Concentration-dependent dynamics of olfactory sensory adaptation in honey bees

Sensory systems continuously adjust their processing of environmental stimuli based on animal's most recent sensory experience, allowing it to optimize the detection and perception of changes in behaviorally relevant information over stimuli that carry little or no predictive value. One of the main phenomena that rapidly adjusts the system is sensory adaptation, which is defined as a decrease in sensitivity or response to a stimulus after sustained exposure to it. In this study, we investigated whether and how olfactory sensory adaptation in honey bees depends on stimulus concentration. Using electroantennograms (EAG), we measured peripheral olfactory receptor neuron (ORN) activity across different concentrations of acetophenone and 1-hexanol. Our findings reveal a strong concentration dependency in adaptation dynamics: both the initial control pulse amplitudes and the adapted-to-control pulse ratios vary significantly by concentration. Furthermore, response temporal dynamics are altered; the width of the adapted pulse, measured as the time the signal remains at 50% of maximum amplitude, increases significantly post-adaptation compared to control pulses, particularly at higher stimulus concentrations. These findings suggest that peripheral sensory responses are dynamically adjusted according to stimulus intensity, which may help maintain effective odor detection in complex and fluctuating olfactory environments.