Brain-Computer-Interfaces(BCI) remain the only way to communication in complete paralysis. In most cases of advanced amyotrophic lateral sclerosis (ALS) with progressive loss of motor functions patients first communicate with eye-trackers, then with decreasing amplitude of eye movements use Hybrid micro-eyemovement-EEG-BCIs and with complete cessation of all motor innervation non-invasive BCIs with EEG or Near-Infrared-Spectroscopy (NIRS) allow simple yes-no communication with high error rates . Finally , in CLIS (complete locked-in state), only invasive recordings of neuronal activity from micro-electrode arrays implanted in cortical tissue may allow voluntary selection of letters and words with changes in cellular responses.We provide examples of each and show that responding from one or few cortical cells may be sufficient for BCI based communication.