Phd in PSYCHOLOGY AND SOCIAL NEUROSCIENCE

Thesis title: VICARIOUS MOTOR AND SOMATOSENSORY EXPERIENCES: NEURAL PATHWAYS TOWARD UNDERSTANDING OTHERS

The comprehension of how and to what extent vicarious activations contribute to our understanding of others' behaviors, expressed in the ability to experience others' actions vicariously and share their emotions and somatic feelings, is at the forefront of Social Neuroscience research. Based on a widely detained assumption of a shared neural representation between actions execution and observation, sustained by a broad system called mirror neuron system (MNS), many research studies have demonstrated how our brain not only reacts to the observation of other people's actions and somatic feelings but also understands and predicts what others do and share the same somatic sensations. Starting from the motor and somatosensory functions supported by the MNS, this thesis will expand to higher social and interpersonal functions such as Action Prediction and vicarious touch sensations. The body of this thesis is divided into two sections: the first part will be focused on the motor domain, and it will address the topic of Action Prediction from a neurofunctional perspective. In particular, it will be evaluated whether healthy aging impacts the neurophysiological processes recruited to anticipate the correct conclusion of simple grasping and pointing actions. The older group revealed significant hypoactivation in posterior parietal regions, whose activity was associated with performance efficiency. These results showed a decreased involvement of visuomotor 'mirror' mechanisms in healthy aging. Future studies might investigate whether this decreased reliability of sensorimotor processes could affect social interactions. Focusing on the somatosensory domain, the second part of this work will address the issue of neutral and affective vicarious tactile sensations. By capitalizing on adopting a virtual body by eliciting a full-body illusion, vicarious tactile sensations elicited over an embodied virtual body will be investigated. In particular, the behavioral study presented will deal with the time course of vicarious touch sensations and the possibility of eliciting embodiment and vicarious touch sensations over a virtual body presented in a 1st person perspective without multisensory cues. The results showed that both full-body illusion and vicarious touch sensations are illusory phenomena that unfold over minutes and cannot be captured in brief epochs, which is optimal for an fMRI study. Even if disentangling brain activity related to these phenomena might be challenging, a block-design fMRI study was designed to further investigate vicarious touch sensations from a neurofunctional perspective and verify whether a vicarious somatosensory tactile homunculus exists, meaning somatotopically representations of vicarious tactile sensations. However, as the COVID-19 pandemic deeply affected the work of this study, only the fMRI design, methods, analyses, and expected results will be presented. Although visually driven maps within the somatosensory cortex have been demonstrated, no previous studies have demonstrated vicarious tactile-driven maps evoked by vicarious sensations over an embodied virtual body. Results in this favor would demonstrate the possibility of using vicarious experiences induced by virtual reality as a powerful tool to study the neural correlates of a wide range of 'simulated' situations with high experimental control. Lastly, neurofunctional results could provide a better understanding of the functional processes behind somatosensory vicarious sensations. This thesis aimed at providing a broader knowledge of the processes and neural mechanisms underlying the understanding and mapping of others into oneself from two different domains. The presented results might have varied implications, from clinical to theoretical approaches.