How Dopamine Affects Connectivity in the Frontal Lobe

This piece, by Onno Berkan, was published on 02/18/25. The original text, by Vogelsang et al., was published by the Journal of Cognitive Neuroscience on 01/01/24.

This UC Berkeley study investigated how dopamine affects communication between different regions of the brain's frontal cortex. The researchers conducted their study with participants who received either a placebo or one of two different dopamine-affecting drugs: bromocriptine (which primarily affects D2 receptors) or tolcapone (which increases dopamine levels, particularly in the frontal cortex). The study used resting-state fMRI to examine how these drugs influenced the communication patterns between different frontal cortex areas.

The research team was particularly interested in six specific regions of the left frontal cortex that are known to be necessary for cognitive control. They used a unique analysis method called spectral Dynamic Causal Modeling (DCM) to measure how these different brain regions influenced each other. This method allowed them to determine whether areas were communicating and the direction of that communication– essentially showing which regions were "leading" and which were "following."

The results revealed some interesting patterns. Both dopamine drugs increased communication from a region called the caudal middle frontal gyrus (cMFG) to other areas of the frontal cortex. This is thought to be where top-down and bottom-up control information converge, which means it’s a vital decision-making center. 

The drugs had different effects on other pathways– they increased communication along some routes while decreasing it along others. Surprisingly, both drugs (despite working in various ways) produced similar overall effects on brain communication patterns.

One limitation of the study was that participants weren't performing any specific tasks during the brain scanning– they were simply resting. While this provided useful baseline information about how dopamine affects brain communication, it doesn't tell us exactly how these changes might affect cognitive performance.

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