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Sunday, July 19 • 8:00pm - 9:00pm
P186: Inhibitory neurons locate at a center of effective cortical networks, and have high ability to control other neurons.

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meeting ID : 942 2840 3499
password   : 985511


Motoki Kajiwara
, Masanori Shimono

The brain is a network system in which excitatory and inhibitory neurons keep the activity balanced in the highly non-uniform connectivity pattern of the microconnectome. It is well known that the relative percentage of inhibitory neurons is much smaller than excitatory neurons. So, in general, how the inhibitory neurons can keep the balance with the surrounding excitatory neurons is an important question.
This study simultaneously recorded electric signals from ~1000 neurons from seven acute brain slices of mice with a MEA (multi-electrode array) to analyze the network architectures of cortical neurons. Subsequently, we analyzed the spike data to reconstruct the causal interaction networks between the neurons from their spiking activities. The utilized analysis mainly consists of the following four steps: first, transfer entropy was adopted from previous research to reconstruct the neural network. Briefly, transfer entropy quantifies the amount of information transferred between neurons and is suitable for the effective connectivity analysis of neural networks. This allowed to elucidate the Microconnectome and the comprehensive and quantitative characteristics of interaction networks among neurons. Second, our study distinguishes between excitatory synapses and inhibitory synapses using a newly developed method called sorted local transfer entropy. Third, we also applied methods from graph theory to evaluate the network architecture. Especially, we observed that the precedence in centrality and controlling ability of inhibitory neurons. The centrality was quantified with K-core centrality, and the controlling ability was quantified with the ratio of nodes included in FVSs (Feedback Vertex Sets). Fourth, we stained acute brain slices and gave layer labels to individual neurons. Further detail will be shown in [1].
As the result, we found that inhibitory neurons, locating highly central and having strong controlling ability of other neurons, mainly locate in deep cortical layers by comparing with distribution of neurons coloured by NeuN immunostaining data. Preceding the observation, we also found that inhibitory neurons show higher firing rate than excitatory neurons, and that their firing rate also closely obey a log-normal distribution as previously known about excitatory neurons. Additionally, their connectivity strengths also obeyed a log-normal distribution.

Acknowledgements: This study was supported by several MEXT fundings (19H05215, 17K19456) and Leading Initiative for Excellent Young Researchers (LEADER) program, and grants from the Uehara Memorial Foundation.

1. Kajiwara M, Nomura R, Goetze F, Akutsu T, Shimono M. Inhibitory neurons are a Central Controlling regulator in the effective cortical microconnectome. bioRxiv. 2020.


Motoki Kajiwara

Master course, Kyoto University

Sunday July 19, 2020 8:00pm - 9:00pm CEST
Slot 01