Frank Rösler, Philipps Universität Marburg Wed 30 May 2007, 17:00 Campus Golm, building 24, room 033/34 In search of the engram: What does brain imaging tell us about the location of the memory trace? Abstract: Where are memories stored in the brain? Both empirical and theoretical work suggests that memories are represented as activation patterns in exactly those cortical areas in which online processing of information during perception or motor planning does take place. I will review a series of studies in which we recorded event-related brain potentials in the EEG and the BOLD response with fMRI to monitor memory-related brain activity. The experiments show that storage and retrieval of long-term memory (LTM) contents produce material-specific activations, i.e. topographically distinct patterns for spatial, verbal, or object information. The topography evoked by LTM tasks was by and large the same as when similar contents had to be manipulated in working memory (WM). Moreover, in both cases, the activation patterns were not only distinct for the different materials, rather, the maximum amplitude of each activation pattern varied systematically with the task demands. More demanding long-term memory search and more demanding working memory transformations resulted in an increase of a negative slow wave amplitude and the corresponding BOLD response. In sum, these studies not only prove a distinct topography for different representations but also that each topography is specifically modulated by the task demands. Moreover, the congruent topography strongly supports the idea that working memory and long-term memory contents are activated within the same cortical areas. The areas, however, which are recruited for a particular LTM or WM task are not congenitally predetermined. We observed that the very same haptic working memory task activated systematically central-parietal areas in sighted controls but occipital areas in congenitally blind people. This suggests kind of an omnipotency of cortical areas for information processing and storage.