movement intention. How...

Interpersonal goal integration model reproduces the medium interaction, but only if the other conditions and the interaction effort are ignored. In a previous study [18], we showed that the interpersonal goal integration model reproduced the medium interaction performance improvement. It can also reproduce the medium interaction data in this study,...

Sensitivity analysis of the interaction models for the two parameters in the simulation. The log of the MAE between the fits from the data and the simulation as a function of q and σμ2. The MAE is relatively insensitive to changes in the strength q and σμ2. The neuromechanical goal sharing model has a lower RMSE than the follow the leader and inter...

This document describes the sensitivity analysis used to find the simulation parameters for the best fit to the data for each mechanism. We also demonstrate that the interpersonal goal sharing model from our previous study can explain the medium performance improvement, but only if the hard and soft interactions and the interaction effort are ignor...

Text file containing data from all 14 dyads in the human-human interaction experiments. Each row comes from a paired data point that compares a connected trial with the proceeding solo trial. Each column contains data in the following order where 1 denotes one partner and 2 the other: solo error (1), solo error (2), connected error (1), connected e...

Text file containing data from all 8 subjects in the haptic tracking experiment. The data is composed of 30 rows and 8 columns, where the first 15 rows are the tracking error in degrees and the last 15 rows denote the connection stiffness of the respective trial in Nm/deg. Each column is from a separate subject. (TXT)

The question of how humans predict outcomes of observed motor actions by others is a fundamental problem in cognitive and social neuroscience. Previous theoretical studies have suggested that the brain uses parts of the forward model (used to estimate sensory outcomes of self-generated actions) to predict outcomes of observed actions. However, this...

Motor contagions refer to implicit effects on one's actions induced by observation of other's actions. Motor contagions are believed to be induced simply by action observation and cause an observer's action to become similar to the observed action. In contrast, here we report a new motor contagion that is induced only when the observation is accomp...

We examine whether non-human looking humanoid robot arms can be perceived as part of one’s own body. In two subsequent experiments, participants experienced high levels of embodiment of a robotic arm that had a blue end effector with no fingers (Experiment 1) and of a robotic arm that ended with a gripper (Experiment 2) when it was stroked synchron...

Humanoid robot embodiment is a recently developed form of mediated embodiment. In 2 studies, we report and quantify a new haptic (touch) illusion during embodiment of a humanoid robot. Around 60% of the users in our studies reported haptic sensations in their real hand when they observed their robot avatar touching a curtain with its hand. Critical...

From a parent helping to guide their child during their first steps, to a therapist supporting a patient, physical assistance enabled by haptic interaction is a fundamental modus for improving motor abilities. However, what movement information is exchanged between partners during haptic interaction, and how this information is used to coordinate a...

Whole-body embodiment studies have shown that synchronized multi-sensory cues can trick a healthy human mind to perceive self-location outside the bodily borders, producing an illusion that resembles an out-of-body experience (OBE). But can a healthy mind also perceive the sense of self in more than one body at the same time? To answer this questio...

When you see an individual holding a baby in front of an elevator, you instinctively move to open the door for him. This seemingly obvious helping action is possible because you are able to immediately characterize, recognize and then understand his actions—that is, recognize the intention behind the observed individual’s actions, estimate the outc...

The question of how we attribute observed body parts as our own, and the consequences of this attribution on our sensory-motor processes, is fundamental to understand how our brain distinguishes between self and other. Previous studies have identified interactions between the illusion of ownership, and multi-sensory integration and cross-sensory pr...

Title - Supplementary material for "Forward modeling the rubber hand: illusion of ownership modifies motor-sensory predictions by the brain" Deatails: supplementary methods and results

Pavlovian conditioning underlies many aspects of pain behavior, including fear and threat detection [1], escape and avoidance learning [2], and endogenous analgesia [3]. Although a central role for the amygdala is well established [4], both human and animal studies implicate other brain regions in learning, notably ventral striatum and cerebellum [...

