Lower neuronal variability in the monkey dorsolateral prefrontal than posterior parietal cortex

Area of Science:

• Neuroscience
• Cognitive Neuroscience

Background:

• The dorsolateral prefrontal cortex (dlPFC) and posterior parietal cortex (PPC) are crucial for cognitive functions like working memory.
• Previous studies noted only minor firing rate differences between dlPFC and PPC neurons during similar tasks.

Purpose of the Study:

• To investigate neuronal response variability differences between the dlPFC and PPC during working memory tasks.
• To determine if neuronal variability correlates with working memory performance.

Main Methods:

• Neuronal activity was recorded from dlPFC and PPC in monkeys performing working memory tasks.
• Measures of neuronal variability, including Fano factor and coefficient of variation, were analyzed.
• Firing rates and task performance were also assessed.

Main Results:

• Neuronal variability, measured by Fano factor, was consistently lower in the dlPFC compared to the PPC across various conditions.
• These variability differences persisted despite minimal firing rate distinctions and higher overall dlPFC firing rates.
• Lower Fano factor values in the dlPFC correlated negatively with working memory task performance.

Conclusions:

• Neuronal response variability, not just firing rate, differentiates dlPFC and PPC function during working memory.
• The dlPFC exhibits more reliable neural representations for working memory information compared to the PPC.
• Findings suggest a functional specialization between these brain regions based on response variability.