Horga Lab

Location and Contact Information

Horga Lab
1051 Riverside Drive, Suite 6100
New York State Psychiatric Institute
New York, NY 10032
United States


Principal Investigators

Our lab mainly focuses on the neurobiological and computational mechanisms of psychotic symptoms in schizophrenia and of related cognitive functions in health, including sensory and reward-based learning and decision-making. Psychosis is characterized by the experience of abnormal percepts, such as hallucinations, and delusional beliefs. While excessive dopamine transmission in the striatum is known to play a role in these symptoms, the cognitive and computational mechanisms mediating psychotic experiences remain unclear. To understand these neural mechanisms, our research uses behavioral paradigms and computational tools in combination with a variety of functional, structural and molecular in vivo neuroimaging techniques (mainly functional Magnetic Resonance Imaging [fMRI] and Positron Emission Tomography [PET]) in healthy humans and patients with psychotic disorders. We also use pharmacological manipulations to understand the relationships between neurotransmission and specific neural computations, and collaborate with other groups to collect invasive and non-invasive electrophysiological data relevant to our research focus.

Sensory learning and hallucinations

Our prior research showed that voice-sensitive regions of the auditory cortex have increased activity while patients experience auditory hallucinations of voices (Horga et al., J Neurosci 2014; Horga et al., J Psychiatry Neurosci 2011). This hallucination-related increase in neural activity was further associated with abnormal learning signals, suggesting that a learning dysfunction could lead to faulty sensory attenuation and hallucinatory percepts (Horga et al., J Neurosci 2014). We have also discovered that abnormal functional connectivity between the striatum and associative cortical regions, including parts of the auditory cortex, relate to psychosis and dopamine receptor density (Horga et al., JAMA Psychiatry 2016). Our current projects aim at elucidating the relationships between dopamine abnormalities and downstream cortical dysfunctions associated with specific symptoms of psychosis and to formalize these mechanisms in a computational model of psychosis. To this end, we are also studying perceptual disturbances in people at clinical high risk for psychosis (Lehembre-Shiah et al., JAMA Psychiatry 2016) in collaboration with Ragy Girgis, MD, and the COPE Clinic at NYSPI. In an EEG study in collaboration with Nima Mesgarani, PhD, we are also investigating the dynamics of sensory gating of irrelevant stimuli during speech processing in schizophrenia and how abnormalities in sensory gating may be relevant to psychosis.

Inference and delusional beliefs

More recently, we have been focusing on the cognitive processes related to inference and belief formation in health and illness. We have developed an incentive-compatible version of the “beads task” to evaluate specific abnormalities in probabilistic inference that may relate to the formation and maintenance of psychotic symptoms, particularly delusional beliefs. We are using a number of other well-established decision-making tasks and computational models to understand whether subjective valuation can explain some of the observed behaviors attributed to delusion-proneness.

Cognitive control, reinforcement learning, and working memory

We have also studied mechanisms related to other cognitive functions in healthy individuals, including cognitive control (Horga et al., J Neurosci 2011), reinforcement learning (Horga and Maia et al., Hum Brain Mapp 2015), and working memory (Cassidy et al., J Neurosci 2016), both in terms of the neural computations that are relevant to adaptive behaviors and the network dynamics that may support them. Building on this work, we have used and are using similar paradigms to investigate cognitive dysfunctions in a number of psychiatric populations in collaboration with other groups. We also collaborate with Sameer Sheth’s group in the Neurosurgery Department at Columbia University to use invasive intra-cranial recordings and advance our understanding of these and other cognitive functions in humans.

Biomarker development

We are also interested in developing neuroimaging biomarkers that can be used to predict clinically relevant outcomes and can be ultimately used to guide clinical decision-making (Abi-Dargham and Horga, Nat Med 2016). Among other promising neuroimaging biomarkers, we are using neuromelanin-sensitive MRI as a potential candidate to predict conversion to overt illness in at risk populations for schizophrenia and Parkinson’s disease.

Lab Members

Lab Members

  • Emeline Lagache, MD

    Postdoctoral Research Fellow

    Emeline Lagache received an engineering degree in the major Informatic and Mathematics from Ecole des Ponts ParisTech (France). She started research in computational biology in Ecole Normale Supérieure Paris with a focus on calcium signaling. She then received an MD degree from University of Rouen (France) and completed a Psychiatry residency, where she particularly focused her clinical training in treatment-resistant psychosis. Since joining Dr. Horga’s lab in 2017, she started applying computational methods (including Bayesian models) to behavior and fMRI data to study the neural basis of sensory learning in relation to psychotic symptoms.

