High Frequency Somatosensory Evoked Magnetic Fields Recorded With Meg (Old)

** Old version - do not use ** This dataset contains somatosensory evoked responses recorded with Elekta TRIUX magnetoencephalography (MEG) system. The purpose of the measurements was specifically to examine high-frequency (HF) somatosensory responses, which have very small amplitude. To this end, a large number of responses (thousands) were recorded with a short interstimulus interval (randomized between 300-350 ms). A constant-current electric stimulator was used, with the electrodes placed around the median nerve at the right wrist. The magnitude of the current was individually determined so that the stimulation was slightly below motor threshold; it was approximately 7 mA. The length of the current pulse was set at 200 microseconds. Both datasets contain raw FIFF files and MRIs in DICOM format. There are two recordings for subject 'A' and one for subject 'B'. The length of each recording is approximately 15 minutes. The data of subject 'A' has more prominent high-frequency responses and smaller stimulator artifact. Both subjects also have a 2-minute empty room recording, acquired just before the actual measurement. MEG recording parameters: sampling frequency 3000 Hz, analog lowpass 1000 Hz. Single-shot HPI was done at the beginning of the measurement, but continuous HPI was not used. No active shielding systems were in use. The data were recorded at the BioMag laboratory of Helsinki University Central Hospital. The two subjects were healthy male volunteers, age 38-40 years.