Body ownership, rubber hand illusion ed esperienza emotiva Correlati neurofisiologici

[Autom. eng. transl.] Consolidated empirical evidence has shown how, by hiding an upper limb from the view of a participant and applying a synchronous tactile stimulation to the real but hidden limb and to a fictitious but visible limb placed in front of the participant, it is possible to induce the perception that this external artifact is part of his body. This experimental procedure involves the appearance of a visuotactile illusion (Rubber Hand Illusion, RHI), used to explore the phenomenological and neural correlates of the sense of body ownership and the embodiment phenomena of external artifacts. Neuroimaging studies have shown how this incorporation experience is associated with the activation of premotor and parietal multimodal areas. On the contrary, there is little evidence relating to the emotional properties of this illusory experience. The present study therefore aims to explore these properties and, in particular, the subjective and neural correlates of emotional experiences related to the "incorporated" limb. Study participants completed three sessions of visuactile stimulation while their cortical activity was monitored and recorded by electroencephalography (EEG). In each session, after an initial resting period and the subsequent induction of RHI, a confederate applied a pleasant stimulation (through a pad) or aversive (through a knife) to the incorporated hand. At the end of each session, participants completed a short questionnaire to probe the quality of their illusion experience. The analysis of electrophysiological data revealed a significant difference between the pleasant and aversive stimulation conditions for the EEG alpha activity at the frontal areas on the right, with a higher prevalence of alpha activity during the pleasant than the aversive stimulation. In light of the functional reading of the modulations of this EEG band and of the models on the frontal lateralization of the neural correlates of the emotional experience, these evidences show that, consistently with a negative emotional response and avoidance, the aversive stimulation of the incorporated hand has resulted in a greater activation of the right prefrontal regions. The results suggest that the incorporation of the external artifact was associated with an effective extension of the sense of body ownership to the object and with the creation of a complex representation of the fictitious limb also as an object of possible experiences connoted affectively.