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Arnaud Cachia

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Edouard Duchesnay

Université Paris Descartes

APHM

University of California, Davis

University of Michigan

McGill University

University of California, San Francisco

Dongbei University of Finance & Economics

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Papers by Arnaud Cachia

Gyral Parcellation of the Cortical Surface Using Geodesic Voronoï Diagrams

Lecture Notes in Computer Science, 2002

In this paper, we propose a generic automatic approach for the parcellation of the cortical surfa... more In this paper, we propose a generic automatic approach for the parcellation of the cortical surface into labelled gyri. These gyri are defined from a set of pairs of sulci selected by the user. The selected sulci are first automatically identified in the data, then projected onto the cortical surface. The parcellation stems from two nested Voronoï diagrams computed geodesically to the cortical surface. The first diagram provides the zones of influence of the sulci. The boundary between the two zones of influence of each selected pair of sulcus stands for a gyrus seed. A second diagram yields the gyrus parcellation. The distance underlying the Voronoï diagram allows the method to extrapolate the gyrus limits where the sulci are interrupted. The method is applied on three different brains.

Study of cortical folding process with prenatal MR imaging

Poster #130 CORTICAL GYRIFICATION AND NEUROLOGICAL SOFT SIGNS IN SCHIZOPHRENIA: MARKERS OF DEVELOPMENTAL LOAD

Schizophrenia Research, 2012

Multi-scale diffeomorphic cortical registration under manifold sulcal constraints

2008 5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro, 2008

Neuroimaging at the group level requires spatial normalization across individuals. This issue has... more Neuroimaging at the group level requires spatial normalization across individuals. This issue has been receiving considerable attention from multiple research groups. Here we suggest a surface-based geometric approach that consists in matching a set of cortical surfaces through their sulcal imprints. We provide the proof-of-concept of this approach by showing 1) how sulci may be automatically identified and simplified from T1-weighted MRI data series, and 2) how this sulcal information may be considered as landmarks for recent measure-based diffeomorphic deformation approaches. In our framework, the resulting 3D transforms are naturally applied to the entire cortical surface and MRI volumes.

Sulcus-Based MR Analysis of Focal Cortical Dysplasia Located in the Central Region

by Arnaud Cachia and Stéphanie Lion

PloS one, 2015

Focal cortical dysplasias (FCDs) are mainly located in the frontal region, with a particular trop... more Focal cortical dysplasias (FCDs) are mainly located in the frontal region, with a particular tropism for the central sulcus. Up to 30% of lesions are undetected (magnetic resonance [MR]-negative FCD patients) or belatedly diagnosed by visual analysis of MR images. We propose an automated sulcus-based method to analyze abnormal sulcal patterns associated with central FCD, taking into account the normal interindividual sulcal variability. We retrospectively studied 29 right-handed patients with FCD in the central region (including 12 MR negative histologically-confirmed cases) and 29 right-handed controls. The analysis of sulcal abnormalities from T1-weighted MR imaging (MRI) was performed using a graph-based representation of the cortical folds and an automated sulci recognition system, providing a new quantitative criterion to describe sulcal patterns, termed sulcus energy. Group analysis showed that the central sulcus in the hemisphere ipsilateral to the FCD exhibited an abnormal s...

Folding of the anterior cingulate cortex partially explains inhibitory control during childhood: a longitudinal study

Developmental cognitive neuroscience, 2014

Difficulties in cognitive control including inhibitory control (IC) are related to the pathophysi... more Difficulties in cognitive control including inhibitory control (IC) are related to the pathophysiology of several psychiatric conditions. In healthy subjects, IC efficiency in childhood is a strong predictor of academic and professional successes later in life. The dorsal anterior cingulate cortex (ACC) is one of the core structures responsible for IC. Although quantitative structural characteristics of the ACC contribute to IC efficiency, the qualitative structural brain characteristics contributing to IC development are less-understood. Using anatomical magnetic resonance imaging, we investigated whether the ACC sulcal pattern at age 5, a stable qualitative characteristic of the brain determined in utero, explains IC at age 9. 18 children performed Stroop tasks at age 5 and age 9. Children with asymmetrical ACC sulcal patterns (n=7) had better IC efficiency at age 5 and age 9 than children with symmetrical ACC sulcal patterns (n=11). The ACC sulcal patterns appear to affect specif...

