Ion channel distributions in cortical neurons are optimized for energy-efficient active dendritic computations

Abstract

The mammalian brain uses more than 20% of the energy consumed by the entire body. This enormous demand for energy is thought to impose strong selective pressure by which neurons evolve in ways that ensure robust function at minimal energy cost. Here we demonstrate that the ion channel expression patterns by which pyramidal tract neurons – the major output cell type of the cerebral cortex – could implement their complex intrinsic physiology is extremely widespread. Surprisingly, this wide spectrum does not reflect morphological variability, but the energy costs for generating dendritic calcium action potentials. We found that energy-efficient calcium action potentials require a low expression of slow inactivating potassium channels in the distal dendrites, an empirical observation whose significance remained unclear for more than a decade. Thus, cortical neurons do not utilize all theoretically possible ways to implement their functions, but instead appear to select those optimized for energy-efficient active dendritic computations.