The sensory responses of cortical neuronal populations following training have been extensively studied. However, the spike firing properties of individual cortical neurons following training remain unknown. Here, we have combined two-photon Ca2+ imaging and single-cell electrophysiology in awake behaving mice following auditory associative training. We find a sparse set (~5%) of layer 2/3 neurons in the primary auditory cortex, each of which reliably exhibits high-rate prolonged burst firing responses to the trained sound. Such bursts are largely absent in the auditory cortex of untrained mice. Strikingly, in mice trained with different multitone chords, we discover distinct subsets of neurons that exhibit bursting responses specifically to a chord but neither to any constituent tone nor to the other chord. Thus, our results demonstrate an integrated representation of learned complex sounds in a small subset of cortical neurons.
Bibliographical noteFunding Information:
The authors are grateful to Dr. X.-Q. Wang, Dr. S. Song, Dr. S. Jacob, Dr. H. Adelsberger, Dr. S. Remy, Dr. O. Barnstedt, M. Fabiszak, Dr. W. Freiwald, Dr. Q. Wen, Dr. D. Kleinfeld, Dr. K. Svoboda, Dr. S. Wu, Dr. R. Quian Quiroga, Dr. J.-D. Wu and Dr. W. Ku for very helpful discussions and comments; to Ms. Jia Lou for help in composing and layout editing of the figures. This study was supported by grants from the National Natural Science Foundation of China (31925018, 31861143038, 31921003, 81671106, 31700933, 81771175, 61705251), the Ministry of Science and Technology of China (2018YFA0109600), the Key Scientific Research Equipment Development Project of the CAS (Super-resolution Microscopy Systems and Key Components, ZDYZ2013-1), and the “100-Talents Program for Elite Engineers” of the CAS (H.J.). A.K. is a Hertie Senior Professor of Neuroscience at TUM and a CAS President’s Distinguished International Visiting Fellow. X.C. is a fellow of the CAS Center for Excellence in Brain Science and Intelligence Technology, and also a member of the Institute of Brain and Intelligence at the Third Military Medical University.
© 2020, The Author(s).