Post-doctoral Fellows
Post-doctoral Fellows
Opher joined the lab in 2000, after completing a PhD in Computational Neuroscience from Hebrew University, and a BS in Mathematics from MIT. He won a Whitaker Distinguished Postdoctoral Fellowship from the Biomedical Engineering program at Johns Hopkins.
He was central to extending the state-space approach to quantify generalization patterns in motor learning. He demonstrated that adaptation was not a process of disturbance rejection, but a process of optimization.
He generously gave his time to help the research of many students, including Maurice Smith, Sarah Hemminger and EunJung Hwang. He subsequently became Assistant Professor of BME at Ben Gurion University, Israel, and then Professor and Chair of the BME Dept. at Ben Gurion University.
Acquisition of internal models of motor tasks in children with autism. JC Gidley-Larson, AJ Bastian, O Donchin, R Shadmehr, and SH Mostofsky (2008) Brain 131:2894-2903.
Learned dynamics of reaching movements generalize from dominant to non-dominant arm. SE Criscimagna-Hemminger, O Donchin, MS Gazzaniga, and R Shadmehr (2003) Journal of Neurophysiology 89:168-176.
Motor adaptation as a process of reoptimization. J Izawa, T Rane, O Donchin, and R Shadmehr (2008) Journal of Neuroscience 28:2883-2891.
Internal models and contextual cues: encoding serial order and direction of movement. SK Wainscott, O Donchin, and R Shadmehr (2005) Journal of Neurophysiology 93:786-800.
Learning dynamics of reaching. R Shadmehr, O Donchin, EJ Hwang, SE Hemminger, and A Rao (2005) Motor Cortex in Voluntary Movements: A distributed system for distributed functions, A. Riehle and E. Vaadia (eds), CRC Press, pp. 297-328.
Change in desired trajectory caused by training in a novel motor task. O Donchin and R Shadmehr (2004) Proc IEEE EMBS 26:4495-4497.
A Gain-Field Encoding of Limb Position and Velocity in the Internal Model of Arm Dynamics. EJ Hwang, O Donchin, MA Smith, and R Shadmehr (2003) PLoS Biology 1(2):209-220.
Quantifying generalization from trial-by-trial behavior of adaptive systems that learn with basis functions: Theory and experiments in human motor control. O Donchin, JT Francis, and R Shadmehr (2003) Journal of Neuroscience, 23:9032-9045.
Learned dynamics of reaching movements generalize from dominant to non-dominant arm. SE Criscimagna-Hemminger, O Donchin, MS Gazzaniga, and R Shadmehr (2003) Journal of Neurophysiology 89:168-176.
Mechanisms influencing acquisition and recall of motor memories. O Donchin, L Sawaki, G Madupu, LG Cohen, and R Shadmehr (2002) Journal of Neurophysiology 88:2114-2123.
Linking motor learning to function approximation: Learning in an unlearnable force field. O Donchin and R Shadmehr (2002) Adv Neural Inform Proc Systems, Dietterich T. G., Becker S., Ghahramani Z. (eds), MIT Press, Cambridge, MA, vol. 14, pp. 197-203.
A real-time state predictor in motor control: study of saccadic eye movements during unseen reaching movements. G Ariff, O Donchin, T Nanayakkara, and R Shadmehr (2002) Journal of Neuroscience 22:7721-7729.
Publications
Publications
Opher Donchin
Opher Donchin
Jörn joined the lab in 2003 after completing his PhD in Psychology from University of California Berkeley. With Jörn, we built an fMRI compatible robot and became the first lab in the world to study reach adaptation using functional magnetic resonance imaging. Jörn brought the tools of statistical learning to the problem of motor adaptation, altering the path of motor learning research to incorporate optimal estimation and control. He subsequently became an Assistant Professor at University of Bangor, UK, then Associate Professor at University College London. He is currently Research Chair for Motor Control and Computational Neuroscience, University of Western Ontario.
The coordination of movement: optimal feedback control and beyond. J Diedrichsen, R Shadmehr, and RB Ivry (2010) Trends in Cognitive Sciences 14:31-39.
Reach adaptation: what determines whether we learn an internal model of the tool or adapt the model of our arm? J Kluzik, J Diedrichsen, R Shadmehr, and AJ Bastian (2008) Journal of Neurophysiology 100:1455-1464.
Active learning: learning a motor skill without a coach. VS Huang, R Shadmehr, and J Diedrichsen (2008) Journal of Neurophysiology 100:879-887.
