Inferior Parietal Cortex Research Articles

Age of Bilingual Onset Shapes the Dynamics of Functional Connectivity and Laterality in the Resting-State.

Bilingualism is known to enhance cognitive function and flexibility of the brain. However, it is not clear how bilingual experience affects the time-varying functional network and whether these changes depend on the age of bilingual onset. This study intended to investigate the bilingual-related dynamic functional connectivity (dFC) based on the resting-state functional magnetic resonance images, including 23 early bilinguals (EBs), 30 late bilinguals (LBs), and 31 English monolinguals. The analysis identified two dFC states, and LBs showed more transitions between these states than monolinguals. Moreover, more frequent left-right switches were found in functional laterality in prefrontal, lateral temporal, lateral occipital, and inferior parietal cortices in EBs compared with LB and monolingual cohorts, and the laterality changes in the anterior superior temporal cortex were negatively correlated with L2 proficiency. These findings highlight how the age of L2 acquisition affects cortico-cortical dFC pattern and provide insight into the neural mechanisms of bilingualism.

Effects of family income on brain functional connectivity in US children: associations with cognition.

Higher family income (FI) is associated with larger cortical gray matter volume and improved cognitive performance in children. However, little is known about the effects of FI on brain functional and structural connectivity. This cross-sectional study investigates the effects of FI on brain connectivity and cognitive performance in 9- to 11-years old children (n = 8739) from the Adolescent Brain Cognitive Development (ABCD) study. Lower FI was associated with decreased global functional connectivity density (gFCD) in the default-mode network (DMN), inferior and superior parietal cortices and in posterior cerebellum, and increased gFCD in motor, auditory, and extrastriate visual areas, and in subcortical regions both for girls and boys. Findings demonstrated high reproducibility in Discovery and Reproducibility samples. Cognitive performance partially mediated the association between FI and DMN connectivity, whereas DMN connectivity did not mediate the association between FI and cognitive performance. In contrast, there was no significant association between FI and structural connectivity. Findings suggest that poor cognitive performance, which likely reflects multiplefactors (genetic, nutritional, the level and quality of parental interactions, and educational exposure [1]), contributes to reduced DMN functional connectivity in children from low-income families. Follow-up studies are needed to help clarify if this leads to reductions in structural connectivity as these children age.

Independent and combined effects of methamphetamine use disorders and APOEε4 allele on cognitive performance and brain morphometry.

Prior studies showed that methamphetamine (METH) users had greater than normal age-related brain atrophy; whether having the apolipoprotein E (APOE)-ε4 allele may be a contributory factor has not been evaluated. We aimed to determine the independent and combined effects of chronic heavy METH use and having at least one copy of the APOE-ε4 allele (APOE-ε4+) on brain morphometry and cognition, especially in relation to aging. We compared brain morphometry and cognitive performance in 77 individuals with chronic heavy METH use (26 APOE-ε4+, 51 APOE-ε4-) and 226 Non-METH users (66 APOE-ε4+, 160 APOE-ε4-), using a 2 × 2 design (two-way analysis of co-variance). Vertex-wise cortical volumes, thickness and seven subcortical volumes, were automatically measured using FreeSurfer. Linear regression between regional brain measures, and cognitive scores that showed group differences were evaluated. Group differences in age-related decline in brain and cognitive measures were also explored. Regardless of APOE-ε4 genotype, METH users had lower Motor Z-scores (P = 0.005), thinner right lateral-orbitofrontal cortices (P < 0.001), smaller left pars-triangularis gyrus volumes (P = 0.004), but larger pallida, hippocampi and amygdalae (P = 0.004-0.006) than nonusers. Across groups, APOE-ε4+ METH users had the smallest volumes of superior frontal cortical gyri bilaterally, and of the smallest volume in left rostral-middle frontal gyri (all P-values <0.001). Smaller right superior-frontal gyrus predicted poorer motor function only in APOE-ε4+ participants (interaction-P < 0.001). Cortical volumes and thickness declined with age similarly across all participants; however, APOE-ε4-carriers showed thinner right inferior parietal cortices than noncarriers at younger age (interaction-P < 0.001). Chronic heavy use and having at least one copy of the APOE-ε4 allele may have synergistic effects on brain atrophy, particularly in frontal cortices, which may contribute to their poorer cognitive function. However, the enlarged subcortical volumes in METH users replicated prior studies, and are likely due to METH-mediated neuroinflammation.

