Mossy Fibers Terminate Directly Within Purkinje Cell Zones During Mouse Development - PubMed (original) (raw)

Mossy Fibers Terminate Directly Within Purkinje Cell Zones During Mouse Development

Roy V Sillitoe. Cerebellum. 2016 Feb.

Abstract

The cerebellum is organized into a map of zones that is manifested in various ways according to gene expression, anatomical connectivity, neuronal firing properties, behavioral specificity, and susceptibility to disease. At the center of every zone is the Purkinje cell, the principal cell type of the cerebellum and sole output of the cerebellar cortex. During development, Purkinje cells are thought to coordinate the zonal patterning of all other cell types. However, the morphogenetic mechanism that mediates the interaction between Purkinje cells and afferent fibers remains unclear. To address this problem in vivo, I took advantage of a rapid fluorescent-based transynaptic tracing approach to determine the nature of mossy fiber to Purkinje cell connectivity during early postnatal development, a period when the afferent map is assembling into clear-cut zonal circuits. By injecting WGA-Alexa 555 into the lower thoracic-upper lumber spinal cord, I found that spinocerebellar mossy fibers transynaptically transfer tracer into zones of Purkinje cells that are directly adjacent to the fibers. The traced Purkinje cell zones formed a zebrin-like pattern that was defined by the expression of neurofilament heavy chain (NFH), a marker of zones in the postnatal developing cerebellum. These results suggest that Purkinje cells generate the zonal circuit map by using molecular cues, neuronal activity, and synaptic contact.

Keywords: Circuitry; Neural tracing; Postnatal; Spinocerebellar; Transynaptic; Zones.

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Figures

Fig 1

a Schematic illustrating the injection of WGA-Alexa 555 into the spinal cord of a pup. b WGA-Alexa 555 tracing of spinocerebellar mossy fibers (arrow) and transynaptic tracing of neuronal somata (double arrow) in the anterior cerebellum. c, d NFH staining revealed a pattern of zones that was complementary to a subset of traced Purkinje cells. e, Some of the WGA-Alexa 555 traced neuronal somata were co-labeled with NFH, a marker for Purkinje cells (yellow circles). The layers of the cerebellar cortex are indicated by ml (molecular layer), pcl (Purkinje cell layer), and gl (granular layer). The scale bar = 100 μm in B (applies to C, D) and 50 μm in E.

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Mossy Fibers Terminate Directly Within Purkinje Cell Zones During Mouse Development - PubMed (original) (raw)