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

Kathryn M Murphy; Steven J Mancini; Katherine V Clayworth; Keon Arbabi; Simon Beshara

doi:10.3389/fncel.2020.00056

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

Front Cell Neurosci. 2020 Mar 17:14:56. doi: 10.3389/fncel.2020.00056. eCollection 2020.

Authors

Kathryn M Murphy^{1

2}, Steven J Mancini¹, Katherine V Clayworth², Keon Arbabi¹, Simon Beshara³

Affiliations

¹ McMaster Integrative Neuroscience Discovery and Study (MiNDS) Program, McMaster University, Hamilton, ON, Canada.
² Department of Psychology, Neuroscience & Behaviour, Faculty of Science, McMaster University, Hamilton, ON, Canada.
³ Division of Neurology, Department of Medicine, Queen's University, Kingston, ON, Canada.

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.

Keywords: adult plasticity; environmental enrichment (EE); monocular deprivation; myelin; myelin basic protein (MBP); somatosensory cortex; visual cortex (V1).