  • Brandon K. Ashinoff, PhD

    Postdoctoral Research Fellow

    Brandon is a Postdoctoral Research Fellow in the Horga Lab. He received his PhD from the School of Psychology at the University of Birmingham, UK, where his research focused on the behavioral and neural mechanisms underlying proactive and reactive distractor inhibition in healthy aging. He has also published papers investigating how video games affect the brain and cognition, as well as their effectiveness as a pedagogical tool. In Dr. Horga’s lab, Brandon’s research will be focused on identifying the neurocognitive mechanisms underlying belief updating, and their role in the development and maintenance of delusions and hallucinations in schizophrenia. The ultimate goal will be to use this research as a foundation for the development of novel non-pharmacological treatments which may be able to provide relief for patients who are treatment refractory with respect to antipsychotic medications.

  • Najate Ojeil, MS, MA, LMHC

    Chief of Assessments and Evaluations

    Najate Ojeil, MS, MA, LMHC, directs clinical assessments and evaluations at the Horga lab and is a senior research scientist at the Center for Practice Innovations. She is also a consultant for Stony Brook University and Intra Cellular Therapy, and serves as the director of the Mental Health Counseling Service Westchester, PLLC. She is an expert in diagnostic evaluations, clinical and neuropsychological assessments, as well as in cognitive behavioral therapy. She provides training and supervision to research coordinators and oversees quality control of clinical evaluations.

  • Nicholas Singletary, BS, MA

    PhD Student

    Nicholas Singletary is a Ph.D. candidate at Columbia in Neurobiology and Behavior. He graduated from Emory University with a B.S. in Neuroscience and Behavioral Biology, where he completed an honors thesis with Dr. Todd Preuss comparing the structural connectivity of human and nonhuman primate dorsomedial prefrontal cortex. He is broadly interested in cognitive neuroscience, and he has collaborated on psychophysics and decision-making studies with Dr. Ennio Mingolla at Northeastern University and Dr. Michael Shadlen at Columbia. Under co-mentorship by Drs. Horga and Jacqueline Gottlieb, his current research focuses on behavioral and neural correlates of belief updating and information sampling, both of which are crucial to real-world decision making.

  • Sylvie Messer, BA

    Research Assistant

    • 646-774-8137

    Sylvie Messer is a research assistant in the Horga Lab. She graduated from Hunter College, CUNY with a Bachelor’s Degree in Psychology. She worked as an undergraduate research assistant in Dr. Joel Erblich’s lab at Hunter College studying alcohol and nicotine from a biopsychosocial perspective. She joined the Horga Lab in February of 2018.  Sylvie helps carry out MRI/fMRI scans under various studies in the lab researching psychosis and schizophrenia. She is also responsible for recruitment and coordination in the lab. She plans to pursue a PhD in Clinical Psychology. 

  • Naomi Hollard

    Undergraduate Student

    Naomi is an undergraduate student at Columbia University majoring in Neuroscience and Behavior. Previously, Naomi worked in Dr. Kate O'Connor-Giles lab at the University of Wisconsin-Madison where Naomi studied the genes involved in neuronal function. In the fall of 2017, Naomi started volunteering in the Horga lab. In her first couple months, she worked on image preprocessing for the Horga Lab. Under the supervision of Dr. Horga and in collaboration with Dr. Ragy Girgis and the COPE clinic, Naomi is leading a project to better understand the circuitry associated with perceptual distortions in patients who are at a clinical high risk of developing schizophrenia. Naomi plans to pursue a PhD in neuroscience.

  • Vanessa Rhee

    Undergraduate Student

    Vanessa is an undergraduate student at Columbia University, majoring in psychology with premedical studies. Since the Fall of 2017, she has volunteered in the Horga lab, working on a project focused on interval timing in healthy individuals and psychotic patients.

  • Quincy Harrison

    Undergraduate Student

    Quincy is an undergraduate student at Columbia University, majoring in biology with premedical studies. He has an interest in the Dopamine Hypothesis of Schizophrenia and the use of neuromelanin as a valid Dopamine biomarker. Quincy works on recruitment and coordination efforts, as well as the beads study in the Horga Lab. Quincy will apply to medical school in the spring of 2018 and pursue a career in psychiatry.

