title: Machine learning fMRI classifier delineates subgroups of schizophrenia patients.
abstract: BACKGROUND
  The search for a validated neuroimaging-based brain marker in psychiatry has thus far been fraught with both clinical and methodological difficulties. The present study aimed to apply a novel data-driven machine-learning approach to functional Magnetic Resonance Imaging (fMRI) data obtained during a cognitive task in order to delineate the neural mechanisms involved in two schizophrenia subgroups: schizophrenia patients with and without Obsessive-Compulsive Disorder (OCD).
  
  
  METHODS
  16 schizophrenia patients with OCD ("schizo-obsessive"), 17 pure schizophrenia patients, and 20 healthy controls underwent fMRI while performing a working memory task. A whole brain search for activation clusters of cognitive load was performed using a recently developed data-driven multi-voxel pattern analysis (MVPA) approach, termed Searchlight Based Feature Extraction (SBFE), and which yields a robust fMRI-based classifier.
  
  
  RESULTS
  The SBFE successfully classified the two schizophrenia groups with 91% accuracy based on activations in the right intraparietal sulcus (r-IPS), which further correlated with reduced symptom severity among schizo-obsessive patients.
  
  
  CONCLUSIONS
  The results indicate that this novel SBFE approach can successfully delineate between symptom dimensions in the context of complex psychiatric morbidity.
authors.affiliation: Functional Brain Center, Wohl Institute for Advanced Imaging, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. Electronic address: maya44@gmail.com.
authors.forename: Maya
authors.initials: M
authors.lastname: Bleich-Cohen
authors.affiliation: The Blavatnik School of Computer Science, Tel Aviv University, Israel.
authors.forename: Shahar
authors.initials: S
authors.lastname: Jamshy
authors.affiliation: Functional Brain Center, Wohl Institute for Advanced Imaging, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Haggai
authors.initials: H
authors.lastname: Sharon
authors.affiliation: Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel; Ambulatory Division, Mental Health Department, Ramat-Hen, Israel.
authors.forename: Ronit
authors.initials: R
authors.lastname: Weizman
authors.affiliation: The Blavatnik School of Computer Science, Tel Aviv University, Israel.
authors.forename: Nathan
authors.initials: N
authors.lastname: Intrator
authors.affiliation: Research Unit, Tirat Carmel Mental Health Center, Tirat Carmel, Haifa, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Poyurovsky
authors.affiliation: Functional Brain Center, Wohl Institute for Advanced Imaging, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel; Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Talma
authors.initials: T
authors.lastname: Hendler
mesh_terms: D000328:Adult; D001185:Artificial Intelligence; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology; D009483:Neuropsychological Tests; D009771:Obsessive-Compulsive Disorder / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D012559:Schizophrenia / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D055815:Young Adult
keywords: MVPA; OCD; Schizo-obsessive; Searchlight; n-back; r-IPS