Experience-Dependent Changes in Myelin Basic Protein Expression in Adult Visual and Somatosensory Cortex

Abstract

An experience-driven increase in oligodendrocytes and myelin in the somatosensory cortex (S1) has emerged as a new marker of adult cortical plasticity. That finding contrasts with the view that myelin is a structural brake on plasticity, and that contributes to ending the critical period (CP) in the visual cortex (V1). Despite the evidence that myelin-derived signaling acts to end CP in V1, there is no information about myelin changes during adult plasticity in V1. To address this, we quantified the effect of three manipulations that drive adult plasticity (monocular deprivation (MD), fluoxetine treatment or the combination of MD and fluoxetine) on the expression of myelin basic protein (MBP) in adult rat V1. In tandem, we validated that environmental enrichment (EE) increased cortical myelin by measuring MBP in adult S1. For comparison with the MBP measurements, three plasticity markers were also quantified, the spine markers drebrin E and drebrin A, and a plasticity maintenance marker Ube3A. First, we confirmed that EE increased MBP in S1. Next, that expression of the plasticity markers was affected in S1 by EE and in V1 by the visual manipulations. Finally, we found that after adult MD, MBP increased in the non-deprived V1 hemisphere, but it decreased in the deprived hemisphere, and those changes were not influenced by fluoxetine. Together, the findings suggest that modulation of myelin expression in adult V1 may reflect the levels of visually driven activity rather than synaptic plasticity caused by adult plasticity.

Development of myelin in fetal and postnatal neocortex of the pig, the European wild boar Sus scrofa

“…Recent data suggest that MBP regulation may not even reflect synaptic plasticity in general. In mouse SC, MBP is regulated by environmental enrichment even weeks after birth with enrichment promoting the integration of newly myelinating oligodendrocytes, whereas in VC MBP is regulated by visual activity and decreases upon visual deprivation (Hughes et al 2018 ; Murphy et al 2020 ). Areal differences already exist at the progenitor level because proliferation of NG2 positive OPCs can be enhanced in mouse barrel cortex after whisker lesion, but not in visual cortex after dark rearing (Mangin et al 2012 ).…”

Microenvironmental interactions of oligodendroglial cells

“…Experience-dependent myelin plasticity affects both visual and somatosensory systems. Monocular deprivation of one eye in adult rats decreases markers of myelination in the related hemisphere of the visual cortex, whereas the non-deprived hemisphere exhibits the opposite (Murphy et al, 2020). This suggests that myelin adapts to the changing balance of cortical neuronal activity.…”

Enriched Environment Effects on Myelination of the Central Nervous System: Role of Glial Cells

“…Many literatures have shown that the brain responds to experience-induced activities [ 30 – 33 ] and environmental changes [ 34 , 35 ]. Changes in myelin sheaths, neurons, and synapses can be observed both in animal and cell culture models.…”