Cortical Gray Matter Thickness and Volume Changes and Their Association with Memory Functions in Hyperthyroid Patients

INTRODUCTION

Hyperthyroidism, characterized by excessive thyroid hormone production, is a common endocrine disorder that affects various physiological processes, including brain function. Recent advancements in neuroimaging techniques have enabled researchers to investigate structural alterations in the brain associated with hyperthyroidism. This study aimed to examine regional cortical thickness and cortical volume differences across the brain between hyperthyroid patients and control subjects.

METHODS

We examined localized cortical thicknesses and volumes in 34 hyperthyroid patients and 35 control subjects with high-resolution T1-weighted images using FreeSurfer software and assessed group differences with analysis of covariance (covariates: age, sex, education, and total intracranial volume). Spearman and partial correlations were performed between clinical variables and cortical thicknesses/volumes and between neuropsychological scores and cortical thicknesses/volumes, respectively.

RESULTS

Hyperthyroid patients exhibited significantly increased cortical thickness in bilateral superior temporal and superior frontal gyri, along with higher cortical volumes in various regions, including the right superior temporal gyrus, right superior parietal gyrus, right rostral and caudal middle frontal gyrus, and left superior frontal gyrus. Notably, thyroid hormones (fT3, fT4) correlated positively with cortical thicknesses and volumes in the superior temporal gyrus and superior frontal gyrus. Additionally, recognition memory scores negatively correlated with the right superior temporal gyrus and right superior frontal gyrus cortical thickness.

CONCLUSION

The observed cortical thickening and increased cortical volume in specific brain areas provide new insights into the pathophysiological mechanism associated with brain impairment in hyperthyroidism.

Diffusion and structural MRI as potential biomarkers in people with Parkinson's disease and cognitive impairment

OBJECTIVE

To explore the neuroimage change in Parkinson's disease (PD) patients with cognitive impairments, this study investigated the correlation between plasma biomarkers and morphological brain changes in patients with normal cognition and mild cognitive impairment. The objective was to identify the potential target deposition regions of the plasma biomarkers and to search for the relevant early neuroimaging biomarkers on the basis of different cognitive domains.

METHODS

Structural brain MRI and diffusion weighted images were analyzed from 49 eligible PD participants (male/female: 27/22; mean age: 73.4 ± 8.5 years) from a retrospective analysis. Plasma levels of α-synuclein, amyloid beta peptide, and total tau were collected. A comprehensive neuropsychological assessment of the general and specific cognitive domains was performed. Difference between PD patients with normal cognition and impairment was examined. Regression analysis was performed to evaluate the correlation between image-derived index and plasma biomarkers or neuropsychological assessments.

RESULTS

Significant correlation was found between plasma Aβ-42 level and fractional anisotropy of the middle occipital, angular, and middle temporal gyri of the left brain, as well as plasma T-tau level and the surface area of the isthmus or the average thickness of the posterior part of right cingulate gyrus. Visuospatial and executive function is positively correlated with axial diffusivity in bilateral cingulate gyri.

CONCLUSION

In nondemented PD patients, the target regions for plasma deposition might be located in the cingulate, middle occipital, angular, and middle temporal gyri. Changes from multiple brain regions can be correlated to the performance of different cognitive domains.

CLINICAL RELEVANCE STATEMENT

Cognitive impairment in Parkinson's disease is primarily linked to biomarkers associated with Alzheimer's disease rather than those related to Parkinson's disease and resembles the frontal variant of Alzheimer's disease, which may guide management strategies for cognitive impairment in Parkinson's disease.

KEY POINTS

• Fractional anisotropy, surface area, and thickness in the cingulate, middle occipital, angular, and middle temporal gyri can be significantly correlated with plasma Aβ-42 and T-tau level. • Axial diffusivity in the cingulate gyri was correlated with visuospatial and executive function. • The pattern of cognitive impairment in Parkinson's disease can be similar to the frontal variant than typical Alzheimer's disease.

Association Between Wnt Target Genes and Cortical Volumes in Alzheimer's Disease

The disproportionate cortical atrophy is an established biomarker for the pathophysiological process of Alzheimer's disease (AD). However, the genetic basis underlying the cortical atrophy remains poorly defined. Herein, we aim to illustrate the effect of the Wnt target genes on the cortical volumes of AD patients. 82 sporadic AD patients were recruited. All the subjects had history survey, blood biochemical examination, cognitive assessment, MRI morphometry and whole exome sequencing. This report focused on 84 common variants (minor allele frequency > 0.01) of 32 Wnt target genes, including the APC, DAAM1, DACT1, DISC1, LATS2, TLR2, WDR61, and the AXIN, DVL, FZD, LRP, TCF/LEF, WNT family genes. The Wnt target genes showed asymmetric effects on the cortical volumes of AD patients. The right temporal/parietal/occipital cortices were more affected than left temporal/parietal/occipital cortices. Nevertheless, the reverse applied to the frontal cortex. The DACT1 affected the cortical thickness most, followed by the TCF3 and APC. The DACT1 rs698025-GG genotype displayed greater right temporal pole and left medial orbito-frontal gyrus than rs698025-GA genotype (2.4 ± 0.4 vs. 2.0 ± 0.6, P = 0.005; 5.2 ± 0.6 vs. 5.0 ± 0.6, P = 0.001). The brain region most influenced by the Wnt target genes was the right calcarine cortex. In conclusion, the common variants of the Wnt target genes exert asymmetric effects on the cortical volumes of AD patients. The Wnt signaling pathway may play a role in the cortical atrophy of AD patients.

Identification of structural brain alterations in adolescents with depressive symptomatology

INTRODUCTION

Depressive symptoms can emerge as early as childhood and may lead to adverse situations in adulthood. Studies have examined structural brain alternations in individuals with depressive symptoms, but findings remain inconclusive. Furthermore, previous studies have focused on adults or used a categorical approach to assess depression. The current study looks to identify grey matter volumes (GMV) that predict depressive symptomatology across a clinically concerning sample of adolescents.

METHODS

Structural MRI data were collected from 338 clinically concerning adolescents (mean age = 15.30 SD=2.07; mean IQ = 101.01 SD=12.43; 132 F). Depression symptoms were indexed via the Mood and Feelings Questionnaire (MFQ). Freesurfer was used to parcellate the brain into 68 cortical regions and 14 subcortical regions. GMV was extracted from all 82 brain areas. Multiple linear regression was used to look at the relationship between MFQ scores and region-specific GMV parameter. Follow up regressions were conducted to look at potential effects of psychiatric diagnoses and medication intake.

RESULTS

Our regression analysis produced a significant model (R2 = 0.446, F(86, 251) = 2.348, p < 0.001). Specifically, there was a negative association between GMV of the left parahippocampal (B = -0.203, p = 0.005), right rostral anterior cingulate (B = -0.162, p = 0.049), and right frontal pole (B = -0.147, p = 0.039) and a positive association between GMV of the left bank of the superior temporal sulcus (B = 0.173, p = 0.029). Follow up analyses produced results proximal to the main analysis.

CONCLUSIONS

Altered regional brain volumes may serve as biomarkers for the development of depressive symptoms during adolescence. These findings suggest a homogeneity of altered cortical structures in adolescents with depressive symptoms.

Multi-modal MRI measures reveal sensory abnormalities in major depressive disorder patients: A surface-based study

BACKGROUND

Multi-modal magnetic resonance imaging (MRI) measures are supposed to be able to capture different brain neurobiological aspects of major depressive disorder (MDD). A fusion analysis of structural and functional modalities may better reveal the disease biomarker specific to the MDD disease.

METHODS

We recruited 30 MDD patients and 30 matched healthy controls (HC). For each subject, we acquired high-resolution brain structural images and resting-state fMRI (rs-fMRI) data using a 3 T MRI scanner. We first extracted the brain morphometric measures, including the cortical volume (CV), cortical thickness (CT), and surface area (SA), for each subject from the structural images, and then detected the structural clusters showing significant between-group differences in each measure using the surface-based morphology (SBM) analysis. By taking the identified structural clusters as seeds, we performed seed-based functional connectivity (FC) analyses to determine the regions with abnormal FC in the patients. Based on a logistic regression model, we performed a classification analysis by selecting these structural and functional cluster-wise measures as features to distinguish the MDD patients from the HC.