Hippocampal-cortical functional connectivity during memory encoding and retrieval

Memory encoding and retrieval are critical sub-processes of episodic memory. While the hippocampus is involved in both, less is known about its connectivity with the neocortex during memory processing in humans. This is partially due to variations in demands in common memory tasks, which inevitably recruit cognitive processes other than episodic memory. Conjunctive analysis of data from different tasks with the same core elements of encoding and retrieval can reduce the intrusion of patterns related to subsidiary perceptual and cognitive processing. Leveraging data from two large-scale functional resonance imaging studies with different episodic memory tasks (514 and 237 participants), we identified hippocampal-cortical networks active during memory tasks. Whole-brain functional connectivity maps were similar during resting state, encoding, and retrieval. Anterior and posterior hippocampus had distinct connectivity profiles, which were also stable across resting state and memory tasks. When contrasting encoding and retrieval connectivity, conjunctive encoding-related connectivity was sparse. During retrieval hippocampal connectivity was increased with areas known to be active during recollection, including medial prefrontal, inferior parietal, and parahippocampal cortices. This indicates that the stable functional connectivity of the hippocampus along its longitudinal axis is superposed by increased functional connectivity with the recollection network during retrieval, while auxiliary encoding connectivity likely reflects contextual factors.

Cortical structural and functional coupling during development and implications for attention deficit hyperactivity disorder

Functional connectivity is scaffolded by the structural connections of the brain. Disruptions of either structural or functional connectivity can lead to deficits in cognitive functions and increase the risk for neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD). To date, very little research has examined the association between structural and functional connectivity in typical development, while no studies have attempted to understand the development of structure-function coupling in children with ADHD. 175 individuals (84 typically developing children and 91 children with ADHD) participated in a longitudinal neuroimaging study with up to three waves. In total, we collected 278 observations between the ages 9 and 14 (139 each in typically developing controls and ADHD). Regional measures of structure-function coupling were calculated at each timepoint using Spearman’s rank correlation and mixed effect models were used to determine group differences and longitudinal changes in coupling over time. In typically developing children, we observed increases in structure-function coupling strength across multiple higher-order cognitive and sensory regions. Overall, weaker coupling was observed in children with ADHD, mainly in the prefrontal cortex, superior temporal gyrus, and inferior parietal cortex. Further, children with ADHD showed an increased rate of coupling strength predominantly in the inferior frontal gyrus, superior parietal cortex, precuneus, mid-cingulate, and visual cortex, compared to no corresponding change over time in typically developing controls. This study provides evidence of the joint maturation of structural and functional brain connections in typical development across late childhood to mid-adolescence, particularly in regions that support cognitive maturation. Findings also suggest that children with ADHD exhibit different patterns of structure-function coupling, suggesting atypical patterns of coordinated white matter and functional connectivity development predominantly in the regions overlapping with the default mode network, salience network, and dorsal attention network during late childhood to mid-adolescence.

Perilesional and contralesional brain activations related to associative encoding of unfamiliar face-names pairs in adults with left chronic stroke with or without ischemic infarct on left inferior frontal gyrus

