The authors regret that the units were not included in the original Table 1 title. The full and correct title has been included below; Table 1. Putamen catechols (pmol/mg wet weight) and catechol ratios in patients with Parkinson's disease or multiple system atrophy and in control subjects. Mean values expressed ±SEM. P values are for independent means t-tests. The authors would like to apologise for any inconvenience caused.