Bodily self-attribution, the feeling that a body (or parts of it) is owned by me, is a fundamental component of one's self. Previous studies have suggested that, in addition to a necessary multi-sensory stimulation, the sense of body ownership is determined by the body model, a representation of our body in the brain. It is however unclear what fea...

Our social skills are critically determined by our ability to understand and appropriately respond to actions performed by others. However despite its obvious importance, the mechanisms enabling action understanding in humans have remained largely unclear. A popular but controversial belief is that parts of the motor system contribute to our abilit...

The typical control of myoelectric interfaces, whether in laboratory settings or real-life prosthetic applications, largely relies on visual feedback because proprioceptive signals from the controlling muscles are either not available or very noisy. We conducted a set of experiments to test whether artificial proprioceptive feedback, delivered non-...

Human dexterity with tools is believed to stem from our ability to incorporate and use tools as parts of our body. However tool incorporation, evident as extensions in our body representation and peri-personal space, has been observed predominantly after extended tool exposures and does not explain our immediate motor behaviours when we change tool...

How do physical interactions with others change our own motor behavior? Utilizing a novel motor learning paradigm in which the hands of two - individuals are physically connected without their conscious awareness, we investigated how the interaction forces from a partner adapt the motor behavior in physically interacting humans. We observed the mot...

Our brain is known to automatically optimize effort expenditure during motor coordination, such that for example, during bimanual braking of a bicycle, a well-oiled brake will automatically be used more than a corroded, heavy brake. But how does our brain infer the effort expenditure? All previous motor coordination models have believed that the ef...

The typical control of myoelectric interfaces, be it in real-life prosthetic applications or laboratory settings, largely relies on visual feedback, while proprioceptive feedback from controlling muscles is not very informative about the task carried out. If proprioceptive feedback were artificially provided to a non-controlling limb, could it be e...

How does the human central nervous system generate appropriate movements to accomplish complex motor tasks, while adapting to the changing environmental conditions? The traditional motor control research has focused on simplified tasks in which healthy human subjects were found to utilise a single solution. In this chapter we present recent works t...

Most of today's robots have rigid structures and actuators requiring complex software control algorithms and sophisticated sensor systems in order to behave in a compliant and safe way adapted to contact with unknown environments and humans. By studying and constructing variable impedance actuators and their control, we contribute to the developmen...

This article presents a versatile controller that enables various contact tooling tasks with minimal prior knowledge of the tooled surface. The controller is derived from results of neuroscience studies that investigated the neural mechanisms utilized by humans to control and learn complex interactions with the environment. We demonstrate here the...

This article presents a versatile controller that enables various contact tooling tasks with minimal prior knowledge of the tooled surface. The controller is derived from results of neuroscience studies that investigated the neural mechanisms utilized by humans to control and learn complex interactions with the environment. We demonstrate here the...

Efficient control of reciprocal activation and cocontraction of the muscles are critical to perform skillful actions with suitable force and impedance. However, it remains unclear how the brain controls force and impedance while recruiting the same set of muscles as actuators. Does control take place at the single muscle level leading to force and...

This paper presents a novel human-like learning controller to interact with unknown environments. Strictly derived from the minimization of instability, motion error, and effort, the controller compensates for the disturbance in the environment in interaction tasks by adapting feedforward force and impedance. In contrast with conventional learning...

This paper presents a novel human-like learning con-troller to interact with unknown environments. Strictly derived from the minimization of instability, motion error, and effort, the controller compensates for the disturbance in the environment in interaction tasks by adapting feedforward force and impedance. In contrast with conventional learning...

Traditionally motor studies have assumed that motor tasks are executed according to a single plan characterized by regular patterns, which corresponds to the minimum of a cost function in extrinsic or intrinsic coordinates. However, the novel via-point task examined in this paper shows distinct planning and execution stages in motion production and...

