Transcranial ultrasonic stimulation modulates single-neuron discharge in macaques performing an antisaccade task

Area of Science:

• Neuroscience
• Neuromodulation
• Brain-computer interfaces

Background:

• Low-intensity transcranial ultrasonic stimulation (TUS) shows promise for non-invasive neuromodulation.
• Previous studies in rodents demonstrated robust effects, but human and large mammal studies yielded modest results.
• Direct recordings of neuronal responses to TUS are lacking, especially in primates.

Purpose of the Study:

• To investigate the effects of TUS on neuronal discharge in awake, behaving monkeys.
• To bridge the gap between rodent and human studies by using a primate model.
• To establish a method for real-time assessment of TUS effects on neuronal activity.

Main Methods:

• Simultaneous transcranial ultrasonic stimulation (TUS) of the frontal eye field (FEF) and recording of action potentials from the supplementary eye field (SEF) in macaques.
• Macaques performed an antisaccade task during stimulation.
• Control stimulation was applied to the visual cortex.

Main Results:

• SEF neuronal activity was significantly modulated shortly after TUS onset.
• 40% of recorded neurons showed significant changes in activity post-TUS.
• Half of the modulated neurons exhibited a transient increase in activity.

Conclusions:

• Non-invasive focused ultrasound's neuromodulatory effects can be assessed in real-time in awake primates.
• This method allows for direct measurement of TUS effects on single neurons.
• The findings support further parametric studies for optimizing TUS and facilitate the development of clinical TUS devices.