Abstract
Action potential (AP)-mediated cell-to-cell communication is essential for the frequency-locking and phase-synchronization of the clock cells within the biological master clock, suprachiasmatic nucleus (SCN). Nevertheless, the morphology of its network connectivity is largely unexplored. Here, with an optimized optogenetic light-stimulation and scanning protocol, we report some key characteristics of the inhibitory receptive field (IRF), the area which brings inhibitory synaptic currents to a given target cell, and basic statistics of the inhibitory network connections of rat SCN clock cells. ChR2 transfected, slice cultures of rat SCN were stimulated by a blue power LED light in a repetitive box-scanning modes, while a target cell was whole-cell patched. The registered inhibitory postsynaptic currents, which were brought by light-induced APs of presynaptic neurons, were mostly GABAergic. The sizes and shapes of IRFs of SCN cells were very diverse, and the number of presynaptic cells making up the IRF of a given target cell followed an exponential distribution with an average value of 8.9 approximately, according to our clustering analysis which is based on a hybrid measure D, combining the physical distance r and the difference in the current amplitudes of two different sites. Although this estimate inevitably depends on the construct of the measure D, it is found not so sensitive on the parameter w, which weighs the relative significance of the current amplitude different with respect to the physical distance r: The average number of presynaptic neurons varies < 26% over a significant range of 0 < w < 30. On average, the presynaptic connection number density around a target cell falls off as an exponentially decreasing function of r. But, its space constant (~210.7 μm) is quite large that long-range (>210.7 μm) neural connections are abundant (>66.9%) within the SCN.
Original language | English |
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Pages (from-to) | 2814-2829 |
Number of pages | 16 |
Journal | European Journal of Neuroscience |
Volume | 50 |
Issue number | 5 |
DOIs | |
Publication status | Published - 2019 Sept 1 |
Bibliographical note
Funding Information:Funding information This work was supported by the Ministry of Science, ICT & Future Planning (MSIP), of Korea (grant No. NRF-2016R1D1A1B03930591). This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (grant No. 2016R1D1A1B03930591, 2019R1A2C2005989). We thank J. H. Hong and anonymous referees for their useful comments and suggestions. WC is supported by Institute for Basic Science (IBS-R023-D1).
Publisher Copyright:
© 2019 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
Keywords
- neural connectome of SCN
- node-degree distribution
- receptive field of SCN clock cells
ASJC Scopus subject areas
- General Neuroscience