This document provides methods and materials involved in detecting and delivering neurochemical signals, electrophysiological signals, ions, or combinations thereof within a mammal. For example, systems that can include one or more implantable devices containing probes configured to detect neurochemical signals (e.g., neurotransmitter concentrations), electrical signals, ions, or combinations thereof and one or more implantable devices containing electrodes and/or microfluidic delivery components configured to deliver neurochemical signals (e.g., neurotransmitters), electrical signals, ions, or combinations thereof to one or more locations within a mammal are provided.
