Dorsal Posterior Cingulate Cortex Research Articles

Differential Effects of Dual and Unihemispheric Motor Cortex Stimulation in Older Adults

Bihemispheric transcranial direct current stimulation (tDCS) is thought to upregulate excitability of the primary motor cortex (M1) using anodal stimulation while concurrently downregulating contralateral M1 using cathodal stimulation. This "dual" tDCS method enhances motor learning in healthy subjects and facilitates motor recovery after stroke. However, its impact on motor system activity and connectivity remains unknown. Therefore, we assessed neural correlates of dual and unihemispheric anodal tDCS effects in 20 healthy older subjects in a randomized, sham-controlled study using a cross-over design. Participants underwent tDCS and simultaneous functional magnetic resonance imaging during a choice reaction time task and at rest. Diffusion tensor imaging (DTI) allowed us to relate potential functional changes to structural parameters. The resting-state analysis demonstrated that, compared with sham, both dual and anodal tDCS decreased connectivity of right hippocampus and M1 (contralateral to the anode position) while increasing connectivity in the left prefrontal cortex. Notably, dual but not anodal tDCS enhanced connectivity of the left dorsal posterior cingulate cortex. Furthermore, dual tDCS yielded stronger activations in bilateral M1 compared with anodal tDCS when participants used either their left or right hand during the motor task. The corresponding tDCS-induced changes in laterality of activations were related to the microstructural status of transcallosal motor fibers. In conclusion, our results suggest that the impact of bihemispheric tDCS cannot be explained by mere add-on effects of anodal and concurrent cathodal stimulation, but rather by complex network modulations involving interhemispheric interactions and areas associated with motor control in the dorsal posterior cingulate cortex.

Mindfulness disposition and default-mode network connectivity in older adults

An extensive body of research defines the default-mode network (DMN) to be one of the critical networks of the human brain, playing a pivotal functional role in processes of internal mentation. Alterations in the connectivity of this network as a function of aging have been found, with reductions associated with functional ramifications for the elderly population. This study examined associations between integrity of the DMN and trait levels of mindfulness disposition, defined by our ability to exert attentional and emotional control in the present moment, and, thereby, bring awareness to immediate experiences. Twenty-five older adults participated in the study and underwent a brief functional magnetic resonance imaging session and filled out questionnaires related to their overall health and mindfulness disposition. Mindfulness disposition was associated with greater connectivity of the DMN, specifically, in the dorsal posterior cingulate cortex and the precuneus. Mindfulness disposition, thus, explains variance in the connectivity of one of the more intrinsic networks of the human brain, known to be critical for promoting self-relevant mental explorations and building cognitive and affective control.

Echoes of the Brain within the Posterior Cingulate Cortex

There is considerable uncertainty about the function of the posterior cingulate cortex (PCC). The PCC is a major node within the default mode network (DMN) and has high metabolic activity and dense structural connectivity to widespread brain regions, which suggests it has a role as a cortical hub. The region appears to be involved in internally directed thought, for example, memory recollection. However, recent nonhuman primate work provides evidence for a more active role in the control of cognition, through signaling an environmental change and the need to alter behavior. For an organism to flexibly react to a changing environment, information processed in functionally distinct brain networks needs to be integrated by such a cortical hub. If the PCC is involved in this process, its brain activity should show a complex and dynamic pattern that partially reflects activity in other brain networks. Using fMRI in humans and a multivariate analysis, we demonstrate that the PCC shows this type of complex functional architecture, where echoes of multiple other brain networks are seen in separable yet overlapping subregions. For example, a predominantly ventral region shows strong functional connectivity to the rest of the DMN, whereas two subregions within the dorsal PCC show high connectivity to frontoparietal networks involved in cognitive control. PCC subregions showed distinct patterns of activity modulation during the performance of an attentionally demanding task, suggesting that parts of the dorsal PCC interact with frontoparietal networks to regulate the balance between internally and externally directed cognition.