Sensory prediction errors drive cerebellum-dependent adaptation of reaching. YW Tseng, J Diedrichsen, JW Krakauer, R Shadmehr, and AJ Bastian (2007) Journal of Neurophysiology 98:54-62.
Dissociating timing and coordination as functions of the cerebellum. J Diedrichsen, SE Criscimagna-Hemminger, and R Shadmehr (2007) Journal of Neuroscience, 27:6291-6301.
A spatially unbiased atlas template of the human cerebellum. J Diedrichsen (2006) NeuroImage 33:127-138.
Neural correlates of reach errors. J Diedrichsen, Y Hashambhoy, T Rane, and R Shadmehr (2005) Journal of Neuroscience 25:9919-9931.
Detecting and adjusting for artifacts in fMRI time series data. J Diedrichsen, and R Shadmehr (2005) NeuroImage 27:624-634.
Publications
Publications
Jörn Diedrichsen
Jörn Diedrichsen
Jean-Jacques joined the lab in 2007 as a postdoc, after having completed his PhD in the Laboratory of Neurophysiology at Université Catholique de Louvain, Belgium. Jean-Jacques mastered the use of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) in our lab, and made important contributions to the theory of temporal discounting and motor control. His research provided new insights into the role of the motor cortex in motor adaptation and generalization. He subsequently was appointed Assistant Professor at Université Catholique de Louvain.
Changes in corticospinal excitability during reach adaptation in force fields. JJ Orban de Xivry, MA Ahmadi-Pajouh, MD Harran, Y Salimpour, and R Shadmehr (2013) Journal of Neurophysiology 109:124-136.
Stimulation of the human motor cortex alters generalization patterns of motor learning. JJ Orban de Xivry, MK Marko, SE Pekny, D Pastor, J Izawa, P Celnik, and R Shadmehr (2011) Journal of Neuroscience, 31:7102-7110.
Contributions of the motor cortex to adaptive control of reaching depend on the perturbation schedule. JJ Orban de Xivry, SE Criscimagna-Hemminger, and R Shadmehr (2011) Cerebral Cortex 21:1475-1484
Temporal discounting of reward and the cost of time in motor control (2010). R Shadmehr, JJ Orban de Xivry, M Xu-Wilson, and TY Shih. Journal of Neuroscience 30:10507-10516.
Publications
Publications
Jean-Jacques Orban de Xivry
Jean-Jacques Orban de Xivry
Thrishantha joined the lab in 2001 as a postdoc after completing a PhD in Control and Robotics from Saga University, Sri Lanka. In our lab he worked on the ability of the brain to predict consequences of motor commands and used saccades as a measure of that prediction. He subsequently became a Radcliff Fellow at Harvard University. He was appointed Associate Professor of Engineering, Imperial College.
Saccade adaptation in response to altered arm dynamics. T Nanayakkara, and R Shadmehr (2003) Journal of Neurophysiolog 90:4016-4021.
A real-time state predictor in motor control: study of saccadic eye movements during unseen reaching movements. G Ariff, O Donchin, T Nanayakkara, and R Shadmehr (2002) Journal of Neuroscience 22:7721-7729.
Publications
Publications
Thrishantha Nanayakkara
Thrishantha Nanayakkara
Adrian joined the lab in 2009 as a postdoc, after completing a PhD from Neuroinformaticsfrom University of Edinburgh, Scotland, undergraduate degree in Mathematics from Cambridge University. He created a new mathematical framework to view the problem of how the brain decides on the vigor of a movement: he posited that whereas a movement may be an opportunity to acquire reward, the objective is to perform movements in such a way as to maximize the rate of reward. He showed that this led to an interesting prediction: as rate of movements are changed, the brain should change the vigor of movements. Experiments that were performed by Thomas Reppert confirmed these predictions with surprising fidelity. He joined the laboratory of Prof. John Krakauer in 2012. He is now Assistant Professor in the Dept. of Neurology, Johns Hopkins School of Medicine.
Persistent residual errors in motor adaptation tasks: reversion to baseline and exploratory escape. Pavan A Vaswani, Lior Shmuelof, Adrian M Haith, RJ Delnicki, Vincent S Huang, Pietro Mazzoni, Reza Shadmehr, and John W Krakauer (2015) Journal of Neuroscience 35:6969-6977
Contributions of the cerebellum and the motor cortex to acquistion and retention of motor memories. David J Herzfeld, Damion Pastor, Adrian M Haith, Yves Rossetti, Reza Shadmehr, and Jacinta O'Shea (2014) NeuroImage 98:147-158
Evidence for hyperbolic temporal discounting of reward in control of movements. AM Haith, TR Reppert, and R Shadmehr (2012) Journal of Neuroscience 32:11727-11736
Sensitivity to prediction error in reach adaptation. MK Marko, AM Haith, MD Harran, and R Shadmehr (2012) Journal of Neurophysiology 108:1752-1663.
