Biology subjects

Ganesh, G.

Publications and source records attributed to Ganesh, G..

3 recordsLinked to original sources

bioRxiv2021

Bodily ownership of an independent supernumerary limb: An exploratory study

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 rubberhand illusion experiment, a plethora of studies has shown that the human representation of self is very plastic. But previous studies have almost exclusively investigated ownership towards substitute artificial limbs, which are controlled by the movements of a real limb and/or limbs from which non-visual sensory feedback is provided on an existing limb. Here, to investigate whether the human brain can own an independent artificial limb, we first developed a novel independent robotic sixth finger. We allowed participants to train using the finger and examined whether it induced changes in the body representation using behavioral as well as cognitive measures. Our results suggest that unlike a substituted artificial limb (like in the rubber hand experiment), it is more difficult for humans to perceive a sense of ownership towards an independent limb. However, ownership does seem possible, as we observed clear tendencies of changes in the body representation that correlated with the cognitive reports of the sense of ownership. Our results provide the first evidence to show that an independent supernumerary limb can be embodied by the human brain.

neuroscience↗

bioRxiv2020

Hierarchical motor adaptations negotiate failures during force field learning

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 we examined human reaching under two force fields types; one that induces failures (i.e., target errors), and the other that does not. Our results show the presence of a distinct failure-driven adaptation process that enables quick task success after failures, and before completion of internal model adaptation, but that can result in persistent changes to the undisturbed trajectory. These behaviors can be explained by considering a hierarchical interaction between internal model adaptation and the failure-driven adaptation of reach direction. Our findings suggest that movement failure is negotiated using hierarchical motor adaptations by humans.

neuroscience↗

bioRxiv2017

Prediction error induced motor contagions in human behaviors

Motor contagions refer to implicit effects on ones actions induced by observation of others actions. Motor contagions are believed to be induced simply by action observation and cause an observers 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 accompanied by prediction errors-differences between actions one observes and those he/she predicts or expects. Moreover, this contagion may not manifest as a similarity between ones own and observed actions. In our experiment, observation of the same action induced distinct motor contagions, depending on whether prediction errors are present or not. In the absence of prediction errors, similarly to previous reports, participants actions changed to become similar to the observed action, while in the presence of prediction errors, their actions changed to diverge away from it. Our results suggest distinct effects of action observation and action prediction on human actions.

neuroscience↗