Cognition and Neuroimaging in Schizophrenia

Cognition and Neuroimaging in Schizophrenia

Differential Neural Responses to Food Images in Women with Bulimia versus Anorexia Nervosa

BackgroundPrevious fMRI studies show that women with eating disorders (ED) have differential neural activation to viewing food images. However, despite clinical differences in their responses to food, differential neural activation to thinking about eating food, between women with anorexia nervosa (AN) and bulimia nervosa (BN) is not known.MethodsWe compare 50 women (8 with BN, 18 with AN and 24 age-matched healthy controls [HC]) while they view food images during functional Magnetic Resonance Imaging (fMRI).ResultsIn response to food (vs non-food) images, women with BN showed greater neural activation in the visual cortex, right dorsolateral prefrontal cortex, right insular cortex and precentral gyrus, women with AN showed greater activation in the right dorsolateral prefrontal cortex, cerebellum and right precuneus. HC women activated the cerebellum, right insular cortex, right medial temporal lobe and left caudate. Direct comparisons revealed that compared to HC, the BN group showed relative deactivation in the bilateral superior temporal gyrus/insula, and visual cortex, and compared to AN had relative deactivation in the parietal lobe and dorsal posterior cingulate cortex, but greater activation in the caudate, superior temporal gyrus, right insula and supplementary motor area.ConclusionsWomen with AN and BN activate top-down cognitive control in response to food images, yet women with BN have increased activation in reward and somatosensory regions, which might impinge on cognitive control over food consumption and binge eating.

Visual Motion Responses in the Posterior Cingulate Sulcus: A Comparison to V5/MT and MST

Motion processing regions apart from V5+/MT+ are still relatively poorly understood. Here, we used functional magnetic resonance imaging to perform a detailed functional analysis of the recently described cingulate sulcus visual area (CSv) in the dorsal posterior cingulate cortex. We used distinct types of visual motion stimuli to compare CSv with V5/MT and MST, including a visual pursuit paradigm. Both V5/MT and MST preferred 3D flow over 2D planar motion, responded less yet substantially to random motion, had a strong preference for contralateral versus ipsilateral stimulation, and responded nearly equally to contralateral and to full-field stimuli. In contrast, CSv had a pronounced preference to 2D planar motion over 3D flow, did not respond to random motion, had a weak and nonsignificant lateralization that was significantly smaller than that of MST, and strongly preferred full-field over contralateral stimuli. In addition, CSv had a better capability to integrate eye movements with retinal motion compared with V5/MT and MST. CSv thus differs from V5+/MT+ by its unique preference to full-field, coherent, and planar motion cues. These results place CSv in a good position to process visual cues related to self-induced motion, in particular those associated to eye or lateral head movements.

Fractionating the Default Mode Network: Distinct Contributions of the Ventral and Dorsal Posterior Cingulate Cortex to Cognitive Control

The posterior cingulate cortex (PCC) is a central part of the default mode network (DMN) and part of the structural core of the brain. Although the PCC often shows consistent deactivation when attention is focused on external events, anatomical studies show that the region is not homogeneous, and electrophysiological recordings in nonhuman primates suggest that it is directly involved in some forms of attention. We report a functional magnetic resonance imaging study of an attentionally demanding task (either a zero- or two-back working memory task). Standard subtraction analysis within the PCC shows a relative deactivation as task difficulty increases. In contrast, a dual-regression functional connectivity analysis reveals a clear dissociation between ventral and dorsal parts of the PCC. As task difficulty increases, the ventral PCC shows reduced integration within the DMN and less anticorrelation with the cognitive control network (CCN) activated by the task. The dorsal PCC shows an opposite pattern, with increased DMN integration and more anticorrelation. At rest, the dorsal PCC also shows functional connectivity with both the DMN and attentional networks. As expected, these results provide evidence that the PCC is involved in supporting internally directed thought, as the region is more highly integrated with the DMN at low task demands. In contrast, the task-dependent increases in connectivity between the dorsal PCC and the CCN are consistent with a role for this region in modulating the dynamic interaction between these two networks controlling the efficient allocation of attention.

