Brain-computer interfaces (BCIs) recording brain signals via implantable sensors aims to substitute, restore, improve, add, or enhance human functions. However, wiring requirements for power transfer and signal transmission, acute immune response to implanted electrodes, and the limited scalability of the ever-popular microelectrode arrays prevent wide adaptation of BCIs. Here, we show that electro-plasmonic nanoparticles, plasmonic nanoparticles loaded with an electrochromic polymer, can overcome the limitations of the conventional implantable microelectrode arrays as BCI probes. Much like radio frequency identification (RFIDs) tags that use backscattering for remote readout, electro-plasmonic nanoparticles report the spiking activity of neurons by modulating the input light and the re-radiated light spectrum.  Our electro-plasmonic nanoantennas are non-invasive, wire-free, highly sensitive (field sensitivity up to 15.5%) and require no surgical implantation. We believe that electro-plasmonic neural probes can help usher in a new era of BCIs.