We investigated visuo-spatial working memory function in eleven frontal lobe-damaged patients (FDP) using a maze task, and compared their performance with that of Parkinson disease patients (PDP) as we reported previously.
The number of trials to find the correct route was greater in the FDPs than in the nine normal controls, and their error patterns were different from those of either the normal controls or PDPs. We found two error patterns : one adopting the same incorrect turn repeatedly at the same position in a maze (type 1), and the other a failure to recall the correct route found in the preceding trial (type 2).
The difference in error patterns between FDPs and PDPs shows that the ability to reject an inappropriate choice and select the correct one is impaired in the FDP, whereas disability in the PDP is mainly caused by deficient encoding and storage function. Consequently, the results suggest that the frontal lobe may play a major part in the monitoring of changing situations and the manipulation of information, rather than encoding and storage during working memory tasks.
