Functional Brain Activity in Altered States of Consciousness Induced By Mechanical Stimulation of the Olfactory Epithelium Gabriele Penazzi , Andrea Zaccaro; Andrea De Vito; Danilo Menicucci; Andrea Piarulli; Luca Bruschini; Angelo Gemignani; Nicola De Pisapia (Department of Psychology and Cognitive Sciences, University of Trento, Ravenna, Emilia-Romagna Italy) C4
According to prior literature, slow-paced breathing exercises, regulating frequency and deepness of respiration, can induce considerable changes in neurophysiological and behavioral responses of the practitioners, thus playing a role in the modulation of consciousness states. Recent findings suggest that the rhythmic passage of airflow through the nostrils is crucial for reaching meditative states of consciousness during slow breathing practices. Here, we designed a specific experimental protocol in order to study the role that induced mechanical nasal stimulation of olfactory epithelium's receptors can have in the modulation of functional connectivity patterns in the brain and on the phenomenological alteration of the state of consciousness perceived by participants. The intrinsic BOLD activity of 16 subjects has been recorded with functional Magnetic Resonance Imaging (fMRI) in 2 different conditions: (1) after 15 minutes of natural breathing (control session), and (2) after 15 minutes of mechanical stimulation of olfactory epithelium. The frequency was set at 0.05 HZ, with a cycle length of 20 s and a continuous odorless air delivery for 8 s each cycle, which was automatically regulated through the use of an electronic device built specifically for this study. After each session, the participants filled the Phenomenology of Consciousness Inventory, a retrospective self-report questionnaire used to quantify the subjective consciousness altered experience. The analyses of the results showed significant modifications in the state of consciousness perceived by the participants in different dimensions of the questionnaire (sense of time, altered experience and state, meaning, perception, etcetera). In neural terms, after the mechanical stimulation of the olfactory epithelium, the comparison of the resting-state activity within sessions showed significant variations in the functional connectivity values among several limbic and cortical areas. These results provide preliminary evidence of the phenomenological and neurophysiological effects of olfactory epithelium stimulation during breathing practices.