ganglia

Ganglia refers to a collection of neuron cell bodies found outside the central nervous system, forming a key part of the peripheral nervous system. In vertebrates, ganglia serve as relay points and processing hubs for sensory and autonomic signals, organized into structures such as dorsal root ganglia and autonomic ganglia. A ganglion typically contains neurons, glial cells, and supporting connective tissue, and its arrangement supports the transmission and modulation of nerve impulses.

The term derives from the Greek ganglion, meaning knot or swelling, reflecting the clustered appearance of these structures. In anatomy, ganglia can be found along peripheral nerves as well as within certain brain and spinal cord regions, where they contribute to signal processing and autonomic regulation.

Ganglia is also the name of an open-source distributed monitoring system designed for high-performance computing clusters and large-scale networks. It enables monitoring of numerous machines by collecting metrics on each node, aggregating data in centralized components, and presenting real-time graphs and dashboards. The architecture typically involves a daemon running on each host to collect metrics and a central aggregator to gather, store, and display the data. Ganglia is designed for scalability, capable of monitoring thousands of nodes, and is commonly used in compute clusters, grids, and data centers to track resource usage and performance trends.

In both senses, the term conveys the idea of a clustered collection that serves as a hub for processing, signaling, or monitoring.