1. Healthy adults aged 18-65 years old will receive one single session of real TPS on the primary motor cortex.
2. Before and after TPS, participants will perform two visuomotor tasks (a simple reaction time task and a nine-hole peg test).
3. The stimulation target on the primary motor cortex will be determined by transcranial magnetic stimulation (TMS). Measurements of the resting motor threshold by TMS will be conducted for each participant before the real TPS session.

Sham stimulation comprises TPS on the vertex as the control region (sham control).

Stimulation duration, intensity, as well as pre- and post stimulation assessments are the same as in the experimental arm.

In this cross-over study, the order of the real and sham stimulation conditions will be randomized and separated by 24 hours.

A single session of TPS will be performed, applying 1000 pulses in the session (single ultrashort (3 μs) ultrasound pulses, 0.2-0.25 mJ mm-2, ~5 Hz pulse frequency)

Primary clinical outcome measure will be a change in movement time in nine-hole peg test after TPS. Less movement time is indicative of greater improvement in hand dexterity and motor function.

Primary clinical outcome measure will be a change in reaction time in Deary-Liewald reaction time task after TPS. Less reaction time is indicative of greater improvement in motor function.

The RMT will be measured before the TPS, which is indicative of the motor excitability. The investigators will explore the correlation between the RMT and post-TPS motor performance measured by the nine-hole peg test; as well as explore correlation between RMT and post-TPS motor performance measured by the Deary-Liewald reaction time task.