Fig. 1. All-fiber-transmission photometry system based on a multi-branch fiber bundle⁹. (a) Schematic diagram of the system; (b) Schematic diagram of animal surgery and virus injection; (c) Averaged DA signal and neuronal Ca²⁺ signal transients in response to unexpected sucrose solution; (d) Averaged DA signal and neuronal Ca²⁺ signal transients in response to phasic and tonic optogenetic stimulation. (Credit: this figure was provided by the authors of Ref.9.)