Shared electrophysiology mechanisms of body ownership and motor imagery

Although we feel, see, and experience our hands as our own (body or hand ownership), recent research has shown that illusory hand ownership can be induced for fake or virtual hands and may useful for neuroprosthetics and brain-computer interfaces. Despite the vast amount of behavioral data on illusory hand ownership, neuroimaging studies are rare, in particular electrophysiological studies. Thus, while the neural systems underlying hand ownership are relatively well described, the spectral signatures of body ownership as measured by electroencephalography (EEG) remain elusive. Here we induce illusory hand ownership in an automated, computer-controlled manner using virtual reality while recording 64-channel EEG and found that illusory hand ownership is reflected by a body-specific modulation in the mu-band over fronto-parietal cortex. In a second experiment in the same subjects, we then show that mu as well as beta-band activity in highly similar fronto-parietal regions was also modulated during a motor imagery task often used in paradigms employing non-invasive brain-computer interface technology. These data provide insights into the electrophysiological brain mechanisms of illusory hand ownership and their strongly overlapping mechanisms with motor imagery in fronto-parietal cortex. They also highlight the potential of combining high-resolution EEG with virtual reality setups and automatized stimulation protocols for systematic, reproducible stimulus presentation in cognitive neuroscience, and may inform the design of non-invasive brain-computer interfaces

When Imagining Yourself in Pain, Visual Perspective Matters : The Neural and Behavioral Correlates of Simulated Sensory Experiences

© 2015 Massachusetts Institute of TechnologyPeer reviewedPublisher PD

Brain-Computer Interface and Motor Imagery Training: The Role of Visual Feedback and Embodiment

Controlling a brain-computer interface (BCI) is a difficult task that requires extensive training. Particularly in the case of motor imagery BCIs, users may need several training sessions before they learn how to generate desired brain activity and reach an acceptable performance. A typical training protocol for such BCIs includes execution of a motor imagery task by the user, followed by presentation of an extending bar or a moving object on a computer screen. In this chapter, we discuss the importance of a visual feedback that resembles human actions, the effect of human factors such as confidence and motivation, and the role of embodiment in the learning process of a motor imagery task. Our results from a series of experiments in which users BCI-operated a humanlike android robot confirm that realistic visual feedback can induce a sense of embodiment, which promotes a significant learning of the motor imagery task in a short amount of time. We review the impact of humanlike visual feedback in optimized modulation of brain activity by the BCI users

The bodily self: Insights from clinical and experimental research

This review article summarizes neuropsychological descriptions of abnormal body representations in brain-damaged patients and recent neuroscientific investigations of their sensorimotor underpinnings in healthy participants. The first part of the article describes unilateral disorders of the bodily self, such as asomatognosia, feelings of amputation, supernumerary phantom limbs and somatoparaphrenia, as well as descriptions of non-lateralized disorders of the bodily self, including Alice in Wonderland syndrome and autoscopic hallucinations. Because the sensorimotor mechanisms of these disorders are unclear, we focus on clinical descriptions and insist on the importance of reporting clinical cases to better understand the full range of bodily disorders encountered in neurological diseases. The second part of the article presents the advantages of merging neuroscientific approaches of the bodily self with immersive virtual reality, robotics and neuroprosthetics to foster the understanding of the multisensory, motor and neural mechanisms of bodily representations

Agency and responsibility over virtual movements controlled through different paradigms of brain−computer interface

Agency is the attribution of an action to the self and is a prerequisite for experiencing responsibility over its consequences. Here we investigated agency and responsibility by studying the control of movements of an embodied avatar, via brain computer interface (BCI) technology, in immersive virtual reality. After induction of virtual body ownership by visuomotor correlations, healthy participants performed a motor task with their virtual body. We compared the passive observation of the subject's ‘own’ virtual arm performing the task with (1) the control of the movement through activation of sensorimotor areas (motor imagery) and (2) the control of the movement through activation of visual areas (steady‐state visually evoked potentials). The latter two conditions were carried out using a brain–computer interface (BCI) and both shared the intention and the resulting action. We found that BCI‐control of movements engenders the sense of agency, which is strongest for sensorimotor areas activation. Furthermore, increased activity of sensorimotor areas, as measured using EEG, correlates with levels of agency and responsibility. We discuss the implications of these results for the neural basis of agency

