# Temporal interference stimulation disrupts spike timing in the primate brain

## TL;DR

This study shows that temporal interference stimulation can non-invasively disrupt brain activity in primates but is too weak to create new rhythms.

## Contribution

The study provides empirical evidence on the effectiveness and limitations of TI stimulation in primates.

## Key findings

- TI reliably alters spike timing but not firing rate in primate neurons.
- TI is 80% weaker than other non-invasive brain stimulation methods.
- TI may be suitable for disrupting pathological oscillatory brain activity.

## Abstract

Electrical stimulation can regulate brain activity, producing clear clinical benefits, but focal and effective neuromodulation often requires surgically implanted electrodes. Recent studies argue that temporal interference (TI) stimulation may provide similar outcomes non-invasively. During TI, scalp electrodes generate multiple electrical fields in the brain, modulating neural activity only at their intersection. Despite considerable enthusiasm for this approach, little empirical evidence demonstrates its effectiveness, especially under conditions suitable for human use. Here, using single-neuron recordings in non-human primates, we establish that TI reliably alters the timing, but not the rate, of spiking activity. However, we show that TI requires strategies—high carrier frequencies, multiple electrodes, and amplitude-modulated waveforms—that also limit its effectiveness. Combined, these factors make TI 80 % weaker than other forms of non-invasive brain stimulation. Although unlikely to cause widespread neuronal entrainment, TI may be ideal for disrupting pathological oscillatory activity, a hallmark of many neurological disorders.

Whether and how temporal interference (TI) stimulation disrupt primate oscillatory brain activity are not fully understood. Here authors show TI stimulation can non-invasively disrupt oscillatory brain activity but three factors make it too weak to impose new rhythms on the primate brain. Thus, it may be a potential method for safely controlling pathological brain activity.