Complex sentence: There is no structural or heating effect that may damage the tissue, with only action potentials generated in the target area; any risks are due to the arrival of action potentials to synapses and the natural activation of the postsynaptic cell.
Split into simpler sentences: There is no structural or heating effect that may damage the tissue; only natural signals (action potentials) are generated in the target area. If there are any risks, these are due to the arrival of action potentials to synapses and the natural activation of the postsynaptic cell.