Amir Shmuel, PhD
Professor
Amir Shmuel鈥檚 research focuses on two goals. One goal is to understand the neuronal mechanisms that underlie functional brain imaging signals and to evaluate the degree to which these signals reflect the locally measured neuronal activity. The second goal is to elucidate the principles and processes used by the cerebral cortex to analyze visual information and to create coherent visual perception. Employing an integrative approach, Shmuel鈥檚 laboratory uses a combination of imaging and electrical recording techniques: functional Magnetic Resonance Imaging (fMRI), optical imaging using intrinsic signals and voltage-sensitive dyes, multi-channel neurophysiological recordings, and neurophysiology simultaneously with fMRI. Together, these techniques encompass multiple levels of spatial and temporal resolution. Brain activity signals obtained by large-scale non-invasive imaging methods are compared to the activity of ensembles of neurons imaged optically, as well as to electrically recorded activity obtained from groups of neurons and single neurons.
Neuroimaging and Neuroinformatics
Chaimow D, Yacoub E, U臒urbil K, Shmuel A (2017) Spatial specificity of the functional MRI blood oxygenation response relative to neuronal activity. NeuroImage, accepted. ISSN 1053-8119,聽.
Chaimow D, U臒urbil K, Shmuel A (2017) Optimization of functional MRI for detection, decoding and high-resolution imaging of the response patterns of cortical columns. NeuroImage, accepted. doi: 10.1016/j.neuroimage.2017.04.011.
Kropf P, Shmuel A (2016) 1-D current-source density (CSD) estimation in inverse theory: a unified framework for higher-order spectral regularization of quadrature and expansion type CSD methods. Neural Computation, 28:1305-1355.
Dawson D, Lewis LB, Carbonell F, Mendola JD, Shmuel A (2016) Partial-correlation based retinotopically organized resting-state functional connectivity within and between areas of the visual cortex reflects more than cortical distance. Brain Connectivity, 6(1):57-75. doi: 10.1089/brain.2014.0331.
Sotero RC, Bortel A, Na鈥檃man S, Mocanu MV, Kropf P, Villeneuve M, Shmuel A (2015) Laminar distribution of phase-amplitude coupling of spontaneous current sources and sinks. Front. Neurosci. 9:454. doi: 10.3389/fnins.2015.00454.
Buxton RB, Griffeth VE, Simon AB, Moradi F, Shmuel A (2014) Variability of the coupling of blood flow and oxygen metabolism responses in the brain: a problem for interpreting BOLD studies but potentially a new window on the underlying neural activity. Front Neurosci., 8:139. Corrigendum DOI: 10.3389/fnins.2014.00241.
Carbonell F, Bellec P, Shmuel A (2014) Quantification of the impact of a confounding variable on functional connectivity confirms anti-correlated networks in the resting-state. Neuroimage, 86:343-53.
Dawson D, Cha K, Lewis LB, Mendola JD, Shmuel A (2013) Evaluation and calibration of functional network modeling methods based on known anatomical connections. Neuroimage, 67: 331鈥�343.
Carbonell F, Bellec P, Shmuel A (2012) Global and system-specific resting-state BOLD fluctuations are uncorrelated: principal component analysis reveals anti-correlated networks. Brain Connectivity, 1 (6): 496-510. 10.
Chaimow D, Yacoub E, Ugurbil K, Shmuel A (2011) Modeling and analysis of mechanisms underlying fMRI-based decoding of information conveyed in cortical columns. Neuroimage, 56 (2): 627-642.
Sotero RC, Bortel A, Mart铆nez-Cancino R, Neupane S, O鈥機onnor P, Carbonell F, Shmuel A (2010) Anatomically-constrained effective connectivity among layers in a cortical column modeled and estimated from local field potentials. Journal of Integrative Neuroscience, 9: 355鈥�379. 12.
Shmuel A, Chaimow D, Raddatz G, Ugurbil K, Yacoub E (2010) Mechanisms underlying decoding at 7 T: Ocular dominance columns, broad structures, and macroscopic blood vessels in V1 convey information on the stimulated eye. Neuroimage, 49:1957鈥�1964.
Shmuel A, Leopold DA (2008) Neuronal correlates of spontaneous fluctuations in fMRI signals in monkey visual cortex: implications for functional connectivity at rest. Human Brain Mapping, 29:751-761.
Keliris G*, Shmuel A* (* co-first authors), Ku SP, Pfeuffer J, Oeltermann A, Steudel T, Ku SP, Logothetis NK (2007), Robust controlled functional MRI in alert monkeys at high magnetic field: effects of jaw and body movements. NeuroImage, 36(3):550-570.
Yacoub E*, Shmuel A* (* co-first authors), Logothetis NK, Ugurbil K (2007), Robust detection of ocular dominance columns in humans using Hahn spin echo BOLD functional MRI at high field. NeuroImage, 37(4):1161鈥�1177.
Shmuel A, Yacoub E, Chaimow D, Logothetis NK, Ugurbil K (2007), Spatio-temporal point-spread function of fMRI signal in human gray matter at 7 Tesla. NeuroImage, 35(2):539-552.
Shmuel A, Augath M, Oeltermann A, Logothetis NK (2006) Negative functional MRI response correlates with decreases in neuronal activity in monkey visual area V1. Nature Neuroscience, 9(4):569-577.
Shmuel A, Korman M, Melnik A, Harel M, Ullman S, Malach R, Grinvald A (2005) Retinotopic axis specificity and selective clustering of feedback projections from V2 to V1 in the owl monkey. The Journal of Neuroscience, 25(8):2117-31.
Swindale NV, Grinvald A, Shmuel A (2003) The spatial pattern of response magnitude and selectivity for orientation and direction in cat visual cortex. Cerebral Cortex, 13(3):225-238.
Shmuel A, Yacoub E, Pfeuffer J, Van De Moortele PF, Adriany G, Hu X, Ugurbil K (2002) Sustained negative BOLD, blood flow and oxygen consumption response and its coupling to the positive response in the human brain. Neuron, 36(6):1195-1210.
Shmuel A, Grinvald A (2000) Coexistence of linear zones and pinwheels within orientation maps in cat visual cortex. Proceedings of the National Academy of Sciences USA 97(10):5568- 5573.
Shmuel A, Grinvald A (1996) Functional organization for direction of motion and its relationship to orientation maps in cat area 18. The Journal of Neuroscience, 16(21):6945-6964, and cover illustration.