Regional brain activity during tasks devoted to the central executive of working memory

Most previous PET studies investigating the central executive (CE) componen t of working memory found activation in the prefrontal cortex. However, the tasks used did not always permit to distinguish precisely the functions of the CE from the storage function of the slave systems. The aim of the pres ent study was to isolate brain areas that subserve manipulation of informat ion by the CE when the influence of storage function was removed. A PET act ivation study was performed with four cognitive tasks, crossing conditions of temporary storage and manipulation of information. The manipulation of i nformation induced an activation in the right (BA 10/46) and left (BA 9/6) middle frontal gyrus and in the left parietal area (BA7). The interaction b etween the storage and manipulation conditions did not reveal any significa nt changes in activation. These results are in agreement with the hypothesi s that CE functions are distributed between anterior and posterior brain ar eas, but could also reflect a simultaneous involvement of controlled (front al) and automatic (parietal) attentional systems. In the other hand, the ab sence of interaction between the storage and manipulation conditions demons trates that the CE is not necessarily related to the presence of a memory l oad. (C) 1999 Elsevier Science B.V. All rights reserved.