Nicotinic modulation of salience network connectivity and centrality in schizophrenia

Although functional abnormalities of the salience network are associated with schizophrenia, the acute effects of nicotine on its function and network dynamics during the resting state in patients are poorly understood. In this study, the effects of a 7 mg nicotine patch (vs. placebo) on salience network connectivity were examined in 17 patients with schizophrenia and 19 healthy subjects. We hypothesized abnormal connectivity between the salience network and other major networks (e.g. executive network) in patients under placebo administration and amelioration of this difference after nicotine. We also examined effects of nicotine on betweenness centrality (a measure of the influence of a region on information transfer throughout the brain) and local efficiency (a measure of local information transfer) of the network. A hybrid independent component analysis (ICA)/seed-based connectivity approach was implemented in which the salience network was extracted by ICA and cortical network peaks (anterior cingulate cortex (ACC), left and right insula) were used as seeds for whole-brain seed-to-voxel connectivity analysis. Significant drug X diagnosis interactions were observed between the ACC seed and superior parietal lobule and ventrolateral prefrontal cortex. A significant interaction effect was also observed between the left insula seed and middle cingulate cortex. During placebo conditions, abnormal connectivity predicted negative symptom severity and lower global functioning in patients. A significant drug X diagnosis interaction was also observed for betweenness centrality of the ACC. These results suggest that nicotine may target abnormalities in functional connectivity between salience and executive network areas in schizophrenia as well as affect the ability of the salience network to act as an integrator of global signaling in the disorder.     

Cognitive dissonance induction in everyday life: An fMRI study

This functional magnetic resonance imaging (fMRI) study explored the neural substrates of cognitive dissonance during dissonance “induction.” A novel task was developed based on the results of a separate item selection study (n = 125). Items were designed to generate dissonance by prompting participants to reflect on everyday personal experiences that were inconsistent with values they had expressed support for. One experimental condition (dissonance) and three control conditions (justification, consonance, and non-self-related inconsistency) were used for comparison. Items of all four types were presented to each participant (n = 14) in a randomized design. The fMRI analysis used a whole-brain approach focusing on the moments dissonance was induced. Results showed that in comparison with the control conditions the dissonance experience led to higher levels of activation in several brain regions. Specifically dissonance was associated with increased neural activation in key brain regions including the anterior cingulate cortex (ACC), anterior insula, inferior frontal gyrus, and precuneus. This supports current perspectives that emphasize the role of anterior cingulate and insula in dissonance processing. Less extensive activation in the prefrontal cortex than in some previous studies is consistent with this study’s emphasis on dissonance induction, rather than reduction. This article also contains a short review and comparison with other fMRI studies of cognitive dissonance.     

Fascículos asociativos ínsulo-operculares: revisión de su anatomía y de las implicaciones para el abordaje transopercular a la ínsula

IntroductionThe insula is a highly connected area, as an intricate network of afferent and efferent projections connect it with adjacent and distant cortical regions.ObjectiveTo perform an extensive review of recent literature to analyse the anatomy of the associative tracts related to the insula.ResultsThe frontal aslant tract, arcuate fasciculus, horizontal portion of the superior longitudinal fasciculus and the middle longitudinal fasciculus are associative tracts connected to the opercula. The inferior fronto-occipital fasciculus (IFOF) and uncinate fasciculus run under the anterior and inferior portion of the insula.Conclusionsthe pars triangularis and orbicularis of the inferior frontal gyrus, as well as the middle and anterior part of the superior temporal gyrus, have few connections with the perisylvian associative network. Consequently, in the trans-opercular approach to the insula, these 2 regions represent anatomical corridors that give access to the insula. The IFOF and the uncinate fasciculus represent the deep functional margin of resection.     

A case of semantic variant primary progressive aphasia with severe insular atrophy

Insular degeneration has been linked to symptoms of frontotemporal dementia (FTD). Presented in this case is a patient exhibiting semantic variant primary progressive aphasia, behavioral disturbance. Upon autopsy, he was found to have severe insular atrophy. In addition, selective serotonin reuptake inhibitors were ineffective in reducing symptoms of obsessive–compulsive behaviors or emotional blunting. This case suggests that Seeley et al.'s (2007 Seeley, W. W., Allman, J. M., Carlin, D. A. and et al. 2007. Divergent social functioning in behavioral variant frontotemporal dementia and Alzheimer disease: Reciprocal networks and neuronal evolution. Alzheimer Disease & Associated Disorders, 21: S50–S57. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar], Alzheimer Disease & Associated Disorders, 21, S50) hypothesis that von Economo neurons and fork cell-rich brain regions, particularly in the insula, are targeted in additional subtypes of FTD beyond the behavioral variant.     

Hemispheric asymmetries in cortical and subcortical anatomy

Previous research studies have reported many hemispherical asymmetries in cortical and subcortical anatomy, but only a subset of findings is consistent across studies. Here, we used improved Freesurfer-based automated methods to analyse the properties of the cortex and seven subcortical structures in 138 young adult subjects. Male and female subjects showed similar hemispheric asymmetries in gyral and sulcal structures, with many areas associated with language processing enlarged in the left hemisphere (LH) and a number of areas associated with visuospatial processing enlarged in the right hemisphere (RH). In addition, we found greater (non-directional) cortical asymmetries in subjects with larger brains. Asymmetries in subcortical structures included larger LH volumes of thalamus, putamen and globus pallidus and larger RH volumes of the cerebellum and the amygdala. We also found significant correlations between the subcortical structural volumes, particularly of the thalamus and cerebellum, with cortical area. These results help to resolve some of the inconsistencies in previous studies of hemispheric asymmetries in brain anatomy.     

