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Human prefrontal cortex: processing and representational perspectives

Nature Reviews Neuroscience volume 4, pages 139147 (2003) | Download Citation

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Abstract

Through evolution, humans have acquired 'higher' cognitive skills — such as language, reasoning and planning — and complex social behaviour. Evidence from neuropsychological and neuroimaging research indicates that the prefrontal cortex (PFC) underlies much of this higher cognition. A number of theories have been proposed for how the PFC might achieve this. Although many of these theories focus on the types of 'process' that the PFC carries out, we argue for the validity of a representational approach to understanding PFC function.

Key points

  • The prefrontal cortex (PFC) has been implicated in a variety of 'higher' cognitive functions — language, abstract reasoning, problem solving, social interactions and planning. A number of theories have been proposed for how the PFC might mediate these functions.

  • This paper proposes five criteria that we believe a theory should meet if it is to provide a useful framework for understanding the functions of the PFC. We provide an overview of some of the key PFC theories and assess how well they meet our criteria.

  • The criteria by which we assess the theories are: (1) specification of the type of information stored in the PFC; (2) consistency with our knowledge of stimulus representation in the brain; (3) consistency with what is known of the evolutionary development of the PFC; (4) ability to test the model and hence to verify or invalidate it; and (5) consistency of the model with available experimental data.

  • A theory might take a processing approach — that is, it might specify computational procedures that are performed by the PFC to manipulate information stored elsewhere in the brain. Alternatively, a theory can take a representational approach — that is, it can specify the type of information that is stored in memories in the PFC. Finally, a theory might have components of both the processing and representational viewpoints.

  • We discuss the main claims of each key theory and review data addressing these claims. The models meet our criteria to varying degrees. All models are supported to some extent by the available cognitive neuroscience data, but not all of the models address all of the available data. In particular, many researchers rely almost solely on functional neuroimaging data and ignore other sources of evidence (such as lesion studies). With respect to specific theories, without modification, no single theory of PFC function seems to explain all of the available data.

  • With respect to the general theoretical approaches, we argue that the representational approach seems to be more consistent with our criteria than does the processing approach. We argue that the representational approach forces a more detailed specification of a theory and thus enables specific hypothesis testing. We argue that adoption of a representational framework is the most parsimonious way to explore the nature of knowledge stored in the human PFC.

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  1. Cognitive Neuroscience Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1440, USA.

    • Jacqueline N. Wood
    •  & Jordan Grafman

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Correspondence to Jordan Grafman.

Glossary

WORKING MEMORY

Activated long-term memory.

SELECTIVE ATTENTION

Ability to focus mental effort on a subset of all available information.

EPISODIC MEMORY

Memory for specific events that are temporally dated; includes the relationships between different events.

SEMANTIC MEMORY

Memory for factual information about the world, concepts and word meaning.

PRIMING

Increased accessibility of information as a result of previous exposure to similar information.

SOMATIC STATES

Emotional state as indicated by musculoskeletal and visceral (body) states.

ASSOCIATIVE STRENGTH

The degree to which different representations are associated.

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https://doi.org/10.1038/nrn1033