Double dissociation of two cognitive control networks in patients with focal brain lesions

Abstract

Neuroimaging studies of cognitive control have identified two distinct networks with dissociable resting state connectivity patterns. This study, in patients with heterogeneous damage to these networks, demonstrates network independence through a double dissociation of lesion location on two different measures of network integrity: functional correlations among network nodes and within-node graph theory network properties. The degree of network damage correlates with a decrease in functional connectivity within that network while sparing the nonlesioned network. Graph theory properties of intact nodes within the damaged network show evidence of dysfunction compared with the undamaged network. The effect of anatomical damage thus extends beyond the lesioned area, but remains within the bounds of the existing network connections. Together this evidence suggests that networks defined by their role in cognitive control processes exhibit independence in resting data.functional MRI | functional connectivity | graph theory | resting state | stroke C ognitive control is required in everyday life to coordinate our thoughts and actions to achieve internal goals while still allowing the flexibility to adjust these goals with changing task demands. Although previous studies have attributed cognitive control to various prefrontal cortical regions (1, 2), recently it has been proposed that a dual-network architecture exists in the human brain in which cognitive control depends on regions that extend beyond the frontal cortex (3). In a recent cross-task analysis, Dosenbach et al. (4) identified a number of regions active during different stages of cognitive control tasks. Given the difficulty in isolating cognitive control networks that are simultaneously active during task performance, the investigators took advantage of the recent advent of resting state functional MRI (rs-fMRI) for detecting spontaneous fluctuations between coherent brain regions. In a follow-up study, these predefined regions of interest (ROIs) obtained from the task data served as seeds in a correlation analysis of rs-fMRI data (3) in which graph theory and hierarchical clustering were applied to the correlation matrices. These analyses identified two distinct networks labeled as fronto-parietal (FP) and cinguloopercular (CO) (Fig. 1A). Based on their role in cognitive tasks, the FP network consists of nodes proposed to provide signals that act on a rapid time scale to initiate and adjust control, whereas the CO network nodes act to provide signals that allow set maintenance over a longer time scale (3,5).Numerous studies using rs-fMRI have shown that neuronal activity is characterized by temporal correlations in blood oxygen level-dependent signal across disparate brain regions (6, 7). These fluctuations seem highly consistent over time and reflect the presence of intrinsic functional (8) and structural (9) connectivity. Among these fluctuations, different networks can be distinguished, many of which show remarkable resemblance to task-related networks (...

Network measures predict neuropsychological outcome after brain injury

“…second, that lesions to locations with low scores on these measures will have more limited consequences. These predictions align with and advance an emerging perspective on the importance of connector regions in brain networks (1,2,14).…”

The modular and integrative functional architecture of the human brain

“…Thus, when the costs of adding connections is significant in the overall energy budget of an organism, as is likely for the brain, modular networks with weaker connectivity between modules than within the modules are superior to nonmodular networks, as they function as well and adapt faster without consuming as much energy. Moreover, a double dissociation was found between two modules, such that, for both modules, damage to a node in one module only caused dysfunction (i.e., a decrease in functional connectivity) in the damaged module, suggesting their autonomy (78). Finally, empirical functional connectivity studies have shown that modules are weakly functionally connected to each other, likely because their computations are predominantly distinct, suggesting modular function (6,7,16,36,79).…”

Longitudinal Effects of Lesions on Functional Networks after Stroke

“…Alterations of functional connectivity in heterogeneous lesions have been previously explored by Nomura et al 11 Patients were examined using a single scan at least 5 months poststroke or injury. The results demonstrated double dissociation of two cognitive control networks (frontoparietal and cinguloopercular).…”

“…As brain functions emerge from interacting regions that are part of a network topology, [1][2][3][4] so too can alterations across networks coincide with various pathological states such as disorders of consciousness, 5,6 Alzheimer's disease, 7 neuropsychiatric disorders, 8 and stroke. [9][10][11][12][13] Stroke lesions provide a unique model of how local damage can result in long-distance alterations. Similar structural damage has been shown to result in different levels of impairment to functionality, and patients can present multiple deficits in the acute phase that are not easily attributed to the direct effect of the focal lesion.…”