Unilateral prefrontal lesions impair memory-guided comparisons of contralateral visual motion

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Primate Studies

Background:

• The role of the lateral prefrontal cortex (LPFC) in working memory is debated.
• Some evidence suggests LPFC supports sensory storage, while other findings indicate a role in attention allocation.

Purpose of the Study:

• To investigate whether the LPFC stores sensory information or allocates attention during working memory tasks.
• To examine the effects of unilateral LPFC lesions on working memory performance in monkeys.

Main Methods:

• Monkeys performed a working memory task involving comparing directions of two moving stimuli with a delay.
• Unilateral lesions were made to the LPFC.
• Performance was assessed by analyzing thresholds for contralesional stimuli at varying delays and attention demands.

Main Results:

• LPFC lesions impaired working memory thresholds for contralesional stimuli, particularly at longer delays.
• Deficits were most pronounced when the task required rapid reallocation of spatial attention.
• The impairments were independent of stimulus features and equally severe for threshold and coherent stimuli.

Conclusions:

• The findings suggest the LPFC is crucial for allocating visual attention to relevant stimuli during working memory maintenance.
• The results challenge the notion that LPFC directly stores sensory information, emphasizing its role in attentional control and access to preserved motion signals.
• Interactions between the LPFC and extrastriate area MT are important for processing motion direction in working memory.