The study of an Ischemic stroke infarction allows verifying how the lesion produces alterations in the neuronal networks resulting in cognitive deficits. It also allows the verification of adaptive and maladaptive cerebral reorganization related to the injury. In our previous fMRI study, we found that patients without ischemic vascular lesions in left inferior frontal gyrus showed an efficient compensation mechanism during the associative encoding of face name pairs, by the increased activation of ventrolateral and dorsolateral areas of contralesional hemisphere associated with better memory performance. While patients with ischemic vascular lesions on left inferior frontal gyrus (IFG) demonstrated worse memory performance and no signs of compensation mechanism. The present study explores more of these findings by analyzing perilesional and contralesional activations related to unfamiliar face name associative encoding in adults with chronic ischemic stroke, with or without left IFG lesion, compared to healthy controls. The main results showed that stroke survivors without lesions in IFG demonstrated increased activation in perilesional and contralesional prefrontal regions associated with better associative memory recognition, which are indicative of adaptive compensatory mechanisms. However, they also showed a negative correlation between the activation of right anterior prefrontal and inferior parietal regions and the associative memory performance, which may indicate the presence of maladaptive interhemispheric disinhibition. On the other hand, stroke survivors with IFG lesions demonstrated negative correlations in activations of the ipsilesional inferior parietal cortex and positive correlations in activations of the left middle frontal gyrus and left precentral cortex, which demonstrate the simultaneous occurrence of adaptive and maladaptive brain reorganization mechanisms in this group. However, the increase in perilesional prefrontal regions, associated with bilateral activation of the hippocampus and amygdala, was not enough to compensate for the inefficiency of associative memory performance. Finally, the differences in activation observed in stroke survivors reflect their clinical heterogeneity and demonstrate that adaptive or maladaptive compensatory mechanisms can coexist in the same group of patients. Furthermore, they reinforce the importance of the left IFG in the associative encoding of unfamiliar face name pairs and may suggest a deficit in associative memory related to injury in this region.

Ictal Fear during parietal seizures.

Ictal fear is characterized by subjective fear sensation and consistent clinical manifestations during seizures. This phenomenon is rarely observed in parietal seizures. We report anatomical electroclinical correlations of an SEEG-recorded seizure with prominent fear semiology. Seizure onset zone was quantified using the Connectivity Epileptogenicity Index method (cEI). Occurrence of fear during seizures was related to the involvement of the left inferior parietal cortex and the superior temporal gyrus without amygdala involvement. Our case confirms that parietal seizure can produce ictal fear without concomitant involvement of the limbic temporal network.

Neurophysiological mechanisms underlying the differential effect of reward prospect on response selection and inhibition

Reward and cognitive control play crucial roles in shaping goal-directed behavior. Yet, the behavioral and neural underpinnings of interactive effects of both processes in driving our actions towards a particular goal have remained rather unclear. Given the importance of inhibitory control, we investigated the effect of reward prospect on the modulatory influence of automatic versus controlled processes during response inhibition. For this, a performance-contingent monetary reward for both correct response selection and response inhibition was added to a Simon NoGo task, which manipulates the relationship of automatic and controlled processes in Go and NoGo trials. A neurophysiological approach was used by combining EEG temporal signal decomposition and source localization methods. Compared to a non-rewarded control group, rewarded participants showed faster response execution, as well as overall lower response selection and inhibition accuracy (shifted speed-accuracy tradeoff). Interestingly, the reward group displayed a larger interference of the interactive effects of automatic versus controlled processes during response inhibition (i.e., a larger Simon NoGo effect), but not during response selection. The reward-specific behavioral effect was mirrored by the P3 amplitude, underlining the importance of stimulus–response association processes in explaining variability in response inhibition performance. The selective reward-induced neurophysiological modulation was associated with lower activation differences in relevant structures spanning the inferior frontal and parietal cortex, as well as higher activation differences in the somatosensory cortex. Taken together, this study highlights relevant neuroanatomical structures underlying selective reward effects on response inhibition and extends previous reports on the possible detrimental effect of reward-triggered performance trade-offs on cognitive control processes.

The Different Impact of Depressive or Manic First-episode on Pediatric Bipolar Disorder Patients: Evidence From Resting-state fMRI

Bipolar disorder may begin as depression or mania, which can affect the treatment and prognosis of bipolar disorder. However, the physiological and pathological differences of pediatric bipolar disorder (PBD) patients with different onset symptoms are not clear. The purpose of this study was to investigate the differences of clinical, cognitive function and intrinsic brain networks in PBD patients with first-episode depression and first-episode mania. A total of 63 participants, including 43 patients and 20 healthy controls, underwent resting-state fMRI scans. PBD patients were classified as first-episode depressive and first-episode manic based on their first-episode symptoms. Cognitive tests were used to measure attention and memory of all participants. Independent component analysis (ICA) was used to extract the salience network (SN), default-mode network (DMN), central executive network (ECN) and limbic network (LN) for each participant. Spearman rank correlation analysis was performed between abnormal activation and clinical and cognitive measures. The results showed that there were differences in cognitive functions such as attention and visual memory between first-episode depression and mania, as well as differences activation in anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), precuneus, inferior parietal cortex and parahippocampus. And significant associations of brain activity with clinical assessments or cognition were found in different patients. In conclusion, we found differential impairments in cognitive and brain network activation in first-episode depressive and first-episode manic PBD patients, and correlations were found between these impairments. These evidences may shed light on the different developmental paths of bipolar disorder.