Lesion analysis of language production deficits in aphasia

Background: Three aspects of language production are impaired to different degrees in individuals with post-stroke aphasia: ability to repeat words and nonwords, name pictures, and produce sentences. These impairments often persist into the chronic stages, and the neuroanatomical distribution of lesions associated with chronicity of each of these impairments is incompletely understood.

Aims: The primary objective of this study was to investigate the lesion correlates of picture naming, sentence production, and nonword repetition deficits in the same participant group because most prior lesion studies have mapped single language impairments. The broader goal of this study was to investigate the extent and degree of overlap and uniqueness among lesions resulting in these deficits in order to advance the current understanding of functional subdivision of neuroanatomical regions involved in language production.

Methods & Procedures: In this study, lesion-symptom mapping was used to determine if specific cortical regions are associated with nonword repetition, picture naming, and sentence production scores. Structural brain images and behavioural performance of 31 individuals with post-stroke left hemisphere lesions and a diagnosis of aphasia were used in the lesion analysis.

Outcomes & Results: Each impairment was associated with mostly unique, but a few shared lesions. Overall, sentence and repetition deficits were associated with left anterior perisylvian lesions, including the pars opercularis and triangularis of the inferior frontal lobe, anterior superior temporal gyrus, anterior portions of the supramarginal gyrus, the putamen, and anterior portions of the insula. In contrast, impaired picture naming was associated with posterior perisylvian lesions including major portions of the inferior parietal lobe and middle temporal gyrus. The distribution of lesions in the insula was consistent with this antero-posterior perisylvian gradient. Significant voxels in the posterior planum temporale were associated with a combination of all three deficits.

Conclusions: These findings emphasise the participation of each perisylvian region in multiple linguistic functions, suggesting a many(functions)-to-many(networks) framework while also identifying functional subdivisions within each region.     

Orbitofrontal extensions of the insular glioma based on subdivision of the uncinate fasciculus

The insular gliomas were classified based on their locations and extensions to the adjacent areas.The insular and orbitofrontal cortices with underlying fiber tracts were studied on ten (20 sides) human cadaveric brains and two heads. Twenty patients with insular gliomas with the orbitofrontal or septal region extensions were studied on preoperative magnetic resonance imaging (MRI).Insular gliomas can extend to the orbitofrontal area dorsolaterally and/or ventromedially through the subdivision of the uncinate fasciculus. The dorsolateral part of the uncinate fasciculus interconnects the temporopolar area to the lateral orbitofrontal cortex through insula, and the ventromedial part of the uncinate fasciculus interconnects the temporopolar area to the medial orbital cortex, gyrus rectus, and septal region. The gyrus rectus infiltration on MRI indicates a ventromedial involvement by passing through the ventromedial part of the uncinate fasciculus. Diffusion tensor imaging (DTI) MRI demonstration of the UF is difficult due to the interruption of the fiber tracts by tumor. Tumor infiltration extending to the gyrus rectus requires a 15° lateral tilting with vertex toward contralateral side, as well as 70° head rotation to the contralateral side of lesion, for exposure of frontal base, septal region, and lateral border of the anterior perforating substance at the same time with the exposure of whole sylvian fissure via transsylvian approach of the insular tumors.An understanding of the orbitofrontal extension of the insular tumor based on the subdivisions of UF is useful in preoperative surgical planning and can assist for gross total resection.     

锥体束受侵犯程度与岛叶胶质瘤患者术后疗效的关系

目的探讨锥体束受侵犯程度与岛叶胶质瘤患者术后疗效的关系。方法回顾性分析2010年7月至2019年7月于中国科学技术大学附属第一医院(安徽省立医院)神经外科行手术治疗的41例岛叶胶质瘤患者的临床资料。根据MRI显示锥体束受侵犯程度将患者分为3型,其中肿瘤仅侵犯岛叶前下部为Ⅰ型,侵犯岛叶后上部为Ⅱ型,浸润破坏内囊结构为Ⅲ型。分析各型患者术前、术后肢体运动功能障碍,病理学类型及术后疗效的差异。结果41例患者中,Ⅰ型18例(43.9%),Ⅱ型20例(48.8%),Ⅲ型3例(7.3%)。Ⅰ型患者术前、术后均无运动功能障碍。Ⅱ型患者术前4例有运动功能障碍,其中3例术后得到了改善,1例症状进一步加重,1例术后新发生了运动功能障碍。Ⅲ型患者术前均有运动功能障碍,术后症状均进一步加重。Ⅰ、Ⅱ、Ⅲ型肿瘤全切除者分别有11例、5例、1例,与Ⅰ型比较,Ⅱ+Ⅲ型肿瘤全切除比例低[分别为26.1%(6/23),11/18],差异有统计学意义(P=0.026);Ⅰ、Ⅱ、Ⅲ型患者中,世界卫生组织(WHO)Ⅲ~Ⅳ级胶质瘤患者分别有3例(3/18)、7例(7/20)、3例(3/3),差异有统计学意义(P=0.015)。术后29例获3~72(22.7±12.0)个月的随访。Ⅰ型患者随访13例,均未复发;Ⅱ型患者随访15例,其中7例复发;Ⅲ型患者随访1例,术后第3个月因残留肿瘤增大而死亡。Kaplan-Meier生存分析3型患者的生存率差异有统计学意义(P<0.01)。结论锥体束受侵犯程度越重,岛叶胶质瘤的病理学级别越高,手术全切除率越低,术后疗效越差。