A new gustometer: Template for the construction of a portable and modular stimulator for taste and lingual touch.

Taste research has been hampered by technical difficulties, mostly because liquid taste stimuli are difficult to control in terms of timing and application area. Exact stimulus control requires a gustometer; yet, existing devices are either not well-documented or rather inflexible. We designed a gustometer based on a computer-controlled, modular pump system, which can be extended through additional hardware modules, e.g. for heating of the stimuli or sending and receiving triggers. All components are available for purchase “off-the-shelf”. The pumps deliver liquids through plastic tubing and can be connected to commercially available or custom-made mouthpieces. We determined the temporal precision of the device. Onset delay showed minuscule variation within pumps (SD < 3 ms) and small differences between pumps (< 4.5 ms). Rise time was less than 2 ms (SD < 2 ms). Dosage volume bias was only 2%. To test whether the hemitongues could be stimulated independently, we conducted a behavioral experiment. 18 participants received tasteless stimuli to the left, right, or both sides of the tongue. The side of stimulation was correctly identified in 91% of the trials, indicating that the setup is suitable for lateralized stimulation. EEG responses to water and salty stimuli were recorded from two participants; the stimulation successfully evoked event-related responses, demonstrating the suitability of the device for use in electrophysiological investigations. We provide a Python-based open-source software package and a web interface to easily operate the system. We thereby hope to facilitate access to state-of-the-art taste research methods and to increase reproducibility across laboratories.