Manuel F. Casanova - US grants

DESCRIPTION: (provided by applicant) It has been proposed that schizophrenia is a consequence of the lateralization of the brain in conjunction with the evolution of human language. Differences have been found between normal and schizophrenic brains in the size and lateralization of temporal lobes. Most work, however, has concentrated on gross structures while ignoring the potential for anatomical differences that may be found in relevant cytoarchitectonic areas. Furthermore, it would be profitable to examine anatomical components that correlate with known functional significance. Such a structure is the minicolumn, a fundamental anatomical and physiological unit of the cortex. The morphology of the minicoiumn has been shown to differ between small architectonic regions, reflecting variation in input, output, and local organization. For this reason, it was chosen as the ideal anatomical marker for the investigation of asymmetrical differences. In our preliminary studies, we examined five morphological features of minicolumns in 11 normal and 5 schizophrenic brains. The results revealed that: 1) differences between normal and schizophrenic brains are found not in the horizontal spacing that separate cell columns internalized structure of the cell columns, and 2) asymmetry of cell columns involves more than one anatomical variable. This project will examine possible differences in lateralization patterns of minicolumns in selected areas of cortex, including a part of Wernicke's language area, in 40 normal and 52 schizophrenic brains derived from the Runwell III collection. Magnified images (1 100x) of Nissl-stained cell columns in Lamina III will be analyzed by powerful computer imaging hardware and software enabling researchers to precisely quantify details of cell column morphology. If the preliminary findings of this study are confirmed, they will demonstrate that the reported differences of the temporal lobe in schizophrenia involve not only size but also a reorganization of a basic unit of function. Another possible outcome is that the number of minicolumns in the temporal lobe may differ without a concomitant change in the structural reorganization.

DESCRIPTION: (provided by applicant) It has been postulated that the prefrontal cortices of schizophrenic patients have less interneuronal space than controls, specifically in areas 9 and 46. This is thought to reflect an alteration in the neuronal circuitry of these areas that according to Selemon et al. (1995) is a possible component of the pathology of schizophrenia. This study, and those that followed, were based on measures of neuronal density. Our goal is two-fold: one is to examine this finding based on the cortical minicolumn, and secondly, to elucidate the distribution of interneuronal space in regards to the morphology of the cell column. Our preliminary study used a small population of normal controls (n = 16) and schizophrenic patients (n = 9), diagnosed according to DSM ffl-R criteria. Our test revealed smaller values for all spacing distances and neuropil space in area 9 of schizophrenic brains. The greatest reduction occurred in the minicolumn compartment where the majority of apical dendrite bundles, thalamocortical, and cortico-cortical fibers are found. This study will examine columnar differences in 40 schizophrenic (DSM IV diagnosis) and 52 controls derived from the Runwell ifi collection. Specimens will be derived from areas 9, 46, 17, and 4 (Brodmann). Magnified images (lOOx) of Nissi-stained cell columns in layers III-VI will be analyzed by powerful computer imaging hardware and software enabling researchers to precisely quantify details of cell column morphology. Stereological techniques will be used to estimate neuronal density. If our preliminary findings are corroborated, the smaller than normal minicolumns will demonstrate a reorganization of brain circuitry most probably defined during development.