Rigorous analyses of the mechanisms human-human physical interaction are only possible if corresponding means of systematically classifying dyad strategies are in place. Previous suggestions for classification of strategies neglect the high level of redundancy that is present when attenuation of external disturbances is required. To address this, w...

This paper investigates whether haptic error amplification using unstable dynamics can be used to train accuracy in micromanipulation. A preliminary experiment first examines the possible confounds of visual magnification and grip force. Results show that micromanipulation precision is not affected by grip force in both naive and experienced subjec...

Behavioral analysis of multi-joint arm reaching has allowed important advances in understanding the control of voluntary movements. Complementing this analysis with functional magnetic resonance imaging (fMRI) would give insight into the neural mechanisms behind this control. However, fMRI is very sensitive to artifacts created by head motion and m...

Many real life tasks that require impedance control to minimize motion error are characterized by multiple solutions where the task can be performed either by co-contracting muscle groups, which requires a large effort, or, conversely, by relaxing muscles. However, human motor optimization studies have focused on tasks that are always satisfied by...

Interaction of a robot with dynamic environments would require continuous adaptation of force and impedance, which is generally not available in current robot systems. In contrast, humans learn novel task dynamics with appropriate force and impedance through the concurrent minimization of error and energy, and exhibit the ability to modify movement...

This paper develops and analyses a biomimetic learning controller for robots. This controller can simultaneously adapt reference trajectory, impedance and feedforward force to maintain stability and minimize the weighted summation of interaction force and performance errors. This controller was inspired from our studies of human motor behavior, esp...

In humans, it is generally not possible to use invasive techniques in order to identify brain activity corresponding to activity of individual muscles. Further, it is believed that the spatial resolution of non-invasive brain imaging modalities is not sufficient to isolate neural activity related to individual muscles. However, this study shows tha...

Real-time acquisition of EMG during functional MRI (fMRI) provides a novel method of controlling motor experiments in the scanner using feedback of EMG. Because of the redundancy in the human muscle system, this is not possible from recordings of joint torque and kinematics alone, because these provide no information about individual muscle activat...

Skilled object manipulation requires knowledge, or internal models, of object dynamics relating applied force to motion , and our ability to handle myriad objects indicates that the brain maintains multiple models . Recent behavioral studies have shown that once learned, an internal model of an object with novel dynamics can be rapidly recruited an...

This paper describes a two-degrees-of-freedom haptic interface to investigate the brain mechanisms of human motor control, which is capable of safely and gently interacting with human arm motion during functional magnetic resonance imaging (fMRI). A hydrostatic transmission separates the interface into a master and an MR compatible slave system, al...

This paper describes a two-degrees-of-freedom haptic interface to investigate the brain mechanisms of human motor control, which is capable of safely and gently interacting with human arm motion during functional magnetic resonance imaging (fMRI). A hydrostatic transmission separates the interface into a master and an MR-compatible slave system, al...

Performing multi-joint arm movements in controllable dynamic environments during functional magnetic resonance imaging (fMRI) could provide important insights into the brain mechanisms involved in human motor control and related dysfunctions. In order to obtain useful data, these movements must be possible and comfortable for the subject within the...

We analyze the dynamics of an MR-compatible hydrostatic transmission designed to transfer power over distances of up to 10 m. In this system, a master actuates a passive slave connected by two hydrostatic lines in a cyclic arrangement. We derive a nonlinear model of this system and use it to analyze the system's behavior and the design parameters....

We are developing haptic interfaces compatible with functional magnetic resonance imaging (fMRI) to study the brain mechanisms of motor control in humans. This paper describes the different phases of our project, examines the constraints and presents possible solutions. The constraints imposed by the harsh yet sensitive MR environment as well as th...

This paper investigates a cable transmission to remotely actuate MR compatible robots over a distance of several meters. Such a transmission could be an interesting solution for haptic interfaces for neuroscience studies performing force feedback during functional magnetic resonance imaging (fMRI), as well as for robots for interventional MRI. MR c...