Changes in saccade kinematics associated with the value and novelty of a stimulus. TR Reppert, JES Choi, AM Haith, and R Shadmehr (2012) Conference on Information Sciences and Systems 46:1-5.
Publications
Publications
Adrian Haith
Adrian Haith
Zahra joined the lab in 1999 as a postdoc. She worked on geometry of generalization in learning of internal models during reaching. She subsequently became an Assistant Professor of Electrical and Computer Engineering, University of Manitoba, Canada. She is now Professor and Canada Research Chair at University of Manitoba
Spatial generalization from learning dynamics of reaching movements. R Shadmehr and ZMK Moussavi (2000) Journal of Neuroscience, 20:7807-7815.
Publications
Publications
Zahra Moussavi
Zahra Moussavi
Jun joined the lab as a postdoc in 2005 after completing his PhD from University of Tokyo. Jun played a leading role in a number of new directions for the lab. He demonstrated that adaptation was not merely a process of canceling a perturbation, but rather re-optimization, i.e., finding a new way to maximize probability of acquiring reward. This implied that there could not be a ‘desired trajectory’ in the brain, but rather that all learning was ultimately a search for reward. He discovered that in cerebellar disease, there was intact learning from reward prediction errors, but a specific impairment in learning from sensory prediction errors. In this way, it was possible to improve performance of cerebellar patients, something that had been very difficult to do before Jun’s work. He discovered that in autism, children exhibited an abnormally strong sensitivity proprioception during learning. Perhaps the most important of his many contributions is the idea that the brain maintains multiple learning systems, and that during motor learning, two systems cooperate: a reward based learning system, and a sensory prediction based learning system. The former is spared in people with cerebellar damage. He discovered a way to behaviorally examine the consequence of learning with each system. He is currently Associate Professor in the Faculty of Engineering, Information, and Systems, University of Tsukuba, Japan.
Reward dependent modulation of movement variability. Sarah E Pekny, Jun Izawa, and Reza Shadmehr (2015) Journal of Neuroscience 35:4015-4024
Cerebellar contributions to reach adaptation and learning sensory consequences of action. J Izawa, SE Criscimagna-Hemminger, and R Shadmehr (2012) Journal of Neuroscience 32:4230-4239.
Motor learning relies on integrated sensory inputs in ADHD, but over-selectively on proprioception in Autism spectrum conditions. J Izawa, SE Pekny, MK Marko, C Haswell, R Shadmehr, and SH Mostofsky (2012) Autism Research 5:124-136
Stimulation of the human motor cortex alters generalization patterns of motor learning. JJ Orban de Xivry, MK Marko, SE Pekny, D Pastor, J Izawa, P Celnik, and R Shadmehr (2011) Journal of Neuroscience, 31:7102-7110.
Learning from sensory and reward prediction errors during motor adaptation. J Izawa and R Shadmehr (2011) PLoS Computational Biology 7:e1002012
Representation of internal models of action in the autistic brain. C Haswell, J Izawa, L Dowell, SH Mostofsky, and R Shadmehr (2009) Nature Neuroscience 12:970-972.
Online processing of uncertain information in visuomotor control. J Izawa and R Shadmehr (2008) Journal of Neuroscience 28:11360-11368.
Motor adaptation as a process of reoptimization. J Izawa, T Rane, O Donchin, and R Shadmehr (2008) Journal of Neuroscience 28:2883-2891.
Publications
Publications
Jun Izawa
Jun Izawa
Arash joined the lab as a postdoc in 2005, after completing his MD and research training from the Institute of Physics and Mathematics, Tehran. He was the first student in the lab to use transcranial magnetic stimulation as a method to investigate the neural basis of motor learning. He is currently Assistant Professor at University of Colorado.
Impairment of retention but not acquisition of a visuomotor skill through time-dependent disruption of primary motor cortex. A Hadipour-Niktarash, CK Lee, JE Desmond, and R Shadmehr (2007) Journal of Neuroscience 27:13413-13419
Publications
Publications
Arash Hadipour-Niktarash
Arash Hadipour-Niktarash
Yousef joined the lab in 2010 as a postdoctoral fellow, after completing his PhD in Electrical Engineering with a thesis in cortical neurophysiology from the Institute of Physics and Mathematics, Tehran. During his postdoctoral period in our lab, he studied neural basis of effort evaluation in the brain. He made a number of discoveries regarding the neural basis of effort evaluation. In particularly, he discovered that in Parkinson’s disease, it was possible to use non-invasive cortical stimulation of the motor cortex to alter the perception of effort and improve the motor symptoms. He completed his postdoctoral fellowship in 2014. He subsequently became a Research Associate at the Functional Neurosurgery Unit of the Johns Hopkins School of Medicine. He is now Assistant Professor at the Johns Hopkins School of Medicine.
