Interactions Between Purkinje Cells and Granule Cells Coordinate the Development of Functional Cerebellar Circuits

Cerebellar development has a remarkably protracted morphogenetic timeline that is coordinated by multiple cell types. Here, we discuss the intriguing cellular consequences of interactions between inhibitory Purkinje cells and excitatory granule cells during embryonic and postnatal development. Purkinje cells are central to all cerebellar circuits, they are the first cerebellar cortical neurons to be born, and based on their cellular and molecular signaling, they are considered the master regulators of cerebellar development. Although rudimentary Purkinje cell circuits are already present at birth, their connectivity is morphologically and functionally distinct from their mature counterparts. The establishment of the Purkinje cell circuit with its mature firing properties has a temporal dependence on cues provided by granule cells. Granule cells are the latest born, yet most populous, neuronal type in the cerebellar cortex. They provide a combination of mechanical, molecular and activity based cues that shape the maturation of Purkinje cell structure, connectivity and function. We propose that the wiring of Purkinje cells for function falls into two developmental phases: an initial phase that is guided by intrinsic mechanisms and a later phase that is guided by dynamically-acting cues, some of which are provided by granule cells. In this review, we highlight the mechanisms that granule cells use to help establish the unique properties of Purkinje cell firing. This article is part of a Special Issue entitled: In Memoriam: Masao Ito-A Visionary Neuroscientist with a Passion for the Cerebellum. (c) 2020 IBRO. Published by Elsevier Ltd. All rights reserved.

Automated summary

Cerebellar development is a complex process involving interactions between inhibitory Purkinje cells and excitatory granule cells, with Purkinje cells considered as master regulators of the process. The connectivity and function of Purkinje cells are influenced by cues provided by granule cells, which help shape the firing properties of Purkinje cells. This dynamic interplay between different cell types is essential for the establishment of mature cerebellar circuits.