Estudo da remodelação dos mapas motores corticais após o acidente vascular encefálico isquêmico: efeito da reabilitação combinada baseada no enriquecimento ambiental e (re)aprendizagem motora

Abstract

Over the past decades, Brazilian population over 60 years of age has increased, as well as chronic diseases related to aging. Among these, stroke, one of the main causes of hospitalizations and mortality in Brazil; causing some type of disability to perform activities of daily living to the majority of patients. Understanding how the rehabilitation process occurs, such as the remodeling of motor maps and motor pathways is of utmost importance. The study of this phenomenon can lead to optimization of rehabilitation and to a better understanding of how drugs can act to restore brain function following stroke. In addition, lesion location and severity are determinant for the level of motor impairment following the insult. Preliminary results obtained by PhD Numa Dancause and PhD Dale Corbett research teams indicated that when the lesion encompass the dorsal striatum, motor representations are extremely impaired. Therefore, it was hypothesized that the dorsal striatum has a determining role in the constitution and possible remodeling of the cortical maps during motor relearning. In addition, subcortical structures may increase activity and assume a more active role in the expression of motor behavior. In this thesis we develop a new methodology to quantify and better understand changes of upper limb movement following stroke in rodents (rats: Article 1; mice: Article 2). Next, we review the main pathways and mechanisms involved in motor relearning following stroke (Article 3). Finally, the main article of this thesis demonstrates how intensive rehabilitation promotes cortical motor map plasticity (Article 4). Intensive rehabilitation led to motor map expansion, increased kinematic movement of the paretic limb, and increased use-dependent activity of compensatory brain regions, such as the contralesional cortex and red nucleus. Here, we propose an intertwined mechanism for severe stroke recovery, which involves bilateral and bi-hemispheric interactions. In short, this thesis corroborates that rehabilitation promotes expansion of cortical motor representations; and advances the knowledge about compensatory recovery following severe stroke in rats.