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Identified Prefrontal Cortex Networks

  • Using connectivity analysis methods with independent component analysis, clustering, and modularity analysis being most commonly used, six networks involving the prefrontal cortex (PFC) have been identified and proposed to mediate cognitive control (figures adapted from [2]):

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  • The Frontal-Parietal Network is formed by the dorsolateral and dorsomedial PFC, the supramarginal gyrus in posterior parietal cortex and subcortical nodes including the dorsal caudate and anterior thalamus

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  • The Salience Network is formed by the anterior insula, adjoining fronto-insular cortex, and dorsal anterior cingulate cortex, with subcortical nodes including the amygdala, substantia nigra, ventral tegmental area, dorsomedial thalamus, hypothalamus, and periaqueductal gray

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  • The Cingulo-Opercular Network is formed by the anterior insula, adjoining fronto-insular cortex and the anterior cingulate cortex and adjacent dorsomedial PFC

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  • The Ventral Attention Network is formed by the ventral-posterior aspects of the inferior frontal gyrus and the temporo-parietal junction in posterior cortex

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  • The Dorsal Attention Network is formed by the frontal eye fields and intra-parietal sulcus

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  • The Default Mode Network is formed by the medial prefrontal cortex, the posterior cingulate cortex, medial temporal lobe, and angular gyrus

  • ​PFC networks operate as distinct and independent functional units in which each PFC node is reciprocally connected to another node in the parietal cortex [2]

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  • Dorsal PFC regions are linked to more dorsal parietal cortical regions whereas ventral PFC regions are linked to more ventral parietal cortical regions, showing a "dorsal-ventral gradient", reflecting the anatomical segregation of pathways associated with three major fibre tracts that connect PFC and parietal cortex: the dorsal, middle, and ventral superior longitudinal fasciculi​

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  • The segregation of PFC networks also extends to distinct subcortical regions as individual networks exhibit different degrees of connectivity to subcortical regions

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  • PFC networks show high functional symmetry across hemispheres by both direct monosynaptic cross-callosal tracts and multi-synaptic links via the cortico-thalamic tract​

General Patterns & Comparison of PFC Networks

PFC Network Dynamics Mediating Cognitive Control

  • ​The dynamic cooperation and competition between PFC networks likely mediates CC: while these networks serve as dedicated and specialized functional units, they do not function in isolation but display complex patterns of context-dependent dynamic interactions (see PFC network dynamics cycle during working memory task trials on the right figure, adapted from [2])

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  • The intrinsic functional symmetry of PFC networks can be shifted with greater right hemisphere response and connectivity associated with visuospatial attention and inhibitory control processes​

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  • The Dorsal Attention Network is primarily involved in the top-down selection of information, whereas the Ventral Attention Network detects behaviorally relevant stimuli and acts as a “circuit breaker” by intervening to shift the top-down selection [7]​

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  • It was demonstrated that the Frontal-Parietal Network and Cingulo-Opercular Network became more integrated with each other during conditions of increased cognitive control, and the integration predicts task accuracy [8]​

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  • Nodes in the Fronto-Parietal Network provide signals on a rapid time scale to initiate, adjust and control the flow of information whereas the nodes in the Cingulo-Opercular Network provide signals that allow for set-maintenance over a longer time scale [9]

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  • The Salience Network plays a crucial role in switching between context-dependent engagement and disengagement of the Frontal-Parietal Network and Default Mode Network [10]

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  • The Frontal-Parietal Network plays a “coordinator” role that flexibly allows nodes in the Cingulo-Opercular Network with a "shifter” role to lend processing resources to other goal-relevant during CC [10]​​

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  • The Default Mode Network plays a crucial role in self-referential processing and the monitoring of the internal mental landscape [11]

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Outstanding Questions & Research Directions

  • The exploration of the dynamic mechanisms of PFC networks is still at the early stage as the picture of the complex dynamics that produce CC and its components are far from clear; how do PFC networks operate on the flow of information at the computational, algorithmic, and mechanistic levels?

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  • Do PFC network dynamics suggest that the organisation and hierarchy of CC component constructs identified by the psychometric approach are valid and accurate?

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  • How are brainstem neuromodulatory systems, such as dopamine, norepinephrine and serotonin, on PFC networks involved in CC?

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  • How does the exploration of PFC network mechanisms inform about deficits in neurodevelopmental and neuropsychiatric conditions, and their treatments? 

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