Fluoxetine and motor imagination to facilitate recovery after ischemic stroke

Plasticity of the brain is thought to play a crucial role in the recovery of motor function after stroke. The main objective of this thesis is to examine the possibility to facilitate the recovery of motor function by investigating (1) the use of psychoactive agents affecting the concentration of neurotransmitters in the brain, and (2) the use of movement imagination. 1. Studies examining the effects of pharmacological interventions show contradicting results since many confounders influence the effects of the psychoactive agents on motor function. We examined the impact of fluoxetine on motor function, and related these outcomes to changes in muscle activity and brain activity. By doing so more insight was obtained in the potential of fluoxetine to affect cortical processes improving the recovery of motor function after stroke. After administration of a single dose of fluoxetine 20 mg in chronic stroke patients an increased muscle activity was found in the paretic arm in both agonistic and antagonistic muscles. A significantly larger brain activity was found in the affected (ipsilateral) hemisphere during execution of the movement by the healthy hand. We found no significant relation between these changes. 2. Other interventions possibly facilitating neuroplasticity are observation and imagination of a movement. A significantly larger modification of the cortical activity was found during the combination of observation and imagination compared to observation-only in healthy subjects, during the whole period of imagination. This suggests an additive effect of imagination to observation. In stroke patients, the motor cortex was found to be activated during imagination. However, the activity of the motor cortex was significantly higher during execution compared to imagination of the movement. The interaction between both therapies was studied as well. Fluoxetine was found to significantly increase the cortical activity related to movement in the non-affected motor cortex during the execution of the movement. During imagination of the movement trends were found indicating the same effect of fluoxetine. The results described in this thesis on the effects of fluoxetine and imagination on the recovery of motor function are very promising and give clear leads for continuation of this line of research.