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

Brain Stimul. 2017 Nov-Dec;10(6):1024-1031. doi: 10.1016/j.brs.2017.07.007. Epub 2017 Jul 26.


Background: Low intensity transcranial ultrasonic stimulation (TUS) has been demonstrated to non-invasively and transiently stimulate the nervous system. Although US neuromodulation has appeared robust in rodent studies, the effects of US in large mammals and humans have been modest at best. In addition, there is a lack of direct recordings from the stimulated neurons in response to US. Our study investigates the magnitude of the US effects on neuronal discharge in awake behaving monkeys and thus fills the void on both fronts.

Objective/hypothesis: In this study, we demonstrate the feasibility of recording action potentials in the supplementary eye field (SEF) as TUS is applied simultaneously to the frontal eye field (FEF) in macaques performing an antisaccade task.

Results: We show that compared to a control stimulation in the visual cortex, SEF activity is significantly modulated shortly after TUS onset. Among all cell types 40% of neurons significantly changed their activity after TUS. Half of the neurons showed a transient increase of activity induced by TUS.

Conclusion: Our study demonstrates that the neuromodulatory effects of non-invasive focused ultrasound can be assessed in real time in awake behaving monkeys by recording discharge activity from a brain region reciprocally connected with the stimulated region. The study opens the door for further parametric studies for fine-tuning the ultrasonic parameters. The ultrasonic effect could indeed be quantified based on the direct measurement of the intensity of the modulation induced on a single neuron in a freely performing animal. The technique should be readily reproducible in other primate laboratories studying brain function, both for exploratory and therapeutic purposes and to facilitate the development of future clinical TUS devices.

Keywords: Brain stimulation; Eye movements; Frontal eye field; Non-human primates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Female
  • Frontal Lobe / physiology
  • Macaca
  • Male
  • Neurons / physiology*
  • Psychomotor Performance / physiology*
  • Saccades / physiology*
  • Ultrasonic Therapy / methods*
  • Ultrasonic Waves*
  • Visual Cortex / physiology
  • Visual Fields / physiology