  • Julianne Cary

    Volunteer Graduate Student

    Julianne is a volunteer in the Horga Lab. She is currently a graduate student in the clinical psychology master’s program at Columbia University's Teacher's College. She graduated from SUNY Oswego with a bachelor's degree in psychology. At SUNY Oswego, Julianne worked with Dr. Emily Bovier in the Sensory Behavior Lab. Her independent research, which was funded by a Psi Chi grant for undergraduate students, researching atypical behavior in relation to sub-clinical schizophrenia symptoms and olfaction deficits. Julianne works on recruitment efforts and clinical assessments in the Horga Lab.  She plans to pursue a PhD in Clinical Psychology.

  • Arianna Noya

    Undergraduate Student

    Arianna Noya is a senior at Barnard College of Columbia University majoring in Neuroscience and Behavior with a behavioral concentration. She is working on her Senior Thesis, which will be focused on healthy patients experiencing delusion-like symptoms who have not been diagnosed with Schizophrenia, but may be at risk for developing the disorder. Her research will be done using a modified version of the bead task to assess the patient's mechanisms of belief updating.  Arianna's plan after graduation is to pursue a Master's in Public Health. 


Previous Lab Members

  • Clifford Cassidy, PhD

    Former Postdoctoral Fellow

  • Seth Baker, BA, MS

    Former Research Assistant

  • Kathleen Fan, MSc

    Former Research Assistant

  • Nina Diamond, BA

    Former Undergraduate Volunteer

Select Publications

  • Selected publications in reverse chronological order (*corresponding author). Read a full list of publications.

  • Sulzer D, Cassidy C, Horga G, Kang UJ, Fahn S, Casella L, Pezzoli G, Langley J, Hu XP, Zucca FA, Isaias IU, Zecca L. “Neuromelanin detection by magnetic resonance imaging (MRI) and its promise as a biomarker for Parkinson's disease.” NPJ Parkinsons Dis. 2018 Apr 10. Download Publication (PDF).

  • Cassidy CM, Balsam PD, Weinstein JJ, Rosengard RJ, Slifstein M, Daw ND, Abi-Dargham A, Horga G. “A Perceptual Inference Mechanism for Hallucinations Linked to Striatal Dopamine.” Curr Biol. 2018 Feb 19. Download Publication (PDF)

  • Lehembre-Shiah E, Leong W, Brucato G, Abi-Dargham A, Lieberman JA, Horga G*, Girgis RR*. Distinct Relationships Between Visual and Auditory Perceptual Abnormalities and Conversion to Psychosis in a Clinical High-Risk Population. JAMA Psychiatry. 2016 Nov 16. Download Publication (PDF)

  • Abi-Dargham A, Horga G. The search for imaging biomarkers in psychiatric disorders. Nat Med. 2016 Nov;22(11):1248-1255. Download Publication (PDF)

  • Alderson-Day B, Diederen K, Fernyhough C, Ford JM, Horga G, Margulies DS, McCarthy-Jones S, Northoff G, Shine JM, Turner J, van de Ven V, van Lutterveld R, Waters F, Jardri R. Auditory Hallucinations and the Brain's Resting-State Networks: Findings and Methodological Observations. Schizophr Bull. 2016 Sep;42(5):1110-23. Download Publication (PDF)

  • Horga G*, Cassidy CM, Xu X, Moore H, Slifstein M, Van Snellenberg JX, Abi-Dargham A. “Dopamine-related disruption of functional topography of striatal connections in unmedicated patients with schizophrenia,” JAMA Psychiatry. 2016 Aug 1;73(8):862-70. Download Publication (PDF)

  • Reinen JM, Van Snellenberg JX, Horga G, Abi-Dargham A, Daw ND, Shohamy D. Motivational Context Modulates Prediction Error Response in Schizophrenia. Schizophr Bull. 2016 Nov;42(6):1467-1475. Download Publication (PDF)

  • Cassidy CM, Van Snellenberg JX, Benavides C, Slifstein M, Wang Z, Moore H, Abi-Dargham A, Horga G*. "Dynamic connectivity between brain networks supports working memory: relationships to dopamine release and schizophrenia," J Neurosci. 2016 Apr 13;36(15):4377-88. Download Publication (PDF)

