Word retrieval in amyotrophic lateral sclerosis: a functional magnetic resonance imaging study

The cognitive impairment revealed in some non-demented amyotrophic lateral sclerosis (ALS) patients is characterized by executive dysfunction with widely repeated de®cits on tests of verbal (letter) ¯uency. However, con¯icting evidence exists of an impairment on other word retrieval tasks, such as confrontation naming, which do not place heavy demands on execu-tive processes. Previous research has demonstrated intact confrontation naming in the presence of verbal ¯uency de®cits, although naming de®cits have been described in other studies. In this investigation, func-tional MRI (fMRI) techniques were employed to explore whether word retrieval de®cits and underlying cerebral abnormalities were speci®c to letter ¯uency, which are more likely to indicate executive dysfunction, or wer