RESULTS

The MDD patients showed significantly lower CV in a cluster involving the right superior temporal gyrus (STG) and middle temporal gyrus (MTG), and lower SA in three clusters involving the bilateral STG, temporal pole gyrus, and entorhinal cortex, and the left inferior temporal gyrus, and fusiform gyrus, than the controls. No significant difference in CT was detected between the two groups. By taking the above-detected clusters as seeds to perform the seed-based FC analysis, we found that the MDD patients showed significantly lower FC between STG/MTG (CV's cluster) and two clusters located in the bilateral visual cortices than the controls. The logistic regression model based on the structural and functional features reached a classification accuracy of 86.7% (p < 0.001) between MDD and controls.

CONCLUSION

The present study showed sensory abnormalities in MDD patients using the multi-modal MRI analysis. This finding may act as a disease biomarker distinguishing MDD patients from healthy individuals.

The neuroanatomical hallmarks of chronic tinnitus in comorbidity with pure-tone hearing loss

Tinnitus is one of the main hearing impairments often associated with pure-tone hearing loss, and typically manifested in the perception of phantom sounds. Nevertheless, tinnitus has traditionally been studied in isolation without necessarily considering auditory ghosting and hearing loss as part of the same syndrome. Hence, in the present neuroanatomical study, we attempted to pave the way toward a better understanding of the tinnitus syndrome, and compared two groups of almost perfectly matched individuals with (TIHL) and without (NTHL) pure-tone tinnitus, but both characterized by pure-tone hearing loss. The two groups were homogenized in terms of sample size, age, gender, handedness, education, and hearing loss. Furthermore, since the assessment of pure-tone hearing thresholds alone is not sufficient to describe the full spectrum of hearing abilities, the two groups were also harmonized for supra-threshold hearing estimates which were collected using temporal compression, frequency selectivity und speech-in-noise tasks. Regions-of-interest (ROI) analyses based on key brain structures identified in previous neuroimaging studies showed that the TIHL group exhibited increased cortical volume (CV) and surface area (CSA) of the right supramarginal gyrus and posterior planum temporale (PT) as well as CSA of the left middle-anterior part of the superior temporal sulcus (STS). The TIHL group also demonstrated larger volumes of the left amygdala and of the left head and body of the hippocampus. Notably, vertex-wise multiple linear regression analyses additionally brought to light that CSA of a specific cluster, which was located in the left middle-anterior part of the STS and overlapped with the one found to be significant in the between-group analyses, was positively associated with tinnitus distress level. Furthermore, distress also positively correlated with CSA of gray matter vertices in the right dorsal prefrontal cortex and the right posterior STS, whereas tinnitus duration was positively associated with CSA and CV of the right angular gyrus (AG) and posterior part of the STS. These results provide new insights into the critical gray matter architecture of the tinnitus syndrome matrix responsible for the emergence, maintenance and distress of auditory phantom sensations.

Functional hyperconnectivity between corticocerebellar networks and altered decision making in young adult cannabis users: Evidence from 7T and multivariate pattern analysis

Decision-making (DM) impairments are important predictors of cannabis initiation and continued use. In cannabis users, how decision-making abnormalities related to structural and functional connectivity in the brain are not fully understood. We employed a three-method multimodal image analysis and multivariate pattern analysis (MVPA) on high dimensional 7 tesla MRI images examining functional connectivity, white matter microstructure and gray matter volume in a group of cannabis users and non-users. Neuroimaging and cognitive analyses were performed on 92 CU and 92 age- matched NU from a total of 187 7T scans. CU were selected on the basis of their scores on the Semi-Structured Assessment for the Genetics of Alcoholism. The groups were first compared on a decision-making test and then on ICA based functional connectivity between corticocerebellar networks. An MVPA was done as a confirmatory analysis. The anatomy of these networks was then assessed using Diffusion Tensor imaging (DTI) and cortical volume analyses. Cannabis Users had significantly higher scores on the Iowa Gambling task (IGT) [Gambling task Percentage larger] and significantly lower scores on the [Gambling task reward Percentage smaller]. Left accumbens (L NAc) volume was significantly larger in cannabis users. DTI analysis between the groups yielded no significant (FWE corrected) differences. Resting state FC analysis of the left Cerebellum region 9 showed enhanced functional connectivity with the right nucleus accumbens and left pallidum and left putamen in CU. In addition, posterior cerebellum showed enhanced functional connectivity (FWE corrected) with 2 nodes of the DMN and left and right paracingulate (sub genual ACC) and the sub callosal cortex in CU. IGT percentage larger scores correlated with posterior cerebellar functional connectivity in non-user women. A multivariate pattern analysis confirmed this cerebellar hyperconnectivity in both groups. Our results demonstrate for the first time that deficits in DM observed in cannabis users are mirrored in hyper connectivity in corticocerebellar networks. Cortical volumes of some of the nodes of these networks showed increases in users. However, the underlying white matter was largely intact in CU. The observed DM deficits and hyper connectivity in resting networks may contribute to difficulties in quitting and/or facilitating relapse.

Differential association of endothelial function with brain structure in youth with versus without bipolar disorder

BACKGROUND

Mood symptoms and disorders are associated with impaired endothelial function, a marker of early atherosclerosis. Given the increased vascular burden and neurostructural differences among individuals with mood disorders, we investigated the endothelial function and brain structure interface in relation to youth bipolar disorder (BD).

METHODS

This cross-sectional case-controlled study included 115 youth, ages 13-20 years (n = 66 BD; n = 49 controls [CG]). Cortical thickness and volume for regions of interest (ROI; insular cortex, ventrolateral prefrontal cortex [vlPFC], temporal lobe) were acquired from FreeSurfer processed T1-weighted MRI images. Endothelial function was assessed using pulse amplitude tonometry, yielding a reactive hyperemia index (RHI). ROI and vertex-wise analyses controlling for age, sex, obesity, and intracranial volume investigated for RHI-neurostructural associations, and RHI-by-diagnosis interactions.

RESULTS

In ROI analyses, higher RHI (i.e., better endothelial function) was associated with lower thickness in the insular cortex (β = -0.19, p_FDR = 0.03), vlPFC (β = -0.30, p_FDR = 0.003), and temporal lobe (β = -0.22, p_FDR = 0.01); and lower temporal lobe volume (β = -0.16, p_FDR = 0.01) in the overall sample. In vertex-wise analyses, higher RHI was associated with lower cortical thickness and volume in the insular cortex, prefrontal cortex (e.g., vlPFC), and temporal lobe. Additionally, higher RHI was associated with lower vlPFC and temporal lobe volume to a greater extent in youth with BD vs. CG.

CONCLUSIONS

Better endothelial function was associated with lower regional brain thickness and volume, contrasting the hypothesized associations. Additionally, we found evidence that this pattern was exaggerated in youth with BD. Future studies examining the direction of the observed associations and underlying mechanisms are warranted.

Machine learning based identification of structural brain alterations underlying suicide risk in adolescents

Suicide is the third leading cause of death for individuals between 15 and 19 years of age. The high suicide mortality rate and limited prior success in identifying neuroimaging biomarkers indicate that it is crucial to improve the accuracy of clinical neural signatures underlying suicide risk. The current study implements machine-learning (ML) algorithms to examine structural brain alterations in adolescents that can discriminate individuals with suicide risk from typically developing (TD) adolescents at the individual level. Structural MRI data were collected from 79 adolescents who demonstrated clinical levels of suicide risk and 79 demographically matched TD adolescents. Region-specific cortical/subcortical volume (CV/SCV) was evaluated following whole-brain parcellation into 1000 cortical and 12 subcortical regions. CV/SCV parameters were used as inputs for feature selection and three ML algorithms (i.e., support vector machine [SVM], K-nearest neighbors, and ensemble) to classify adolescents at suicide risk from TD adolescents. The highest classification accuracy of 74.79% (with sensitivity = 75.90%, specificity = 74.07%, and area under the receiver operating characteristic curve = 87.18%) was obtained for CV/SCV data using the SVM classifier. Identified bilateral regions that contributed to the classification mainly included reduced CV within the frontal and temporal cortices but increased volume within the cuneus/precuneus for adolescents at suicide risk relative to TD adolescents. The current data demonstrate an unbiased region-specific ML framework to effectively assess the structural biomarkers of suicide risk. Future studies with larger sample sizes and the inclusion of clinical controls and independent validation data sets are needed to confirm our findings.