Occurrence of neuronal dysfunction during the first 5 years of multiple sclerosis is associated with cognitive deterioration

Brain neuronal injury is present in patients suffering from multiple sclerosis (MS) from the earliest stage of the disease; however, the functional counterpart of early neuronal injury is largely unknown. The goal of this study was to assess the potential impact of early neuronal dysfunction affecting white matter (WM), grey matter (GM), or the cerebellum on cognitive deterioration and/or EDSS progression during the first 5 years of MS. Magnetic resonance spectroscopic (MRS) examinations and neuropsychological assessments were performed in 23 patients included after the first clinical attack of MS and 24 healthy controls. The same protocol was performed in patients after a follow-up of 5 years. Metabolic neuronal function was assessed in WM (splenium of corpus callosum), GM (dorsal posterior cingulate cortex), and the cerebellum by evaluating N-acetylaspartate (NAA) levels. During follow-up, 39% of patients showed cognitive deterioration and 43% showed a deterioration in their EDSS. Patients with cognitive deterioration had greater NAA level reductions during follow-up in the cerebellum (p = 0.003) and WM (p = 0.02) compared to patients without cognitive deterioration. In addition, patients with cognitive deterioration had higher progression of T2 lesion load (T2LL) during the follow-up period compared to patients without cognitive deterioration (p = 0.03). No differences between patients with and without EDSS progression in terms of NAA levels or T2LL were observed. The present longitudinal study found evidence that, during the first 5 years of MS, cognitive deterioration is associated with the progression of neuronal dysfunction and tissue injury as assessed by MRS and T2LL, respectively.

Reduced gray matter volume of dorsal cingulate cortex in patients with obsessive–compulsive disorder: A voxel‐based morphometric study

Previous morphometric studies using magnetic resonance imaging (MRI) have revealed structural brain abnormalities in obsessive-compulsive disorder (OCD). The aim of the present study was to investigate the alterations in brain structure of patients with OCD using a voxel-based morphometry (VBM) method. Sixteen patients with OCD free of comorbid major depression, and 32 sex- and age-matched healthy subjects underwent MRI using a 1.5-T MR scanner. OCD severity was assessed with the Yale-Brown Obsessive-Compulsive Scale (mean ± SD: 22 ± 7.6; range: 7-32). MR images were spatially normalized and segmented using the VBM5 package (http://dbm.neuro.uni-jena.de/vbm/). Statistical analysis was performed using statistical parametric mapping software. Significant reductions in regional gray matter volume were detected in the left caudal anterior cingulate cortex and right dorsal posterior cingulate cortex in the patients with OCD as compared to healthy controls (uncorrected, P < 0.001). No significant differences in white matter volumes were observed in any brain regions of the patients. No significant correlation between Yale-Brown Obsessive-Compulsive Scale score and regional gray matter or white matter volume was observed. Regional gray matter alteration in the dorsal cingulate cortex, which is suggested to play a role in non-emotional cognitive processes, may be related to the pathophysiology in OCD.

Influence of Satiety and Subjective Valence Rating on Cerebral Activation Patterns in Response to Visual Stimulation with High-Calorie Stimuli among Restrictive Anorectic and Control Women

