Investigating working memory updating processes of the human subcortex using 7T MRI

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Dopamine's role in working memory updating is suggested by prior research.
• The striatum is hypothesized to be critical for working memory gating.

Purpose of the Study:

• Investigate subcortical and dopaminergic involvement in working memory updating subprocesses.
• Examine the role of the striatum in working memory gating.

Main Methods:

• Utilized the reference-back task and ultrahigh field 7 Tesla functional magnetic resonance imaging (fMRI).
• Employed a scanning protocol optimized for subcortical BOLD sensitivity.

Main Results:

• No subcortical activation observed during working memory gate opening; frontoparietal regions were predominantly activated.
• Subcortical activation was noted during gate closing.
• Widespread subcortical activation, including basal ganglia, occurred in a ready-to-update state.
• Activation in dopamine-producing midbrain regions, striatum, thalamus, and prefrontal cortex was observed during information substitution.

Conclusions:

• Findings challenge the concept of a striatal gating mechanism for working memory.
• The basal ganglia appear involved in general updating processes, not specifically gate control.
• Information substitution into working memory is a midbrain-driven updating process involving the basal ganglia-thalamo-cortical loop, potentially modulated by dopamine.