Table 2 |.

Evidence of a requirement for oligodendrocyte and myelin plasticity in learning and memory

Learning paradigm	Age	Manipulation	Behavioural outcome and timeline	conclusion	Refs
Motor learning (complex wheel with irregularly spaced rungs)	P60–90	Conditional Myrf deletion in OPCs, preventing OPC differentiation	Impaired running speed on complex wheel (2 h after wheel exposure and throughout 8 days of training)	Oligodendrogenesis is required for motor learning	17,38
Motor learning (pull and hold lever)	P60	Expression of extra copies of PLP1, producing thinner myelin and abnormal oligodendrocyte processes	Impaired success rate (9 days after training and throughout 1 additional week of training)	Normal myelin architecture is required for motor learning	46
Spatial learning (water maze)	P70–84	Conditional Myrf deletion in OPCs, preventing OPC differentiation	Less time spent in platform zone (24 h, 28 days after training)	Oligodendrogenesis is required for recent and remote recall but not initial spatial learning	18
Spatial learning (water maze)	P120	Conditional Olig2 deletion in OPCs, impairing OPC differentiation	Less time spent in platform zone (24 h after training)	Oligodendrogenesis is required for recent recall but not initial spatial learning	3
Spatial learning (water maze)	P540	Conditional Chrm1 deletion in OPCs, increasing OPC differentiation	More time spent in platform zone (24 h after training)	Increasing oligodendrogenesis in aged mice improves recent recall without altering initial spatial learning	3
Fear learning (contextual fear conditioning)	P56	Conditional Myrf deletion in OPCs, preventing OPC differentiation	Less time freezing in conditioned context (30 days after conditioning)	Oligodendrogenesis is required for remote recall but not initial fear learning or recent recall	19
Spatial learning (T-maze)	P56	Conditional Cdk5 deletion from oligodendrocyte lineage cells, impairing myelination from P14 onwards (possibly earlier)	Impaired performance (after 3 h in maze), contextual/cue fear conditioning and rotarod test	Normal myelination is required for a wide range of learning and memory tasks	52
Fear learning (passive avoidance and contextual and cued fear conditioning)			Impaired performance (after 24 h)
Motor learning (rotarod)			Impaired performance (after 3 trials)
Motor learning (rotarod)	‘Adult’; specific age not specified	Conditional expression of constitutively active MEK1 in mature oligodendrocytes, increasing myelin thickness in optic nerve, corpus callosum and spinal cord	No alteration in 5 days of rotarod test	Inducing hypermyelination in existing oligodendrocytes improves recent recall of a contextual fear memory but not motor learning or recent recall of a cue-related fear memory	107
Fear learning (contextual fear conditioning and cued fear conditioning)			More freezing in conditioned context but no change in freezing to conditioned cue after 24 h)

This table lists studies demonstrating a requirement for oligodendroglia-related processes in learning and memory but not studies only describing experience-induced or learning-induced oligodendroglial plasticity. OPC, oligodendrocyte precursor cell; P, postnatal day.