Effects of temperature and analyte application technique on neuron-based chemical sensing

Results are presented which enhance the field of neuron-based sensing by providing insight on the effects of operating temperature and analyte application technique (pulse versus back-mixed) on sensing properties. In these studies, serotonin sensing attributes of giant visceral neurons VV1 and VV2 from the pond snail Lymnea stagnalis were measured. Experiments using a rapid fluid-exchange system reveal a concentration-dependent increase in maximum firing frequency similar to that reported earlier for a slow well-mixed application. With a rapid application, however, the maximum firing frequency is reached more quickly, and there is less cell-to-cell variability in both the maximum response and sensitivity. Given an application technique, an increase in temperature causes an increase in sensitivity and maximum firing frequency, as well as a decrease in the time required for the response to return to baseline following removal of the analyte. To provide insights on the kinetics of the serotonin-induced response, the effects of temperature and concentration on the rates of activation, recovery and desensitization were examined in detail. In general, it was found that an increase in temperature increases the rates of activation and desensitization, while the effects on recovery were not apparent. In addition, both the rates of activation and desensitization have a direct dependence on concentration while the rate of recovery has an inverse dependence.