Barry Horwitz, Ph.D.
Chief Section on Brain Imaging and Modeling Voice, Speech, and Language Branch
NIDCD/NIH Bldg. 10, Rm. 8S235 MSC 1407 9000 Rockville Pike Bethesda, MD 20892 Phone: (301) 594–7755 Fax: (301) 480–5625 E-mail: horwitz@helix.nih.gov
Ph.D., University of Pennsylvania, 1972
Research Statement
The major research focus of the Brain Imaging and Modeling Section concerns ascertaining how interacting brain regions (i.e., neural networks) implement specific cognitive tasks, especially those associated with audition and language. We also study how these networks are altered in brain disorders. These issues are addressed by combining computational neuroscience techniques with neuroscientific data, especially those acquired using functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). The network analysis methods allow us to evaluate how brain operations differ between tasks, and between normal and patient populations, thus permitting us to determine which networks are dysfunctional and the role neural plasticity plays in enabling compensatory behavior to occur. Central to this research is the use of large-scale biologically realistic network models that relate neuroanatomical and neurophysiological data to the signals measured by functional brain imaging. Not only does computational modeling help interpret the meaning of functional brain imaging data, it also provides a framework to generate and quantitatively test hypotheses concerning the mechanisms by which specific cognitive tasks are implemented in the brain.
Research in our section is divided into three main interconnected areas: (1) designing and executing neuroscientific experiments - primarily functional brain imaging studies; (2) network analysis of functional and effective connectivity between important brain regions based on these data; and (3) development and implementation of large-scale neural models aimed at determining how the functional brain imaging signals from some of these experiments are related to the underlying cellular neural activity. In particular, these approaches are applied to high-level auditory and language function. Because many of the analytic and computational methods used were originated by us, ongoing methodological development of these approaches also continues as a major activity.
Recent Accomplishments
We have focused on using multisensory stimuli with fMRI to elucidate cognitive function relating to language processing, including such activities as naming, categorization and recognition of speech and non-speech stimuli. For example we examined the effects of training subjects on perceiving pairs of sensory stimuli using delayed-match-to-sample (DMS) tasks. The DMS task involves the presentation of a stimulus, a delay, and the presentation of a second stimulus; the subject responds as to whether the second stimulus matches the first. There exists much data (functional, neuroanatomical, electrophysiological and cognitive) from humans and primates about this type of task. We have implemented computational neural models for both visual (Tagamets and Horwitz, 1998; Horwitz and Tagamets, 1999) and auditory (Husain et al., 2004) DMS tasks that generate simulated neural data and simulated functional neuroimaging data that agree with experimental findings. Recently, we have used MEG to study modulation of auditory cortex during the DMS task, and we are now incorporating the simulation of MEG data into our large-scale modeling framework.
Remembering associations between names and objects is fundamental to language. In one recent study, we taught subjects to associate pairs of auditory and visual stimuli, and then investigated long-term memory storage. We examined the effect of retention interval (immediate vs. one month) and language on the neural correlates of auditory–visual memory storage using fMRI and a paired associates (PA) task.
We are also interested in studying auditory disorders and their impact on language understanding using fMRI. For these studies we examine the performance of subjects with hearing impairment and related squeal to gain a better understanding of their impact on the network of brain regions that process and construct auditory percepts. For example, one recent study compared patients with hearing loss with tinnitus and without tinnitus.
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Lab Personnel
Yvonne Bennett, Ph.D., Research Fellow, 301-594-7758 (Send e-mail) Jieun Kim, Ph.D., Visiting Fellow, 301-594-7757 (Send e-mail) Feng Rong, Ph.D., Visiting Fellow, 301-435-5141 (Send e-mail) Jason F. Smith, Ph.D., Postdoctoral Fellow, 301-451-1647 (Send e-mail) Fatima Husain, Ph.D., Ph.D. Special Volunteer, 217-333-7561 (Send e-mail)
Selected Publications
- Horwitz B. Relating fMRI and PET signals to neural activity by means of large-scale neural models. Neuroinformatics 2(2):251–66, 2004.
