@article {69634,
	title = {Why do we have so many excitatory neurons?},
	journal = {bioRxiv},
	year = {2024},
	month = {2024 Oct 05},
	abstract = {<p>Approximately four in five neurons are excitatory. This is true across functional regions and species. Why do we have so many excitatory neurons? Little is known. Here we provide a normative answer to this question. We designed a task-agnostic, learning-independent and experiment-testable measurement of functional complexity, which quantifies the network{\textquoteright}s ability to solve complex problems. Using the larval Drosophila whole-brain electron microscopy connectome, we discovered the optimal Excitatory-Inhibitory (E-I) ratio that maximizes the functional complexity: 75-81\% percentage of neurons are excitatory. This number is consistent with the true distribution observed via scRNA-seq. We found that the abundance of excitatory neurons confers an advantage in functional complexity, but only when inhibitory neurons are highly connected. In contrast, when the E-I identities are sampled uniformly (not dependent on connectivity), the optimal E-I ratio falls around equal population size, and its overall achieved functional complexity is sub-optimal. Our functional complexity measurement offers a normative explanation for the over-abundance of excitatory neurons in the brain. We anticipate that this approach will further uncover the functional significance of various neural network structures.</p>
},
	doi = {10.1101/2024.09.24.614724},
	url = {https://doi.org/10.1101/2024.09.24.614724},
	author = {Wang, Qingyang and Cardona, Albert and Zlatic, Marta and Vogelstein, Joshua T. and Priebe, Carey E.}
}
