Integrating Molecular, Cellular, and Systems Approaches to Repairing the Brain After Stroke

A stroke implies a sudden and spontaneous onset of neurological symptoms due to a vascular insult. Despite the brain’s inherent capacity for plasticity and spontaneous improvement, strokes still leave many patients with devastating deficits that can permanently affect independence and quality of life. This chapter focuses on ways to help restore the functionality of the central nervous system (CNS) after this type of injury. Understanding how neurons interact on both individual (i.e. cellular and molecular) and population (i.e. synapses and circuits) levels is crucial to developing successful restorative strategies, as is appreciating how these interactions change over the injury-recovery timeline. The CNS has several characteristics that make its restitution exceptionally difficult; beyond even its incredible intricacy, its parenchymal cells, or neurons, do not regenerate well after injury, and this damaged neuronal substrate embodies a consciousness system that must be engaged in its own recovery. In fact, there is now data suggesting that conscious intention, often invoked through goal-oriented rehabilitation, plays a crucial role in facilitating functional plasticity and long-range axonal sprouting. To capitalize on this principle, neural interfaces and electrical stimulation strategies are being integrated into rehabilitation paradigms to provide critically-timed feedback that can reinvigorate injured circuits. Combining these approaches with interventions at the cellular and molecular level (e.g. immunological or genetic modulations aimed at promoting neuronal outgrowth, or stem cells that can replace damaged parenchyma) has the chance to improve neurological recovery to back toward baseline levels. Ultimately, because cells of the CNS do not regrow on their own, and because regrowth and synapse formation does not necessarily ensure restoration of function, harmonious application of synergistic approaches at both the micro- and macroscopic levels will be needed to establish long-lasting functional plasticity and meaningful recovery.