Biochemical networks in nervous systems: expanding neuronal information capacity beyond voltage signals

In addition to synaptically mediated signals that are based on changes in m embrane potential, neurons also generate and receive many types of signals that involve biochemical pathways, some of which are independent of voltage . Although networks of biochemical pathways have often been thought of as b eing only neuromodulatory, recent computational and experimental studies ha ve highlighted how these pathways can also integrate and transfer informati on themselves. Interactions between biochemical pathways involving positive and negative feedback loops allow biochemical signals to exhibit emergent properties, most notably bistability and oscillations. New and evolving tec hniques, including real-time imaging of second messengers, hold the promise of illuminating information processing that cannot be detected using micro electrodes, and revealing how 'biochemical integration' might contribute to the computational abilities of the nervous system.