Background: There is evidence that patients with anorexia nervosa (AN) demonstrate specific cerebral activation patterns in response to visual food stimulation. We postulated that cerebral activation patterns could represent different perceptions of high-calorie images during hunger and satiety and could be determined by patients’ subjective ratings. Methods: After 6 h of starvation and also in a state of satiety, 12 female patients with AN and 12 normal-weight women were assessed by use of fMRI with high-calorie food images. All patients suffered from a restrictive type of AN. Heart rates, subjective ratings of satiety and valences of the visual stimuli were assessed. Results: Food stimuli presented during a state of hunger were associated with significant activation of the anterior cingulate cortex and insula in the control group and of the prefrontal and central cortices and insula in the AN group. During the hunger state activation in AN of the dorsal posterior cingulate cortex was revealed compared to the controls. In the state of satiety, activation of the left insula was observed in the AN group. Use of the food valence judgment as a covariate confirmed the insula activation and revealed additional activation of the orbitofrontal, cingulate and medial temporal cortices. Conclusion: Our results indicate differences in cerebral activation patterns due to different perceptions of high-calorie food images, modulated by feelings of hunger or satiety, among AN patients with modulation by subjective ratings of food valence.

Negative affectivity, self-referential processing and the cortical midline structures

The neural bases of the association between negative affectivity and self-focus remain unknown in healthy subjects. Building on the role of the cortical midline structures (CMS) in self-referential processing, we hypothesized that negative affectivity in healthy subjects would be associated with an increased activation of the CMS during self-referential processing. We presented positive and negative pictures to 45 healthy subjects during fMRI and asked them to judge whether the pictures were related to themselves or not (self condition), or whether the pictures were positive or negative (general condition). Negative affectivity was measured by the level of harm avoidance (HA) with the Temperament and Character Inventory. Self-referential processing activated the CMS, including the dorsal and ventral medial prefrontal cortex (MPFC) and the posterior cingulate cortex (PCC). A higher HA score was associated with a greater activation of the dorsal MPFC and PCC during self-referential processing, this greater activation being more pronounced for negative pictures in the dorsal MPFC. This increased activation of the CMS may embody the association between negative affectivity and self-focus in healthy subjects, as previously observed in major depression. Within the CMS, the dorsal MPFC may play a key role in negative affectivity, integrating an increased attention to negative stimuli with an increased attention to the self.

Bursts of 15–30 Hz oscillations following noxious laser stimulus originate in posterior cingulate cortex

Previous EEG studies reported the presence of synchronised 15–30 Hz oscillations in vertex electrodes following innocuous somatosensory stimulation and noxious laser stimulation. The purpose of the present study was to analyse the sources of poststimulus increases of 15–30 Hz oscillations during noxious laser stimulation of four different body regions and to compare the sources of the poststimulus synchronisation with the sources of the N2 component of laser-evoked potential (LEP). In 10 healthy subjects, moderately painful laser stimuli were applied to the dorsum of the right hand, dorsum of the right foot, right groin, and right side of the face. EEG data, recorded from 111 scalp sites, were analysed using event-related desynchronisation method and source dipole analysis. A profound amplitude increase of 15–30 Hz oscillations peaking 1–2 s after noxious laser stimulation was found during stimulation of each body part. The sources of these oscillations were located in the dorsal posterior cingulate cortex and showed no somatotopic arrangement. The sources of the N2–LEP component were located in the anterior mid-cingulate cortex 25–30 mm rostral to the sources of 15–30 Hz oscillations. The amplitude of the poststimulus synchronisation of 15–30 Hz oscillations correlated ( P < 0.05) with the amplitude of N2–LEP component. Results show that noxious laser stimuli induce bursts of 15–30 Hz oscillations in the posterior cingulate cortex. The poststimulus increases of 15–30 Hz oscillations may stand for transient cortical inhibition possibly aiding temporary suppression of motor programs that have been primed by noxious stimulation.