Childhood abuse and cortical gray matter volume in patients with major depressive disorder

Childhood abuse is associated with brain structural alterations; however, few studies have investigated the association between specific types of childhood abuse and cortical volume in patients with major depressive disorder (MDD). We aimed to investigate the association between specific types of childhood abuse and gray matter volumes in patients with MDD. Seventy-five participants with MDD and 97 healthy controls (HCs) aged 19-64 years were included. Cortical gray matter volumes were compared between MDD and HC groups, and also compared according to exposure to each type of specific childhood abuse. Emotional, sexual, and physical childhood abuse were assessed using the 28-item Childhood Trauma Questionnaire. Patients with MDD showed a significantly decreased gray matter volume in the right anterior cingulate gyrus (ACG). Childhood sexual abuse (CSA) was associated with significantly decreased gray matter volume in the right middle occipital gyrus (MOG). In the post-hoc comparison of volumes of the right ACG and MOG, MDD patients with CSA had significantly smaller volumes in the right MOG than did MDD patients without CSA or HCs. The right MOG volume decrease could be a neuroimaging marker associated with CSA and morphological changes in the brain may be involved in the pathophysiology of MDD.

Language reorganization in patients with left-hemispheric gliomas is associated with increased cortical volume in language-related areas and in the default mode network

BACKGROUND

Language function may reorganize to overcome focal impairment; however, the relation between functional and structural changes in patients with brain tumors remains unclear. We investigated the cortical volume of atypical language dominant (AD) patients with left frontal-insular high-grade (HGG) and low-grade glioma (LGG). We hypothesized atypical language being associated with areas of increased cortical volume in the right hemisphere, including language areas homologues.

METHODS

Patient were recruited following the criteria: left frontal-insular glioma; functional MRI and 3DT1-weighted images; no artifacts. We calculated an hemispheric language laterality index (LI), defined as: AD if LI < .2; left-dominant (LD) if LI ≥ .2. We measured cortical volume in three voxel-based morphometry (VBM) analyses: total AD vs. LD patients; AD vs. LD in HGG; AD vs. LD in LGG. We repeated the analysis in AD vs. LD healthy controls (HC). A minimum threshold of t > 2 and corrected p < .025 (Bonferroni) was employed.

RESULTS

We recruited 119 patients (44LGG, 75HGG). Hemispheric LI demonstrated 64/119AD and 55/119LD patients. The first VBM analysis demonstrated significantly increased cortical volume in AD patients in the right inferior frontal gyrus (IFG), right superior temporal gyrus (STG), right insula, right fusiform gyrus (FG), right precentral gyrus, right temporal-parietal junction, right posterior cingulate cortex (PCC), right hippocampus, right- and left cerebellum. AD patients with HGG showed the same areas of significantly increased cortical volume. AD patients with LGG displayed significantly increased cortical volume in right IFG, right STG, right insula, right FG, right anterior cingulate cortex, right PCC, right dorsal-lateral prefrontal cortex. HC showed no significant results.

CONCLUSION

Right-sided (atypical) language activations in patients with left-hemispheric gliomas are associated with areas of increased cortical volume. Additionally, default mode network nodes showed greater cortical volume in AD patients regardless of the tumor grade, supporting the idea of these cortices participating in the development of language plasticity.

Heart rate variability (HRV) changes and cortical volume changes in a randomized trial of five weeks of daily HRV biofeedback in younger and older adults

Previous studies indicate that the structure and function of medial prefrontal cortex (PFC) and lateral orbitofrontal cortex (OFC) are associated with heart rate variability (HRV). Typically, this association is assumed to reflect the PFC's role in controlling HRV and emotion regulation, with better prefrontal structural integrity supporting greater HRV and better emotion regulation. However, as a control system, the PFC must monitor and respond to heart rate oscillatory activity. Thus, engaging in regulatory feedback during heart rate oscillatory activity may over time help shape PFC structure, as relevant circuits and connections are modified. In the current study with younger and older adults, we tested whether 5 weeks of daily sessions of biofeedback to increase heart rate oscillations (Osc+ condition) vs. to decrease heart rate oscillations (Osc- condition) affected cortical volume in left OFC and right OFC, two regions particularly associated with HRV in prior studies. The left OFC showed significant differences in volume change across conditions, with Osc+ increasing volume relative to Osc-. The volume changes in left OFC were significantly correlated with changes in mood disturbance. In addition, resting low frequency HRV increased more in the Osc+ than in the Osc- condition. These findings indicate that daily biofeedback sessions regulating heart rate oscillatory activity can shape both resting HRV and the brain circuits that help control HRV and regulate emotion.

Lithium increases cortical and subcortical volumes in subjects with bipolar disorder

Bipolar disorder (BD) is a highly variable and burdensome disease for patients and caregivers. A BD diagnosis almost triples the likelihood of developing dementia as the disease progresses. Neurocognitive reserve appears to be one of the most important influences on lifelong functional outcomes and quality of life in BD. Though several prior studies have assessed the effects of lithium on regional gray and white matter volumes in this population, representative cohorts are typically middle-aged, have a more severe pathology, and are not as commonly assessed in the depressive phase (which represents the majority of most patients' lifespans outside of remission). Here we have shown that positive adaptations with lithium can be observed throughout the brain after only six weeks of monotherapy at low-therapeutic serum levels. Importantly, these results remove some confounders seen in prior studies (patients were treatment free at time of enrollment and mostly treatment naïve). This cohort also includes underrepresented demographics in the literature (young adult patients, mostly bipolar II, and exclusively in the depressed phase). These findings bolster the extensive body of evidence in support of long-term lithium therapy in BD, furthering the possibility of its expanded use to wider demographics.

Orbitofrontal cortex volume links polygenic risk for smoking with tobacco use in healthy adolescents

BACKGROUND

Tobacco smoking remains one of the leading causes of preventable illness and death and is heritable with complex underpinnings. Converging evidence suggests a contribution of the polygenic risk for smoking to the use of tobacco and other substances. Yet, the underlying brain mechanisms between the genetic risk and tobacco smoking remain poorly understood.

METHODS

Genomic, neuroimaging, and self-report data were acquired from a large cohort of adolescents from the IMAGEN study (a European multicenter study). Polygenic risk scores (PGRS) for smoking were calculated based on a genome-wide association study meta-analysis conducted by the Tobacco and Genetics Consortium. We examined the interrelationships among the genetic risk for smoking initiation, brain structure, and the number of occasions of tobacco use.

RESULTS

A higher smoking PGRS was significantly associated with both an increased number of occasions of tobacco use and smaller cortical volume of the right orbitofrontal cortex (OFC). Furthermore, reduced cortical volume within this cluster correlated with greater tobacco use. A subsequent path analysis suggested that the cortical volume within this cluster partially mediated the association between the genetic risk for smoking and the number of occasions of tobacco use.

CONCLUSIONS

Our data provide the first evidence for the involvement of the OFC in the relationship between smoking PGRS and tobacco use. Future studies of the molecular mechanisms underlying tobacco smoking should consider the mediation effect of the related neural structure.

Sex difference in tDCS current mediated by changes in cortical anatomy: A study across young, middle and older adults

INTRODUCTION

The observed variability in the effects of transcranial direct current stimulation (tDCS) is influenced by the amount of current reaching the targeted region-of-interest (ROI). Age and sex might affect current density at target ROI due to their impact on cortical anatomy. The present tDCS simulation study investigates the effects of cortical anatomical parameters (volumes, dimension, and torque) on simulated tDCS current density in healthy young, middle-aged, and older males and females.