DESCRIPTION (provided by applicant): All subcortical arrangements are primarily nuclear in type. The cortex was the first part of the brain to evolve a radial and laminar arrangement of cells. The resultant modular arrangement is based on the cell minicolumn: a self-contained ecosystem of connectivity linking afferent, efferent and interneuronal connections. Our preliminary study of the fundamental processing unit of the cortex, the minicolumn, indicates that the modular neocortical organization in the brains of autistic individuals differs from that of controls. More specifically, a study of 3 neocortical sites in 9 autistic brains and an equal number of normal controls has shown significant differences in the horizontal spacing that separates minicolumns. It also revealed differences in their internal structure: less neuropil space in the periphery of the minicolumn and increased mean cell spacing. Similar abnormalities have now been reported in Asperger's syndrome but appear absent in Down syndrome (a control group added for mental retardation). This study will examine differences in minicolumnar morphometry between 24 autistic brains and 24 controls, matched for age and sex, from both the Autism Tissue Program and the Yakovlev-Haleem Collection (Armed Forces Institute of Pathology). The patients provide a new cohort not previously examined by the investigator. Ten Down syndrome brains will provide a second control group. Sampled cortical regions include Brodmann's areas 4, 9, 10, 17, 21, 22, 30, 33, and 39, which represent sensory, motor, association and limbic cortex obtained from 4 different brain lobes. The study will utilize quantified computer imaging and stereology in both Nissl and myelin-stained material. The parameters tested include the width of minicolumns, the amount of neuropil space within them, the mean cell density within each minicolumn, individual lamina depth, cell size and type (pyramidal versus non pyramidal), and the distribution of cell types among different lamina. The study will employ inter-myelinated bundle measurements as a way of corroborating our minicolumnar width parameters. We will compare the results within multiple regions of the cortex as well as for lateralization. Finally, we will correlate our minicolunmar parameters with different dimensions on the ADI. This study aims at better understanding the neuroanatomical basis of autism. If validated, positive results from our studies will yield a great understanding of autism. For example, many alleged animal models of autism lack the human neuroanatomic information to justify their utility. Candidate gene studies could also be refined if neuroanatomic development in autism was better understood. Treatment modalities, especially neuropharmaceutical agents, will prove more specific as their targets are better understood.

Project summary Autism is a pervasive developmental disorder of childhood characterized by deficits in social interaction, language, and stereotyped behaviors and restricted range of interests. Recent studies on postmortem tissue suggest that autism is associated with cortical cytoarchitectural abnormalities. In brief, reports on independent populations have shown a reduction in the neuropil space at the periphery of the minicolumn. This is the compartment where lateral inhibition sharpens the borders of minicolumns and increases their definition. The primary source of for this inhibitory effect is derived from axon bundles of double-bouquet cells. The axons of double bouquet cells arrange themselves in essentially repeatable patterns varying between 15 ¿m and 30 ¿m wide, perpendicular to the cortical surface. This grant attempts to preferentially strengthen the inhibitory surround of minicolumns by taking advantage of the geometry of double bouquet cells. We will use the principle of induction to induce electrical currents in double bouquet cells by applying a coil of wire energized by a capacitor (Transcranial Magnetic Stimulator or TMS) to provide a magnetic field orthogonal to the plane of the coil. Slow or low frequency TMS will enhance interneuron inhibition which in turn will enhance spatial contrast needed to optimize functional discrimination in minicolumnar units. The trial will recruit 70 autistic patients and 30 controls matched for age, sex, IQ, and socio-economic class. Outcome measures will include behavioral and electrophysiological measures. Overall, our project will link behavioral, clinical, and neurophysiological (qEEG, ERP) responses during cognitive tests and TMS treatment outcomes with an underlying neuropathology model (minicolumnar pathology and lateral inhibition deficits) derived from investigations in our laboratory. The results of the proposed study will help understand the specific social communication and cognitive deficits associated with developmental abnormalities of functions within cortical circuitry, and thereby contribute to understanding the brain substrates of behavioral dysfunctions typical for autism. The proposal represents a new development in combining TMS with functional outcome measures (cognitive ERP, EEG), using TMS as a theory-guided psychiatric therapy in autism.

