Table 2 Non-invasive brain stimulation techniques: basic principles, target areas, and typical parameters

Transcranial magnetic stimulation

Use of magnetic fields to induce electric currents

Dorsolateral prefrontal cortex

Frequency: 1–20 Hz

(TMS)

in targeted brain regions

(DLPFC), motor cortex

Intensity: 50–100% of motor threshold

Pulse width: 100–300 microseconds

Transcranial direct current

Application of weak direct current through scalp

Dorsolateral prefrontal cortex

Current intensity: 1–2 mA

Stimulation (tDCS)

Electrodes to modulate cortical excitability

(DLPFC), motor cortex

Duration: 10–30 min

Polarity: anodal or cathodal

Transcranial alternating current

Delivery of sinusoidal current with specific frequency

Various depending on frequency

Frequency: varies (10–100 Hz)

Stimulation (tACS)

To target brain regions

And desired effect

Amplitude: typically 1–2 mA

Duration: varies (10–30 min)

Transcranial focused ultrasound

Use of ultrasound waves to target and modulate

Various depending on target region

Intensity: varies

(tFUS)

brain regions

(motor cortex, hippocampus)

Frequency: varies

Duration: varies