Development of a prototype for the analysis of multiple responses of the autonomic nervous system

The autonomic nervous system (ANS) drives different non-voluntary responses, which can be investigated by multiple sensors. We propose a modular hardware prototype for the noninvasive acquisition, processing and transmission of biological signals to analyze the ANS in synchrony with the video recording of the pupil. The implementation includes 1) two noninvasive sensors, a pulse oximeter and an electrodermal activity sensor, 2) a module able to collect the information and send it to the PC via USB and 3) a graphic user interface for visualization, synchronization and data saving. A series of experimental tests were performed to investigate the effect of different stimulations: light, dental occlusion, transcutaneous electrical nerve stimulation (TENS) and mental efforts. They indicate the reliability of the system and the importance of the joint detection of more signals for discriminating different states of the ANS. Specifically, heart rate, Galvanic response and pupil size were compared, showing some coherence in their oscillations and a different ability to discriminate between the stimulation conditions. Their joint detection is thus important for discriminating different states of the ANS.