Coherence between fMRI time-series distinguishes two spatial working memory networks.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• Working memory relies on distributed brain networks.
• Previous research showed distinct cortical areas maintain different neural codes during memory delays.
• Functional interactions between these brain regions were previously unaddressed.

Purpose of the Study:

• To formally characterize functional interactions between brain regions within working memory networks.
• To investigate how the type of representational code maintained during a memory delay influences these interactions.

Main Methods:

• Utilized coherence, a bivariate technique, to measure functional interactions between brain areas.
• Focused on frontal eye fields (FEF) as a seed region.
• Analyzed interactions based on different representational codes (sensory vs. motor).

Main Results:

• The type of representational code maintained in working memory influences frontal-parietal interactions.
• Coherence between FEF and oculomotor areas increased when a motor representation was strategic.
• Coherence between FEF and higher-order heteromodal areas (e.g., dlPFC) increased when a sensory representation was required.

Conclusions:

• Functional connectivity within working memory networks is biased by the nature of the information being maintained.
• Dynamic adjustments in neural coding strategies are reflected in changing patterns of brain region interactions.
• This study provides a formal characterization of functional interactions, advancing our understanding of working memory networks.