Authors:

HENSON, R.N.A., HORNBERGER, M., & Rugg, M.D.

Reference:

Year of publication:

2005

CBU number:

5935

Abstract:

Based on an ERP study by Rugg et al. (1998), we attempted to isolate the hemodynamic correlates of recollection, familiarity and implicit memory within a single verbal recognition memory task using event-related fMRI. Words were randomly cued for either deep or shallow processing, and then intermixed with new words for yes/no recognition. The number of studied words was such that, while most were recognized (ìhitsî), an appreciable number of shallow-studied words were not (ìmissesî). Comparison of deep hits versus shallow hits at test revealed activations in regions including left inferior parietal gyrus. Comparison of shallow hits versus shallow misses revealed activations in regions including bilateral intraparietal sulci, left posterior middle frontal gyrus and left frontopolar cortex. Comparison of hits versus correct rejections revealed a relative deactivation in an anterior left medial temporal region (most likely perirhinal cortex). Comparison of shallow misses versus correct rejections did not reveal response decreases in any regions expected on the basis of previous imaging studies of priming. Given these and previous data, we associate the left inferior parietal activation with recollection, the left anterior medial temporal deactivation with familiarity, and the intraparietal and prefrontal responses with target detection. The absence of differences between shallow misses and correct rejections means that the hemodynamic correlates of implicit memory remain unclear.