Effects of transcranial focused ultrasound stimulation to human lateral geniculate nucleus on visual perception and steady-state visual evoked potentials

Transcranial focused ultrasound stimulation (TUS) is a novel method that non-invasively alters neural activity in deep brain regions. To facilitate the integration of TUS into cognitive neuroscience and neuropsychiatry, researchers sought to explore the correlation between various sonication parameters and neuromodulatory effects.

Their study focused on the human subcortical visual pathway, employing steady-state visual evoked potentials (SSVEPs) and contrast-response psychophysics as neural and behavioral indicators of visual pathway function.

Utilizing structural MRIs and acoustic simulations, the researchers targeted the lateral geniculate nucleus (LGN), employing a neuronavigated depth-steerable 4-element TUS transducer at a range of pulse repetition frequencies (PRFs) with 68 W/cm2 of free-water ISPPA and a 10% duty cycle. Participants were unaware of the stimulation conditions due to a white-noise auditory mask.

Out of 25 neurotypical participants, none observed any changes in SSVEP response amplitude, SSVEP response latency, or perceptual behavior following TUS stimulation.

Further analysis of the simulated transducer positions revealed that the LGN was likely within the TUS focus in most participants. However, there was no correlation between the accuracy of targeting and the observed changes in neural activity during TUS. The findings suggest a need for caution when considering the impact of neuronavigated TUS for online causal manipulations in cognitive and clinical neuroscience.