Longitudinal changes in brain structure and their relationship with subclinical psychiatric symptoms in parents who lost their only child in China

ABSTRACT Background: Losing an only child (Shidu) is a grievous traumatic event that may affect brain structure, even if it does not lead to psychiatric disorders. However, longitudinal changes in brain structure and their relationship to subclinical psychiatric symptoms (SPS) have not been well investigated in Shidu parents without any psychiatric disorders (SDNP). Objectives: This study aimed to investigate cross-sectional and longitudinal changes in cortical thickness and surface area in SDNP, and to explore their relationship with SPS. Methods: A total of 50 SDNP and 40 matched healthy controls (HC) were enrolled. All participants underwent structural MRI scans and clinical assessment at baseline and at the 5-year follow-up. Differences in brain structural phenotypes (cortical thickness, surface area, and their annual rate of change) between the SDNP and HC groups were compared using FreeSurfer. Correlations between significant brain structural phenotypes and SPS in the SDNP group were evaluated using multiple linear regressions. Results: The SDNP group showed a smaller surface area in the left inferior parietal cortex than the HC group at baseline and follow-up. The SDNP group showed slower rates of cortical thinning and surface area loss in several brain regions than the HC group from baseline to follow-up. Moreover, slower rates of cortical thinning in the left insula, superior frontal cortex, and superior temporal cortex were associated with greater reductions in avoidance, depression, and trauma re-experiencing symptoms scores over time in the SDNP group, respectively. Conclusions: Shidu trauma-induced structural abnormalities in the inferior parietal cortex may persist over time and be independent of the severity of psychiatric symptoms. The expansion of prefrontal, temporal, and insular cortex implicated in emotional regulation may contribute to improvements in psychiatric symptoms in Shidu parents.

Perception-Action Integration Is Altered in Functional Movement Disorders.

Although functional neurological movement disorders (FMD) are characterized by motor symptoms, sensory processing has also been shown to be disturbed. However, how the integration of perception and motor processes, essential for the control of goal-directed behavior, is altered in patients with FMD is less clear. A detailed investigation of these processes is crucial to foster a better understanding of the pathophysiology of FMD and can systematically be achieved in the framework of the theory of event coding (TEC). The aim was to investigate perception-action integration processes on a behavioral and neurophysiological level in patients with FMD. A total of 21 patients and 21 controls were investigated with a TEC-related task, including concomitant electroencephalogram (EEG) recording. We focused on EEG correlates established to reflect perception-action integration processes. Temporal decomposition allowed to distinguish between EEG codes reflecting sensory (S-cluster), motor (R-cluster), and integrated sensory-motor processing (C-cluster). We also applied source localization analyses. Behaviorally, patients revealed stronger binding between perception and action, as evidenced by difficulties in reconfiguring previously established stimulus-response associations. Such hyperbinding was paralleled by a modulation of neuronal activity clusters, including reduced C-cluster modulations of the inferior parietal cortex and altered R-cluster modulations in the inferior frontal gyrus. Correlations of these modulations with symptom severity were also evident. Our study shows that FMD is characterized by altered integration of sensory information with motor processes. Relations between clinical severity and both behavioral performance and neurophysiological abnormalities indicate that perception-action integration processes are central and a promising concept for the understanding of FMD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Biotribology in the Cognitive Domain: Investigation of the Neural Response to a Textured Tactile Stimulus using Event-Related Potentials (ERP)