DESCRIPTION (provided by applicant): The minicolumn is a basic anatomical and physiological element of the mammalian cerebral cortex, comprising a linear array of pyramidal cell bodies, their projections, and accompanying GABAergic interneurons. Postmortem studies of the organization of pyramidal cell arrays in autism have revealed that minicolumns in the brains of autistic patients are narrower. Since the minicolumn re-iterates itself millions of times throughout the brain, variations in the total number and width of minicolumns may result in macroscopic changes to the brain's surface area, folding (gyrification), and white matter pathways linking regional networks of minicolumns. In effect, data derived from comparative anatomy studies indicates that minicolumnar findings, if generalized, have specific gross correlates that can be detected by MRI. These changes include alterations in the gyral window, gray/white matter ratio, parcellation of the white matter, and size of the corpus callosum. This grant proposes studying a unique series of cases (n = 58) derived from the Autism Tissue Program (ATP). All of the cases included in this study had clinical documentation and a postmortem MRI. Autism was diagnosed according to DSM-IV-TR and ADI-R criteria. There are three specific aims to our study: 1) To quantify and compare the radial structure of dendritic bundles in the cerebral cortex of postmortem autistic patients and controls, 2) To determine the correlation between minicolumnar structure defined by fiber bundles and white matter distribution in the brains of postmortem autistic patients and controls, and 3) To perform a cluster analysis of autism diagnostic criteria and morphometric measurements. Specific aim 3 is an exploratory study that will attempt to provide construct validity to a current diagnostic scheme (ADI-R) by correlating clinical parameters to obtained neuropathological/neuroimaging data. All of the aims are in-keeping with the research objectives of the applied request for applications (RFA-MH-09-170). In order to achieve our specific aims the proposed study will correlate anthropometric indices (MRI) to specific minicolumnar parameters. Postmortem data will be derived from the analysis of apical dendritic bundles in nine cortical areas that display varying degrees of cytoarchitectural differentiation: paralimbic, high- order (hetermodal) association, modality-specific (unimodal) association, and idiotypic areas (primary sensory/motor cortices) (BA 4, 9, 10, 17, 21, 22, 33, 39, and 40). Other areas, i.e., corticoid and all cortical formations, were not included in our sampling scheme due to their lack of minicolumnar organization. The analysis of specific minicolumnar compartments will allow us to screen a series of anatomical elements incriminated in previous studies, i.e., minicolumnar narrowing most prominently in the peripheral neuropil space. Preliminary findings suggest: 1) high predictive ability between macro- and microscopic parameters, and 2) a high degree of diagnostic (autism) selectivity when combining the different anthropometric indices espoused in this grant proposal. PUBLIC HEALTH RELEVANCE: This project attempts to establish a correlation between autopsy and neuroimaging findings in autism. The intent is to develop markers of the condition that can be detected while the patient is alive. Another innovative aspect of the proposal is an attempt to validate current diagnostic screening techniques against autopsy findings.

DESCRIPTION (provided by applicant): The R13 mechanism would be used to support a scientific conference, Anatomical and functional modularity of the cerebral cortex, focusing on recent studies describing the organization of the cerebral cortex from a modular perspective, and how the same provides for translational perspectives into clinical practice. The conference would provide a cohesive forum on the latest anatomical and physiological approaches to understanding the basic components of cortical modularity and their involvement in different pathological states, e.g., autism, dyslexia, and ADHD. It will disseminate, for example, recent work regarding the use of minicolumns as neural prosthetics agents for cases of stroke/neurodegenerative disorders and how timing in neural firing between different layers of a minicolumn may provide for higher cognitive functions. The symposium seeks to encourage communication and in-depth discussion of a broad range of subjects under the unifying theme of cortical modularity. The topics covered at the conference would span a wide spectrum of resolution, that is, from minicolumns and their parcellation into different components (e.g., apica dendritic bundles) all the way to macrocolumns and networks of the same. The sessions of the symposium span four major areas: 1) Anatomy and Development (encompassing both embryology and anatomical compartmentalization of neocortical modules), 2) Anthropology (addressing how encephalization has proceeded through the addition of supernumerary minicolumns), 3) Computer modeling and electrophysiology (emphasizing the minicolumn's prowess for parallel processing and how empirical models of neural connectivity help explain the emergent properties of modules), and 4) Pathology (a discussion of several conditions where abnormalities of minicolumns have been implicated).