[[Focused ultrasound]] (FUS) involves using [[ultrasonic wave]]s that can be precisely targeted and focused on specific brain [[region]]s. When applied with [[microbubble]]s, small gas-filled bubbles injected into the bloodstream, FUS can transiently disrupt the BBB. This [[disruption]] allows therapeutic [[agent]]s to cross the [[blood-brain barrier]] and enter the brain [[tissue]], where they can exert their effects.