Dissociation Of working memory from decision making within the human prefrontal cortex

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuroanatomy

Background:

• Working memory and decision-making are core cognitive functions.
• The precise neural substrates underlying these functions remain incompletely understood.
• Previous research suggests potential anatomical segregation but lacks direct evidence.

Purpose of the Study:

• To test if working memory and decision-making are distinct cognitive functions.
• To determine if these functions depend on separate anatomical substrates in the prefrontal cortex.
• To investigate the role of ventromedial (VM) and dorsolateral/medial (DL/M) prefrontal cortices in these cognitive processes.

Main Methods:

• A lesion study involving normal controls and subjects with focal prefrontal lesions (VM or DL/M).
• Participants performed modified delay tasks to assess working memory.
• Participants completed a gambling task to measure decision-making abilities.

Main Results:

• Subjects with anterior VM lesions were impaired in decision-making but not working memory.
• Subjects with posterior VM lesions were impaired in both tasks.
• Subjects with right DL/M lesions were impaired in working memory but not decision-making.
• Left DL/M subjects showed no significant impairments.

Conclusions:

• A cognitive and anatomical double dissociation was found between decision-making (anterior VM) and working memory (right DL/M).
• This study provides the first direct human evidence using the lesion method for this dissociation.
• The ventromedial prefrontal region is critically important for decision-making, independent of working memory.