White matter abnormalities revealed by DTI correlate with interictal grey matter FDG-PET metabolism in focal childhood epilepsies

Epileptic disorders : international epilepsy journal with videotape, 2012

For patients with focal epilepsy scheduled for surgery, including MRI-negative cases, (18)FDG-PET... more For patients with focal epilepsy scheduled for surgery, including MRI-negative cases, (18)FDG-PET was shown to disclose hypometabolism in the seizure onset zone. However, it is not clear whether grey matter hypometabolism is informative of the integrity of the surrounding white matter cerebral tissue. In order to study the relationship between metabolism of the seizure onset zone grey matter and the integrity of the surrounding white matter measured by diffusion tensor imaging (DTI), we performed a monocentric prospective study (from 2006 to 2009) in 15 children with pharmacoresistant focal epilepsy, suitable for interictal (18)FDG-PET, T1-, T2-, FLAIR sequence MRI and DTI. Children had either positive or negative MRI (eight with symptomatic and seven with cryptogenic epilepsies, respectively). Seven children subsequently underwent surgery. Standardised uptake values of grey matter PET metabolism were compared with DTI indices (fractional anisotropy [FA], apparent diffusion coeffici...

Anatomically constrained surface parameterization for cortical localization

by Arnaud Cachia and Olivier Coulon

Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention, 2005

We present here a method that aims at defining a surface-based coordinate system on the cortical ... more We present here a method that aims at defining a surface-based coordinate system on the cortical surface. Such a system is needed for both cortical localization and intersubject matching in the framework of neuroimaging. We propose an automatic parameterization based on the spherical topology of the grey/white matter interface of each hemisphere and on the use of naturally organized and reproducible anatomical features. From those markers used as initial constraints, the coordinate system is propagated via a PDE solved on the cortical surface.

Brain morphometry using 3D moment invariants

Medical image analysis, 2004

This paper advocates the use of shape descriptors based on moments of 3D coordinates for morphome... more This paper advocates the use of shape descriptors based on moments of 3D coordinates for morphometry of the cortical sulci. These descriptors, which have been introduced more than a decade ago, are invariant relatively to rotations, translations and scale and can be computed for any topology. A rapid insight into the derivation of these invariants is proposed first. Then, their potential to characterize shapes is shown from a principal component analysis of the 12 first invariants computed for 12 different deep brain structures manually drawn for 7 different brains. Finally, these invariants are used to find some correlates of handedness and sex among the shapes of 116 different cortical sulci automatically identified in each of 142 brains of the ICBM database.

Object-based strategy for morphometry of the cerebral cortex

Information processing in medical imaging : proceedings of the ... conference, 2003

Most of the approaches dedicated to automatic morphometry rely on a point-by-point strategy based... more Most of the approaches dedicated to automatic morphometry rely on a point-by-point strategy based on warping each brain towards a reference coordinate system. In this paper, we describe an alternative object-based strategy dedicated to the cortex. This strategy relies on an artificial neuroanatomist performing automatic recognition of the main cortical sulci and parcellation of the cortical surface into gyral patches. A set of shape descriptors, which can be compared across subjects, is then attached to the sulcus and gyrus related objects segmented by this process. The framework is used to perform a study of 142 brains of the ICBM database. This study reveals some correlates of handedness on the size of the sulci located in motor areas, which seem to be beyond the scope of the standard voxel based morphometry.

Relationship between simultaneously acquired resting-state regional cerebral glucose metabolism and functional MRI: A PET/MR hybrid scanner study

