# Population rate coding in recurrent neuronal networks with undetermined-type neurons

## TL;DR

This study explores population rate coding in recurrent neural networks with neurons of undetermined excitatory or inhibitory effects, revealing that such models can effectively encode stimuli and are enhanced by specific parameter combinations.

## Contribution

It introduces a novel neural network model with undetermined neuron types, demonstrating effective stimulus encoding and the importance of receptor co-release in neural coding.

## Key findings

- Networks encode stimuli well with undetermined neurons
- Intermediate recurrent probability enhances encoding performance
- Parameter tuning improves population rate coding

## Abstract

Neural coding is a key problem in neuroscience, which can promote people's understanding of the mechanism that brain processes information. Among the classical theories of neural coding, the population rate coding has been studied widely in many works. Most computational studies considered the neurons and the corresponding presynaptic synapses as pre-determined excitatory or inhibitory types. According to physiological evidence, however, that the real effect of a synapse is inhibitory or excitatory is determined by the type of the activated receptors. The co-release of excitatory and inhibitory receptors in the same synapse exists widely in the brain. In this paper, we study the population rate coding in recurrent neuronal networks with undetermined neurons and synapses, different from the traditional works, in which one neuron can perform either excitatory or inhibitory effect to the corresponding postsynaptic neurons. We find such neuronal networks can encode the stimuli information in population firing rate well. We find that intermediate recurrent probability together with moderate Inhibitory-Excitatory strength ratio can enhance the encoding performance. Suitable combinations of the previous two parameters with the noise intensity, the excitatory synaptic strength and the synaptic time constant have promoting effects on the performance of population rate coding. Finally, we compare the performance of population rate coding between the traditional (determined) model and ours, and we find that it is rational to consider the co-release of inhibitory and excitatory receptors.