  • Van Snellenberg JX, Girgis RR, Horga G, van de Giessen E, Sliftein M, Ojeil N, Weinstein JJ, Moore H, Lieberman JA, Shohamy D, Smith EE, Abi-Dargham A. “Mechanisms of working memory impairment in schizophrenia,” Biol Psychiatry. 2016 Oct 15;80(8):617-26. Download Publication (PDF)

  • Colibazzi T, Horga G, Wang Z, Huo Y, Corcoran C, Klahr K, Brucato G, Girgis R, Gill K, Abi-Dargham A, Peterson BS. “Neural Dysfunction in Cognitive Control Circuits in Persons at Clinical High-Risk for Psychosis,” Neuropsychopharmacology. 2016 Apr;41(5):1241-50. Download Publication (PDF)

  • Horga G, Maia TV, Marsh R, Hao X, Xu D, Duan Y, Tau GZ, Graniello B, Wang Z, Kangarlu A, Martinez D, Packard MG, Peterson BS. “Changes in Corticostriatal Connectivity During Reinforcement Learning in Humans,” Hum Brain Mapp. 2015 Feb;36(2):793-803. Download Publication (PDF)

  • Horga G*, Schatz KC, Abi-Dagham A, Peterson BS. “Deficits in Predictive Coding Underlie Hallucinations in Schizophrenia,” J Neurosci. 2014 Jun 11;34(24):8072-82. Download Publication (PDF)

  • Horga G, Abi-Dargham A. “The Striatum and Dopamine: A Crossroad of Risk for Schizophrenia,” JAMA Psychiatry. 2014 May 12. Download Publication (PDF)

  • Horga G*, Fernandez-Egea E, Mane A, Font M, Schatz KC, Falcon C, Lomena F, Bernardo M, Parellada E. “Brain metabolism during hallucination-like auditory stimulation in schizophrenia,” PLoS One. 2014 Jan 8;9(1): e84987. Download Publication (PDF)

  • Peterson BS, Wang Z, Horga G, Warner V, Liu J, Graniello G, Rutherford B, Gerber A, Wickramaratne P, Garcia F, Wang P, Yu S, Hao X, Adams PB, Klahr KW, Qian M, Weissman MM. “Brain Activations Discriminate Risk and Resilience Endophenotypes From Markers of Lifetime Illness in Familial Major Depressive Disorder,” JAMA Psychiatry. 2014 Feb;71(2):136-48. Download Publication (PDF)

  • Marsh R, Horga G, Parashar N, Wang Z, Peterson BS, Simpson HB. “Altered Activation in Fronto-Striatal Circuits During Sequential Processing of Conflict in Unmedicated Adults with Obsessive-Compulsive Disorder,” Biol Psychiatry. 2013 Apr 15;75(8):615-22. Download Publication (PDF)

  • Horga G, Maia TV, Wang P, Wang Z, Marsh R, Peterson BS. “Adaptation to conflict via context-driven anticipatory signals in the dorsomedial prefrontal cortex,” J Neurosci. 2011 Nov 9;31(45):16208-16. Download Publication (PDF)

  • Horga G, Maia TV. Conscious and unconscious processes in cognitive control: a theoretical perspective and a novel empirical approach. Front Hum Neurosci. 2012 Jul 4;6:199. Download Publication (PDF)

  • Marsh R, Horga G, Wang Z, Wang PW, Klahr KW, Berner LA, Walsh BT, Peterson BS. “An fMRI study of self-regulatory control and conflict resolution in adolescents with Bulimia Nervosa,” Am J Psychiatry. 2011 Nov;168(11):1210-20. Download Publication (PDF)

  • Horga G, Bernacer J, Dusi N, Entis JJ, Kingwai Chu, Hazlett EA, Haznedar MM, Kemether E, Byne W, Buchsbaum MS. “Correlations between ventricular enlargement and gray and white matter volumes of cortex, thalamus, striatum and internal capsule in schizophrenia,” Eur Arch Psychiatry Clin Neurosci. 2011 Mar 24. Download Publication (PDF)

  • Horga G, Parellada E, Lomena F, Fernandez-Egea E, Mane A, Font M, Falcon C, Konova A, Pavia J, Ros D, Bernardo M. “Differential brain glucose metabolic patterns in antipsychotic-naive first episode schizophrenia with and without auditory verbal hallucinations,” J Psychiatry Neurosci. 2011 Jan 1;36(1):100085. Download Publication (PDF)