Remembering the past with slow breathing associated with activity in the parahippocampus and amygdala

Breathing plays an important role in perception of odors and the experience of emotions. We used the dipole tracing method to analyze brain areas related to odor-induced autobiographical memory and emotions estimated from averaged electroencephalograms triggered by inspiration onset during odor presentation. Odor stimuli were perfumes subjects named that elicited a specific, pleasant and personal memory as well as two pleasant odors for controls. The perfumes induced specific emotional responses during memory retrieval, arousal level of the memory, feelings of pleasantness and a sense of familiarity with the odor. Respiration measurement indicated that tidal volume increased and respiratory frequency decreased during presentation of perfume stimuli, showing a deep and slow breathing pattern. Throughout the olfactory stimulation, electroencephalograms and respiration were simultaneously recorded. In the averaged potentials, low frequency oscillation was phase-locked to inspiration. Dipole analysis showed that perfumes activated more widespread areas of the right parahippocampal cortex and converged in the right amygdala compared to control odors. Slow breathing synchronized with odor-induced autobiographical memory and emotions may be subconsciously stored in the parahippocampal cortex and amygdala.