Sparse spike trains and the limitations of rate codes underlying rapid behaviour

Abstract

Animals live in highly dynamic worlds, utilising sensorimotor circuits to rapidly process information and drive behaviours. For example, dragonflies are aerial predators which react to movements of prey within tens of milliseconds. These pursuits are likely controlled by identified neurons in the dragonfly, which have well-characterized physiological responses to moving targets. Predominantly, neural activity in these circuits are interpreted in the context of a rate code, where information is conveyed by changes in the number of spikes over a given time. However, such a description of neuronal activity is difficult to achieve in real-world, real-time scenarios. Here, we contrast a neuroscientists post-hoc view of spiking activity with the information available to the animal in real-time. We describe how performance of a rate code is readily overestimated and outline a rate codes significant limitations in driving rapid behaviours.