These structures are enriched in filamentous forms of the synaptic protein α-synuclein4, 5 as well as the small regulatory protein ubiquitin.

However, it is unknown whether taxa that induce specific immune responses, such as the segmented filamentous bacteria in mice, protect against metabolic disease.

Mostly, this relates to the release of certain chemicals when axons, the filamentous connections between nerve cells, are damaged.