Noninvasive mapping of the electrically stimulated mouse brain using photoacoustic microscopy

Photoacoustic imaging techniques possess high optical contrast with ultrasonic resolution while exceeding imaging depths of pure optical techniques, affording high resolution images deep within scattering biological tissues. In this work, we employ reflection-mode photoacoustic microscopy to non-invasively monitor hemodynamic contrasts and map brain activity. Changes in vascular dynamics of the mouse somatosensory cortex were evoked through electrical stimulation of the hindpaw, resulting in increased photoacoustic intensities spatially correlated with contra-lateral vasculature. Results demonstrate the ability to map brain activation with vascular resolution in three-dimensions, as well as monitor single-vessel hemodynamics with millisecond temporal resolution. Furthermore, these results implicate the feasibility of photoacoustic microscopy to probe intra-cortical single-vessel hemodynamics and pave the way for more extensive functional brain imaging studies.