Distractor-resistant Short-Term Memory Is Supported by Transient Changes in Neural Stimulus Representations

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Working Memory Research

Background:

• Goal-directed behavior relies on maintaining information despite distractions.
• Brain mechanisms for distractor-resistant short-term memory (STM) are not fully understood.
• Previous research implicated lateral prefrontal cortex, but recent studies highlight posterior cortices.

Purpose of the Study:

• To investigate the neural basis of STM maintenance across different delay phases, including during distraction.
• To determine the role of posterior versus lateral prefrontal cortices in distractor-resistant STM.
• To examine how the neural representation of STM content changes in the presence of distractors.

Main Methods:

• Used a delayed match-to-sample task with fMRI (functional Magnetic Resonance Imaging).
• Employed multivariate searchlight analyses to decode STM contents (faces vs. houses).
• Analyzed data across three delay phases: pre-distractor, distractor-filled, and post-distractor.

Main Results:

• STM contents were decodable above chance in occipital, temporal, and posterior parietal areas during all delay phases.
• Decoding performance generalized between pre- and post-distractor delays, but not to the distractor delay.
• Neural activity during distraction transiently changed but was reinstated post-distraction; performance correlated with behavior in house trials.

Conclusions:

• Distributed posterior cortices, not lateral prefrontal cortices, are crucial for active maintenance during and after distraction.
• The neural code for STM undergoes transient changes when distractors are present and is reinstated afterward.
• Active STM maintenance is particularly critical for house stimuli, while face stimuli may engage long-term memory more.