The role of the posterior cingulate cortex in cognition and disease

Abstract

The posterior cingulate cortex is a highly connected and metabolically active brain region. Recent studies suggest it has an important cognitive role, although there is no consensus about what this is. The region is typically discussed as having a unitary function because of a common pattern of relative deactivation observed during attentionally demanding tasks. One influential hypothesis is that the posterior cingulate cortex has a central role in supporting internally-directed cognition. It is a key node in the default mode network and shows increased activity when individuals retrieve autobiographical memories or plan for the future, as well as during unconstrained 'rest' when activity in the brain is 'free-wheeling'. However, other evidence suggests that the region is highly heterogeneous and may play a direct role in regulating the focus of attention. In addition, its activity varies with arousal state and its interactions with other brain networks may be important for conscious awareness. Understanding posterior cingulate cortex function is likely to be of clinical importance. It is well protected against ischaemic stroke, and so there is relatively little neuropsychological data about the consequences of focal lesions. However, in other conditions abnormalities in the region are clearly linked to disease. For example, amyloid deposition and reduced metabolism is seen early in Alzheimer's disease. Functional neuroimaging studies show abnormalities in a range of neurological and psychiatric disorders including Alzheimer's disease, schizophrenia, autism, depression and attention deficit hyperactivity disorder, as well as ageing. Our own work has consistently shown abnormal posterior cingulate cortex function following traumatic brain injury, which predicts attentional impairments. Here we review the anatomy and physiology of the region and how it is affected in a range of clinical conditions, before discussing its proposed functions. We synthesize key findings into a novel model of the region's function (the 'Arousal, Balance and Breadth of Attention' model). Dorsal and ventral subcomponents are functionally separated and differences in regional activity are explained by considering: (i) arousal state; (ii) whether attention is focused internally or externally; and (iii) the breadth of attentional focus. The predictions of the model can be tested within the framework of complex dynamic systems theory, and we propose that the dorsal posterior cingulate cortex influences attentional focus by 'tuning' whole-brain metastability and so adjusts how stable brain network activity is over time.

Cortical pathology in multiple sclerosis detected by the T1/T2‐weighted ratio from routine magnetic resonance imaging

“…Currently, we cannot distinguish whether the relation is specific for MS or physiological, as MuSIC subscores were not determined in our HC group and none of the mean values of the MuSIC subscores differed significantly from those given in the original publication on MuSIC 22. Nevertheless, our finding corresponds with cognitive deficits in patients having suffered from damage to the posterior cingulate cortex 36. This relation is commonly explained by the finding that the posterior cingulate cortex is an important hub in the default mode network, which is also altered in MS 44, 45…”

“…The posterior cingulate is assumed to play a central role for internally directed cognition, retrieval of memory, and attention,36 which are in part covered by our clinical scores (see Table 2). Because correlation between the cluster values of the left and right posterior cingulate cortex was high ( R 2  = 0.7) and because we had no hypothesis on lateralized effects, we used the individual mean values (collapsed across hemispheres) of both clusters for correlation with the 12 clinical scores given in Table 2.…”

The Dissociative Subtype of Posttraumatic Stress Disorder: Unique Resting-State Functional Connectivity of Basolateral and Centromedial Amygdala Complexes

“…The dorsal PCC also showed greater functional connectivity between the left CMA in the PTSD+DS group as compared with the PTSD − DS group. Generally, the PCC has been shown to be associated with visuospatial orientation that is mediated through its extensive parietal lobe connections and assessment of self-relevant sensations (Vogt and Laureys, 2005), and recently it has been suggested that the dorsal PCC is involved in conscious, awareness, and attention (Leech and Sharp, 2014). Moreover, the dorsal PCC is implicated in orienting the body toward innocuous and noxious somatosensory stimuli and mediates nociception, the encoding and processing of harmful stimuli (Vogt and Laureys, 2005).…”

Cognitive impairment in epilepsy: the role of reduced network flexibility

“…Anterior cingulate/medial superior frontal cortex has been identified as a key region that implements “task sets”, setting brain state in a domain independent manner 20, 21. Posterior cingulate cortex, a major hub of the default mode network, plays a central role in cognition, modulating interactions between the default mode network and cognitive networks that are important for task performance 22. Furthermore, steady state connectivity analyses in epilepsy have repeatedly pointed to the presence of dysfunction within the default mode network 23…”