During clinical trials on patients suffering from neurological disorders, it has been observed that some patients obtain dramatic improvements in motor control and/or higher mental functioning, when they receive a combination of dextromethorphan and quinidine, at suitable dosages. Improved motor control has been exemplified to date by improved ability to swallow and/or speak, among victims of stroke, head injury, or ALS. Improved higher mental functioning has been exemplified in better job performance, increased ability to analyze and solve problems, and increased ability to have successful and satisfying interactions with other people. These types of effects can be seen in a relatively brief time period, such as within several days to a week.