An automated tactile discrimination learning task for freely-moving mice.
1 Institute of Experimental Epileptology and Cognition Research
2 Medical Biophysics, Institute for Physiology and Pathophysiology, Heidelberg University
3 Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg University
4 Neuro and Sensory Physiology, Institute for Physiology and Pathophysiology, Heidelberg University
Sensory discrimination tasks are valuable tools to study neuronal mechanisms of perception and learning. In recent years, novel discrimination tasks have been developed for electrophysiological or imaging studies in head-fixed mice. However, discrimination tasks in which neurophysiological recordings are implemented into a more ecologically realistic setting with freely moving animals are still relatively scarce, especially for somatosensory studies. This study introduces a tactile discrimination task for freely moving mice, integrating electrophysiology and calcium imaging with cellular resolution. In this go/no-go paradigm, mice learn to discriminate between different aperture widths in order to forage for food rewards on a linear platform. We demonstrate that the task is whisker-dependent and that mice reliably discriminate aperture differences as small as 6 mm. The automation of the setup minimizes confounding factors; for example, the experimenter can leave the room during the recordings. The setup’s high flexibility facilitates investigations into diverse behavioral features, including tactile discrimination thresholds, valence-dependent behavior, and cognitive flexibility following a reversal of the task rule. The learning is highly stereotypical and reproducible across individual mice, with approximately 500 trials to reach expert level and approximately 1000 trials to relearn the rule after rule switching. We further demonstrate that electrophysiological recordings and calcium imaging can be conducted in the same paradigm such that multiple behavioral read-outs (learning progression, whisker motion, whisker touch, reward licking) can be synchronized with respective electrophysiological and imaging data, providing valuable data to help elucidate neural mechanisms of cognition and sensory processing.