Tactile communication tools such as tactile graphics and braille used by the blind and visually impaired (BVI) rely on the sense of touch to convey information. Limitations in the skin's perceptive resolution and inefficiencies in the representation of tactile information within a modest amount of page space pose challenges in representing scientific information such as those commonly encountered in the STEM fields. To overcome such limitations, the tribological factors affecting perception and the subsequent quantification of perception using a reliable metric unaffected by subjectivity are essential. In this study, direct observation of the neural activity in response to a tactile stimulus using event-related potentials (ERP) is presented, and its viability to consistently quantify the neural activity and locate the cortical regions involved in tactile stimulus processing has been investigated. A control sample with no textures and a textured sample that presents a change from smooth to rough textures were used as stimuli. The ERP data were collected using a 64-electrode electroencephalography (EEG) system. A squared difference approach was used to measure the differences in the electric potential amplitude caused by the control sample and the textured sample. The primary somatosensory cortex (SI) and posterior parietal cortex (PPC) of the brain showed persistent activity, suggesting that these areas were frequently involved in processing the tactile stimulus used in this study. Surprising results were observed when the temporal cortex and inferior parietal cortex (IPC) that have not been previously shown to be involved in processing tactile stimulations also showed persistent activity. However, their proximity to the primary somatosensory cortex and posterior parietal cortex suggests that areas adjacent to these cortices might also be involved in tactile stimulus processing. Overall, the analysis results showed that ERP could be used as a quantitative and objective tool in studying the cognitive response to tactile stimuli.

Yoga prevents grey matter volume decline in women at risk for Alzheimer’s Disease: A randomized controlled trial

AbstractBackgroundFemale sex, subjective cognitive decline (SCD), and cardiovascular risk factors (CVRF) are known risk factors for developing Alzheimer’s disease (AD). We previously demonstrated that yoga improved depression, resilience, memory and executive functions, increased hippocampal choline concentrations and modulated brain connectivity in older adults with mild cognitive impairment. In this study (NCT03503669), we investigated brain gray matter volume (GMV) changes in older women with SCD and CVRF following three months of yoga compared to memory training (MET).MethodsEleven women (mean age = 61.45, SD = 6.58) with CVRF and SCD completed twelve weeks of Kundalini yoga (KY) and Kirtan Kriya (KK), while eleven women (mean age = 64.55, SD = 6.41) underwent MET. T1‐weighted MRI scans were acquired at baseline and follow‐up using a Siemens 3T Prisma scanner. We used Freesurfer 6 and longitudinal two‐step models to test group differences in symmetrized percent change in GMV. Resulting clusters were corrected and Monte‐Carlo simulations applied at an alpha level of 0.05. Region‐of‐interest analysis was performed for hippocampus and amygdala.ResultsCompared to KY+KK, MET showed reductions in GMV in left prefrontal, pre‐ and post‐central, supramarginal, superior temporal and pericalcarine cortices, right paracentral, postcentral, superior and inferior parietal cortices, the banks of the superior temporal sulcus, and the pars opercularis. Right hippocampal volume increased after yoga but did not survive corrections.ConclusionYoga training may offer neuroprotective effects compared to MET in preventing neurodegenerative changes and cognitive decline, even over short time intervals. Future analyses will address changes in functional connectivity in both groups.

Mild behavioral impairment linked to phenoconversion to Alzheimer’s disease and cortical thinning in mild cognitive impairment