- Marrelec, G., Kim, J., Doyon, J., Horwitz, B. Large scale neural model validation of partial correlation analysis for effective connectivity investigation in functional MRI. Human Brain Mapp. (in press).
- Wen, S., Ulloa, A., Husain, F., Horwitz, B., Contreras-Vidal, J.L. Simulated neural dynamics of decision-making in an auditory delayed match-to-sample task. Biol. Cybernetics 99: 15-27, 2008.
- Stephan, K.E., Riera, J. J., Deco, G., Horwitz, B. The Brain Connectivity Workshops: Moving the frontiers of computational systems neuroscience. Neuroimage 42: 1-9, 2008.
- Kim, J., Horwitz, B.: Investigating the neural basis of fMRI-based functional connectivity in a blocked design: Application to interregional correlations and psych-physiological interactions. Magnetic Resonance Imaging 26: 583-593, 2008.
- Horwitz, B., Wise, R.J.S.: PET research of language, in Handbook of the Neuroscience of Language, ed. by B. Stemmer and H. A. Whitaker, Academic Press, pp. 71-80, 2008.
- Horwitz, B., Smith, J.F. A link between neuroscience and informatics: Large-scale modeling of memory processes. Methods 44: 338-347, 2008.
- Horwitz, B., Husain, F.T.: Simulation frameworks for large-scale brain systems, In Handbook of Brain Connectivity, ed. by V.K. Jirsa and A.R. McIntosh, Springer-Verlag, pp. 275-302, 2007.
- Marrelec, G., Horwitz, B., Kim, J., Pelegrini-Issac, M., Benali, H., Doyon, J. Using partial correlation to enhance structural equation modeling of functional MRI data. Magnetic Resonance Imaging 25: 1181-1189, 2007.
- Husain, F.T., Horwitz, B. Experimental-neuromodeling framework for understanding auditory object processing: Integrating data across multiple scales. J. Physiology-Paris 100: 133-141, 2006.
- Husain, F.T., McKinney, C.M., Horwitz, B. Frontal cortex connectivity changes during sound categorization. Neuroreport 17: 617-621, 2006.
- Husain, F.T., Fromm, S.J., Pursley, R.H., Hosey, L.A., Braun, A.R., Horwitz, B. Neural bases of categorization of simple speech and nonspeech sounds. Human Brain Mapp. 27: 636-651, 2006.
- Lee, L., Friston, K.J., Horwitz, B. Large-scale neural models and Dynamic Causal Modelling. NeuroImage 30: 1243-1254, 2006.
Mottaghy, F.M., Willmes, K., Horwitz, B., Mueller, H.-W., Krause, B.J., Sturm, W. Systems level modeling of a neuronal network subserving intrinsic alertness. Neuroimage 29: 225-233, 2006.
- Horwitz, B., Glabus, M. Neural modeling and functional brain imaging: The interplay between data-fitting and simulation approachesInt. Rev. Neurobiol. 66: 267-290, 2005.
- Luo, H., Husain, F.T., Horwitz, B., Poeppel, D. Discrimination and categorization of speech and non-speech sounds in an MEG delayed-match-to-sample study. NeuroImage 28: 59-71, 2005.
- Husain, F.T., Lozito, T., Ulloa, A., Horwitz, B. Investigating the neural basis of the auditory continuity illusion. J. Cogn. Neurosci. 17: 1275-1292, 2005.
- Horwitz, B., Warner, B., Fitzer, J., Tagamets, M.-A., Husain, F.T., Long, T.W. Investigating the neural basis for functional and effective connectivity: Application to fMRI. Phil. Trans. Roy. Soc. Lond. B 360: 1093-1108, 2005.
- Horwitz, B. Integrating neuroscientific data across spatiotemporal scales. Comptes rendus Biologies 328: 109-118, 2005.
- Horwitz B. Relating fMRI and PET signals to neural activity by means of large-scale neural models. Neuroinformatics 2(2):251–66, 2004.
