Investigation on hemodynamic responses induced by peripheral and central FUS stimulation

Focused ultrasound (FUS) can modulate peripheral and central nervous systems. Functional ultrasound (fUS) can monitor neural activation in the brain via neurovascular coupling. In this paper, we investigated the hemodynamic responses induced by FUS neuromodulation on the peripheral and central nervous systems in mice. As far as peripheral FUS stimulation is concerned, cerebral blood volume (CBV) increases in somatosensory region and thalamus were observed and correlates with muscle activities measured with two unipolar electrodes at tibialis anterior muscle. It is shown that nerve displacement is followed by compound muscle activation which is followed by CBV increases in two region of interests. In case of central FUS stimulation, we demonstrated highly lateralized hemodynamic responses corresponding to sonicated sides using 4-MHz FUS with displacement imaging. Based on Pearson’s correlation coefficient, activated pixels showed robust hemodynamic responses over trials at different sonication sides where mean CBV increases, peaks at 3 ~ 4 s, and undergoes an undershoot before being stabilized to the baseline. In addition, the correlation map follows the spatial distribution of interframe displacement, which may indicate that the observed hemodynamic responses under our FUS parameters is mainly driven by acoustic radiation force.