AbstractBackgroundMild Behavioral Impairment (MBI) is a neurobehavioral syndrome characterized by later life emergence of sustained neuropsychiatric symptoms, as an at‐risk state for dementia (Ismail Z, Alzheimers Dement, 2016). However, the associations between MBI and a risk of phenocoversion to dementia and its neuroanatomical correlates in MCI are still unclear.MethodA total 1326 older adults with MCI was followed for a mean of 3.0 ± 2.0 years. MBI was approximated using a transformation algorithm for the neuropsychiatric inventory at baseline. Two‐step cluster analysis was used to explore classes of 5 MBI domains (decreased motivation, affective dysregulation, impulse dyscontrol, social inappropriateness, abnormal perception/thought content). A Cox regression analysis was applied to investigate the association between the clusters and phenoconversion to AD. A subset of participants (n = 225) underwent 3D T1‐weighted MRI scans and cortical thickness was compared among the clusters of MBI domains.ResultThe cluster analysis identified 3 groups of participants: (1) people without MBI (47.8%, asymptomatic); (2) people with only affective dysregulation (29.3%, affective dysregulation); (3) people with relatively high probability of affective dysregulation, followed by impulse dyscontrol and affective dysregulation (22.9%, multiple domains). Compared to the asymptomatic, multiple domains was associated with a higher risk of phenoconversion to AD (hazard ratio = 2.589 [1.981 – 3.385], p = &lt; 0.001), but affective dysregulation did not predict phenoconversion (1.204 [0.896 – 1.620], p = 0.219) (Fig 1). MCI individuals with symptoms in multiple domains revealed thinning in the bilateral superior and inferior parietal, superior temporal, and prefrontal cortex, and the right precuneus compared to those with only affective dysregulation (Fig 2). We did not find differences in cortical thickness between phenocoverter and non‐phenoconverter, and interaction of clusters of MBI domains and phenoconversion.ConclusionThe multiple co‐occuring MBI domains in individuals with MCI are associated with a higher risk of phenoconversion to AD. Moreover, MCI individuals with symptoms in multiple domains revealed cortical thinning in the superior parietal and precuneus, which have suggested as AD signatures (Dickerson BC, Cereb Cortex, 2009). These results suggest that evaluation of MBI and neuroimaging characteristics could be useful for risk stratification in MCI individuals.

Poor Oral Health and Risk of Incident Dementia: A Prospective Cohort Study of 425,183 Participants.

The association between poor oral health and the risk of incident dementia remains unclear. To investigate the associations of poor oral health with incident dementia, cognitive decline, and brain structure in a large population-based cohort study. A total of 425,183 participants free of dementia at baseline were included from the UK Biobank study. The associations between oral health problems (mouth ulcers, painful gums, bleeding gums, loose teeth, toothaches, and dentures) and incident dementia were examined using Cox proportional hazards models. Mixed linear models were used to investigate whether oral health problems were associated with prospective cognitive decline. We examined the associations between oral health problems and regional cortical surface area using linear regression models. We further explored the potential mediating effects underlying the relationships between oral health problems and dementia. Painful gums (HR = 1.47, 95% CI [1.317-1.647], p < 0.001), toothaches (HR = 1.38, 95% CI [1.244-1.538], p < 0.001), and dentures (HR = 1.28, 95% CI [1.223-1.349], p < 0.001) were associated with increased risk of incident dementia. Dentures were associated with a faster decline in cognitive functions, including longer reaction time, worse numeric memory, and worse prospective memory. Participants with dentures had smaller surface areas of the inferior temporal cortex, inferior parietal cortex, and middle temporal cortex. Brain structural changes, smoking, alcohol drinking, and diabetes may mediate the associations between oral health problems and incident dementia. Poor oral health is associated with a higher risk of incident dementia. Dentures may predict accelerated cognitive decline and are associated with regional cortical surface area changes. Improvement of oral health care could be beneficial for the prevention of dementia.

Longitudinal evolution of cortical thickness signature reflecting Lewy body dementia in isolated REM sleep behavior disorder: a prospective cohort study

