Superior Intraparietal Sulcus Controls the Variability of Visual Working Memory Precision

Area of Science:

• Neuroscience
• Cognitive Psychology
• Computational Neuroscience

Background:

• Working memory (WM) capacity is limited by cognitive resources needed to maintain information.
• Increased WM load reduces precision and increases variability of WM performance over time.
• Neural codes in sensory cortex are linked to WM precision, but variability under load is poorly understood.

Purpose of the Study:

• Investigate the neural mechanisms underlying variability in visual working memory precision under varying cognitive load.
• Examine how the superior intraparietal sulcus (IPS) and primary visual cortex (V1) contribute to WM stability.
• Integrate computational modeling with fMRI to understand brain-behavior relationships in WM.

Main Methods:

• Combined functional magnetic resonance imaging (fMRI) with computational modeling of behavioral data.
• Utilized a delayed color-estimation working memory task with varying loads (1, 3, or 5 colors).
• Analyzed load-dependent BOLD signals in V1 and IPS, and decoded memory stimuli from IPS activity.

Main Results:

• Behavioral results confirmed reduced WM precision and increased variability with higher loads.
• Load-related BOLD signals in IPS and V1 correlated with individual differences in WM precision variability.
• Higher IPS activity correlated with reduced precision variability, stabilizing performance, while V1 showed the opposite effect.
• Decoding accuracy of memory stimuli from the left IPS declined with increasing load.

Conclusions:

• The superior IPS plays a crucial role in stabilizing visual working memory performance under high cognitive load.
• IPS may stabilize WM by mitigating the increase in precision variability associated with higher memory demands.
• Findings highlight the importance of integrating cognitive modeling with neuroimaging for understanding brain-behavior links in WM.