Summary: The study aims to address the neurobiological basis of cognitive impairments in chronic cocaine users by investigating the potential impact of an acute potassium channel blockade on working memory performance and other cognitive functions.

Summary: The goal of this clinical trial is to evaluate if combining a medication that can help improve walking in people with multiple sclerosis (MS) with a physical therapy program is better for improving walking than either treatment alone. The main questions this study will answer are: * Does combining dalfampridine with physical therapy improve mobility more than physical therapy without concurrent da...

Summary: The purpose of this study is to test a strategy to potentiate functional recovery of lower limb motor function in individuals with spinal cord injury (SCI). The FDA approved drug, Dalfampridine (4-AP). 4-AP will be used twice-daily in combination of Spike-timing-dependent plasticity (STDP) stimulation and STDP stimulation with limb training.