The role of prefrontal cortex in working memory: examining the contents of consciousness.

Working memory enables us to hold in our 'mind's eye' the contents of our conscious awareness, even in the absence of sensory input, by maintaining an active representation of information for a brief period of time. In this review we consider the functional organization of the prefrontal cortex and its role in this cognitive process. First, we present evidence from brain-imaging studies that prefrontal cortex shows sustained activity during the delay period of visual working memory tasks, indicating that this cortex maintains on-line representations of stimuli after they are removed from view. We then present evidence for domain specificity within frontal cortex based on the type of information, with object working memory mediated by more ventral frontal regions and spatial working memory mediated by more dorsal frontal regions. We also propose that a second dimension for domain specificity within prefrontal cortex might exist for object working memory on the basis of the type of representation, with analytic representations maintained preferentially in the left hemisphere and image-based representations maintained preferentially in the right hemisphere. Furthermore, we discuss the possibility that there are prefrontal areas brought into play during the monitoring and manipulation of information in working memory in addition to those engaged during the maintenance of this information. Finally, we consider the relationship of prefrontal areas important for working memory, both to posterior visual processing areas and to prefrontal areas associated with long-term memory.

[1]  M. Mishkin,et al.  Non-spatial memory after selective prefrontal lesions in monkeys , 1978, Brain Research.

[2]  B. Milner,et al.  Deficits on subject-ordered tasks after frontal- and temporal-lobe lesions in man , 1982, Neuropsychologia.

[3]  J. Fuster,et al.  Functional interactions between inferotemporal and prefrontal cortex in a cognitive task , 1985, Brain Research.

[4]  D. Stuss,et al.  The Frontal Lobes , 1986 .

[5]  P. Goldman-Rakic.  Cellular and circuit basis of working memory in prefrontal cortex of nonhuman primates. , 1990, Progress in brain research.

[6]  J M Fuster,et al.  Behavioral electrophysiology of the prefrontal cortex of the primate. , 1990, Progress in brain research.

[7]  Leslie G. Ungerleider,et al.  Dissociation of object and spatial visual processing pathways in human extrastriate cortex. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[8]  D. J. Felleman,et al.  Distributed hierarchical processing in the primate cerebral cortex. , 1991, Cerebral cortex.

[9]  Alan C. Evans,et al.  Dissociation of human mid-dorsolateral from posterior dorsolateral frontal cortex in memory processing. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[10]  P. Goldman-Rakic,et al.  Dissociation of object and spatial processing domains in primate prefrontal cortex. , 1993, Science.

[11]  Alan C. Evans,et al.  Functional activation of the human frontal cortex during the performance of verbal working memory tasks. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[12]  G. McCarthy,et al.  Echo-planar magnetic resonance imaging studies of frontal cortex activation during word generation in humans. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Edward E. Smith,et al.  Spatial working memory in humans as revealed by PET , 1993, Nature.

[14]  P. Goldman-Rakic,et al.  Functional magnetic resonance imaging of human prefrontal cortex activation during a spatial working memory task. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[15]  Leslie G. Ungerleider,et al.  The functional organization of human extrastriate cortex: a PET-rCBF study of selective attention to faces and locations , 1994, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[16]  M. Petrides.  Comparative architectonic analysis of the human and the macaque frontal cortex , 1994 .

[17]  B. J. Casey,et al.  Activation of the prefrontal cortex in a nonspatial working memory task with functional MRI , 1994, Human brain mapping.

[18]  Alan D. Baddeley,et al.  Developments in the concept of working memory. , 1994 .

[19]  F. Craik,et al.  Hemispheric encoding/retrieval asymmetry in episodic memory: positron emission tomography findings. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[20]  Leslie G. Ungerleider,et al.  ‘What’ and ‘where’ in the human brain , 1994, Current Opinion in Neurobiology.

[21]  Jemett L. Desmond,et al.  Semantic encoding and retrieval in the left inferior prefrontal cortex: a functional MRI study of task difficulty and process specificity , 1995, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[22]  Leslie G. Ungerleider.  Functional Brain Imaging Studies of Cortical Mechanisms for Memory , 1995, Science.

[23]  T. Allison,et al.  Face-sensitive regions in human extrastriate cortex studied by functional MRI. , 1995, Journal of neurophysiology.

[24]  M. D’Esposito,et al.  The neural basis of the central executive system of working memory , 1995, Nature.

