An MEG compatible system for measuring skin conductance responses.

We present the design of a low-cost system for recording galvanic skin conductance responses (SCRs) from humans in a magnetically shielded room (MSR) simultaneously to magnetoencephalography (MEG). Such a system was so far not available to the MEG community. Its availability is of utmost importance for neuroscience, since it will allow the concurrent assessment of the autonomic and central nervous system activity. The overall system design optimizes high signal to noise ratio (SNR) of SCRs and achieves minimal distortion of the MEG signal. Its development was based on a fiber-optic transformer, with voltage to optical transduction inside the MSR and demodulation outside the MSR. The system was calibrated and tested inside the MEG environment by using a 151-channel CTF whole head system (VSM MedTech Ltd.). MEG measurements were recorded simultaneously to SCRs from five healthy participants to test whether the developed system does not generate artifacts in the MEG data. Two measurements were performed for each participant; one without the system in the MSR, and one with the system in the MSR, connected to the participant and in operation. The data were analyzed using the time and frequency domains in separate statistical analysis. No significant differences were observed between the two sessions for any statistic index. Our results show that the system allows high quality simultaneous recordings of SCRs and MEG signals in the MSR, and can therefore be used as routine addendum to neuroscience experiments.