The effects of a single dose of fluoxetine on practice-dependent plasticity

To determine whether a single dose of fluoxetine increases corticomotoneuronal excitability, motor performance and practice-dependent plasticity.

Twelve healthy adults completed this placebo-controlled, pseudo-randomized, double-blind crossover study. Transcranial magnetic stimulation (TMS) was used to assess corticomotoneuronal excitability, and two uni-axial accelerometers measured kinetics of fastest possible ballistic voluntary thumb movements and TMS-evoked thumb movements. Six hours after administration of either 20 mg of the serotonin reuptake inhibitor fluoxetine or placebo, participants practiced ballistic thumb movements in the direction opposite to the TMS-evoked thumb movements. The primary outcome of this study was the proportion of thumb movements that fell within the target-training zone (TTZ) during and for 30 min after the practice.

All participants demonstrated practice-dependent plasticity evidenced by an increase of TMS-evoked thumb movements falling into the TTZ (P = 0.045), with no difference between drugs. There was a significant increase in peak acceleration of the practiced voluntary thumb movements (P = 0.002), but no DRUG by TIME interaction. Motor-evoked potential amplitudes were not changed by drug intake or practice.

A single dose of 20 mg of fluoxetine did not enhance corticomotoneuronal excitability, performance of a ballistic thumb movement task, or practice-dependent plasticity in healthy adults.

Longer administration fluoxetine may be necessary to enhance motor performance and plasticity.