Ultrasonic neuromodulation in a rat model: in vivo determination of the acoustic pressure threshold and spatial distribution in the brain
Résumé
The recent discovery that low-intensity pulsed ultrasound can be used to stimulate the brain non-invasively and without any noticeable tissue damage is expected to have a major impact in neuroscience in the coming years. Nevertheless, this emerging field also raised a lot of unanswered questions: how does ultrasound affect neurons on a molecular and cellular level? Does it correspond to a pure mechanical interaction? A controversy even rose on whether an intensity threshold exists for inducing a neurological response or if such an effect always occurs whatever the ultrasonic intensity. In this study, the motor responses of rats (N=6) were investigated as a function of the in situ excitation pressure level and a sharp threshold was observed at 0.5MPa. Moreover a set of micro CT-based simulations were performed in order to investigate the pressure distribution in the cranial cavity. The presence of modes in the cavity was observed thus refuting the hypothesis of a localized excitation in the state of art experiments. The corresponding mechanical stress imposed on brain tissue give new insights for understanding the underlying potential mechanisms.
Domaines
Acoustique [physics.class-ph]
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