fMRI evidence for dissociation between priming and conscious recognition

Evidence from recent studies challenge traditional memory system accounts of separate mechanisms for implicit and explicit memory. The motive behind the present study was to further investigate whether common activations can be detected during explicit and implicit memory performance when using the same procedure for both tasks. Functional magnetic resonance imaging (fMRI) showed separate neural activation to perceptual repetition priming and perceptual recognition of real and nonsense objects, both in terms of the brain regions involved and in the direction of repeated-novel activations. Repetition priming showed deactivation for repeated stimuli in regions not overlapping regions activated in conscious recognition, activation patterns in the two tasks involved largely separate networks. Common activations were observed in three areas, considered as being involved in processes such as stimulus analyses, task monitoring and attention, i.e., processes external to memory. We interpret this as indicating an almost complete dissociation between the networks involved in priming and recognition memory.