METHODOLOGY

Individualized head models from 240 subjects (120 males, 18-87 years of age) were used to identify the estimated current density (2 mA current intensity, 25 cm² electrode) from two simulated tDCS montages (CP5_CZ and F3_FP2) targeting the inferior parietal lobule (IPL) and middle frontal gyrus (MFG), respectively. Cortical parameters including segmented brain volumes (cerebrospinal fluid [CSF], grey and white matter), cerebral-dimensions (length/width &length/height) and brain-torque (front and back shift, petalia, and bending) were measured using the magnetic resonance images (MRIs) from each subject. The present study estimated sex differences in current density at these target ROIs mediated by these cortical parameters within each age group.

RESULTS

For both tDCS montages, females in the older age group received higher current density than their male counterparts at the target ROIs. No sex differences were observed in the middle-aged group. Males in the younger age group had a higher current density than females, only for the parietal montage. Across all age groups, CSF, and grey matter volumes significantly predicted the current intensity estimated at the target sites. In the older age group only, brain-torque was a significant mediator of the sex difference.

CONCLUSIONS

Our findings demonstrate the presence of sex differences in the simulated tDCS current density, however this pattern differed across age groups and stimulation locations. Future studies should consider influence of age and sex on individual cortical anatomy and tailor tDCS stimulation parameters accordingly.

Investigation of cortical thickness and volume during spontaneous attacks of migraine without aura: a 3-Tesla MRI study

BACKGROUND

Structural imaging has revealed changes in cortical thickness in migraine patients compared to healthy controls is reported, but presence of dynamic cortical and subcortical changes during migraine attack versus inter-ictal phase is unknown. The aim of the present study was to investigate possible changes in cortical thickness during spontaneous migraine attacks. We hypothesized that pain-related cortical area would be affected during the attack compared to an inter-ictal phase.

METHODS

Twenty-five patients with migraine without aura underwent three-dimensional T1-weighted imaging on a 3-Tesla MRI scanner during spontaneous and untreated migraine attacks. Subsequently, 20 patients were scanned in the inter-ictal phase, while 5 patients did not show up for the inter-ictal scan. Four patients were excluded from the analysis because of bilateral migraine pain and another one patient was excluded due to technical error in the imaging. Longitudinal image processing was done using FreeSurfer. Repeated measures ANOVA was used for statistical analysis and to control for multiple comparison the level of significance was set at p = 0.025.

RESULTS

In a total of 15 patients, we found reduced cortical thickness of the precentral (p = 0.023), pericalcarine (p = 0.024), and temporal pole (p = 0.017) cortices during the attack compared to the inter-ictal phase. Cortical volume was reduced in prefrontal (p = 0.018) and pericalcarine (p = 0.017) cortices. Hippocampus volume was increased during attack (p = 0.007). We found no correlations between the pain side or any other clinical parameters and the reduced cortical size.

CONCLUSION

Spontaneous migraine attacks are accompanied by transient reduced cortical thickness and volume in pain-related areas. The findings constitute a fingerprint of acute pain in migraine patients, which can be used as a possible biomarker to predict antimigraine treatment effect in future studies.

TRIAL REGISTRATION

The study was registered at ClinicalTrials.gov ( NCT02202486 ).

Cortical morphometric correlational networks associated with cognitive deficits in first episode schizophrenia

Schizophrenia (SCZ) is a chronic cognitive and behavioral disorder associated with abnormal cortical activity during information processing. Several brain structures associated with the seven performance domains evaluated using the MATRICS (Measurement and Treatment Research to Improve Cognition in Schizophrenia) Consensus Cognitive Battery (MCCB) have shown cortical volume loss in first episode schizophrenia (FES) patients. However, the relationship between morphological organization and MCCB performance remains unclear. Therefore, in the current observational study, high-resolution structural MRI scans were collected from 50 FES patients, and the morphometric correlation network (MCN) using cortical volume was established to characterize the cortical pattern associated with poorer MCCB performance. We also investigated topological properties, such as the modularity, the degree and the betweenness centrality. Our findings show structural volume was directly and strongly associated with the cognitive deficits of FES patients in the precuneus, anterior cingulate, and fusiform gyrus, as well as the prefrontal, parietal, and sensorimotor cortices. The medial orbitofrontal, fusiform, and superior frontal gyri were not only identified as the predominant nodes with high degree and betweenness centrality in the MCN, but they were also found to be critical in performance in several of the MCCB domains. Together, these results suggest a widespread cortical network is altered in FES patients and that performance on the MCCB domains is associated with the core pathophysiology of SCZ.

Substantially thinner internal granular layer and reduced molecular layer surface in the cerebellar cortex of the Tc1 mouse model of down syndrome - a comprehensive morphometric analysis with active staining contrast-enhanced MRI

Down Syndrome is a chromosomal disorder that affects the development of cerebellar cortical lobules. Impaired neurogenesis in the cerebellum varies among different types of neuronal cells and neuronal layers. In this study, we developed an imaging analysis framework that utilizes gadolinium-enhanced ex vivo mouse brain MRI. We extracted the middle Purkinje layer of the mouse cerebellar cortex, enabling the estimation of the volume, thickness, and surface area of the entire cerebellar cortex, the internal granular layer, and the molecular layer in the Tc1 mouse model of Down Syndrome. The morphometric analysis of our method revealed that a larger proportion of the cerebellar thinning in this model of Down Syndrome resided in the inner granule cell layer, while a larger proportion of the surface area shrinkage was in the molecular layer.

Association between cortical volume and gray-white matter contrast with second generation antipsychotic medication exposure in first episode male schizophrenia patients

This cross-sectional study examines the differences in cortical volume and gray-to-white matter contrast (GWC) in first episode schizophrenia patients (SCZ) compared to healthy control participants (HC) and in SCZ patients as a function of exposure to second generation antipsychotic medication. We hypothesize 1) SCZ exhibit regionally lower cortical volumes relative to HCs, 2) cortical volume will be greater with longer exposure to second generation antipsychotics prior to the MRI scan, and 3) lower GWC with longer exposure to second generation antipsychotics prior to the MRI scan, suggesting more blurring from greater intracortical myelin. To accomplish this, MRI scans from 71 male SCZ patients treated with second generation oral risperidone and 42 male HCs were examined. 3D T1-weighted MPRAGE images collected at 1.5T were used to estimate cortical volume and GWC by sampling signal intensity at 30% within the cortical ribbon. Average cortical volume and GWC were calculated and compared between SCZ and HC. Cortical volume and GWC in SCZ patients were correlated with duration of medication exposure for the time period prior to the scan. First-episode SCZ patients had significantly lower cortical volume compared to HCs in bilateral temporal, superior and rostral frontal, postcentral gyral, and parahippocampal regions. In SCZ patients, greater cortical volume was associated with (log-transformed) duration of second-generation antipsychotic medication exposure in bilateral precuneus, right lingual, and right superior parietal regions. Lower GWC was correlated with longer duration of medication exposure bilaterally in the superior frontal lobes. In summary, second generation antipsychotics may increase cortical volume and decrease GWC in first episode SCZ patients.

Cortical and subcortical volume differences between Benign Epilepsy with Centrotemporal Spikes and Childhood Absence Epilepsy

OBJECTIVE

Benign Childhood Epilepsy with Centrotemporal Spikes (BECTS) and Childhood Absence Epilepsy (CAE) are the most common childhood epilepsy syndromes and they share a similar age-dependence. However, the two syndromes clearly differ in seizures and EEG patterns. The aim of this study is to investigate whether children of the same age with BECTS, CAE and typically-developing children have significant differences in grey matter volume that may underlie the different profiles of these syndromes.

METHODS

Twenty one patients with newly-diagnosed BECTS and 18 newly diagnosed and drug naïve CAE were included and compared to 31 typically-developing children. Voxel-based morphometry was utilized to investigate grey matter volume differences among BECTS, CAE, and controls. We also examined the effect of age on grey matter volume in all three groups. In addition to the whole brain analysis, we chose regions of interest analysis based on previous literature suggesting the involvement of these regions in BECTS or CAE. The group differences of grey matter volume was tested with 2-sample t-test for between two groups' comparisons and ANOVA for three group comparisons.