Changes in corticospinal excitability during reach adaptation in force fields. Jean-Jacques Orban de Xivry, Mohammad Ali Ahmadi-Pajouh, Michele D Harran, Youseph Salimpour, and Reza Shadmehr (2013) Journal of Neurophysiology 109:124-136.
Motor costs and the coordination of the two arms. Yousef Salimpour and Reza Shadmehr (2014) Journal of Neuroscience 34:1806-1818.
Altering effort costs in Parkinson's disease with non-invasive cortical stimulation. Yousef Salimpour, Zoltan K Mari, and Reza Shadmehr (2015) Journal of Neuroscience,35:12287-12302.
Publications
Publications
Yousef Salimpour
Yousef Salimpour
Aysha joined the lab in 2008 as a postdoc after completing her PhD in Psychology from University of Virginia. Aysha made the interesting discovery that the fast component of the motor memory was very likely neurally distinct from the slow component. She made this inference by inventing a task in which she could selectively disrupt the fast process via a task the engaged the declarative memory system. She was awarded an NRSA postdoctoral grant. She subsequently took a position as Research Scientist, Ipsos Public Affairs.
A shared resource between declarative memory and motor memory. A Keisler and R Shadmehr (2010) Journal of Neuroscience 30:14915-14924.
Publications
Publications
Aysha Keisler
Aysha Keisler
Goran joined the lab in 2000 as a postdoc. He worked on mechanical design, construction, and control of a six-legged running robot. The robot achieved the speed of six body lengths per second. He also worked on measuring changes in feedback control of the arm during motor adaptation, discovering that impedance of the arm changed as people learned to interact with a force field. He subsequently became a faculty member in the University of Nis. He is currently Professor of Electronic Engineering, and head of the Control Engineering group, University of Nis, Serbia.
Parametric models for motion planning and control in biomimetic robotics. GS Dordevic, M Rasic, and R Shadmehr (2005) IEEE Transactions in Robotics 21:80-92. Abstract
Learning dynamics of reaching movements results in the modification of arm impedance and long-latency perturbation responses. T Wang, GS Dordevic, and R Shadmehr (2001) Biological Cybernetics 85:437-448.
Publications
Publications
Goran S. Dordevic (Djordjevic)
Goran S. Dordevic (Djordjevic)
Joe joined the lab in 2001 as a postdoc, after completing a PhD in Neuroscience at the George Washington University. He worked on state-space methods and its application to motor adaptation, as well as the effect of time on motor memory. He was subseqently appointed Associate Professor of Physiology at the State University of New York.
Quantifying generalization from trial-by-trial behavior of adaptive systems that learn with basis functions: Theory and experiments in human motor control. O Donchin, JT Francis, and R Shadmehr (2003) Journal of Neuroscience, 23:9032-9045.
Generalization as a function of velocity and duration: human reaching movements. JT Francis (2008) Experimental Brain Research 186:23-37.
Publications
Publications
Joe Francis
Joe Francis
Ash joined the lab in 2000 as a postdoc. He worked on learning of cue-dependent force fields and the ability of the human brain to associate context to internal models of fields. He subsequently became an Assistant Professor at Columbia University.
Learning dynamics of reaching. R Shadmehr, O Donchin, EJ Hwang, SE Hemminger, and A Rao (2005) Motor Cortex in Voluntary Movements: A distributed system for distributed functions, A. Riehle and E. Vaadia (eds), CRC Press, pp. 297-328.
Publications
Publications
Ash Rao
Ash Rao
Caterina joined the lab in 1998 as a postdoc. She worked on electromyographic signs of motor dysfunction in genetically at risk but clinically asymptomatic Huntington's disease individuals. She subsequently became Assistant Professor of Epidemiology, University of Pittsburgh School of Medicine.
Caterina Rosano
Caterina Rosano
Sang June joined the lab in 2005, after completing his PhD in Mechanical Engineering from Columbia University. Using the framework of optimal estimation, he investigated the role of sensory and process noise in trial-to-trial motor learning. He is currently an Associate Professor of Mechanical Engineering at California State University, Fullerton.
Sang Jun Oh
Sang Jun Oh