Dysregulated left inferior parietal activity in schizophrenia and depression: functional connectivity and characterization

Abstract

The inferior parietal cortex (IPC) is a heterogeneous region that is known to be involved in a multitude of diverse different tasks and processes, though its contribution to these often-complex functions is yet poorly understood. In a previous study we demonstrated that patients with depression failed to deactivate the left IPC during processing of congruent audiovisual information. We now found the same dysregulation (same region and condition) in schizophrenia. By using task-independent (resting state) and task-dependent meta-analytic connectivity modeling (MACM) analyses we aimed at characterizing this particular region with regard to its connectivity and function. Across both approaches, results revealed functional connectivity of the left inferior parietal seed region with bilateral IPC, precuneus and posterior cingulate cortex (PrC/PCC), medial orbitofrontal cortex (mOFC), left middle frontal (MFG) as well as inferior frontal (IFG) gyrus. Network-level functional characterization further revealed that on the one hand, all interconnected regions are part of a network involved in memory processes. On the other hand, sub-networks are formed when emotion, language, social cognition and reasoning processes are required. Thus, the IPC-region that is dysregulated in both depression and schizophrenia is functionally connected to a network of regions which, depending on task demands may form sub-networks. These results therefore indicate that dysregulation of left IPC in depression and schizophrenia might not only be connected to deficits in audiovisual integration, but is possibly also associated to impaired memory and deficits in emotion processing in these patient groups.

Dynamic connectivity states estimated from resting fMRI Identify differences among Schizophrenia, bipolar disorder, and healthy control subjects

“…Abnormal FC in left IFG, MiFG, and IFG was found in SZ patients (Jeong et al, 2009; Müller et al, 2013). …”

Comparison of structural covariance with functional connectivity approaches exemplified by an investigation of the left anterior insula

“…That is, we tested whether the conditional probability of activation given a particular label [P(Activation|Task)] was higher than the baseline probability of activating the region in question per se [P(Activation)]. Significance was established using a binomial test (p < .05, corrected for multiple comparisons using FDR; Müller et al, 2013; Rottschy et al, 2013). In the reverse inference approach, the functional profile was determined by identifying the most likely behavioral domains and paradigm classes given activation in a particular region.…”

The multiple neural networks of familiarity: A meta-analysis of functional imaging studies

“…Thus, lPFC activation would reflect that processing of stimuli that are identified as familiar may engage a more exhaustive search for details, which suggests more detailed processing of familiar stimuli (Wheeler & Buckner, 2004). In contrast, it has been suggested that the mPFC may belong to a system (in association with amygdala and ACC) that exerts emotion-driven influences on action selection (Ernst & Paulus, 2005;Müller, Cieslik, Laird, Fox, & Eickhoff, 2013;Ridderinkhof, Van den Wildenberg, Segalowitz, & Carter, 2004). Thus, both in the paradigms with and without encoding, activations within the lPFC (i.e., the inferior frontal gyrus) may be associated with the cognitive assessment of familiarity, whereas those within the medial PFC (mPFC) may reflect affective appraisal (Ernst & Paulus, 2005;Martínez-Selva, Sánchez-Navarro, Bechara, & Román, 2006;Ridderinkhof et al, 2004).…”