RESULTS

In the whole brain group comparisons, the grey matter volume in CAE was significantly decreased in the areas of right inferior frontal and anterior temporal compared to BECTS and controls (F_2,67  = 27.53, p < 0.001). In the control group, grey matter volume in bifrontal lobes showed a negative correlation with age (r=-0.54, p < 0.05), whereas no correlation was found in either CAE or BECTS. With ROI analyses, the grey matter volume of posterior thalami was increased in CAE compared to other 2 groups (p < 0.05).

SIGNIFICANCE

This study shows that there are grey matter volume differences between CAE and BECTS. Our findings of grey matter volume differences may suggest that there may be localized, specific differences in brain structure between these two types of epilepsy.

Clinical Implication of Altered Inhibitory Response in Patients with Post-traumatic Stress Disorder: Electrophysiological Evidence from a Go/Nogo Task

Inhibitory dysfunction is closely associated to post-traumatic stress disorder (PTSD). The present study investigated the neurophysiological evidence for and the brain regions related to inhibitory dysfunction in PTSD. Fifty patients with PTSD and 63 healthy controls (HCs) participated in a Go/Nogo task combined with electroencephalographic recordings. The N2-P3 complexes of event-related potentials (ERPs) elicited during the Nogo condition were compared between groups. Participants underwent structural magnetic resonance imaging to examine cortical volumes and completed questionnaires. Correlations between altered ERPs and cortical volumes of regions of interest as well as psychological symptoms were analysed. Nogo-N2 latencies at five electrode sites (Fz, FCz, Cz, CPz, and Pz) were significantly delayed in patients with PTSD compared to HCs. Nogo-N2 latency had a significant negative correlation with the volume of gyrus in the inferior frontal cortex, orbitofrontal cortex, amygdala, and medial prefrontal cortex. Nogo-N2 latency was significantly and positively correlated with catastrophizing, anxiety, and perceived threat. These findings show inhibitory dysfunction in patients with PTSD, reflected by the delay in Nogo-N2 latencies. They also indicate that Nogo-N2 latencies are associated with smaller cortical volumes responsible for inhibition as well as with major symptoms of PTSD.

Differences in brain surface area and cortical volume between suicide attempters and non-attempters with major depressive disorder

The neurobiological causes underlying suicidal behaviors in major depressive disorder (MDD) have not been identified. This study was performed to investigate the differences in brain cortical thickness, surface area, and volume between suicide attempters and non-attempters with MDD. We performed magnetic resonance imaging (MRI) in 38 MDD patients (18-65 years old; 18 male, 20 female) with and without a history of suicide attempts. FreeSurfer software was used to compare the cortical thickness, surface area, and volume of 19 suicide attempters with MDD and 19 suicide non-attempters with MDD, while controlling for age, sex, mean area (or volume), and severity of depression. Compared with suicide non-attempters, suicide attempters with MDD exhibited a larger surface area in the left postcentral area and left lateral occipital area and a larger cortical volume in the left postcentral area and left lateral orbitofrontal area. Suicide attempters exhibited a smaller surface area in the left superior frontal area than suicide non-attempters. The present findings provide evidence for neuroanatomical risk factors of suicide in MDD. Further research to replicate these results and determine the mechanisms underlying these findings is needed.

Impact of Polygenic Risk for Schizophrenia on Cortical Structure in UK Biobank

BACKGROUND

Schizophrenia is a neurodevelopmental disorder with many genetic variants of individually small effect contributing to phenotypic variation. Lower cortical thickness (CT), surface area, and cortical volume have been demonstrated in people with schizophrenia. Furthermore, a range of obstetric complications (e.g., lower birth weight) are consistently associated with an increased risk for schizophrenia. We investigated whether a high polygenic risk score for schizophrenia (PGRS-SCZ) is associated with CT, surface area, and cortical volume in UK Biobank, a population-based sample, and tested for interactions with birth weight.

METHODS

Data were available for 2864 participants (n_male/n_female = 1382/1482; mean age = 62.35 years, SD = 7.40). Linear mixed models were used to test for associations among PGRS-SCZ and cortical volume, surface area, and CT and between PGRS-SCZ and birth weight. Interaction effects of these variables on cortical structure were also tested.

RESULTS

We found a significant negative association between PGRS-SCZ and global CT; a higher PGRS-SCZ was associated with lower CT across the whole brain. We also report a significant negative association between PGRS-SCZ and insular lobe CT. PGRS-SCZ was not associated with birth weight and no PGRS-SCZ × birth weight interactions were found.

CONCLUSIONS

These results suggest that individual differences in CT are partly influenced by genetic variants and are most likely not due to factors downstream of disease onset. This approach may help to elucidate the genetic pathophysiology of schizophrenia. Further investigation in case-control and high-risk samples could help identify any localized effects of PGRS-SCZ, and other potential schizophrenia risk factors, on CT as symptoms develop.

Vulnerability to mood degradation during sleep deprivation is influenced by white-matter compactness of the triple-network model

Sleep deprivation (SD) is often associated with significant shifts in mood state relative to baseline functioning. Prior work suggests that there are consistent trait-like differences among individuals in the degree to which their mood and performances are affected by sleep loss. The goal of this study was to determine the extent to which trait-like individual differences in vulnerability/resistance to mood degradation during a night of SD are dependent upon region-specific white and grey matter (WM/GM) characteristics of a triple-network model, including the default-mode network (DMN), control-execution network (CEN) and salience network (SN). Diffusion-weighted and anatomical brain data were collected from 45 healthy individuals several days prior to a 28-h overnight SD protocol. During SD, a visual analog mood scale was administered every hour from 19:15 (time point1; TP1) to 11:15 (TP17) the following morning to measure two positive and six negative mood states. Four core regions within the DMN, five within the CEN, and seven within the SN were used as regions of interest (ROIs). An index of mood resistance (IMR) was defined as the averaged differences between positive and negative mood states over 12 TPs (TP5 to TP16) relative to baseline (TP1 to TP4). For each ROI, characteristics of WM - quantitative anisotropy (QA) and mean curvature index (WM-MCI), and GM - cortical volume (CV) and GM-MCI were estimated, and used to predict IMR. WM characteristics, particularly QA, of all of regions within the DMN, and most of the regions within the CEN and SN predicted IMR during SD. In contrast, most ROIs did not show significant association between IMR and any of the GM characteristics (CV and MCI) or WM MCI. Our findings suggest that greater resilience to mood degradation induced by total SD appears to be associated with more compact axonal pathways within the DMN, CEN and SN.

Brain asymmetry differences between Chinese and Caucasian populations: a surface-based morphometric comparison study

Asymmetry has been proved to exist in the human brain structure, function and behavior. Most of the existing brain asymmetry findings are originated from the western populations, while studies about the brain structural and functional asymmetries in East Asians are limited. Extensive evidence suggested that cultural differences, e.g. education and language, may lead to differences in brain structure and function between races. Therefore, we hypothesized that differences in brain structural asymmetries exist between East Asians and Westerners. In this study, we performed a comprehensive surface-based morphometric (SBM) analysis of brain asymmetries in cortical thickness, volume and surface area in two well-matched groups of right-handed, Chinese (n = 45) and Caucasian (n = 45) young male adults (age = 22-29 years). Our results showed consistent inter-hemispheric asymmetries in the three brain morphological measures in multiple brain regions in the Chinese young adults, including the temporal, frontal, parietal, occipital, insular cortices and the cingulate gyrus. Comparing with the Caucasians, the Chinese group showed greater structural asymmetry in the frontal, temporal, occipital and insular cortices, and smaller asymmetry in the parietal cortex and cingulate gyrus. These findings could provide a new neuroanatomical basis for understanding the distinctions between East Asian and Caucasian in brain functional lateralization.

