Perceiving and acting in a world with others: Social influence on sensorimotor processing as revealed by cognitive neuroscience, virtual reality and neuroimaging

Chairs: Christophe Lopez & Patricia Romaiguère

Laboratoire de Neurosciences Intégratives et Adaptatives, CNRS - Université de Provence, Marseille, France

Abstract:

Recent discoveries in neuroscience indicate that the human brain can mirror others' actions and perceptions, suggesting that one can experience and share others' feelings and emotions, such as pain and disgust, through simulation processes. The present symposium will highlight recent advances to understand how the presence of conspecifics in our environment changes the way we process sensory signals and interact with objects. In four talks, we will present data from cognitive neuroscience and neuroimagery showing the influence of others on cognitive and motor activities − including body parts ownership, action execution and understanding − as well as on perceptual activities, such as vestibular and tactile perception. Patricia Romaiguère will present a series of fMRI experiments showing that the extrastriate body area (EBA) is involved in self-other discrimination and in understanding actions of others. The importance of the social context in affordances (action potentialities) has been investigated in virtual environments and will be discussed by Marcello Costantini. Christophe Lopez will show that observing bodies submitted to passive whole-body rotations influences vestibular self-motion perception and will speculate on the existence of a “vestibular mirror neuron system”. Finally, Roberto Martuzzi will demonstrate that being touched by others can modify ownership for one’s own body and will describe underpinning neural mechanisms in the primary somatosensory cortex. Recent findings presented during this symposium should stimulate the inclusion of social determinants in currents models of sensorimotor processing and should provide neuroscientific bases for philosophical concepts such as intersubjectivity.

Talk 1:

Lateral occipital cortex and self-other processing

Patricia Romaiguère¹ and Olivier Felician<sup>2

1</sup> Laboratoire de Neurosciences Intégratives et Adaptatives, CNRS – Aix-Marseille Université, Marseille, France
² Brain Dynamics Institute, INSERM, Aix-Marseille Université, Marseille, France


Because humans are a social species, we interact with others on every aspect of life. Much information on others identities, emotions and intentions can be gathered from visual processing of their faces. However, the rest of the body also carries substantial information. Body movements are an essential communication media, whether for identifying others intentions or actions or for learning from them. Over the last ten years, much attention has been given to an area in the lateral occipital cortex, named Extrastiate Body Area (EBA), that responds to vision of body parts when presented as photographs, line drawings, stick figures or silhouettes. However, responses in EBA have also been observed during imagined or executed movements. It is also more activated in response to images of body parts presented from an allocentric rather than an egocentric perspective. Taken together, these findings suggest that EBA is not only involved in the visual processing of static body representations, but could represent the body in a multisensory and dynamic manner. EBA is very likely involved in self processing as well as in disentangling self- from other bodies and actions. In the present talk we will present results from several experiments exploring the role of EBA in self-other discrimination and in understanding others actions. Taken together, our results suggest a strong implication of EBA in the processing of dynamic and socially relevant body and action representations.

Talk 2:

Putting affordances in social context

Marcello Costantini
Laboratory of Neuropsychology and Cognitive Neuroscience, Department of Neuroscience and imaging, University G. d’Annunzio, Chieti, Italy & Institute for Advanced Biomedical Technologies - ITAB, Foundation University G. d’Annunzio, Chieti, Italy

Although perception and action have been widely investigated on the assumption that they can be completely accounted for by focusing on single individuals, several cognitive neuroscientists, experimental and developmental psychologists and philosophers have recently argued for the need to  take a social perspective on perceptual, motor and cognitive activities. Progress has been made by researchers in investigating the different levels of real-time social interactions by studying how mechanisms of sharing attention and action might subserve joint attention and action. However, little research has directly explored whether and to what extent sharing and joining attention and action could shape the perception of target objects as well as whether and to what extend object perception in social contexts, far from being a private business of single perceivers, could tell us something about the mechanisms underlying the primary ways in which we interact with others. In this talk, by taking advantage of empirical data collected in my laboratory, I will try to answer the following questions: How does our perception of objects change in a social context, at least at the basic level? Is it the case that the possibility for other individuals to act on an object modifies the way in which that object is given to us, starting from its affording features? And to what extent can such change shed light on the basic mechanisms of social engagement?

Talk 3:

Being moved by the self and others: empathy traits influence vestibular mechanisms of self-motion perception

Christophe Lopez^1,2, Caroline J. Falconer¹ and Fred W. Mast^1
1 Department of Psychology, University of Bern, Bern, Switzerland
² Laboratoire de Neurosciences Intégratives et Adaptatives, CNRS - Aix-Marseille
Université, Marseille, France

The observation of conspecifics influences our bodily perceptions and actions: Contagious yawning, contagious itching, or empathy for pain, are all examples of mechanisms based on resonance between self and others. These effects are associated with a mirror neuron system, which has been demonstrated for the processing of motor, auditory and tactile information. To date, however, no study has yet investigated the role of a mirror system in self-motion perception. Using a state-of-the-art full-body  motion we showed that vestibular perception is modulated by the observation of a full body (either one’s own body or another age- and gender-matched body) in motion. Viewing one’s own body or another body being passively rotated influenced vestibular perception, but in different ways. The observation of one’s own body in motion disrupted the detection of physical self-motion when it was incongruent, while the observation of incongruent motion of another body had a weaker influence. In addition, we found that empathy traits modulated this effect: The congruency effect was correlated with individual empathy scores, subjects with high empathy scores being more disturbed by the observation of another body being moved incoherently. The results from this study provide first evidence for a vestibular mirror system.

Talk 4:

Body ownership as manipulated by a simple social interaction is reflected in hand-specific subregions of primary somatosensory area: an ultra-high 7T fMRI study


Roberto Martuzzi, Olaf Blanke

Laboratory of Cognitive Neuroscience, Ecole Polytechnique Fédérale de Lausanne,
Lausanne, Switzerland

The experience that our body and its parts belong to us is a key aspect of the ‘self’ and daily social life and is called body ownership. It has been shown that ownership can experimentally be changed such as in the rubber hand illusion (Botvinick and Cohen, 1998) or the numbness illusion (NI; Dieguez et al., 2009). In these illusions the hand or finger of another person is felt as one’s own and have been linked to primary somatosensory cortex (S1) as well as other parietal and frontal regions. Focusing on the NI and S1 activity, I will first describe a 7T fMRI method for mapping single finger representations in three of the four Brodmann areas (BA) forming S1, namely BA3b, 1, and 2, observing in each BA a complete representation of all fingers. We used this method as a functional localizer and manipulated the timing and the agent (self or other) to study whether and how body ownership relates to finger specific regions. Our results show that BA1 (but not BA3b and 2) of the stroking hand, at each single finger region, reflects body ownership as quantified through the NI. Additionally, BA3b (but not BA1 and 2) of the touched hand showed a reduced response during self-touch (compared to being touched by another person) conditions. These results suggest that well-localized S1 activity reflects body ownership when interacting with other people and that this interaction involves differently BA3b and 1, depending on whether we are touching or are being touched.