Leonardo Cohen, MD
Entry Id: TP-45

Overview
The goal of our research is to understand the mechanisms underlying plastic changes in the human central nervous system and develop novel therapeutic approaches for recovery of function based on these advances. Most of our work has focused in plasticity of the human motor system. More recently, we became interested in the study of plastic changes across sensory modalities (blindness). We have studied plastic changes in patients with lesions in the central nervous system like hemispherectomy, stroke, and spinal cord injury and in the peripheral nervous system like amputations. In healthy volunteers, we studied plastic changes associated with transient deafferentation.

The main technique employed is transcranial magnetic stimulation. In this respect we are interested in the development of this technique as a tool to help us to understand mechanisms of human plasticity and to modulate plastic changes in humans. A multimodality approach is applied to the understanding of mechanisms of plasticity including PET scanning, fMRI, MEG and EEG when appropriate. Our research protocols are focused in the evaluation of patients with stroke, amputations, and blindness and to the study of plasticity in healthy volunteers (see NIH Clinical Center home page).

Our work in the last few years has focused on the assessment of plastic changes in human motor function after a variety of interventions and injuries. We have advanced in the understanding of the mechanisms, time-profile and site where plasticity takes place after a variety of disorders and in particular in relation to motor learning. Our future goals are to improve our understanding of the mechanisms underlying plasticity of function in humans and its functional relevance. On the basis of these mechanisms, we are starting to design and test interventions to improve motor disability after human diseases, for example stroke.

Structure of the Clinical Training Program
This is a two-year fellowship program designed for physicians planning a career in academic neurology with a focus on the clinical neurophysiology and neuroimaging of recovery of function after stroke and other cortical injuries. Additional features of this program include the development of Clinical expertise in diagnosis and treatment of movement disorders. Trainees will develop expertise in at least one branch of clinical neurophysiology (for example transcranial magnetic stimulation) or neuroimaging (functional MRI or PET). Research will focus on the physiology and pathophysiology of recovery of function after injury including mastering the technique of transcranial magnetic stimulation, EEG analysis or functional neuroimaging. By the end of the first year, an original research protocol should be written that would be executed in the second year. Fellows are expected to attend the weekly journal club and the weekly unit meeting where they are exposed to the different protocols and techniques utilized in the unit. They are also expected to attend the meetings of the NIH integrative neuroscience interest group. Written evaluation of performance will be at 6 month intervals. Fellows should take the NIH Clinical Center course in clinical research (Introduction to the Principles and Practice of Clinical Research) in their first year. At least one additional course should be taken in biostatistics. Fellows attend the Branch's outpatient clinic each Monday afternoon which focuses on movement disorders and also the Stroke Neurorehabilitation Clinic.

