Lokalizacija stimuliranega signala audio korteksa posnetega z magnetometrom na kalijeve pare

We present results of our study in localization of the auditory evoked magnetic field measured by a noncryogenic potassium vapour atomic magnetometer (PVAM) [5]. The magnetometer was operating in a spin-exchange relaxation-free (SERF) regime at low magnetic flux densities and high alkali-metal vapour density [1]. Audio stimulation of short 1 kHz pulse trains was applied by a pneumatic earphone. After rejecting the subject’s heart-beat signals, signals originating from eye movements and disturbances due to mechanical vibrations, the N100m could be seen in several channels of the 256-channel atomic magnetometer. This was achieved by combining the magnetometer channels into a gradiometer configuration: one magnetometer was selected as a reference channel and other channels were subtracted from this reference. Using ten gradiometric channels with the best signal-tonoise ratio the approximate source localization of the auditory evoked field was determined by applying two methods: i) non-linear least-square fitting procedure using a current dipole source model in a conducting sphere model, and ii) minimum norm estimaton (MNE) method.