Spatiotemporal Analysis of Brain Activity Response Using Near Infrared Spectroscopy

Abstract

—Near infrared spectroscopy (NIRS) is an optical imaging tool that provides cerebral hemodynamics in response to changes in neural activity. Analysis of hemodynamic response to evoked stimulation is a research topic that tries to understand the mechanism of stimulation perception. In that context, cross correlation and optical flow were used to identify spatiotemporal features of brain activity after acupuncture stimulation in NIRS data. The results presented bilateral activations in the primary somatosensory cortex which were consistent with similar studies. The time dependent cross correlation analysis exhibited dominant channels and delays among channels that can be seen as relationships between cortical areas. The optical flow computation showed the origin of cortical activity and the spatial distribution of the evoked response in the brain cortex. This study contributes to the research field to investigate hemodynamic response in the cerebral cortex after evoked stimulation using near infrared spectroscopy.  Index Terms—hemodynamic response, evoked stimulation, fNIRS, optical flow, cortical activity