Jennifer L. Robinson

Meta-Analysis of Gray Matter Anomalies in Schizophrenia: Application of Anatomic Likelihood Estimation and Network Analysis

BACKGROUND Although structural neuroimaging methods have been widely used to study brain morphology in schizophrenia, synthesizing this literature has been difficult. With the increasing popularity of voxel-based morphometric (VBM) methods in which group differences are reported in standardized coordinates, it is possible to apply powerful meta-analytic techniques initially designed for functional neuroimaging. In this study, we performed a voxelwise, coordinate-based meta-analysis to better conceptualize the neuroanatomic correlates of schizophrenia. METHODS Thirty-one peer-reviewed articles, with a total of 1195 patients with schizophrenia contrasted with 1262 healthy volunteers, were included in the meta-analysis. Coordinates from each article were used to create a statistical map that estimated the likelihood of between-group gray matter density differences at every brain voxel. These results were subsequently entered into a network analysis. RESULTS Patients had reduced gray matter density relative to control subjects in a distributed network of regions, including bilateral insular cortex, anterior cingulate, left parahippocampal gyrus, left middle frontal gyrus, postcentral gyrus, and thalamus. Network analysis grouped these regions into four distinct networks that potentially represent different pathologic processes. Patients had increased gray matter density in striatal regions. CONCLUSIONS This study expands on previous meta-analyses of the neuroanatomy of schizophrenia by elucidating a series of brain networks disrupted by the illness. Because it is possible that these networks are influenced by independent etiologic factors, this work should foster more detailed neural models of the illness and focus research designed to discover the mechanisms of gray matter reduction in schizophrenia.

ALE Meta-Analysis Workflows Via the Brainmap Database: Progress Towards A Probabilistic Functional Brain Atlas.

With the ever-increasing number of studies in human functional brain mapping, an abundance of data has been generated that is ready to be synthesized and modeled on a large scale. The BrainMap database archives peak coordinates from published neuroimaging studies, along with the corresponding metadata that summarize the experimental design. BrainMap was designed to facilitate quantitative meta-analysis of neuroimaging results reported in the literature and supports the use of the activation likelihood estimation (ALE) method. In this paper, we present a discussion of the potential analyses that are possible using the BrainMap database and coordinate-based ALE meta-analyses, along with some examples of how these tools can be applied to create a probabilistic atlas and ontological system of describing function–structure correspondences.

Metaanalytic connectivity modeling: delineating the functional connectivity of the human amygdala.

Functional neuroimaging has evolved into an indispensable tool for noninvasively investigating brain function. A recent development of such methodology is the creation of connectivity models for brain regions and related networks, efforts that have been inhibited by notable limitations. We present a new method for ascertaining functional connectivity of specific brain structures using metaanalytic connectivity modeling (MACM), along with validation of our method using a nonhuman primate database. Drawing from decades of neuroimaging research and spanning multiple behavioral domains, the method overcomes many weaknesses of conventional connectivity analyses and provides a simple, automated alternative to developing accurate and robust models of anatomically‐defined human functional connectivity. Applying MACM to the amygdala, a small structure of the brain with a complex network of connections, we found high coherence with anatomical studies in nonhuman primates as well as human‐based theoretical models of emotive‐cognitive integration, providing evidence for this novel methods utility. Hum Brain Mapp, 2010.

The BrainMap strategy for standardization, sharing, and meta-analysis of neuroimaging data.

BackgroundNeuroimaging researchers have developed rigorous community data and metadata standards that encourage meta-analysis as a method for establishing robust and meaningful convergence of knowledge of human brain structure and function. Capitalizing on these standards, the BrainMap project offers databases, software applications, and other associated tools for supporting and promoting quantitative coordinate-based meta-analysis of the structural and functional neuroimaging literature.FindingsIn this report, we describe recent technical updates to the project and provide an educational description for performing meta-analyses in the BrainMap environment.ConclusionsThe BrainMap project will continue to evolve in response to the meta-analytic needs of biomedical researchers in the structural and functional neuroimaging communities. Future work on the BrainMap project regarding software and hardware advances are also discussed.

The functional connectivity of the human caudate: An application of meta-analytic connectivity modeling with behavioral filtering

Meta-analysis based techniques are emerging as powerful, robust tools for developing models of connectivity in functional neuroimaging. Here, we apply meta-analytic connectivity modeling to the human caudate to 1) develop a model of functional connectivity, 2) determine if meta-analytic methods are sufficiently sensitive to detect behavioral domain specificity within region-specific functional connectivity networks, and 3) compare meta-analytic driven segmentation to structural connectivity parcellation using diffusion tensor imaging. Results demonstrate strong coherence between meta-analytic and data-driven methods. Specifically, we found that behavioral filtering resulted in cognition and emotion related structures and networks primarily localized to the head of the caudate nucleus, while perceptual and action specific regions localized to the body of the caudate, consistent with early models of nonhuman primate histological studies and postmortem studies in humans. Diffusion tensor imaging (DTI) revealed support for meta-analytic connectivity modelings (MACM) utility in identifying both direct and indirect connectivity. Our results provide further validation of meta-analytic connectivity modeling, while also highlighting an additional potential, namely the extraction of behavioral domain specific functional connectivity.

