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Is the prefrontal cortex necessary for delay task performance? Evidence from lesion and FMRI data.
Mark D'Esposito1, Jeffrey W Cooney, Adam Gazzaley
1Helen Wills Neuroscience Institute, University of California-Berkeley, 132 Barker Hall, Berkeley, CA 94720-3190, USA. despo@berkeley.edu
Summary
The prefrontal cortex (PFC) is not essential for working memory storage or rehearsal. Lesions to the PFC did not impair these functions, suggesting posterior networks support retention and bilateral PFC activation during tasks may reflect other processes.
Area of Science:
- Neuroscience
- Cognitive Psychology
Background:
- The prefrontal cortex (PFC) is widely implicated in working memory.
- However, its essential role in specific working memory processes remains debated.
Purpose of the Study:
- To clarify the necessity of the PFC for storage and rehearsal/maintenance in verbal working memory.
- Investigate PFC contributions using both lesion patient behavior and healthy subject neuroimaging.
Main Methods:
- Assessed behavioral performance of patients with left or right lateral PFC lesions on working memory tasks.
- Utilized functional magnetic resonance imaging (fMRI) to measure neural activity in healthy subjects during similar tasks.
Main Results:
- PFC lesions did not significantly impact storage capacity, supporting the role of posterior cortical networks.
- PFC lesions also did not impair rehearsal/maintenance processes, contrary to observed bilateral PFC activation in healthy subjects.
- Healthy subjects showed bilateral PFC activation during a verbal delayed recognition task.
Conclusions:
- Working memory storage relies on posterior cortical networks, not necessarily the PFC.
- Rehearsal/maintenance processes may involve bilateral PFC engagement but are not dependent on it.
- Findings have implications for understanding functional recovery and rehabilitation after frontal lobe injury.