Neurotransmitters carrying specific chemical information play a key role in the nervous system, which inspires ion-based devices to mimic biological functions of nervous system, including sensing, transduction, and computing. In this work, the interaction mechanism of zwitterionic amino acids, glycine (Gly), and gamma-aminobutyric acid (GABA) (two common inhibitory neurotransmitters) are analyzed with porous carbon electrodes. The charge balance of these zwitterionic neurotransmitters relies on zwitterion protonation in the vicinity of the negative electrodes (produced cations adsorbed by the negative electrode) and deprotonation near the positive electrode (produced anions to balance the positive charges) as demonstrated based on the theoretical dissociation analyses and local pH measurements. Additionally, electrosorption-induced concentration changes of Gly and GABA in aqueous solutions and phosphate-buffered saline (PBS) solutions are realized by electrosorption via nanoporous carbon electrodes. Based on this mechanistic understanding, the ionologic functions in printed ionic electrolyte double-layer transistors are demonstrated. These neurotransmitter-based iontronic devices hold potential for further organism-machine interfacing and neuromorphic computing applications.