NeuroImage, 2015

Recently introduced hybrid PET/MR scanners provide the opportunity to measure simultaneously, and... more Recently introduced hybrid PET/MR scanners provide the opportunity to measure simultaneously, and in direct spatial correspondence, both metabolic demand and functional activity of the brain, hence capturing complementary information on the brain's physiological state. Here we exploited PET/MR simultaneous imaging to explore the relationship between the metabolic information provided by resting-state fluorodeoxyglucose-PET (FDG-PET) and fMRI (rs-fMRI) in neurologically healthy subjects. Regional Homogeneity (ReHo), Fractional Amplitude of Low Frequency Fluctuations (fALFF), and Degree of Centrality (DC) maps were generated from the rs-fMRI data in 23 subjects, and voxel-wise comparison to glucose uptake distribution provided by simultaneously acquired FDG-PET was performed. The mutual relationships among each couple of these four metrics were explored in terms of similarity, both of spatial distribution across the brain and the whole group, and voxel-wise across subjects, taking into account partial volume effects by adjusting for gray matter (GM) volume. Although a significant correlation between the spatial distribution of glucose uptake and rs-fMRI derived metrics was present, only a limited percentage of GM voxels correlated with PET across subjects. Moreover, the correlation between the spatial distributions of PET and RS-fMRI-derived metrics is spatially heterogeneous across both anatomic regions and functional networks, with lowest correlation strength in the limbic network (Spearman rho around -0.11 for DC), and strongest correlation for the default-mode network (up to 0.89 for ReHo and 0.86 for fALFF). Overall, ReHo and fALFF provided significantly higher correlation coefficients with PET (p=10 -8 and 10 -7 , respectively) as compared to DC, while no significant differences were present between ReHo and fALFF. Local GM volume variations introduced a limited overestimation of the rs-fMRI to FDG correlation between the modalities under investigation through partial volume effects. These novel results provide the basis for future studies of alterations of the coupling between brain metabolism and functional connectivity in pathologic conditions.

A framework to study the cortical folding patterns

NeuroImage, 2004

This paper describes a decade-long research program focused on the variability of the cortical fo... more This paper describes a decade-long research program focused on the variability of the cortical folding patterns. The program has developed a framework of using artificial neuroanatomists that are trained to identify sulci from a database. The framework relies on a renormalization of the brain warping problem, which consists in matching the cortices at the scale of the folds. Another component of the program is the search for the alphabet of the folding patterns, namely, a list of indivisible elementary sulci. The search relies on the study of the cortical folding process using antenatal imaging and on backward simulations of morphogenesis aimed at revealing traces of the embryologic dimples in the mature cortical surface. The importance of sulcalbased morphometry is illustrated by a simple study of the correlates of handedness on asymmetry indices. The study shows for instance that the central sulcus is larger in the dominant hemisphere. D

White matter diffusion abnormalities from DTI and high angular resolution diffusion imaging (HARDI) correlate with grey matter FDG-PET metabolism in epileptic children

NeuroImage, 2009

Deviations in cortex sulcation associated with visual hallucinations in schizophrenia

Molecular Psychiatry, 2014

Hallucinations, and auditory hallucinations (AH) in particular, constitute the most typical and d... more Hallucinations, and auditory hallucinations (AH) in particular, constitute the most typical and disabling schizophrenia symptoms. Although visual hallucinations (VH) have been largely neglected in psychiatric disorders, a recent review reported a 27% mean prevalence of VH in schizophrenia patients. The pathophysiology underlying VH in schizophrenia remains elusive. Several schizophrenia studies reported a significant effect of age on VH; therefore, we tested the hypothesis that the neurodevelopmental model of schizophrenia may explain VH occurrence. We analyzed cortex sulcation, a marker of brain development, in healthy controls (HCs) and two subgroups of carefully selected schizophrenia patients suffering from hallucinations: patients with only AH (that is, patients who never reported VH) and patients with audio-visual hallucinations (A+VH). Different cortical sulcation and leftright sulcal asymmetry were found between A+VH and AH patients, with decreased sulcation in both A+VH and AH patients in comparison with the HCs. Although a specific association between VH and neurodegenerative mechanisms, for example, in Body-Lewy Dementia or Parkinson's Disease, has previously been reported in the literature, the current study provides the first neuroimaging evidence of an association between VH and neurodevelopmental mechanisms.