- Deco G, Rolls ET, Horwitz B. "What" and "where" in visual working memory: a computational neurodynamical perspective for integrating FMRI and single-neuron data. Journal of Cognitive Neuroscience 16(4):683–701, 2004.
- Ibanez V, Pietrini P, Furey ML, Alexander GE, Millet P, Bokde AL, Teichberg D, Schapiro MB, Horwitz B, Rapoport SI. Resting state brain glucose metabolism is not reduced in normotensive healthy men during aging, after correction for brain atrophy. Brain Research Bulletin 63(2):147–54, 2004.
- Horwitz B, Braun AR. Brain network interactions in auditory, visual and linguistic processing. Brain and Language 89(2):377–84, 2004.
- Husain FT, Tagamets MA, Fromm SJ, Braun AR, Horwitz B. Relating neuronal dynamics for auditory object processing to neuroimaging activity: a computational modeling and an fMRI study. Neuroimage 21(4):1701–20, 2004.
- Glabus MF, Horwitz B, Holt JL, Kohn PD, Gerton BK, Callicott JH, Meyer-Lindenberg A, Berman KF. Interindividual differences in functional interactions among prefrontal, parietal and parahippocampal regions during working memory. Cerebral Cortex 13(12):1352–61, 2003.
- Teipel SJ, Schapiro MB, Alexander GE, Krasuski JS, Horwitz B, Hoehne C, Moller HJ, Rapoport SI, Hampel H. Relation of corpus callosum and hippocampal size to age in nondemented adults with Down's syndrome. The American Journal of Psychiatry 160(10):1870–8, 2003.
- Horwitz B. The elusive concept of brain connectivity. Neuroimage 19(2 Pt 1):466–70, 2003.
- Horwitz B, Amunts K, Bhattacharyya R, Patkin D, Jeffries K, Zilles K, Braun AR. Activation of Broca's area during the production of spoken and signed language: a combined cytoarchitectonic mapping and PET analysis. Neuropsychologia 41(14):1868–76, 2003.
- Sevostianov A, Fromm S, Nechaev V, Horwitz B, Braun A. Effect of attention on central auditory processing: an fMRI study. the International Journal of Neuroscience 112(5):587–606, 2002.
- Sevostianov A, Horwitz B, Nechaev V, Williams R, Fromm S, Braun AR. fMRI study comparing names versus pictures of objects. Human0 Brain Mapping 16(3):168–75, 2002.
- Horwitz B, Poeppel D. How can EEG/MEG and fMRI/PET data be combined? Human Brain Mapping 17:1–3, 2002.
- Husain FT, Nandipati G, Braun AR, Cohen LG, Tagamets MA, Horwitz B. Simulating transcranial magnetic stimulation during PET with a large-scale neural network model of the prefrontal cortex and the visual system. Neuroimage 5:58–73, 2002.
- Bokde AL, Tagamets MA, Friedman RB, Horwitz B. Functional interactions of the inferior frontal cortex during the processing of words and word-like stimuli. Neuron 30:609–617, 2001.
- Tagamets MA, Horwitz B. Interpreting PET and fMRI measures of functional neural activity: the effects of synaptic inhibition on cortical activation in human imaging studies. Brain Research Bulletin 54:267–273, 2001.
- Horwitz B, Friston KJ, Taylor JG. Neural modeling and functional brain imaging: an overview. Neural Networks 13:829–846, 2000.
- Tagamets MA, Horwitz B. A model of working memory: bridging the gap between electrophysiology and human brain imaging. Neural Networks 13:941–952, 2000.
- Horwitz B, Tagamets MA. Predicting human functional maps with neural net modeling. Human Brain Mapping 8:137–142, 1999.
- Horwitz B, Tagamets MA, McIntosh AR. Neural modeling, functional brain imaging, and cognition. Trends in Cognitive Science 3:91–98, 1999.
- Tagamets MA, Horwitz B. Integrating electrophysiological and anatomical experimental data to create a large-scale model that simulates a delayed match-to-sample human brain imaging study. Cerebral Cortex 8:310–320, 1998.
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