Dopaminergic Modulation of the Central Executive, Default Mode, and Salience Networks

Understanding the complex interactions between neurotransmitters and large-scale brain networks is crucial for unraveling the underlying neurochemical mechanisms of cognitive processes. Although brain functions are modulated by a large number of neurotransmitters, one stands out for its key involvement in cognition: dopamine. This compound has been shown, although not consistently, to affect three of the main brain networks: the salience network (SN), the central executive network (CEN), and the default mode network (DMN). Specifically, an increase in dopamine has been often associated with an increase in intra SN-connectivity, resulting in a heightened negative coupling between the CEN and DMN. However, not only these results remain uncertain, but research in the field remains incomplete as until now, it has maintained a narrow focus. Thus, the present fMRI study aimed to expand on previous findings, by investigating the effects of dopamine on the SN, CEN and DMN during a working...Show moreUnderstanding the complex interactions between neurotransmitters and large-scale brain networks is crucial for unraveling the underlying neurochemical mechanisms of cognitive processes. Although brain functions are modulated by a large number of neurotransmitters, one stands out for its key involvement in cognition: dopamine. This compound has been shown, although not consistently, to affect three of the main brain networks: the salience network (SN), the central executive network (CEN), and the default mode network (DMN). Specifically, an increase in dopamine has been often associated with an increase in intra SN-connectivity, resulting in a heightened negative coupling between the CEN and DMN. However, not only these results remain uncertain, but research in the field remains incomplete as until now, it has maintained a narrow focus. Thus, the present fMRI study aimed to expand on previous findings, by investigating the effects of dopamine on the SN, CEN and DMN during a working memory task. We recruited 30 healthy participants, all of which took part in two sessions, during which we manipulated their dopamine levels in the brain. To this end, in each session they received either a placebo or L-dopa, a precursor of dopamine known to increase the brain’s dopamine production and availability. During each session, participants underwent fMRI scanning, while performing a working memory task consisting of alternating working memory and rest blocks. Based on previous research, we hypothesized that dopamine would lead to a faster switch between the CEN and DMN when switching between working memory and rest blocks. In addition, we hypothesized that this faster switch would be driven by a higher intra SN connectivity. Results of paired permutation testing, as well as of a three-way ANOVA, revealed a lack of the expected dopamine-dependent changes. Dopamine did not significantly affect the switch between the CEN and DMN, nor it affected SN connectivity. These findings contradict previous literature, and call for further investigation of the dopaminergic modulation of these networks and their interactions.Show less

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Dopaminergic Modulation of the Central Executive, Default Mode, and Salience Networks