Fig. 1.

Neuronal activity and experience may bias myelination bidirectionally. Schematic of two complementary mechanisms by which neuronal activity putatively shapes myelination. A: previous literature has largely focused on increases in myelination. Several strands of evidence suggest that both increases in neuronal activity and experience (such as motor learning) may drive such increases in myelin during adulthood. However, the question remains open whether axonal diameter is regulated in a similar manner. B: summary of the deprivation-driven mechanism described by Sinclair and colleagues (2017). The results suggest that auditory globular bushy cell projections in the auditory brain stem (left) are affected by sensory deprivation, which leads to decreases in their myelin thickness and axonal diameter (right). Though it is foreseeable that sensory deprivation may lead to an overall decrease of neuronal firing and that the deprivation-driven response may be inactivity dependent, the specific pattern of neuronal activity triggered by auditory deprivation was not explored.