Choice-option evaluation is preserved in early Huntington and Parkinson's disease.

The ability to choose effectively when faced with potential risks and rewards is fundamental for adaptive survival. The striatum has a well-established role supporting learning from the outcomes of decisions, but it remains unclear whether this structure is also necessary for computing expected value (i.e., advantageousness of potential decisions) when all information is explicitly given. We addressed this question presenting simple monetary gambles, where all decisional parameters were given and outcome feedback was absent, to patients with early Huntington's and Parkinson's disease, taken as complementary models of striatal dysfunction. Behavioural responses and associated times were found to be unaltered. This negative finding suggests that striatal activity may not be essential for decision-making in situations where all information is provided and learning from outcomes is unnecessary.