Conclusion: Key Issues for Future Research in the Neuroscience of Hallucinations

Brain folding in schizophrenia

The making of the brain: the cortical folding process assessed by advanced MR image analysis

Pediatric brain glucose metabolism analysis using PET and SPM

by Arnaud Cachia and R. Trebossen

WHITE MATTER DIFFUSION ABNORMALITIES CORRELATE WITH GREY MATTER FDG-PET METABOLISM IN EPILEPTIC CHILDREN

SCALE RELATIONSHIP BETWEEN BRAIN VOLUME AND CORTEX AREA: AN ALLOMETRIC STUDY IN SUBJECTS AT RISK MENTAL STATE AND FIRST-EPISODE PSYCHOSIS PATIENTS

Gyral Parcellation of the Cortical Surface Using Geodesic Voronoï Diagrams

Lecture Notes in Computer Science, 2002

In this paper, we propose a generic automatic approach for the parcellation of the cortical surfa... more In this paper, we propose a generic automatic approach for the parcellation of the cortical surface into labelled gyri. These gyri are defined from a set of pairs of sulci selected by the user. The selected sulci are first automatically identified in the data, then projected onto the cortical surface. The parcellation stems from two nested Voronoï diagrams computed geodesically to the cortical surface. The first diagram provides the zones of influence of the sulci. The boundary between the two zones of influence of each selected pair of sulcus stands for a gyrus seed. A second diagram yields the gyrus parcellation. The distance underlying the Voronoï diagram allows the method to extrapolate the gyrus limits where the sulci are interrupted. The method is applied on three different brains.

Study of cortical folding process with prenatal MR imaging

Poster #130 CORTICAL GYRIFICATION AND NEUROLOGICAL SOFT SIGNS IN SCHIZOPHRENIA: MARKERS OF DEVELOPMENTAL LOAD

Schizophrenia Research, 2012

Multi-scale diffeomorphic cortical registration under manifold sulcal constraints

2008 5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro, 2008

Neuroimaging at the group level requires spatial normalization across individuals. This issue has... more Neuroimaging at the group level requires spatial normalization across individuals. This issue has been receiving considerable attention from multiple research groups. Here we suggest a surface-based geometric approach that consists in matching a set of cortical surfaces through their sulcal imprints. We provide the proof-of-concept of this approach by showing 1) how sulci may be automatically identified and simplified from T1-weighted MRI data series, and 2) how this sulcal information may be considered as landmarks for recent measure-based diffeomorphic deformation approaches. In our framework, the resulting 3D transforms are naturally applied to the entire cortical surface and MRI volumes.

Sulcus-Based MR Analysis of Focal Cortical Dysplasia Located in the Central Region

by Arnaud Cachia and Stéphanie Lion

PloS one, 2015

Focal cortical dysplasias (FCDs) are mainly located in the frontal region, with a particular trop... more Focal cortical dysplasias (FCDs) are mainly located in the frontal region, with a particular tropism for the central sulcus. Up to 30% of lesions are undetected (magnetic resonance [MR]-negative FCD patients) or belatedly diagnosed by visual analysis of MR images. We propose an automated sulcus-based method to analyze abnormal sulcal patterns associated with central FCD, taking into account the normal interindividual sulcal variability. We retrospectively studied 29 right-handed patients with FCD in the central region (including 12 MR negative histologically-confirmed cases) and 29 right-handed controls. The analysis of sulcal abnormalities from T1-weighted MR imaging (MRI) was performed using a graph-based representation of the cortical folds and an automated sulci recognition system, providing a new quantitative criterion to describe sulcal patterns, termed sulcus energy. Group analysis showed that the central sulcus in the hemisphere ipsilateral to the FCD exhibited an abnormal s...

Folding of the anterior cingulate cortex partially explains inhibitory control during childhood: a longitudinal study

Developmental cognitive neuroscience, 2014

Difficulties in cognitive control including inhibitory control (IC) are related to the pathophysi... more Difficulties in cognitive control including inhibitory control (IC) are related to the pathophysiology of several psychiatric conditions. In healthy subjects, IC efficiency in childhood is a strong predictor of academic and professional successes later in life. The dorsal anterior cingulate cortex (ACC) is one of the core structures responsible for IC. Although quantitative structural characteristics of the ACC contribute to IC efficiency, the qualitative structural brain characteristics contributing to IC development are less-understood. Using anatomical magnetic resonance imaging, we investigated whether the ACC sulcal pattern at age 5, a stable qualitative characteristic of the brain determined in utero, explains IC at age 9. 18 children performed Stroop tasks at age 5 and age 9. Children with asymmetrical ACC sulcal patterns (n=7) had better IC efficiency at age 5 and age 9 than children with symmetrical ACC sulcal patterns (n=11). The ACC sulcal patterns appear to affect specif...

