Brain activity during intra- and cross-modal priming: new empirical data and review of the literature

A positron emission tomography (PET) study was conducted to investigate the neurofunctional correlate of auditory within-modality and auditory-to-visual cross-modality stem completion priming. Compared to the auditory-to-auditory priming condition, cross-modality priming was associated with a significantly larger regional cerebral blood flow (rCBF) decrease at the boundary between left inferior temporal and fusiform gyri, brain regions previously associated with modality independent lexical retrieval and reading. Instead, within-modality auditory priming was associated with a bilateral pattern of prefrontal rCBF increase. This was likely the expression of more efficient access to output lexical representations and involuntary retrieval of the recent episode during which the just generated word had been encountered.