An important objective of functional neuroimaging research is to identify neuroanatomical correlates of memory processes such as encoding and retrieval. In typical studies directed at this goal, however, the to-be-remembered information has been presented in a single perceptual modality. Under these conditions it is not known whether the observed brain activity reflects the studied memory process as such or only the memory process in the given modality. The positron emission tomography (PET) study reported here was designed to identify brain regions involved in encoding and retrieval processes specific to visual and haptic modalities, as well as those common to the two modalities. These latter, common regions, were assumed to be associated with "transperceptual" encoding and retrieval processes. Abstract three-dimensional objects, difficult to describe verbally, served as to-be-remembered materials. A multivariate partial least squares analysis of the PET data revealed that transperceptual encoding processes activated right medial temporal lobe, superior prefrontal cortex bilaterally, and posterior inferior temporal gyrus bilaterally. Transperceptual recognition activations were observed in two right orbitofrontal regions and in anterior cingulate. These results provide initial evidence that some processes involved in memory encoding and retrieval operate beyond perceptual processes and in that sense are transperceptual.
Copyright 2001 Academic Press.