If so, the n-back may be a useful task for assessment of working memory ability within the context of clinical neuropsychological evaluation.ĭespite its widespread use in neuroimaging studies, examination of the n-back as a clinical measure has received little attention. This suggests that n-back performance may be sensitive to the integrity of the frontal lobes, with greater working memory loads placing greater demand upon frontally mediated cognitive functions. Behavioral performance on the n-back has been shown to discriminate between patients with dorsolateral prefrontal cortex dysfunction (e.g., schizophrenic patients) and healthy controls ( Perlstein, Carter, Noll, & Cohen, 2001). Neuroimaging studies have demonstrated that increased working memory load on the n-back is associated with poorer performance in healthy participants and increased activation of the dorsolateral and inferior frontal regions of the prefrontal cortex ( Braver et al., 1997 Manoach et al., 1997 Ragland et al., 2002). One promising aspect of the n-back is that there appear to be distinct neural substrates associated with task performance. It parametrically varies working memory load, and thus task difficulty, while keeping overall task procedures constant across conditions. The n-back is a sequential letter memory task frequently used in neuroimaging research ( Braver et al., 1997 Manoach et al., 1997 Perlstein, Dixit, Carter, Noll, & Cohen, 2003 Ragland et al., 2002). Working memory, Executive function, Information processing speed, Parkinson's disease, Neuropsychology Introduction Results suggest the n-back is not a pure measure of working memory, but may be able to detect subtle differences in cognitive functioning between PD patients and controls. Relative to controls, PD patients performed less accurately on the n-back and showed a trend toward slower reaction times, but did not differ on any of the neuropsychological measures. N-back accuracy significantly correlated with a measure of processing speed (Trail Making Test Part A) at the 2-back load. Results revealed no correlation between n-back performance and digit span backward. The relationship between n-back performance and scores on measures of processing speed was also examined, as was the ability of the n-back to detect potential between-groups differences in control and Parkinson's disease (PD) groups. We examined convergent validity of the n-back with an established measure of working memory, digit span backward. The n-back is a putative working memory task frequently used in neuroimaging research however, literature addressing n-back use in clinical neuropsychological evaluation is sparse.
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