A neurocomputational account of cognitive deficits in Parkinson's disease

► Impaired rule switching and selection can account for many Parkinson's disease (PD) deficits. ► According to the COVIS theory of categorization, these operations are mediated by dopamine levels. ► Reducing the amount of dopamine in COVIS produces cognitive deficits similar to those present in normal aging and PD. ► COVIS has been used to simulate five well-known tasks used to assess PD cognitive deficits.