[25]  Edward E. Smith,et al.  Spatial versus Object Working Memory: PET Investigations , 1995, Journal of Cognitive Neuroscience.

[26]  P. Goldman-Rakic.  Architecture of the Prefrontal Cortex and the Central Executive , 1995, Annals of the New York Academy of Sciences.

[27]  Cheryl L. Grady,et al.  Hemispheric differences in neural systems for face working memory: A PET‐rCBF study , 1995 .

[28]  P. Goldman-Rakic,et al.  Activation of human prefrontal cortex during spatial and nonspatial working memory tasks measured by functional MRI. , 1996, Cerebral cortex.

[29]  M. Denis,et al.  Functional Anatomy of Spatial Mental Imagery Generated from Verbal Instructions , 1996, The Journal of Neuroscience.

[30]  R. Buckner.  Beyond HERA: Contributions of specific prefrontal brain areas to long-term memory retrieval , 1996, Psychonomic bulletin & review.

[31]  Leslie G. Ungerleider,et al.  Object and spatial visual working memory activate separate neural systems in human cortex. , 1996, Cerebral cortex.

[32]  A. Berthoz,et al.  Functional Anatomy of a Prelearned Sequence of Horizontal Saccades in Humans , 1996, The Journal of Neuroscience.

[33]  Edward E. Smith,et al.  Dissociation of Storage and Rehearsal in Verbal Working Memory: Evidence From Positron Emission Tomography , 1996 .

[34]  S E Petersen,et al.  A positron emission tomography study of the short-term maintenance of verbal information , 1996, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[35]  J. Fuster.  Memory in the cerebral cortex : an empirical approach to neural networks in the human and nonhuman primate , 1996 .

[36]  R. Dolan,et al.  Active representation of shape and spatial location in man. , 1996, Cerebral cortex.

[37]  Alan C. Evans,et al.  Evidence for a two-stage model of spatial working memory processing within the lateral frontal cortex: a positron emission tomography study. , 1996, Cerebral cortex.

[38]  J. Jonides,et al.  Dissociating verbal and spatial working memory using PET. , 1996, Cerebral cortex.

[39]  T. Paus.  Location and function of the human frontal eye-field: A selective review , 1996, Neuropsychologia.

[40]  Leslie G. Ungerleider,et al.  Face encoding and recognition in the human brain. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[41]  J. Haxby,et al.  Functional Magnetic Resonance Imaging of Human Visual Cortex during Face Matching: A Comparison with Positron Emission Tomography , 1996, NeuroImage.

[42]  R. Desimone,et al.  Neural Mechanisms of Visual Working Memory in Prefrontal Cortex of the Macaque , 1996, The Journal of Neuroscience.

[43]  J V Haxby,et al.  Dissociation of saccade-related and pursuit-related activation in human frontal eye fields as revealed by fMRI. , 1997, Journal of neurophysiology.

[44]  A. Dale,et al.  Late Onset of Anterior Prefrontal Activity during True and False Recognition: An Event-Related fMRI Study , 1997, NeuroImage.

[45]  Leslie G. Ungerleider,et al.  Transient and sustained activity in a distributed neural system for human working memory , 1997, Nature.

[46]  A. Owen.  The Functional Organization of Working Memory Processes Within Human Lateral Frontal Cortex: The Contribution of Functional Neuroimaging , 1997, The European journal of neuroscience.

[47]  P. Goldman-Rakic,et al.  Areal segregation of face-processing neurons in prefrontal cortex. , 1997, Science.

[48]  Edward E. Smith,et al.  Temporal dynamics of brain activation during a working memory task , 1997, Nature.

[49]  S C Rao,et al.  Integration of what and where in the primate prefrontal cortex. , 1997, Science.

[50]  N. Kanwisher,et al.  The Fusiform Face Area: A Module in Human Extrastriate Cortex Specialized for Face Perception , 1997, The Journal of Neuroscience.

[51]  B. J. McCurtain,et al.  Dorsal cortical regions subserving visually guided saccades in humans: an fMRI study. , 1998, Cerebral cortex.

[52]  M. D’Esposito,et al.  Functional MRI studies of spatial and nonspatial working memory. , 1998, Brain research. Cognitive brain research.

[53]  Leslie G. Ungerleider,et al.  An area specialized for spatial working memory in human frontal cortex. , 1998, Science.

[54]  Differences in transient FMRI responses during face encoding and recognition in a working memory task , 1999 .