%B Neuroimage %I Elsevier %C New York, USA %T Effect of healthy aging on the cholinergic modulation of the interaction between prefrontal cortex (PFC) activity and visual working memory (vWM) task difficulty %D 2003 %A Emiliano Ricciardi %A Pietro Pietrini %A Stanley I. Rapoport %A Mark B. Schapiro %A Maura L. Furey %L eprints3321