White matter abnormalities revealed by DTI correlate with interictal grey matter FDG-PET metabolism in focal childhood epilepsies

Epileptic disorders : international epilepsy journal with videotape, 2012

For patients with focal epilepsy scheduled for surgery, including MRI-negative cases, (18)FDG-PET... more For patients with focal epilepsy scheduled for surgery, including MRI-negative cases, (18)FDG-PET was shown to disclose hypometabolism in the seizure onset zone. However, it is not clear whether grey matter hypometabolism is informative of the integrity of the surrounding white matter cerebral tissue. In order to study the relationship between metabolism of the seizure onset zone grey matter and the integrity of the surrounding white matter measured by diffusion tensor imaging (DTI), we performed a monocentric prospective study (from 2006 to 2009) in 15 children with pharmacoresistant focal epilepsy, suitable for interictal (18)FDG-PET, T1-, T2-, FLAIR sequence MRI and DTI. Children had either positive or negative MRI (eight with symptomatic and seven with cryptogenic epilepsies, respectively). Seven children subsequently underwent surgery. Standardised uptake values of grey matter PET metabolism were compared with DTI indices (fractional anisotropy [FA], apparent diffusion coeffici...

Anatomically constrained surface parameterization for cortical localization

by Arnaud Cachia and Olivier Coulon

Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention, 2005

We present here a method that aims at defining a surface-based coordinate system on the cortical ... more We present here a method that aims at defining a surface-based coordinate system on the cortical surface. Such a system is needed for both cortical localization and intersubject matching in the framework of neuroimaging. We propose an automatic parameterization based on the spherical topology of the grey/white matter interface of each hemisphere and on the use of naturally organized and reproducible anatomical features. From those markers used as initial constraints, the coordinate system is propagated via a PDE solved on the cortical surface.

Brain morphometry using 3D moment invariants

Medical image analysis, 2004

This paper advocates the use of shape descriptors based on moments of 3D coordinates for morphome... more This paper advocates the use of shape descriptors based on moments of 3D coordinates for morphometry of the cortical sulci. These descriptors, which have been introduced more than a decade ago, are invariant relatively to rotations, translations and scale and can be computed for any topology. A rapid insight into the derivation of these invariants is proposed first. Then, their potential to characterize shapes is shown from a principal component analysis of the 12 first invariants computed for 12 different deep brain structures manually drawn for 7 different brains. Finally, these invariants are used to find some correlates of handedness and sex among the shapes of 116 different cortical sulci automatically identified in each of 142 brains of the ICBM database.

Object-based strategy for morphometry of the cerebral cortex

Information processing in medical imaging : proceedings of the ... conference, 2003

Most of the approaches dedicated to automatic morphometry rely on a point-by-point strategy based... more Most of the approaches dedicated to automatic morphometry rely on a point-by-point strategy based on warping each brain towards a reference coordinate system. In this paper, we describe an alternative object-based strategy dedicated to the cortex. This strategy relies on an artificial neuroanatomist performing automatic recognition of the main cortical sulci and parcellation of the cortical surface into gyral patches. A set of shape descriptors, which can be compared across subjects, is then attached to the sulcus and gyrus related objects segmented by this process. The framework is used to perform a study of 142 brains of the ICBM database. This study reveals some correlates of handedness on the size of the sulci located in motor areas, which seem to be beyond the scope of the standard voxel based morphometry.

Relationship between simultaneously acquired resting-state regional cerebral glucose metabolism and functional MRI: A PET/MR hybrid scanner study

