Episodic retrieval activates the precuneus irrespective of the imagery content of word pair associates - A PET study

The aim of this study was to evaluate further the role of the precuneus in episodic memory retrieval. The specific hypothesis addressed was that the p recuneus is involved in episodic memory retrieval irrespective of the image ry content. Two groups of six right-handed normal male volunteers took part in the study. Each subject underwent six [O-15]butanol-PET scans. In each of the six trials, the memory task began with the injection of a bolus of 1 500 MBq of [O-15]butanol. For Group 1, 12 word pair associates were present ed visually, for Group 2 auditorily, The subjects of each group had to lear n and retrieve two sets of 12 word pairs each. One set consisted of highly imaginable words and another one of abstract words. Words of both sets were not related semantically, representing 'hard' associations. The presentati ons of nonsense words served as reference conditions. We demonstrate that t he precuneus shows consistent activation during episodic memory retrieval. Precuneus activation occurred in visual and auditory presentation modalitie s and for both highly imaginable and abstract words. The present study ther efore provides further evidence that the precuneus has a specific function in episodic memory retrieval as a multimodal association area.