Neurophysiological correlates of the rubber hand illusion in late evoked and alpha/beta band activity

The rubber hand illusion (RHI) allows insights into how the brain resolves conflicting multisensory information regarding body position and ownership. Previous neuroimaging studies have reported a variety of neurophysiological correlates of illusory hand ownership, with conflicting results likely originating from differences in experimental parameters and control conditions. Here, we overcome these limitations by using a fully automated and precisely-timed visuo-tactile stimulation setup to record evoked responses and oscillatory responses in participants who felt the RHI. Importantly, we relied on a combination of experimental conditions to rule out confounds of attention, body-stimulus position and stimulus duration and on the combination of two control conditions to identify neurophysiological correlates of illusory hand ownership. In two separate experiments we observed a consistent illusion-related attenuation of ERPs around 330 ms over frontocentral electrodes, as well as decreases of frontal alpha and beta power during the illusion that could not be attributed to changes in attention, body-stimulus position or stimulus duration. Our results reveal neural correlates of illusory hand ownership in late and likely higher-order rather than early sensory processes, and support a role of premotor and possibly intraparietal areas in mediating illusory body ownership

Body schema plasticity after stroke: Subjective and neurophysiological correlates of the rubber hand illusion

[EN] Stroke can lead to motor impairments that can affect the body structure and restraint mobility. We hypothesize that brain lesions and their motor sequelae can distort the body schema, a sensorimotor map of body parts and elements in the peripersonal space through which human beings embody the reachable space and ready the body for forthcoming movements. Two main constructs have been identified in the embodiment mechanism: body-ownership, the sense that the body that one inhabits is his/her own, and agency, the sense that one can move and control his/her body. To test this, the present study simultaneously investigated different embodiment subcomponents (body-ownership, localization, and agency) and different neurophysiological measures (galvanic skin response, skin temperature, and surface electromyographic activity), and the interaction between them, in clinically-controlled hemiparetic individuals with stroke and in healthy subjects after the rubber hand illusion. Individuals with stroke reported significantly stronger body-ownership and agency and reduced increase of galvanic skin response, skin temperature, and muscular activity in the stimulated hand. We suggest that differences in embodiment could have been motivated by increased plasticity of the body schema and pathological predominance of the visual input over proprioception. We also suggest that differences in neurophysiological responses could have been promoted by a suppression of the reflex activity of the sympathetic nervous system and by the involvement of the premotor cortex in the reconfiguration of the body schema. These results could evidence a body schema plasticity promoted by the brain lesion and a main role of the premotor cortex in this mechanism.This work was supported by Ministerio de Economia y Competitividad of Spain (Project NeuroVR, TIN2013-44741-R, Project REACT, TIN2014-61975-EXP, and Grant BES-2014-068218), and by Universitat Politecnica de Valencia (Grant PAID-10-14).Llorens Rodríguez, R.; Borrego, A.; Palomo, P.; Cebolla, A.; Noé-Sebastián, E.; Bermúdez I Badia, S.; Baños Rivera, RM. (2017). Body schema plasticity after stroke: Subjective and neurophysiological correlates of the rubber hand illusion. Neuropsychologia. 96:61-69. https://doi.org/10.1016/j.neuropsychologia.2017.01.00761699

Coaching Imagery to Athletes with Aphantasia

We administered the Plymouth Sensory Imagery Questionnaire (Psi-Q) which tests multi-sensory imagery, to athletes (n=329) from 9 different sports to locate poor/aphantasic (baseline scores <4.2/10) imagers with the aim to subsequently enhance imagery ability. The low imagery sample (n=27) were randomly split into two groups who received the intervention: Functional Imagery Training (FIT), either immediately, or delayed by one month at which point the delayed group were tested again on the Psi-Q. All participants were tested after FIT delivery and six months post intervention. The delayed group showed no significant change between baseline and the start of FIT delivery but both groups imagery score improved significantly (p=0.001) after the intervention which was maintained six months post intervention. This indicates that imagery can be trained, with those who identify as having aphantasia (although one participant did not improve on visual scores), and improvements maintained in poor imagers. Follow up interviews (n=22) on sporting application revealed that the majority now use imagery daily on process goals. Recommendations are given for ways to assess and train imagery in an applied sport setting