ITBS-induced LTP-like plasticity parallels oscillatory activity changes in the primary sensory and motor areas of macaque monkeys

Abstract

Recently, neuromodulation techniques based on the use of repetitive transcranial magnetic stimulation (rTMS) have been/nproposed as a non-invasive and efficient method to induce in vivo long-term potentiation (LTP)-like aftereffects. However,/nthe exact impact of rTMS-induced perturbations on the dynamics of neuronal population activity is not well understood./nHere, in two monkeys, we examine changes in the oscillatory activity of the sensorimotor cortex following an intermittent/ntheta burst stimulation (iTBS) protocol. We first probed iTBS modulatory effects by testing the iTBS-induced facilitation of/nsomatosensory evoked potentials (SEP). Then, we examined the frequency information of the electrocorticographic signal,/nobtained using a custom-made miniaturised multi-electrode array for electrocorticography, after real or sham iTBS. We/nobserved that iTBS induced facilitation of SEPs and influenced spectral components of the signal, in both animals. The latter/neffect was more prominent on the h band (4–8 Hz) and the high c band (55–90 Hz), de-potentiated and potentiated/nrespectively. We additionally found that the multi-electrode array uniformity of b (13–26 Hz) and high c bands were also/nafflicted by iTBS. Our study suggests that enhanced cortical excitability promoted by iTBS parallels a dynamic reorganisation/nof the interested neural network. The effect in the c band suggests a transient local modulation, possibly at the level of/nsynaptic strength in interneurons. The effect in the h band suggests the disruption of temporal coordination on larger/nspatial scales.