BackgroundThe isolated rapid-eye-movement sleep behavior disorder (iRBD) is a prodromal condition of Lewy body disease including Parkinson's disease and dementia with Lewy bodies (DLB). We aim to investigate the longitudinal evolution of DLB-related cortical thickness signature in a prospective iRBD cohort and evaluate the possible predictive value of the cortical signature index in predicting dementia-first phenoconversion in individuals with iRBD.MethodsWe enrolled 22 DLB patients, 44 healthy controls, and 50 video polysomnography-proven iRBD patients. Participants underwent 3-T magnetic resonance imaging (MRI) and clinical/neuropsychological evaluations. We characterized DLB-related whole-brain cortical thickness spatial covariance pattern (DLB-pattern) using scaled subprofile model of principal components analysis that best differentiated DLB patients from age-matched controls. We analyzed clinical and neuropsychological correlates of the DLB-pattern expression scores and the mean values of the whole-brain cortical thickness in DLB and iRBD patients. With repeated MRI data during the follow-up in our prospective iRBD cohort, we investigated the longitudinal evolution of the cortical thickness signature toward Lewy body dementia. Finally, we analyzed the potential predictive value of cortical thickness signature as a biomarker of phenoconversion in iRBD cohort.ResultsThe DLB-pattern was characterized by thinning of the temporal, orbitofrontal, and insular cortices and relative preservation of the precentral and inferior parietal cortices. The DLB-pattern expression scores correlated with attentional and frontal executive dysfunction (Trail Making Test-A and B: R = − 0.55, P = 0.024 and R = − 0.56, P = 0.036, respectively) as well as visuospatial impairment (Rey-figure copy test: R = − 0.54, P = 0.0047). The longitudinal trajectory of DLB-pattern revealed an increasing pattern above the cut-off in the dementia-first phenoconverters (Pearson’s correlation, R = 0.74, P = 6.8 × 10−4) but no significant change in parkinsonism-first phenoconverters (R = 0.0063, P = 0.98). The mean value of the whole-brain cortical thickness predicted phenoconversion in iRBD patients with hazard ratio of 9.33 [1.16–74.12]. The increase in DLB-pattern expression score discriminated dementia-first from parkinsonism-first phenoconversions with 88.2% accuracy.ConclusionCortical thickness signature can effectively reflect the longitudinal evolution of Lewy body dementia in the iRBD population. Replication studies would further validate the utility of this imaging marker in iRBD.

Correspondence between BOLD fMRI task response and cerebrovascular reactivity across the cerebral cortex.

BOLD sensitivity to baseline perfusion and blood volume is a well-acknowledged fMRI confound. Vascular correction techniques based on cerebrovascular reactivity (CVR) might reduce variance due to baseline cerebral blood volume, however this is predicated on an invariant linear relationship between CVR and BOLD signal magnitude. Cognitive paradigms have relatively low signal, high variance and involve spatially heterogenous cortical regions; it is therefore unclear whether the BOLD response magnitude to complex paradigms can be predicted by CVR. The feasibility of predicting BOLD signal magnitude from CVR was explored in the present work across two experiments using different CVR approaches. The first utilized a large database containing breath-hold BOLD responses and 3 different cognitive tasks. The second experiment, in an independent sample, calculated CVR using the delivery of a fixed concentration of carbon dioxide and a different cognitive task. An atlas-based regression approach was implemented for both experiments to evaluate the shared variance between task-invoked BOLD responses and CVR across the cerebral cortex. Both experiments found significant relationships between CVR and task-based BOLD magnitude, with activation in the right cuneus (R 2 = 0.64) and paracentral gyrus (R 2 = 0.71), and the left pars opercularis (R 2 = 0.67), superior frontal gyrus (R 2 = 0.62) and inferior parietal cortex (R 2 = 0.63) strongly predicted by CVR. The parietal regions bilaterally were highly consistent, with linear regressions significant in these regions for all four tasks. Group analyses showed that CVR correction increased BOLD sensitivity. Overall, this work suggests that BOLD signal response magnitudes to cognitive tasks are predicted by CVR across different regions of the cerebral cortex, providing support for the use of correction based on baseline vascular physiology.

Deep learning applied to EEG source-data reveals both ventral and dorsal visual stream involvement in holistic processing of social stimuli

Perception of social stimuli (faces and bodies) relies on “holistic” (i.e., global) mechanisms, as supported by picture-plane inversion: perceiving inverted faces/bodies is harder than perceiving their upright counterpart. Albeit neuroimaging evidence suggested involvement of face-specific brain areas in holistic processing, their spatiotemporal dynamics and selectivity for social stimuli is still debated. Here, we investigate the spatiotemporal dynamics of holistic processing for faces, bodies and houses (adopted as control non-social category), by applying deep learning to high-density electroencephalographic signals (EEG) at source-level. Convolutional neural networks were trained to classify cortical EEG responses to stimulus orientation (upright/inverted), separately for each stimulus type (faces, bodies, houses), resulting to perform well above chance for faces and bodies, and close to chance for houses. By explaining network decision, the 150–200 ms time interval and few visual ventral-stream regions were identified as mostly relevant for discriminating face and body orientation (lateral occipital cortex, and for face only, precuneus cortex, fusiform and lingual gyri), together with two additional dorsal-stream areas (superior and inferior parietal cortices). Overall, the proposed approach is sensitive in detecting cortical activity underlying perceptual phenomena, and by maximally exploiting discriminant information contained in data, may reveal spatiotemporal features previously undisclosed, stimulating novel investigations.