Cortical morphologic changes in recent-onset, drug-naïve idiopathic generalized epilepsy

PURPOSE

Only a few studies have investigated the brain morphology abnormalities in structural MRI in patients with drug-naïve idiopathic generalized epilepsy (IGE) and mainly focused on brain volume changes. In the present study, we aimed to investigate the changes in three morphologic measurement differences including cortical thickness, cortical volume, and surface area using FreeSurfer in a pediatric cohort of recent-onset, drug-naïve IGE.

METHODS

Forty-five recent-onset, drug-naïve patients diagnosed with IGE and 32 demographically matched healthy controls were recruited. All participants underwent structural MRI scans with a 3.0 T MR system. FreeSurfer, an automated cortical surface reconstruction toolbox, was applied to compare the cortical morphology between patients and controls. The brain regions with significant group differences after multiple comparison correction were extracted in common space for each patient, and then correlated with their clinical characteristics (including onset age, duration of epilepsy, and mini-mental state examination (MMSE)) using partial correlation analysis with age, sex and intracranial volume as covariates.

RESULTS

Compared with controls, IGE patients showed decreased cortical thickness in the left rostral middle frontal gyrus, decreased cortical volume in the right cuneus and left superior frontal gyrus that extended to the precentral gyrus, and decreased surface area in the right cuneus and right inferior parietal gyrus. None of these regions showed significant relationships with clinical measurements in the patient group.

CONCLUSION

Our findings suggest that cortical thickness, cortical volume, and surface area changes occurred in the early stage of IGE. These findings provide structural neuroimaging evidence underlying the pathology of IGE.

Mapping cortical surface features in treatment resistant schizophrenia with in vivo structural MRI

Decreases in cortical volume (CV), thickness (CT) and surface area (SA) have been reported in individuals with schizophrenia by in vivo MRI studies. However, there are few studies that examine these cortical measures as potential biomarkers of treatment resistance (TR) and treatment response (NTR) in schizophrenia. This study used structural MRI to examine differences in CV, CT, and SA in 42 adults with schizophrenia (TR = 21, NTR = 21) and 23 healthy controls (HC) to test the hypothesis that individuals with TR schizophrenia have significantly greater reductions in these cortical measures compared to individuals with NTR schizophrenia. We found that individuals with TR schizophrenia showed significant reductions in CV and CT compared to individuals with NTR schizophrenia in right frontal and precentral regions, right parietal and occipital cortex, left temporal cortex and bilateral cingulate cortex. In line with previous literature, the temporal lobe and cingulate gyrus in both patient groups showed significant reductions of all three measures when compared to healthy controls. Taken together these results suggest that regional changes in CV and CT may index mechanisms specific to TR schizophrenia and potentially identify patients with TR schizophrenia for earlier treatment.

Does experienced pain affects local brain volumes? Insights from a clinical acute pain model

Background/Objective:To study pain-brain morphometry associations as a function of post-surgery stages (anesthesia, pain and analgesia) in an acute pain model. Method:Impacted mandible third molar were extracted. Before surgery, an anatomical T1 scan was obtained. Regional brain volumen and subcortical nuclei shapes were obtained. Statistical analyses were done using multiple regression, being pain scores the predictors and voxel volumes, subcortical nuclei volumes and subcortical nuclei shapes, the outcomes. Results:Pain was significantly larger at pain than at anesthesia and analgesia stages, and was higher during anesthesia than during analgesia. Pain intensity was related to grey matter in several cortical (Insula, Mid Frontal and Temporal Gyruses, Precuneus, Anterior Cingulate), and subcortical nuclei (Hippocampus, Thalamus, Putamen, Amygdala), depending of the post-surgical stage. A larger number of brain areas showed significance at pain that at anesthesia and analgesia stages. Conclusions:The relationships of regional brain volumes and subcortical nuclei shapes with pain scores seemed to be unsteady, as they changed with the patient's actual pain stage.

Variation in fourteen brain structure volumes in schizophrenia: A comprehensive meta-analysis of 246 studies

Despite hundreds of structural MRI studies documenting smaller brain volumes on average in schizophrenia compared to controls, little attention has been paid to group differences in the variability of brain volumes. Examination of variability may help interpret mean group differences in brain volumes and aid in better understanding the heterogeneity of schizophrenia. Variability in 246 MRI studies was meta-analyzed for 13 structures that have shown medium to large mean effect sizes (Cohen's d≥0.4): intracranial volume, total brain volume, lateral ventricles, third ventricle, total gray matter, frontal gray matter, prefrontal gray matter, temporal gray matter, superior temporal gyrus gray matter, planum temporale, hippocampus, fusiform gyrus, insula; and a control structure, caudate nucleus. No significant differences in variability in cortical/subcortical volumes were detected in schizophrenia relative to controls. In contrast, increased variability was found in schizophrenia compared to controls for intracranial and especially lateral and third ventricle volumes. These findings highlight the need for more attention to ventricles and detailed analyses of brain volume distributions to better elucidate the pathophysiology of schizophrenia.

Effects of HIV Infection, methamphetamine dependence and age on cortical thickness, area and volume

OBJECTIVE

This study examined the effects of HIV infection, methamphetamine dependence and their interaction on cortical thickness, area and volume, as well as the potential interactive effects on cortical morphometry of HIV and methamphetamine with age.

METHOD

T1-weighted structural images were obtained on a 3.0T General Electric MR750 scanner. Freesurfer v5.3.0 was used to derive cortical thickness, area and volume measures in thirty-four regions based on Desikan-Killiany atlas labels.

RESULTS

Following correction for multiple statistical tests, HIV diagnosis was not significantly related to cortical thickness or area in any ROI, although smaller global cortical area and volume were seen in those with lower nadir CD4 count. HIV diagnosis, nevertheless, was associated with smaller mean cortical volumes in rostral middle frontal gyrus and in the inferior and superior parietal lobes. Methamphetamine dependence was significantly associated with thinner cortex especially in posterior cingulate gyrus, but was not associated with cortical area or volume following correction for multiple statistical tests. We found little evidence that methamphetamine dependence moderated differences in cortical area, volume or thickness for any ROI in the HIV seropositive group. Interactions with age revealed that HIV diagnosis attenuated the degree of age-related cortical thinning seen in non-infected individuals; intercepts indicated that young HIV seropositive individuals had thinner cortex than non-infected peers.

CONCLUSIONS

Methamphetamine dependence does not appear to potentiate a reduction of cortical area, volume or thickness in HIV seropositive individuals. The finding of thinner cortex in young HIV seropositive individuals and the association between CD4 nadir and global cortical area and volume argue for prioritizing early antiretroviral treatment.

Brain structural basis of individual variability in dream recall frequency

Recent neuroimaging studies have indicated that inter-individual variability in dream recall frequency (DRF) is associated with both resting-state regional cerebral blood flow and task-induced brain activations. However, the brain structure underpinning this inter-individual variability in DRF remains unclear. The aim of the current study is to investigate the relationship between brain structural characteristics and DRF. We collected both T1-weighted and diffusion tensor magnetic resonance imaging data from 43 healthy volunteers. DRF was obtained from a two-week sleep diary with a subjective report of dream recall upon waking every morning. General linear model analysis was used to evaluate the relationship between brain structural characteristics (cortical volume and white matter integrity) and DRF. Not only the cortical volume of the medial portion of the right fusiform gyrus and parahippocampal gyrus but also the fractional anisotropy of white matter fibers connected to these regions were significantly negatively correlated with DRF, and these relationships were not modulated by a regular sleep. These findings provide direct evidence that brain structural characteristics are associated with inter-individual variability in DRF and may help us to better understand the structural mechanisms in the brain underlying dream recall.

Concussion induces focal and widespread neuromorphological changes

Concussion induces transient, and oftentimes chronic, lingering impairment to mental functioning, which must be driven by some underlying neurobiological perturbation - however, the physical changes related to sequelae are difficult to detect. Previous imaging studies on concussion have focused on alterations to cortical anatomy, but few have examined the cerebrum, subcortex, and cerebellum. Here, we present an analysis of these structures in a single cohort (all males, 21 patients, 22 controls) using MRI and diagnosed with a single-concussive episode in the acute and sub-acute stages of injury. Structural images were segmented into 78 cortical brain regions and 81,924 vertices using the CIVET algorithm. Subcortical volumetric analyses of the cerebellum, thalamus, globus pallidus, caudate and putamen were conducted following segmentation. Participants with concussion were found to have reduced white and grey matter volume, total cortical volume, as well as cortical thinning, primarily in left frontal areas. No differences were observed in the cerebellum or subcortical structures. In conclusion, just a single concussive episode induces measurable changes in brain structure manifesting as diffuse and local patterns of altered neuromorphometry.