Graded cutaneous electrical vs thermal stimulation in humans shows different insular and cingulate cortex activation

Pain can result from various sensory input modalities. To elucidate the differences of cortical responses to graded electrical and thermal stimulation, functional magnetic resonance imaging (fMRI) results of two studies using the same stimulation paradigms but different modalities with 15 healthy subjects each are compared. During painful electrical stimulation contralateral dorsal posterior insula and ventral posterior anterior cingulate cortex (ACC) activated more. During thermal stimulation, there was more activation in ipsilateral primary motor area (MI)/primary sensory area (SI) complex and premotor areas as well as dorsal posterior ACC. Thus electrostimulation preferably activates structures of the lateral pain projection system resulting in contralateral dorsal posterior insula and ventral posterior ACC activation. During thermal stimulation, more dorsal areas of the posterior ACC activated. The activation of ipsilateral MI/SI complex and premotor areas may be attributed to the slower perception of thermal stimuli and resulting re-evaluation. This has to be taken into account in the interpretation of other cross-modality studies as well.

Hemispheric asymmetry in cognitive division of anterior cingulate cortex: A resting-state functional connectivity study

The cognitive division of anterior cingulate cortex (ACC-cd) plays an important role in cognitive control via a distributed attention network. The structural hemispheric asymmetries of ACC have been revealed by several neuroimaging studies. However potential functional hemispheric asymmetries of ACC remain less clear. Investigating the functional hemispheric asymmetries of ACC helps for a better understanding of ACC function. The aim of this study was to use resting-state functional magnetic resonance imaging (fMRI) to examine hemispheric differences in the functional networks associated with ACC-cd in the two hemispheres. ROI-based functional connectivity analysis was performed on a group of 49 right-handed healthy volunteers. The left and right ACC-cd showed significant differences in their patterns of connectivity with a variety of brain regions, including the dorsolateral prefrontal cortex, inferior parietal lobule, superior parietal lobule and dorsal posterior cingulate cortex in their ipsilateral cerebral cortex, as well as cerebellar tonsil and inferior semilunar lobule in their contralateral cerebellar hemisphere. Specifically, for these areas, we found significantly greater connectivity strength with ACC-cd in the right hemisphere than the left, regardless of whether the connection was positive or negative. The current results highlight the presence of clear asymmetries in functional networks associated with ACC-cd. Future functional imaging studies are needed to give greater attention to the lateralized ACC functional networks which are observed.

Modulation of a Human Memory Circuit by Subsyndromal Depression in Late Life: A Functional Magnetic Resonance Imaging Study

Functional deactivation of the posteromedial cortex (PMC) seems to be a physiologic process underlying normal memory. The authors examined whether older subjects with subsyndromal depressive symptoms show impaired PMC deactivation. Subjects underwent 4T functional magnetic resonance imaging scan while performing a novel and familiar face-name associative encoding task. The Beck-II Depression Inventory (BDI) was used to self-rate depression symptoms. A novel-minus-familiar encoding contrast was built into a simple regression model showing brain activation magnitudes that covaried with BDI score. A region-of-interest mask was applied to isolate the PMC and other midline structures of the default-mode network. The study was conducted at a university-based medical center. Participants included 62 nondemented subjects aged 55-85, with and without mild memory deficits. BDI scores ranged from 0 to 17. Analysis revealed a distinct PMC cluster confined to the dorsal posterior cingulate cortex (BA 31) whose activity correlated significantly with BDI score. A multiple regression model further showed that BDI score, as well as a history of depression and current use of antidepressants, had a significant effect on cluster variance, while age, education, gender, and mini-mental state exam scores did not. Our findings raise the hypothesis that subsyndromal depressive symptoms in late life may impair physiological PMC deactivation in the dorsal posterior cingulate cortex. A prospective study of a full spectrum of depressed patients may be warranted.

