Discussion of nunuphar's comment: The behavior they use (locomotion in an open field) is not a behavior likely to be highly dependent on striatal circuits and velocity may not be good measure for the effects of their manipulations. There is virtually no discussion of that the animals actually were doing in the open field (grooming, sitting, sleeping, ect), so the reader gets a very poor sense of what effect the manipulations were actually having. It would be much more appealing to use a different behavioral task.