Functional neuroimaging of short-term memory: The neural mechanisms of mental storage

Cowan argues that the true short-term memory (STM) capacity limit is about 4 items. Functional neuroimaging data converge with this conclusion, indica ting distinct neural activity patterns depending on whether or not memory t ask-demands exceed this limit. STM for verbal information within that capac ity invokes focal prefrontal cortical activation that increases with memory load. STM for verbal information exceeding that capacity invokes widesprea d prefrontal activation in regions associated with executive and attentiona l processes that may mediate chunking processes to accommodate STM capacity limits.