NeuroImage, 2015

Recently introduced hybrid PET/MR scanners provide the opportunity to measure simultaneously, and... more Recently introduced hybrid PET/MR scanners provide the opportunity to measure simultaneously, and in direct spatial correspondence, both metabolic demand and functional activity of the brain, hence capturing complementary information on the brain's physiological state. Here we exploited PET/MR simultaneous imaging to explore the relationship between the metabolic information provided by resting-state fluorodeoxyglucose-PET (FDG-PET) and fMRI (rs-fMRI) in neurologically healthy subjects. Regional Homogeneity (ReHo), Fractional Amplitude of Low Frequency Fluctuations (fALFF), and Degree of Centrality (DC) maps were generated from the rs-fMRI data in 23 subjects, and voxel-wise comparison to glucose uptake distribution provided by simultaneously acquired FDG-PET was performed. The mutual relationships among each couple of these four metrics were explored in terms of similarity, both of spatial distribution across the brain and the whole group, and voxel-wise across subjects, taking into account partial volume effects by adjusting for gray matter (GM) volume. Although a significant correlation between the spatial distribution of glucose uptake and rs-fMRI derived metrics was present, only a limited percentage of GM voxels correlated with PET across subjects. Moreover, the correlation between the spatial distributions of PET and RS-fMRI-derived metrics is spatially heterogeneous across both anatomic regions and functional networks, with lowest correlation strength in the limbic network (Spearman rho around -0.11 for DC), and strongest correlation for the default-mode network (up to 0.89 for ReHo and 0.86 for fALFF). Overall, ReHo and fALFF provided significantly higher correlation coefficients with PET (p=10 -8 and 10 -7 , respectively) as compared to DC, while no significant differences were present between ReHo and fALFF. Local GM volume variations introduced a limited overestimation of the rs-fMRI to FDG correlation between the modalities under investigation through partial volume effects. These novel results provide the basis for future studies of alterations of the coupling between brain metabolism and functional connectivity in pathologic conditions.

A framework to study the cortical folding patterns

NeuroImage, 2004

This paper describes a decade-long research program focused on the variability of the cortical fo... more This paper describes a decade-long research program focused on the variability of the cortical folding patterns. The program has developed a framework of using artificial neuroanatomists that are trained to identify sulci from a database. The framework relies on a renormalization of the brain warping problem, which consists in matching the cortices at the scale of the folds. Another component of the program is the search for the alphabet of the folding patterns, namely, a list of indivisible elementary sulci. The search relies on the study of the cortical folding process using antenatal imaging and on backward simulations of morphogenesis aimed at revealing traces of the embryologic dimples in the mature cortical surface. The importance of sulcalbased morphometry is illustrated by a simple study of the correlates of handedness on asymmetry indices. The study shows for instance that the central sulcus is larger in the dominant hemisphere. D

White matter diffusion abnormalities from DTI and high angular resolution diffusion imaging (HARDI) correlate with grey matter FDG-PET metabolism in epileptic children

NeuroImage, 2009

Deviations in cortex sulcation associated with visual hallucinations in schizophrenia

Molecular Psychiatry, 2014

Hallucinations, and auditory hallucinations (AH) in particular, constitute the most typical and d... more Hallucinations, and auditory hallucinations (AH) in particular, constitute the most typical and disabling schizophrenia symptoms. Although visual hallucinations (VH) have been largely neglected in psychiatric disorders, a recent review reported a 27% mean prevalence of VH in schizophrenia patients. The pathophysiology underlying VH in schizophrenia remains elusive. Several schizophrenia studies reported a significant effect of age on VH; therefore, we tested the hypothesis that the neurodevelopmental model of schizophrenia may explain VH occurrence. We analyzed cortex sulcation, a marker of brain development, in healthy controls (HCs) and two subgroups of carefully selected schizophrenia patients suffering from hallucinations: patients with only AH (that is, patients who never reported VH) and patients with audio-visual hallucinations (A+VH). Different cortical sulcation and leftright sulcal asymmetry were found between A+VH and AH patients, with decreased sulcation in both A+VH and AH patients in comparison with the HCs. Although a specific association between VH and neurodegenerative mechanisms, for example, in Body-Lewy Dementia or Parkinson's Disease, has previously been reported in the literature, the current study provides the first neuroimaging evidence of an association between VH and neurodevelopmental mechanisms.

Conclusion: Key Issues for Future Research in the Neuroscience of Hallucinations

Brain folding in schizophrenia

The making of the brain: the cortical folding process assessed by advanced MR image analysis

Pediatric brain glucose metabolism analysis using PET and SPM

by Arnaud Cachia and R. Trebossen

WHITE MATTER DIFFUSION ABNORMALITIES CORRELATE WITH GREY MATTER FDG-PET METABOLISM IN EPILEPTIC CHILDREN

SCALE RELATIONSHIP BETWEEN BRAIN VOLUME AND CORTEX AREA: AN ALLOMETRIC STUDY IN SUBJECTS AT RISK MENTAL STATE AND FIRST-EPISODE PSYCHOSIS PATIENTS