Embarking on my PhD journey at the University of Geneva, I had the great opportunity to explore the fascinating topics of face perception and subconscious processing. In my first project, we used real-time fMRI neurofeedback to understand how specific brain areas contribute to recognizing faces. It was a challenging yet rewarding endeavour, offering surprising insights. My second study ventured into subliminal face perception, revealing how our brains process information without our conscious awareness. Both projects opened new doors in neuroscience, and I'm excited to share these explorations with you through the abstracts and posters below as well as a video of the introduction part of my PhD defense.
Dept. of Neurosciences, University Medical School of Geneva, Switzerland
Neurofeedback allows learning self-regulation of specific brain regions based on real-time functional magnetic resonance imaging (rt-fMRI). We leveraged this technique to dissect the roles of two tightly interconnected areas implicated in face perception, by interleaving a visual task with upregulation of either the occipital (OFA) or the fusiform face-responsive areas (FFA). Experimental participants (N=22) successfully enhanced their target region when compared to a yoked control group (N=20). Regulation was face-selective, as evidenced by concomitant increases in other nodes of the face processing network. Critically, face detection was faster with enhanced FFA activity but hindered by enhanced OFA, whereas face identity recognition was optimal with concomitant increases in both FFA and OFA. These results argue against traditional models assuming a progression of face perception from posterior occipital to more anterior fusiform cortex, and instead support non-hierarchical models where FFA mediates initial face detection and OFA contributes to subsequent identity recognition.
Dept. of Neurosciences, University Medical School of Geneva, Switzerland
Research in healthy people indicate that briefly presented face stimuli in masking paradigms can evoke subliminal activation in specific visual areas, while they are not consciously perceived by the subject (Brooks et al., 2012). In the current project, real-time fMRI neurofeedback (NFB) was used to train 20 healthy volunteers, over the course of 3 sessions, to enhance such subliminal activation in the fusiform face area (FFA). A matched control group (n=19) underwent the same training protocol but received a feedback signal based on right inferior parietal sulcus (IPS) activity. While being presented with masked subliminal fearful faces, 11 participants from the FFA-group successfully learned to self- regulate their right FFA evoked neural response (FFA-learners). Similarly, in the IPS group, 9 participants gained voluntary control over their IPS activity (IPS-learners). Further, successful FFA training resulted in subsequent enhancement of subliminal face processing, as measured by a subliminal priming task. These neural enhancements were in turn associated with improved behavioral detection of subliminal faces in a rapid visual masking paradigm after compared to before training. IPS learners showed no such effects. The specificity of these effects in the FFA-trained group strongly suggests that NFB-training led to functional changes in perceptual processing of subliminal face information within FFA, rather than being driven by enhanced top-down attentional modulation from IPS. This underscores the potential of NFB in enhancing non-conscious brain processes and provides opportunities for future therapeutic interventions.