Thalamo-cortical circuits during sensory attenuation in emerging psychosis: a combined magnetoencephalography and dynamic causal modelling study

Evidence suggests that schizophrenia (ScZ) involves impairments in sensory attenuation. It is currently unclear, however, whether such deficits are present during early-stage psychosis as well as the underlying network and the potential as a biomarker. To address these questions, Magnetoencephalography (MEG) was used in combination with computational modeling to examine M100 responses that involved a “passive” condition during which tones were binaurally presented, while in an “active” condition participants were asked to generate a tone via a button press. MEG data were obtained from 109 clinical high-risk for psychosis (CHR-P) participants, 23 people with a first-episode psychosis (FEP), and 48 healthy controls (HC). M100 responses at sensor and source level in the left and right thalamus (THA), Heschl’s gyrus (HES), superior temporal gyrus (STG) and right inferior parietal cortex (IPL) were examined and dynamic causal modeling (DCM) was performed. Furthermore, the relationship between sensory attenuation and persistence of attenuated psychotic symptoms (APS) and transition to psychosis was investigated in CHR-P participants. Sensory attenuation was impaired in left HES, left STG and left THA in FEP patients, while in the CHR-P group deficits were observed only in right HES. DCM results revealed that CHR-P participants showed reduced top-down modulation from the right IPL to the right HES. Importantly, deficits in sensory attenuation did not predict clinical outcomes in the CHR-P group. Our results show that early-stage psychosis involves impaired sensory attenuation in auditory and thalamic regions but may not predict clinical outcomes in CHR-P participants.

Functional and effective connectivity analysis of drug-resistant epilepsy: a resting-state fMRI analysis.

Epilepsy is considered as a neural network disorder. Seizure activity in epilepsy may disturb brain networks and damage brain functions. We propose using resting-state functional magnetic resonance imaging (rs-fMRI) data to characterize connectivity patterns in drug-resistant epilepsy. This study enrolled 47 participants, including 28 with drug-resistant epilepsy and 19 healthy controls. Functional and effective connectivity was employed to assess drug-resistant epilepsy patients within resting state networks. The resting state functional connectivity (FC) analysis was performed to assess connectivity between each patient and healthy controls within the default mode network (DMN) and the dorsal attention network (DAN). In addition, dynamic causal modeling was used to compute effective connectivity (EC). Finally, a statistical analysis was performed to evaluate our findings. The FC analysis revealed significant connectivity changes in patients giving 64.3% (18/28) and 78.6% (22/28) for DMN and DAN, respectively. Statistical analysis of FC was significant between the medial prefrontal cortex, posterior cingulate cortex, and bilateral inferior parietal cortex for DMN. For DAN, it was significant between the left and the right intraparietal sulcus and the frontal eye field. For the DMN, the patient group showed significant EC connectivity in the right inferior parietal cortex and the medial prefrontal cortex for the DMN. There was also bilateral connectivity between the medial prefrontal cortex and the posterior cingulate cortex, as well as between the left and right inferior parietal cortex. For DAN, patients showed significant connectivity in the right frontal eye field and the right intraparietal sulcus. Bilateral connectivity was also found between the left frontal eye field and the left intraparietal sulcus, as well as between the right frontal eye field and the right intraparietal sulcus. The statistical analysis of the EC revealed a significant result in the medial prefrontal cortex and the right intraparietal cortex for the DMN. The DAN was found significant in the left frontal eye field, as well as the left and right intraparietal sulcus. Our results provide preliminary evidence to support that the combination of functional and effective connectivity analysis of rs-fMRI can aid in diagnosing epilepsy in the DMN and DAN networks.