Impulsivity across the psychosis spectrum: Correlates of cortical volume, suicidal history, and social and global function

Patients with psychotic disorders appear to exhibit greater impulsivity-related behaviors relative to healthy controls. However, the neural underpinning of this impulsivity remains uncertain. Furthermore, it remains unclear how impulsivity might differ or be conserved between psychotic disorder diagnoses in mechanism and manifestation. In this study, self-reported impulsivity, measured by Barratt Impulsiveness Scale (BIS), was compared between 305 controls (HC), 139 patients with schizophrenia (SZ), 100 with schizoaffective disorder (SZA), and 125 with psychotic bipolar disorder (PBP). In each proband group, impulsivity was associated with regional cortical volumes (using FreeSurfer analysis of T1 MRI scans), suicide attempt history, Global Assessment of Functioning (GAF), and Social Functioning Scale (SFS). BIS scores were found to differ significantly between participant groups, with SZA and PBP exhibiting significantly higher impulsivity than SZ, which exhibited significantly higher impulsivity than HC. BIS scores were significantly related to suicide attempt history, and they were inversely associated with GAF, SFS, and bilateral orbitofrontal cortex (OFC) volume in both SZA and PBP, but not SZ. These findings indicate that psychotic disorders, particularly those with prominent affective symptoms, are characterized by elevated self-reported impulsivity measures. Impulsivity's correlations with suicide attempt history, GAF, and SFS suggest that impulsivity may be a mediator of clinical outcome. The observed impulsivity-OFC correlations corroborate the importance of OFC deficits in impulsivity. These correlations' presence in SZA and PBP but not in SZ suggests that impulsivity may have different underlying mechanisms in affective and non-affective psychotic disorders.

Trajectories of cortical surface area and cortical volume maturation in normal brain development

This is a report of developmental trajectories of cortical surface area and cortical volume in the NIH MRI Study of Normal Brain Development. The quality-controlled sample included 384 individual typically-developing subjects with repeated scanning (1–3 per subject, total scans n=753) from 4.9 to 22.3 years of age. The best-fit model (cubic, quadratic, or first-order linear) was identified at each vertex using mixed-effects models, with statistical correction for multiple comparisons using random field theory. Analyses were performed with and without controlling for total brain volume. These data are provided for reference and comparison with other databases. Further discussion and interpretation on cortical developmental trajectories can be found in the associated Ducharme et al.׳s article “Trajectories of cortical thickness maturation in normal brain development – the importance of quality control procedures” (Ducharme et al., 2015) [1].

Trajectories of cortical thickness maturation in normal brain development--The importance of quality control procedures

Several reports have described cortical thickness (CTh) developmental trajectories, with conflicting results. Some studies have reported inverted-U shape curves with peaks of CTh in late childhood to adolescence, while others suggested predominant monotonic decline after age 6. In this study, we reviewed CTh developmental trajectories in the NIH MRI Study of Normal Brain Development, and in a second step, evaluated the impact of post-processing quality control (QC) procedures on identified trajectories. The quality-controlled sample included 384 individual subjects with repeated scanning (1-3 per subject, total scans n=753) from 4.9 to 22.3years of age. The best-fit model (cubic, quadratic, or first-order linear) was identified at each vertex using mixed-effects models. The majority of brain regions showed linear monotonic decline of CTh. There were few areas of cubic trajectories, mostly in bilateral temporo-parietal areas and the right prefrontal cortex, in which CTh peaks were at, or prior to, age 8. When controlling for total brain volume, CTh trajectories were even more uniformly linear. The only sex difference was faster thinning of occipital areas in boys compared to girls. The best-fit model for whole brain mean thickness was a monotonic decline of 0.027mm per year. QC procedures had a significant impact on identified trajectories, with a clear shift toward more complex trajectories (i.e., quadratic or cubic) when including all scans without QC (n=954). Trajectories were almost exclusively linear when using only scans that passed the most stringent QC (n=598). The impact of QC probably relates to decreasing the inclusion of scans with CTh underestimation secondary to movement artifacts, which are more common in younger subjects. In summary, our results suggest that CTh follows a simple linear decline in most cortical areas by age 5, and all areas by age 8. This study further supports the crucial importance of implementing post-processing QC in CTh studies of development, aging, and neuropsychiatric disorders.

Neuroanatomical correlates of individual differences in social anxiety in a non-clinical population

Socially anxious individuals are characterized as those with distorted negative self-beliefs (NSBs), which are thought to enhance reactions of social distress (emotional reactivity) and social avoidance (social functioning). However, it remains unclear whether individual differences in social distress and social avoidance are represented by differences in brain morphometry. To probe into these neural correlates, we analyzed magnetic resonance images of a sample of 130 healthy subjects and used the Connectome Computation System (CCS) to evaluate these factors. The results showed that social distress was correlated with the cortical volume of the right orbitofrontal cortex (OFC) and the subcortical volume of the left amygdala, while social avoidance was correlated with the cortical volume of the right dorsolateral prefrontal cortex (DLPFC). Additionally, loneliness might mediate the relationship between the amygdala volume and the social distress score. Our results demonstrated that social distress and social avoidance were represented by segregated cortical regions in the healthy individuals. These findings might provide a valuable basis for understanding the stable brain structures underlying individual differences in social anxiety.

Sex differences in cortical volume and gyrification in autism

Background

Male predominance is a prominent feature of autism spectrum disorders (ASD), with a reported male to female ratio of 4:1. Because of the overwhelming focus on males, little is known about the neuroanatomical basis of sex differences in ASD. Investigations of sex differences with adequate sample sizes are critical for improving our understanding of the biological mechanisms underlying ASD in females.

Methods

We leveraged the open-access autism brain imaging data exchange (ABIDE) dataset to obtain structural brain imaging data from 53 females with ASD, who were matched with equivalent samples of males with ASD, and their typically developing (TD) male and female peers. Brain images were processed with FreeSurfer to assess three key features of local cortical morphometry: volume, thickness, and gyrification. A whole-brain approach was used to identify significant effects of sex, diagnosis, and sex-by-diagnosis interaction, using a stringent threshold of p < 0.01 to control for false positives. Stability and power analyses were conducted to guide future research on sex differences in ASD.

Results

We detected a main effect of sex in the bilateral superior temporal cortex, driven by greater cortical volume in females compared to males in both the ASD and TD groups. Sex-by-diagnosis interaction was detected in the gyrification of the ventromedial/orbitofrontal prefrontal cortex (vmPFC/OFC). Post-hoc analyses revealed that sex-by-diagnosis interaction was driven by reduced vmPFC/OFC gyrification in males with ASD, compared to females with ASD as well as TD males and females. Finally, stability analyses demonstrated a dramatic drop in the likelihood of observing significant clusters as the sample size decreased, suggesting that previous studies have been largely underpowered. For instance, with a sample of 30 females with ASD (total n = 120), a significant sex-by-diagnosis interaction was only detected in 50 % of the simulated subsamples.

Conclusions

Our results demonstrate that some features of typical sex differences are preserved in the brain of individuals with ASD, while others are not. Sex differences in ASD are associated with cortical regions involved in language and social function, two domains of deficits in the disorder. Stability analyses provide novel quantitative insights into why smaller samples may have previously failed to detect sex differences.

Electronic supplementary material

The online version of this article (doi:10.1186/s13229-015-0035-y) contains supplementary material, which is available to authorized users.

Impact of the Baltimore Experience Corps Trial on cortical and hippocampal volumes

INTRODUCTION

There is a substantial interest in identifying interventions that can protect and buffer older adults from atrophy in the cortex and particularly, the hippocampus, a region important to memory. We report the 2-year effects of a randomized controlled trial of an intergenerational social health promotion program on older men's and women's brain volumes.

