Ambulatory physiologic monitoring system supporting EMA with self-administered visual evoked potential recording at randomized intervals

This paper provides an overview of an ambulatory 24-hour physiologic recording system supporting ecological momentary assessments (EMAs) which include visual evoked potentials (VEPs) in the subject´s normal living environment. The PDA-based system´s EMA methods include oral recording, questionnaire, and reaction-time-type attention testing. This report focuses on the system´s unique capability of subject-administered VEP testing in the remote environment. Results reported include single-subject VEP waveforms recorded in the subject´s home during the evening portion of a 24 hour period at scheduled times the subject was unaware of in advance. The VEP testing paradigm was a 100 trial, Go/NoGo type test. The visual stimuli were presented on the handheld PDA device with wireless stimulus marker trigger information being transmitted to the ambulatory EEG recording unit via a Bluetooth interface. Post-acquisition editing and analysis results demonstrate reliable ambulatory VEPs can be obtained. The system implementation is a further extension of our work investigating the identification of stress-related physiologic marker information in a primary caregiver´s home environment. The demonstrated EMA-based VEP recording capabilities added to our previously reported 24-hour ambulatory data collection platform (CAMAS) open the door to new opportunities supplementing studies in fields such as ambulatory psychophysiology and cognitive-neuroscience.