Virtual Neurons Reveal How Magnetic Pulses Rewire the Brain

Repetitive transcranial magnetic stimulation (rTMS) is a powerful non-invasive tool for influencing brain activity, yet the precise mechanisms governing how it rewires neural connections remain somewhat mysterious. Addressing this blind spot, scientists have developed a comprehensive new modelling framework capable of simulating rTMS-induced synaptic plasticity—the ability of synapses to strengthen or weaken over time—in biophysically realistic neurons.

By integrating a voltage-dependent plasticity model with electrical field simulations, the team successfully replicated 'long-term potentiation' (LTP) in virtual hippocampal cells. This process, essential for memory and learning, was observed to be strongly distance-dependent; stimulation at 10 Hz triggered changes primarily at proximal synapses close to the neuron's centre, aligning perfectly with previous biological experiments. Conversely, reducing the frequency to 5 Hz or 1 Hz resulted in a predicted decrease in plasticity amplitude.

The study also explored complex patterns like theta-burst stimulation (TBS). The model demonstrated that rMS TBS-evoked plasticity is remarkably robust, facilitated by dendritic spikes—sharp electrical pulses in the neuron's branches—and remains effective even when inhibitory signals attempt to suppress it. This high-resolution modelling offers a vital platform for screening stimulation parameters, allowing researchers to refine rTMS protocols efficiently before clinical application.