METHODS

The Brain Health Study simultaneously enrolled, evaluated, and randomized 111 men and women (58 interventions; 53 controls) within the Baltimore Experience Corps Trial to evaluate the intervention impact on biomarkers of brain health at baseline and annual follow-ups during the 2-year trial exposure.

RESULTS

Intention-to-treat analyses on cortical and hippocampal volumes for full and sex-stratified samples revealed program-specific increases in volumes that reached significance in men only (P's ≤ .04). Although men in the control arm exhibited age-related declines for 2 years, men in the Experience Corps arm showed a 0.7% to 1.6% increase in brain volumes. Women also exhibited modest intervention-specific gains of 0.3% to 0.54% by the second year of exposure that contrasted with declines of about 1% among women in the control group.

DISCUSSION

These findings showed that purposeful activity embedded within a social health promotion program halted and, in men, reversed declines in brain volume in regions vulnerable to dementia.

CLINICAL TRIAL REGISTRATION

NCT0038.

Altered cortical structures and tract integrity of the mirror neuron system in association with symptoms of schizophrenia

The mirror neuron system (MNS) may be implicated in schizophrenia. This study investigated MNS structures, including the pars opercularis (Pop), the supramarginal gyrus (SMg), the third branch of the superior longitudinal fasciculus, and callosal fibers interconnecting bilateral Pop (CC-Pop) and SMg (CC-SMg), and clarified their relationships with positive and negative symptoms of schizophrenia. Participants comprised 32 schizophrenia patients and 32 matched controls who received T1-weighted structural magnetic resonance imaging (MRI, T1WI) and diffusion spectrum imaging (DSI). The cortical measures were computed from the T1WI data. Tract integrity was assessed using a tractography-based analysis of the generalized fractional anisotropy (GFA) derived from the DSI data. Pearson׳s correlations and multiple linear regression analysis were used to investigate the associations between MNS structures and positive and negative symptom scores of schizophrenia. Cortical thickness in bilateral Pop and SMg were significantly thinner and mean GFA of CC-Pop was significantly decreased in patients. Negative symptoms were significantly correlated with left SMg volume, and positive symptoms were significantly correlated with right SMg thickness. Multiple linear regression analysis showed left SMg volume to be the strongest contributor to the negative symptoms. The association between left SMg volume and negative symptoms may reflect the degree of social cognition impairment in schizophrenia.

Similar cortical but not subcortical gray matter abnormalities in women with posttraumatic stress disorder with versus without dissociative identity disorder

Neuroanatomical evidence on the relationship between posttraumatic stress disorder (PTSD) and dissociative disorders is still lacking. We acquired brain structural magnetic resonance imaging (MRI) scans from 17 patients with dissociative identity disorder (DID) and co-morbid PTSD (DID-PTSD) and 16 patients with PTSD but without DID (PTSD-only), and 32 healthy controls (HC), and compared their whole-brain cortical and subcortical gray matter (GM) morphological measurements. Associations between GM measurements and severity of dissociative and depersonalization/derealization symptoms or lifetime traumatizing events were evaluated in the patient groups. DID-PTSD and PTSD-only patients, compared with HC, had similarly smaller cortical GM volumes of the whole brain and of frontal, temporal and insular cortices. DID-PTSD patients additionally showed smaller hippocampal and larger pallidum volumes relative to HC, and larger putamen and pallidum volumes relative to PTSD-only. Severity of lifetime traumatizing events and volume of the hippocampus were negatively correlated. Severity of dissociative and depersonalization/derealization symptoms correlated positively with volume of the putamen and pallidum, and negatively with volume of the inferior parietal cortex. Shared abnormal brain structures in DID-PTSD and PTSD-only, small hippocampal volume in DID-PTSD, more severe lifetime traumatizing events in DID-PTSD compared with PTSD-only, and negative correlations between lifetime traumatizing events and hippocampal volume suggest a trauma-related etiology for DID. Our results provide neurobiological evidence for the side-by-side nosological classification of PTSD and DID in the DSM-5.

Relationship between trait impulsivity and cortical volume, thickness and surface area in male cocaine users and non-drug using controls

BACKGROUND

Trait impulsivity is commonly associated with cocaine dependence. The few studies that have investigated the relation between trait impulsivity and cortical morphometry, have shown a distinct relation between impulsivity and cortical volume (CV) of temporal, frontal and insula cortex. As CV is the function of cortical surface area (SA) and cortical thickness (CT) impulsivity may be differently associated to SA than to CT.

METHOD

Fifty-three cocaine users (CU) and thirty-five controls (HC) (males aged 18-55 years) completed the Barrat impulsiveness scale and a structural scan was made on a 3T MRI scanner. CV, SA and CT were measured using Freesurfer. Multivariate analysis was used to test for group differences and group by impulsivity interaction effects in CV, SA and ST across nine regions of interest in the temporal, frontal and insular cortices. Possible confounding effects of drug- and alcohol exposure were explored.

RESULTS

Compared to HC, CU had a smaller SA of the superior temporal cortex but a larger SA of the insula. There were divergent relations between trait impulsivity and SA of the superior temporal cortex and insula (positive in HC, negative in CU) and CT of the anterior cingulate cortex (negative in HC, positive in CU). Within CU, there was a negative association between monthly cocaine use and CT of the insula and superior temporal cortex.

DISCUSSION

The distinct relation between trait impulsivity and cortical morphometry in CU and HC might underlie inefficient control over behavior resulting in maladaptive impulsive behaviour such as cocaine abuse.

Cortical thickness, cortical and subcortical volume, and white matter integrity in patients with their first episode of major depression

BACKGROUND

The uncertainty over the true morphological changes in brains with major depressive disorder (MDD) underlines the necessity of comprehensive studies with multimodal structural brain imaging analyses. This study aimed to evaluate the differences in cortical thickness, cortical and subcortical volume, and white matter integrity between first episode, medication-naïve MDD patients and healthy controls.

METHODS

Subjects with their first episode of MDD whose illness duration had not exceeded 6 months (n=20) were enrolled in this study and were compared to age-, sex-, and education level-matched healthy controls (n=22). All participants were subjected to T1-weighted structural magnetic resonance imaging (MRI). We used an automated procedure of FreeSurfer and Tract-based spatial statistics (TBSS) to analyze differences in cortical thickness, cortical and subcortical volume, and white matter integrity between two groups.

RESULTS

The patients with first episode MDD exhibited significantly reduced cortical volume in the caudal anterior cingulate gyrus (P<0.0015) compared to healthy controls. We also observed altered white matter integrity in the body of the corpus callosum (P<0.01), reduced cortical volume of the caudal middle frontal gyrus and medial orbitofrontal gyrus, and enlarged hippocampal volume in the first episode MDD patients.

LIMITATIONS

We relied on a relatively small sample size and cortical volume reduction in several brain regions was not replicated in the analysis of cortical thickness.

CONCLUSIONS

Using multimodal imaging analyses on medication-naïve first episode MDD patients, we demonstrated fundamental structural alteration of brain gray and white matter, such as reduced cortical volume of the caudal ACC and white matter integrity in the body of the corpus callosum.

Rapid changes in brain structure predict improvements induced by perceptual learning. Neuroimage. 2013;81:205-212. [PMID: 23702411 DOI: 10.1016/j.neuroimage.2013.05.058]

Practice-dependent changes in brain structure can occur in task relevant brain regions as a result of extensive training in complex motor tasks and long-term cognitive training but little is known about the impact of visual perceptual learning on brain structure. Here we studied the effect of five days of visual perceptual learning in a motion-color conjunction search task using anatomical MRI. We found rapid changes in gray matter volume in the right posterior superior temporal sulcus, an area sensitive to coherently moving stimuli, that predicted the degree to which an individual's performance improved with training. Furthermore, behavioral improvements were also predicted by volumetric changes in an extended white matter region underlying the visual cortex. These findings point towards quick and efficient plastic neural mechanisms that enable the visual brain to deal effectively with changing environmental demands.