Contribution of lexico-semantic processes to verbal short-term memory tasks: A PET activation study

Recent studies have demonstrated the intervention of long-term memory proce sses in verbal STM tasks and several cognitive models have been proposed to explain these effects. A PET study was performed in order to determine whe ther supplementary cerebral areas are involved when subjects have to execut e short-term memory tasks for items having representations in long-term mem ory (in comparison to items without such representations: words vs non-word s). Results indicate that verbal STM for words specifically involves the le ft middle temporal gyrus (BA 21) and temporo-parietal junction (BA 39). The se areas can be associated with lexical and semantic processes. These resul ts are in agreement with cognitive models that postulate the simultaneous i nfluence of lexical and semantic long-term representations on verbal STM pr ocesses and/or a lexico-semantic buffer.