Information transmission at 500 bits/s by action potentials in a mechanosensory neuron of the cockroach

Action potentials are widely used to transmit information within nervous systems but information encoding and transmission rates by action potentials are poorly understood. In the absence of knowledge about encoding, most previous work has used signal-to-noise ratios to estimate information capacities. We used a mechanosensory neuron to transmit information by a simple encoding scheme that allowed us to measure the transmission rate directly. Using either mechanical or electrical stimulation, information was transmitted at rates up to 500 bits/s, higher than ever reported before for real action potentials. However, the maximum possible message length decreased strongly with transmission rate, from ~infinite at 100 bits/s to ~100 ms at 500 bits/s, probably due to ionic adaptation processes within the neuronal membrane.