• Buch ER, Modir SA, Fourkas AD, Weber C, Birbaumer N and LG Cohen (2012) Parietofrontal integrity determines neural modulation associated with grasping imagery after stroke. Brain Jan 9. PMID: 22232595
• Song S, Sharma N, Buch ER and LG Cohen (2012) White matter microstructural correlates of superior long-term skill gained implicitly under randomized practice Cerebral Cortex (in press) PMID: 21926382 Abe M, Schambra H, Wassermann EM, Luckenbaugh D, Schweighofer N and LG Cohen (2011) Reward improves long-term retention of a motor memory through induction of offline memory gains. Current Biology 21(7):557-62.
• Harris-Love ML, Morton S, Perez MA, Cohen LG (2011) Mechanisms of training-induced reaching improvement in severely hemiparetic stroke patients. Neurorehabilitation and Neural Repair 5:398-411. Referred to in Faculty of 1000 Biology [disclaimer].
• Censor N, Dimyan MA, Cohen LG (2010) Modification of existing human motor memories is enabled by primary cortical processing during memory reactivation. Current Biology 14;20(17):1545-9. See Dispatch on this article (Current Biology 2010 20(17) pp. R709 - R710)
• Fritsch B, Reis J, Martinovich K, Schambra H, Ji Y, Cohen LG* and Lu B* (* co-senior and corresponding authors, 2010). DC stimulation promotes motor learning by a form of synaptic potentiation that depends on BDNF secretion. Neuron 66(2):198-204.
• Tanaka S, Honda M, Hanakawa S and LG Cohen (2010) Differential Contribution of the Supplementary Motor Area to Stabilization of a Procedural Motor Skill Acquired Through Different Practice Schedules. Cerebral Cortex 20(9):2114-21.
• Reis J, Schambra HM, Cohen LG*, Buch ER, Fritsch B, Zarahn E, Celnik PA and JW Krakauer (* corresponding author) (2009) Noninvasive cortical stimulation enhances skill acquisition over multiple days through an effect on consolidation. Proceedings of the National Academy of Sciences 106:1590-5. See commentary [disclaimer].
• Perez M, Tanaka S, Wise S, Sadato N, Tanabe HC, Willingham DT and LG Cohen. (InPress) Neural substrates underlying intermanual transfer of a newly acquired motor skill, Current Biology.
• Duque J, Mazzocchio R, Stefan K, Hummel F, Olivier F and LG Cohen. (InPress) Memory formation in the motor cortex ipsilateral to a training hand, Cerebral Cortex.
• Perez M, Wise SP, Willingham DT and LG Cohen (2007) Neurophyisological mechanisms involved in transfer of procedural knowledge, Journal of Neuroscience 27, 1045-53. Full Text/Abstract
• Stefan K, Cohen LG, Duque J, Mazzocchio R, Celnik P, Sawaki P, Ungerleider L and J Classen (2005) Formation of a motor memory by action observation, Journal of Neuroscience 25, 9339-9346
• Hummel F, Celnik P, Giraux P, Floel A, Wu W-H, Gerloff C and LG Cohen (2005) Effects of noninvasive cortical stimulation on skilled motor function in chronic stroke, Brain 128, 490-499. Full Text/Abstract
• Amedi A, Floel A, Knetch S, Zohary E and LG Cohen (2004) Transcranial magnetic stimulation of the occipital pole interferes with verbal processing in blind subjects, Nature Neuroscience 7, 1266-1270
• Werhahn KJ, Mortensen J, VanBoven RW, Zeuner KE and LG Cohen. (2002) Enhanced tactile spatial perception and cortical processing during acute hand deafferentation, Nature Neuroscience 5, 936-8

Mari Tobita, MD
(Univ of Pennsylvania, PA)

Susan Schwerin, PhD
(University of Florida)

Anusha Venkatakrishnan
(University of Maryland)

Marco Sandrini, PhD
(University of Trento, Italy)

Jay Edelman, PhD
(Professor Physiology, City College NY, on Sabbatical)

Nitzan Censor, PhD
(Weizmann Institute, Israel)

Eran Dayan, PhD
(Weizmann Institute, Israel)

Sunbin Sylvie Song
(Georgetown University)

Anusha Venkatakrishnan
(University of Maryland)

Timea Hodics
(Georgetown University)

Ethan Buch
(NIH-Oxford PhD Program)

Mathias Winkosky- 2009-2011
PhD Student
(University of Tubingen, Germany)
Univ of Tubingen, Germany

Mathias Wahl, MD- 2009-2010
Resident in Neurology
(University of Frankfurt, Germany)
Univ of Frankfurt, Germany

Anna Kuppuswamy, PhD.- 2009-2010
Department of Psychology
(UCL, London)
University of Leeds, UK

Surjo Soekadar- 2008-2011
Resident in Psychiatry
(University of Tubingen, Germany)
Univ of Tubingen, Germany

Mitsunari Abe, MD, PhD- 2008-2011
Assist Professor, National Inst
(University of Kyoto, Japan)
of Neuroscience, Tokyo, Japan

Katherine Deutsch- 2008-2011
National Institute of Neurological Disorders and Stroke, NIH
(University College, London, UK)

Nick Sharma- 2008-2012
National Institute of Neurological Disorders and Stroke, NIH
(University of Cambridge, UK)

Stephanie Maxwell- 2008-2011
Program Manager
(Georgetown University)
Traumatic Brain Injury
Office of the Surgeon General
Department of the Army

Heidi Schambra, NINDS- 2007-2011
Assist Prof, Columbia University
(Harvard University)
New York, NY

Alissa Fourkas- 2006-2011
National Institute of Neurological Disorders and Stroke, NIH
(Univ of Tuebingen)

Michael Dimyan- 2006-2011
Assist Prof, Dep of Neurology
(Harvard University)
Univ of Maryland, MD

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