Reappraisal of Bergmann glial cells as modulators of cerebellar circuit function - PubMed (original) (raw)

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Reappraisal of Bergmann glial cells as modulators of cerebellar circuit function

Chris I De Zeeuw et al. Front Cell Neurosci. 2015.

Abstract

Just as there is a huge morphological and functional diversity of neuron types specialized for specific aspects of information processing in the brain, astrocytes have equally distinct morphologies and functions that aid optimal functioning of the circuits in which they are embedded. One type of astrocyte, the Bergmann glial cell (BG) of the cerebellum, is a prime example of a highly diversified astrocyte type, the architecture of which is adapted to the cerebellar circuit and facilitates an impressive range of functions that optimize information processing in the adult brain. In this review we expand on the function of the BG in the cerebellum to highlight the importance of astrocytes not only in housekeeping functions, but also in contributing to plasticity and information processing in the cerebellum.

Keywords: Bergmann glia; astrocytes; cerebellar zone; cerebellum; neuron-glia interactions; zebrin.

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Figures

Figure 1

Figure 1

Embedding of Bergmann glial cells in cerebellar circuits and zones (A). Arrangement of BGs relative to a single purkinje cell (PC). Left: Single BG indicating that radial fibers predominantly branch in the parasagittal plane, i.e., along the rostro-caudal axis of the cerebellum. BGs have up to 5 radial fibers that extend over the full depth of the molecular layer. In addition, BG radial fibers give off small side branches or BG microdomains (not shown) that predominantly wrap around parallel fiber- PC synapses (Grosche et al., 2002). Right: planes at different depths illustrating the PC-BG relationship. Inset 1: PC layer with arrangement of a monolayer of BG and PC somata at a density of 8 BGs (blue) to 1 PC. Inset 2: molecular layer BG processes arrange in palisades to maximize interaction with parallel fibers. Inset 3: BG fibers terminate at the surface with bulbous end-feet, the function of which has not been studied. (B) Zonation in the cerebellum. Left: Zebrin II (zebrin) expression in the cerebellum follows a pattern consisting of rostro-caudal parasagittal stripes that constitute functional modules with distinct input-output relationships. Right: coronal section through a cerebellar folium showing clear delineation of zebrin-positive, or negative borders. Other proteins such as the HSP25 display staining complementary to Zebrin II. BGs display a similar zonal expression of HSP25 (Reeber et al., 2014), but with less distinct boundaries due to their morphology. R: rostral, C: caudal, M: medial, L: lateral.

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