Automated quantification of head-twitch response in mice via ear tag reporter coupled with biphasic detection

Background: Head-twitch response (HTR) is a manifestation of the serotonergic system behavioral pharmacology commonly used as a proxy of psychedelic drug action in rodents. New method: We developed a minimally invasive magnetic ear tag reporter and designed a detection system that performs a comprehensive characterization of each potential HTR event on an electromagnetic readout. Results: Magnetic ear tags were easy to install and generally well tolerated by the animals. On the low-threshold first phase of detection, the tags' signal recorded in a magnetometer was filtered and screened for potential HTR events. On the second phase, the detector performed a comprehensive spectral analysis evaluation of each event and identified the HTR characteristic distribution of power density. Our system delivered satisfactory performance in the identification of pharmacologically-induced HTR and discrimination power against common non-HTR behaviors. Comparison with existing methods: Our system offers a high-throughput solution for studying HTR in mice employing minimally invasive procedures and superior standalone discriminative power compared to our previously reported fully-automated approach. Conclusions: High-throughput identification of HTR utilizing magnetic ear-tagging and biphasic detection delivers satisfactory detection and discrimination power employing less invasive procedures.