Memory's echo: Vivid remembering reactivates sensory-specific cortex

A fundamental question in human memory is how the brain represents sensory- specific information during the process of retrieval. One hypothesis is tha t regions of sensory cortex are reactivated during retrieval of sensory-spe cific information (1-3). Here we report findings from a study in which subj ects learned a set of picture and sound items and were then given a recall test during which they vividly remembered the items while imaged by using e vent-related functional MRI, Regions of visual and auditory cortex were act ivated differentially during retrieval of pictures and sounds, respectively . Furthermore, the regions activated during the recall test comprised a sub set of those activated during a separate perception task in which subjects actually viewed pictures and heard sounds. Regions activated during the rec all test were found to be represented more in late than in early visual and auditory cortex. Therefore, results indicate that retrieval of vivid visua l and auditory information can be associated with a reactivation of some of the same sensory regions that were activated during perception of those it ems.