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| Dietmar Plenz, Ph.D., Investigator |
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Dr. Plenz is Chief of the Section on Critical Brain Dynamics in the Intramural Research Program at the NIMH. He attended college at the Universities of Mainz and Tuebingen, Germany. Under the supervision of Prof. Valentino Braitenberg and Ad Aertsen, he received his Ph.D. in 1993 at the Max-Planck Institute of Biological Cybernetics/University Tuebingen, where he pioneered the development of in vitro cortex networks to study the emergence of neuronal population dynamics. During his 3 year postdoctoral fellowship with Stephen T. Kitai at the University of Tennessee, Memphis, he developed advanced cortex-forebrain neuronal cultures that allowed him to identify the mechanisms underlying distinct activity patterns that characterize normal and abnormal population dynamics in cortex and basal ganglia. Dr. Plenz joined the NIMH as an Investigator in 1999 and was promoted to Senior Investigator with tenure in 2006. His laboratory combines electrophysiological and imaging techniques and neuronal modeling to study the self-organization of neural networks.
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Staff:
- Timothey Bellay, B.Sc., Graduate Student, (301) 402-6947 bellayt@mail.nih.gov
- Gireesh E. Dharmaraj, M.B.B.S., Special Volunteer, (301) 451-2686 elakkat@mail.nih.gov
- Andreas Klaus, M.S., Graduate Student, (301) 451-2868 klausam@mail.nih.gov
- Sinisa Pajevic, Ph.D., Staff Scientist, (301) 435-504 pajevic@helix.nih.gov
- Thomas Petermann, Ph.D., Postdoctoral Fellow, (301) 402-2249 T.Petermann@a3.epfl.ch
- Woodrow Shew, Ph.D., Postdoctoral Fellow, (301) 402-6946 sheww@mail.nih.gov
- Craig V. Stewart, M.S., Research Assistant, (301) 402-6820 stewartc@intra.nimh.nih.gov
- Tara Thiagarajan, Ph.D., Special Volunteer, (301) 402-2255 tct212@gmail.com
- Hongdian Yang, B.Sc., Predoctoral Fellow, (301) 402-2255 hongdian@mail.nih.gov
- Shan Yu, Ph.D., Postdoctoral Fellow, (301) 402-4536 yushan@mail.nih.gov
Research Interests:
Complex systems, when poised at the transition between order and disorder, exhibit scale-free, power law dynamics. These critical systems are highly adaptive and flexibly process and store information, which for decades prompted the conjecture that the brain might operate at criticality. Our discovery of neuronal avalanches in superficial layers of cortex in 2001 provides solid experimental evidence that indeed the brain might be critical. The spatio-temporal, synchronized activity patterns of avalanches form a scale-free organization that spontaneously emerges in vitro in slice cultures and acute slices and in vivo in the anesthetized rat. We recently demonstrated in collaboration with the Nicolelis lab at Duke that ongoing activity in awake monkeys is composed of neuronal avalanches. This introduces criticality as a precise, quantitative framework of the awake state that allows cortex to expand during development and evolution without fundamental changes in architecture.
Avalanches are established at the time of superficial cortex layer differentiation, require balanced fast excitation and inhibition, and are regulated via an inverted-U profile of NMDA/dopamine-D1 interaction, well known from cognitive task paradigms, e.g. working memory. Their internal organization forms a small-world topology that combines local diversity with efficient global communication. Neuronal synchronization in the form of avalanches naturally incorporates gamma-oscillations and cascades, e.g. synfire chains. The size and timing of a single avalanche is governed by two fundamental power laws, who are equivalent to those found for other critical systems e.g. the Gutenberg-Richter law for earthquake sizes and the Omori-law, which describes the occurence of aftershocks following a main earthquake.
Overall, our results demonstrate that neuronal avalanches are a critical network dynamics at which the cortex gains universal properties found at criticality. This constitutes a novel framework for precisely quantifying cortex functions such as identifying pathological brain states, or the maximal dynamic range in input-output processing.
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Selected Recent Publications:
Thiagarajan, T. C., Lebedev, M. A., Nicolelis, M. A.and D. Plenz (InPress) Coherence potentials: loss-less, all-or-none network events in the cortex, PLoS Biol..
Shew, W., Yang, H., Petermann, T., Roy, R., and D. Plenz (InPress) Neuronal avalanches imply maximum dynamic range in cortical networks at criticality, J. Neurosci..
Petermann, T., Thiagarajan, T.C., Lebedev, M., Nicolelis, M., Chialvo, R.C. and D. Plenz (2009) Ongoing cortical activity in awake monkeys composed of neuronal avalanches , Proc. Natl. Acad. Sci. U. S. A. 106(37), 15921-6.
Full Text/Abstract
Gireesh, E. D. and D. Plenz (2008) Neuronal avalanches organize as nested theta and beta/gamma-oscillations during development of cortical layer 2/3 , Proc. Natl. Acad. Sci. U. S. A. 105, 7576-7581.
Full Text/Abstract
Stewart CV, Plenz D (2008) Homeostasis of neuronal avalanches during postnatal cortex development in vitro, J Neurosci Meth 169, 405-416.
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Pajevic, S. and D. Plenz (2008) Efficient network reconstruction from dynamical cascades identifies small-world topology of neuronal avalanches , PLoS Comp. Biol. 5, e1000271.
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Plenz D, Thiagarajan T (2007) The organizing principles of neuronal avalanches: cell assemblies in the cortex, TINS 30, 101 - 110.
Full Text/Abstract
All Selected Publications
Contact Information:
Dr. Dietmar Plenz
Section on Critical Brain Dynamics
LSN/NIMH
Porter Neuroscience Research Center
Bldg 35, rm 3A-100
Bethesda, MD 20892-3726
Telephone: (301) 402-2249 (office),
(301) 402-2249 (laboratory),
(301) 480-7480 (fax)
Email: plenzd@mail.nih.gov
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