The possibility that adult organisms exhibit myelin plasticity has recently become a topic of great interest. Many researchers are exploring the role of myelin growth and adaptation in daily functions such as memory and motor learning. Here we consider evidence for three different potential categories of myelin plasticity: the myelination of previously bare axons, remodeling of existing sheaths, and the removal of a sheath with replacement by a new internode. We also review evidence that points to the importance of neural activity as a mechanism by which oligodendrocyte precursor cells (OPCs) are cued to differentiate into myelinating oligodendrocytes, which may potentially be an important component of myelin plasticity. Finally, we discuss demyelination in the context of traumatic neural injury and present an argument for altering neural activity as a potential therapeutic target for remyelination following injury. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 108-122, 2018.

The etiology of postconcussive symptoms is not clearly understood. Development of etiological models of those symptoms will be helpful for accurate diagnosis and for planning effective treatment. Such a model should characterize the role of subject characteristics (education, premorbid intelligence), social psychological factors and symptom validity. Toward that end, the present study examined the association of postconcussive complaints and cognitive performance with symptom attribution and level of effort on testing. In a sample of 155 veterans, attribution to concussion was associated with endorsement of more severe postconcussive complaints, after controlling for the effects of other factors such as subject characteristics. Similarly, effort was associated with cognitive performance after controlling for the effects of these other factors. The present findings are consistent with previous reports that illness perception and effort on testing are associated with postconcussive complaints. This supports previous recommendations to routinely educate all concussion patients immediately after injury to reduce distorted perceptions and related persistent complaints. Finally, these findings highlight a need for routine assessment of patients' perception of their injury to identify cases that may require psychotherapy to address any misattributions that develop.

Electrical stimulation of the cervical spinal cord is gaining traction as a therapy following spinal cord injury; however, it is difficult to target the cervical motor region in a rodent using a non-penetrating stimulus compared with direct placement of intraspinal wire electrodes. Penetrating wire electrodes have been explored in rodent and pig models and, while they have proven beneficial in the injured spinal cord, the negative aspects of spinal parenchymal penetration (e.g., gliosis, neural tissue damage, and obdurate inflammation) are of concern when considering therapeutic potential. We therefore designed a novel approach for epidural stimulation of the rat spinal cord using a wireless stimulation system and ventral electrode array. Our approach allowed for preservation of mobility following surgery and was suitable for long term stimulation strategies in awake, freely functioning animals. Further, electrophysiology mapping of the ventral spinal cord revealed the ventral approach was suitable to target muscle groups of the rat forelimb and, at a single electrode lead position, different stimulation protocols could be applied to achieve unique activation patterns of the muscles of the forelimb.