A new @PNASNews paper by Laurent Koessler al. is foundational for the field of transcranial Direct Current Stimulation (tDCS). pnas.org/doi/10.1073/pnas.24… The paper adds to literature showing that small electric fields (<0.5 V/m) can produce acute and lasting changes in neuronal function. As I see it, this paper bridges decades of animal research with human protocols. Dozens of DC stimulation studies in brain slices are based around modulating repeated evoked response (eg. physoc.onlinelibrary.wiley.c…). This is inherently "functional targeting" since the ongoing (evoked) activity is specifically modulated. Laurent KOESSLER show the analog in humans alongside exhaustive controls and analysis. Koessler et al use HD-tDCS, though not an explicitly focalized montage. Still, results may not have been so conclusive used sponge-pad electrodes. The authors demonstrate neuromodulation at conventional (2 mA) intensities but note electric fields increase linearity with applied current- further enhancing outcomes. I only disagree with the implication there is evidence for increased risk (eg. 4 mA). Summary: Koessler et al. meaningfully add to the literature that 2 mA (~0.5 V/m) tDCS modulate brain activity in a targeted manner.