The influence of parental history of Alzheimer's disease and apolipoprotein E 4 on the BOLD signal during recognition memory

First-degree family history (FH) of sporadic Alzheimer's disease and the apolipoprotein E epsilon4 allele (APOE4) are risk factors for Alzheimer's disease that may affect brain function prior to onset of clinical symptoms. In this functional MRI (fMRI) study, we used an episodic recognition task that required discrimination of previously viewed (PV) and novel (NV) faces to examine differences in blood oxygen level dependent (BOLD) signal due to risk factors in 74 middle-aged cognitively normal individuals. The group effects on this recognition task were tested with a 2 x 2 ANCOVA factorial design (+FH/-FH and +APOE4/-APOE4). There were significant APOE4 and FH effects in the left dorsal posterior cingulate cortex and precuneus, where decreased risk resulted in greater activity during recollection. Recognition performance was positively correlated with BOLD signal in the left posterior hippocampus, parahippocampal-retrosplenial gyrus and left superior frontal cortex regardless of risk factors. To examine condition-specific group effects, both the PV and NV faces were tested further in separate 2 x 2 ANCOVAs. Both models revealed an APOE effect, with the -APOE4 group showing stronger signal than the +APOE4 group in anterior cingulate cortices, while a FH effect was found in the dorsal cuneus and medial frontal cortices with the -FH group showing stronger signal than the +FH group. Finally, interactions between APOE4 and FH effects were found bilaterally in the fusiform gyrus. These results suggest that risk factors and cognitive performance each influence brain activity during recognition. The findings lend further support to the idea that functional brain changes may begin far in advance of symptomatic Alzheimer's disease.

Activation of the posterior cingulate by semantic priming: A co-registered ERP/fMRI study

Although the N400 is the best understood semantically sensitive component of the event-related potential (ERP), others have been observed as well. In an earlier lexical decision study, an N300 ERP was found to be enhanced to unprimed targets, although the effect could also be characterized as a prolonged P2 to primed targets as described in other reports. Because its scalp topography suggested its neural source might be of interest, a source localization was conducted that suggested that this component emanated from the dorsal posterior cingulate cortex (dPCC). In order to confirm this word N300 localization, a functional magnetic resonance imaging (fMRI) study was conducted to replicate the ERP study with a separate sample of 17 participants in an event-related design, using a 3-T scanner. A significant activation in the right dPCC was found corresponding to the N300 localization. The activation was greater on the related prime trials, supporting the characterization of the ERP component as being a P2 rather than an N300. A review is provided which suggests that a number of separate lines of ERP research regarding the word N300, the picture N300, the word P2, the phonological mismatch negativity, and the word midline frontal negativity may be most parsimoniously regarded as dealing with the same ERP component and that they all therefore emanate from the dPCC. It is suggested that this region plays a role in stimulus–response mapping in polymodal fashion. It is also suggested that the ERP component be termed a P2-dPCC.

The neural processing of moral sensitivity to issues of justice and care

The empirical and theoretical consideration of ethical decision making has focused on the process of moral judgment; however, a precondition to judgment is moral sensitivity, the ability to detect and evaluate moral issues [Rest, J. R. (1984). The major components of morality. In W. Kurtines & J. Gewirtz (Eds.), Morality, moral behaviour, and moral development (pp. 24–38). New York, NY: Wiley]. Using functional magnetic resonance imaging (fMRI) and contextually standardized, real life moral issues, we demonstrate that sensitivity to moral issues is associated with activation of the polar medial prefrontal cortex, dorsal posterior cingulate cortex, and posterior superior temporal sulcus (STS). These activations suggest that moral sensitivity is related to access to knowledge unique to one's self, supported by autobiographical memory retrieval and social perspective taking. We also assessed whether sensitivity to rule-based or “justice” moral issues versus social situational or “care” moral issues is associated with dissociable neural processing events. Sensitivity to justice issues was associated with greater activation of the left intraparietal sulcus, whereas sensitivity to care issues was associated with greater activation of the ventral posterior cingulate cortex, ventromedial and dorsolateral prefrontal cortex, and thalamus. These results suggest a role for access to self histories and identities and social perspectives in sensitivity to moral issues, provide neural representations of the subcomponent process of moral sensitivity originally proposed by Rest, and support differing neural information processing for the interpretive recognition of justice and care moral issues.