Bodily self-consciousness as a framework to link sensory information and self-related components of episodic memory: behavioral, neuroimaging, and clinical evidence

The recollection of sensory information and subjective experience related to a personal past event depends on our episodic memory (EM). At the neural level, EM retrieval is linked with the reinstatement of hippocampal activity thought to recollect the sensory information experienced and stored in the cortex. At encoding, the sensory information also includes many bodily cues (i.e., touch, proprioception). Such integrated bodily signals are the basis of a sensorimotor form of self-consciousness called bodily self-consciousness (BSC). BSC consists of subjective experiences like the sense of ownership, first-person perspective, and the sense of agency, recruiting a distributed neural system consisting of premotor (PMC), supplementary motor (SMA), and posterior parietal regions. However, although both BSC and EM rely on the integration of sensory stimuli, the neural mechanism associating BSC and EM are still not known. In my thesis, I designed a new experimental procedure using virtual reality (VR) and motion tracking to investigate the behavioral and neural correlates of BSC, EM, and their interactions. I fully adapted the procedures to fMRI in order to test the impact of BSC manipulation at encoding on EM retrieval and its subjective components. The first part of my thesis investigated how different levels of BSC (visuomotor and perspectival congruency) during encoding impacted EM (Study 1) and the subjective re-experience of the memory called autonoetic consciousness (ANC; Study 2). In Study 1, I found that hippocampal reinstatement was enhanced and coupled with key BSC areas (PMC, SMA) only for preserved BSC characterized by visuomotor and perspectival congruency. Study 2 showed that the strength of recollection correlated with the strength of the subjective experience at encoding only under visuomotor and perspectival congruency. This relationship between ANC and BSC was mediated by the insula, a structure related to BSC and also linked with emotions in the EM field.In the second part of my thesis, I investigated the paradigm used in Studies 1 and 2 in clinical populations presenting damage to the medial temporal lobe (Study 3) or cortical areas (Study 4). In Study 3, I tested a rare case of amnestic patient with bilateral damage to the hippocampal complex. Despite preserved BSC, the patient showed a decreased EM when encoded under a BSC characterized by visuomotor and perspectival congruency. In Study 4, I tested whether damage to frontal cortex, including PMC, in motor stroke patients alters the impact of BSC state in EM. Preliminary results indicated that memory performance for scene encoded under visuomotor and perspectival congruency was not enhanced in stroke patients with impaired BSC. Finally, in the last part of my thesis (Study 5), I discuss the importance of VR technology in the study of BSC and what to improve in VR aesthetics to boost BSC effects in future studies.In summary, I designed a new experimental protocol using VR and motion tracking to investigate the impacts of BSC and its related subjective experience on EM. I adapted the design to fMRI to investigate the neural correlates of the association of these two processes. I linked these results in light of a rare case of an amnestic patient with a specific EM deficit and a group of motor stroke patients with lesions involved in BSC processes. My thesis contributes to linking sensory information processing, self-consciousness, and EM within a common framework: BSC.