Odorant perception and active olfaction: a study of olfactory magnetic fields evoked by odorant pulse stimuli synchronized with respiratory cycle

This paper presents a study on the odorant perception and active olfaction for human olfactory senses and their active locations of estimated signal sources in the brain. In these experiments olfactory event-related potentials were measured by electroencephalography (EEG) and olfactory event-related magnetic fields were also measured by magnetoencephalography (MEG) using a 122 ch whole-head neuromagnetometer. Odorant stimuli were actively given into the right or left nose cavity through a thin silicon tube using a mask attached on the subject´s face by an odorant pulse synchronized with the subject´s respiratory cycle. MEG main response waves were sharply detected and these signal sources were estimated to exist as two dipoles bilaterally at the orbito-frontal lobe in the brain. In the authors´ second experiments olfactory event-related magnetic fields were measured by an oddball paradigm using two odorants and these estimated signal sources were obtained in a few superior temporal regions. These active responses for odorants show one the capabilities of the role on the olfactory perception and active olfaction