Department of Molecular Physiology, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
Kenichi Ohki
Department of Molecular Physiology, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan; Department of Physiology, The University of Tokyo School of Medicine, Tokyo, Japan; International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo School of Medicine, Tokyo, Japan; Institute for AI and Beyond, The University of Tokyo School of Medicine, Tokyo, Japan; CREST, Japan Science and Technology Agency, Saitama, Japan
Department of Biophysics, Kyoto University Graduate School of Science, Kyoto, Japan; CREST, Japan Science and Technology Agency, Saitama, Japan; Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
The developing neocortex exhibits spontaneous network activity with various synchrony levels, which has been implicated in the formation of cortical circuits. We previously reported that the development of callosal axon projections, one of the major long-range axonal projections in the brain, is activity dependent. However, what sort of activity and when activity is indispensable are not known. Here, using a genetic method to manipulate network activity in a stage-specific manner, we demonstrated that network activity contributes to callosal axon projections in the mouse visual cortex during a ‘critical period’: restoring neuronal activity during that period resumed the projections, whereas restoration after the period failed. Furthermore, in vivo Ca2+ imaging revealed that the projections could be established even without fully restoring highly synchronous activity. Overall, our findings suggest that spontaneous network activity is selectively required during a critical developmental time window for the formation of long-range axonal projections in the cortex.
