Beams of ultrasound provide a non-invasive method to specifically alter activity deep within a primate's brain. Changes were long-lasting and yet reversible: forty seconds of repetitive ultrasound triggered changes that lasted up to two hours without inducing structural damage.

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Beams of ultrasound provide a non-invasive method to specifically alter activity deep within a primate's brain. Changes were long-lasting and yet reversible: forty seconds of repetitive ultrasound triggered changes that lasted up to two hours without inducing structural damage.