Neuromodulation
Focused ultrasound can stimulate or suppress neural activity, depending on the parameters of the energy applied to neural tissue.
The mechanical effects of focused ultrasound are thought to dominate this mechanism, however, there is evidence of neuromodulation during various brain treatments at temperatures below the thermal ablation threshold.
Neuromodulatory effects could potentially enable a range of therapeutic benefits including:
- verifying targets in the brain prior to ablative procedures;
- suppressing epileptic seizures or symptoms of psychiatric disorders; and
- temporarily blocking nerves to treat pain;
Studies have shown that the mechanical effects of pulsed focused ultrasound can reversibly decrease the functionality of targeted neurons. This allows for the temporary blocking of neural signals from targeted locations within the brain or spinal/peripheral nerves. Such techniques hold promise in the treatment of epilepsy or chronic pain.
Conversely, pulsed focused ultrasound can be used to stimulate targeted neurons. Ultrasound energy with specific pulse parameters can trigger the activation and propagation of neural signals that could stimulate precise areas of the brain. This would enable the possibility of mapping neural networks and enhancing our understanding of the brain.
Finally, the thermal effects of focused ultrasound can also be used to induce neuromodulation. When brain tissue is raised to a slightly elevated temperature—lower than that required for thermal ablation—neural signals may be temporarily suppressed in that area. This technique can be used to confirm the target in the brain during neurological treatments (e.g. essential tremor) before delivering the therapeutic dose of ultrasound energy to create a permanent lesion.
Clinical trials are ongoing using neuromodulation to treat depression, obsessive-compulsive disorder, epilepsy, addiction, stroke, traumatic brain injury, and anxiety, among others.
Click here for additional references from PubMed.