Working Memory Contributions Minireview to Human Learning

1998). This minireview briefly considers PET and fMRI Charlestown, Massachusetts 02129 evidence regarding the role of prefrontal cortex in epi-Department of Psychology sodic memory and highlights the parallels between Harvard University these results and those from studies of working memory. Cambridge, Massachusetts 02138 Two patterns are emphasized. First, studies of episodic memory suggest that activation in inferior prefrontal cor-tices is associated with the nature of the material being Understanding the cognitive and neural architectures processed (semantic, phonological, visuospatial) rather that support learning (memory encoding) and remem-than the nature of the episodic memory operations being bering (memory retrieval) is a fundamental goal of hu-performed (encoding or retrieval). These activations man memory research. This endeavor is challenging, as may reflect the recruitment of material-specific working memory is not a unitary system but rather consists of memory operations that support access to, maintenance of, and evaluation of specific event attributes. multiple forms of learning and remembering that differ Second, studies of episodic memory suggest that acti-in their functional characteristics and neuroanatomic vation in dorsolateral and anterior prefrontal cortices substrates (Schacter and Tulving, 1994). This minireview is material independent and is modulated by episodic considers two forms of memory, episodic memory and retrieval but not by episodic encoding. These activations working memory. Episodic memory is a form of long-may reflect the recruitment of material-independent term memory that supports the conscious remembrance working memory operations that support the manipula-of everyday experiences. For example, the ability to re-tion of the contents of working memory. member what you had for dinner last night typically Inferior Prefrontal Contributions requires retrieval from episodic memory and depends to Episodic Memory upon having initially encoded that information into epi-Recent PET and fMRI studies suggest that there are sodic memory. Working memory, in contrast, is a tran-functionally distinct regions in left and right inferior pre-sient form of memory that supports the temporary stor-frontal cortices that are engaged during both episodic age and maintenance of internal representations and learning and episodic remembering, with the specific mediates the controlled manipulation of these represen-regions engaged dependent on the nature of the mate-tations (Baddeley and Hitch, 1994). For example, men-rial being processed (verbal–semantic or visuospatial). tally rehearsing a phone number so that it is available These material-specific patterns of activation may re-moments later depends on working memory mainte-flect the recruitment of material-or process-specific nance operations. working memory operations. Both episodic memory and working memory are par-Verbal–Semantic …