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

  • 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.

     

    See CV here

  • Kenneth Wengler, PhD

    Postdoctoral Research Fellow

    Kenneth Wengler is a Postdoctoral Research Fellow in the Horga Lab. He received his BS in Physics from St. John’s University and PhD in Biomedical Engineering from Stony Brook University where his research focused on the development of novel MRI sequences and analysis methods to study diffusion, perfusion, and exchange. His work at Stony Brook University also included the application of MRS, ASL, and neuromelanin-sensitive MRI to study psychiatric disorders. Kenneth joined Dr. Horga’s lab in 2019, where his research is focused on the development of neuromelanin-sensitive MRI as a biomarker for predicting conversion to overt illness in at risk populations for schizophrenia. His interests also include the application of computational methods to behavior and fMRI data to study the cognitive neuroscience mechanisms of delusions and hallucinations, and the use of PET and MRI to investigate the associated biological mechanisms that are involved.

     

    See CV here

  • Andra Mihali, PhD

    Postdoctoral Research Fellow

    Andra Mihali is a Postdoctoral Research Fellow in the Horga Lab. She received her BA in Biochemistry from Columbia University and her PhD in Neural Science from NYU, mentored by prof. Wei Ji Ma.  She worked on developing tasks aimed to quantify and understand differences in the precisions of visual representations and perceptual decisions, in neurotypicals as well as observers with ADHD. To this end, she used psychophysics, eye tracking and computational modeling.  In April 2019, she joined Dr. Horga's lab, with the aim of combining these methods with neural measures of dopamine function to better understand psychosis and inform individualized treatment.  Her project focuses on developing psychophysical markers to quantify perceptual distortions and understand how people make use of and update beliefs about the reliability of their sensory information.

     

    See CV Here

  • 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.

     

    See CV here

  • 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.

     

    See CV here

  • Sylvie Messer, BA

    Research Assistant, PhD Student

    Sylvie Messer has been a research assistant in the Horga Lab since February of 2018. She graduated from Hunter College, CUNY with a Bachelor’s Degree in Psychology and worked as a research assistant in Dr. Joel Erblich’s alcohol and nicotine lab there. In the Horga Lab, Sylvie helps carry out MRI/fMRI scans under various studies investigating delusions and hallucinations in patients with schizophrenia. She is a Clinical Health Psychology Ph.D. student at Ferkauf Graduate School of Psychology at Yeshiva University.  She is carrying out her research project in the Horga Lab under the supervision of Drs. Andrea Weinberger and Guillermo Horga. Sylvie will be investigating smoking behavior in patients with schizophrenia and those at clinical high-risk for developing schizophrenia using a Bayesian paradigm. 

    See CV here

  • Garrett Salzman, BA

    Research Assistant

    Garrett Salzman joined the Horga Lab in June of 2019 as a research assistant. She graduated from Macalester College in 2019 with a BA in Neuroscience. While at Macalester, she worked in an eye-tracking lab focusing on psycholinguistic research. She also volunteered in a lab at the University of Minnesota studying non-suicidal self-injury in adolescent girls. In the Horga Lab, Garrett is responsible for recruiting and coordinating research participants. She also carries out imaging procedures and other behavioral tasks. She is considering pursuing a PhD in Neuroscience.

     

    See CV here

  • 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.

     

    See CV here

Collaborators

Previous Lab Members

  • Emeline Lagache, MD

    Postdoctoral Research Fellow

  • 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

  • Vanessa Rhee, BS

    Former Undergraduate Volunteer

  • Quincy Harrison, BS

    Former Undergraduate Student

  • Naomi Hollard, BA

    Former Undergraduate Student

  • Arianna Noya, BA

    Former Undergraduate Student

Select Publications

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

  • Seth C. Baker, Anna B. Konova, Nathaniel D. Daw and Guillermo Horga. "A distinct inferential mechanism for delusions in schizophrenia," Brain: A Journal of Neurology. 2019 Jan 16: 142; 1797-1812. Download Publication (PDF)

  • Clifford M. Cassidy, Fabio A. Zucca, Ragy R. Girgis, Seth C. Baker, Jodi J. Weinstein, Madeleine E. Sharp, Chiara Bellei, Alice Valmadre, Nora Vanegas, Lawrence S. Kegeles, Gary Brucato, Un Jung Kang, David Sulzer, Luigi Zecca, Anissa Abi-Dargham, and Guillermo Horga. "Neuromelanin-sensitive MRI as a noninvasive proxy measure of dopamine function in the human brain," PNAS. March 12, 2019 116 (11) 5108-5117. Download Publication (PDF)

  • 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)