I had difficulty with this too. Impulsivity exists in PD without DBS, and no-one seems to understand why. It's alter ego, apathy, also exists, and no-one understands why. This exercise described how people are shown line art and are somehow rewarded for making choices, but does not describe the process well, except to remark that those who made the faster choices were also less accurate (made poorer choices). It does not demonstrate how value in choice was decided, so it is very hard to know how to 'read' this study.

It also does not have any thing that shows whether the people who received DBS, regardless of whether they were receiving stimulation or not, had a prior history of impulsivity, or any behavioural changes in decision making.

It is important that these issues are understood, but they are there in the larger community of people with PD, not just those who have had DBS. They are often related to medication, or specific types of medication, and sometimes the behaviours are not reversed when medication is discontinued.

My question would be; 'Does this study help identify why stimulation induces impulsivity?' and a further one would relate to medication and whether it is doing the same thing.............