Statistically inferred neuronal connections in subsampled neural networks strongly correlate with spike train covariance

Abstract

Statistically inferred neuronal connections from observed spike train data are often skewed from ground truth by factors such as model mismatch, unobserved neurons, and limited data. Spike train covariances, sometimes referred to as “functional connections,” are often used as a proxy for the connections between pairs of neurons, but reflect statistical relationships between neurons, not anatomical connections, and moreover are not casual. Connections inferred by maximum likelihood inference, by contrast, can be constrained to be causal. However, we show in this work that the inferred connections in spontaneously active networks modeled by stochastic leaky integrate-and-fire networks strongly reflect covariances between neurons, not causal information, when many neurons are unobserved or when neurons are weakly coupled. This phenomenon occurs across different network structures, including random networks and balanced excitatory-inhibitory networks.