Acute effects of hydrocortisone on the human brain: An fMRI study

Cortisol is essential for regulating all cell types in the body, including those in the brain. Most information concerning cortisols cerebral effects comes from work in nonhumans. This is a first effort to use functional magnetic resonance imaging (fMRI) to study the time course and locus of cortisols effects on selected brain structures in resting humans. We repeatedly scanned 21 healthy young adults over 45 min to examine changes in the brains activity 5 min before, and for 40 min after, an IV injection of 10mg of hydrocortisone (N=11) or saline placebo (N=10). At 15-18 min postinjection we observed in the hydrocortisone group reduced activity in the hippocampus and amygdala that reached a peak response minimum at 25-30 min postinjection (-1 Standard Deviation) relative to placebo. No such effect was seen in the thalamus. Functional MRI appears to be a safe, noninvasive method to study the time course and anatomical effects of glucocorticoids in the human brain.

Fronto-limbic circuitry in euthymic bipolar disorder: Evidence for prefrontal hyperactivation

Functional magnetic resonance imaging (fMRI) studies of bipolar disorder have revealed fronto-limbic abnormalities in patients during manic and depressive episodes. However, relatively few studies have examined neural activity during euthymia, leaving unanswered questions concerning the impact of mood state on activity in these brain regions. In the present study, we examined 15 remitted bipolar type I patients and 16 demographically matched healthy comparison subjects during performance on an affective face-matching task previously shown to elicit amygdala hyperactivation and prefrontal hypoactivation in manic relative to healthy subjects. In our euthymic sample, amygdala activation did not differ from controls. However, bipolar patients showed hyperactivation in inferior prefrontal cortical regions compared with controls, a finding that contrasts with the hypoactivation previously reported in this region in manic patients. Given the reciprocal relationship between the prefrontal cortex and limbic structures, we propose state-related amygdala activity, similar to that of healthy controls, may be associated with prefrontal hyperactivation when bipolar patients are asymptomatic.

Differential activation of the anterior cingulate cortex and caudate nucleus during a gambling simulation in persons with a family history of alcoholism: Studies from the Oklahoma Family Health Patterns Project

Individuals with a family history of alcoholism (FH+) are at enhanced risk of developing an alcohol or other substance use disorder relative to those without this history (FH-). Recent studies comparing FH+ and FH- individuals have revealed differences in cognition, emotion processing, sociability, and decision-making. These differences suggest possible altered brain functioning in FH+ individuals that may play a crucial role in vulnerability to substance use disorders. In the present study, 15 FH+ and 19 FH- individuals performed the Iowa Gambling Task (IGT), a simulated card game requiring integration of payoff-to-penalty ratios, while undergoing functional magnetic resonance imaging. All participants performed the task more conservatively as the session progressed, and the FH groups achieved similar payoffs by the end of the game. Imaging revealed a distributed network of brain regions that was engaged when subjects performed this task, including the right inferior frontal and postcentral gyri, left parahippocampal gyrus, insula and precuneous cortices, left inferior and superior parietal lobules, left lentiform nucleus and bilateral culmen, claustrum, lingual gyri and cerebellar tonsils. Despite a lack of behavioral differences between groups, the FH+ participants showed significantly more activation in the left dorsal anterior cingulate cortex and left caudate nucleus. These findings correspond to models of risk in FH+ persons that postulate biases in brain decision-making systems as underlying elevated risk for alcoholism.

Thalamic medial dorsal nucleus atrophy in medial temporal lobe epilepsy: A VBM meta-analysis

Purpose Medial temporal lobe epilepsy (MTLE) is associated with MTLE network pathology within and beyond the hippocampus. The purpose of this meta-analysis was to identify consistent MTLE structural change to guide subsequent targeted analyses of these areas. Methods We performed an anatomic likelihood estimation (ALE) meta-analysis of 22 whole-brain voxel-based morphometry experiments from 11 published studies. We grouped these experiments in three ways. We then constructed a meta-analytic connectivity model (MACM) for regions of consistent MTLE structural change as reported by the ALE analysis. Key findings ALE reported spatially consistent structural change across VBM studies only in the epileptogenic hippocampus and the bilateral thalamus; within the thalamus, the medial dorsal nucleus of the thalamus (MDN thalamus) represented the greatest convergence (P < 0.05 corrected for multiple comparisons). The subsequent MACM for the hippocampus and ipsilateral MDN thalamus demonstrated that the hippocampus and ipsilateral MDN thalamus functionally co-activate and are nodes within the same network, suggesting that MDN thalamic damage could result from MTLE network excitotoxicity. Significance Notwithstanding our large sample of studies, these findings are more restrictive than previous reports and demonstrate the utility of our inclusion filters and of recently modified meta-analytic methods in approximating clinical relevance. Thalamic pathology is commonly observed in animal and human studies, suggesting it could be a clinically useful indicator. Thalamus-specific research as a clinical marker awaits further investigation.

Gender differences in working memory networks: A BrainMap meta-analysis

Gender differences in psychological processes have been of great interest in a variety of fields. While the majority of research in this area has focused on specific differences in relation to test performance, this study sought to determine the underlying neurofunctional differences observed during working memory, a pivotal cognitive process shown to be predictive of academic achievement and intelligence. Using the BrainMap database, we performed a meta-analysis and applied activation likelihood estimation to our search set. Our results demonstrate consistent working memory networks across genders, but also provide evidence for gender-specific networks whereby females consistently activate more limbic (e.g., amygdala and hippocampus) and prefrontal structures (e.g., right inferior frontal gyrus), and males activate a distributed network inclusive of more parietal regions. These data provide a framework for future investigations using functional or effective connectivity methods to elucidate the underpinnings of gender differences in neural network recruitment during working memory tasks.