Speaker of Workshop 4
Will talk about: Functional connectivities in cortical networks at criticality
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.
One of the major challenges in neuroscience is the identification of normal cortex dynamics. Recent progress in my lab has identified three features that characterize ongoing cortical dynamics: neuronal avalanches, coherence potentials, and integrative weight organization. These features emerge as three precisely identifiable dynamical aspects of brain activity. At criticality, the myriads of interactions between nerve cells are exquisitely balanced leading to a scale-invariant organization of neuronal avalanches that optimizes numerous aspects of information transfer. At this critical point, coherence potentials emerge that represent perfect coupling of neuronal groups across multiple cortical sites. Coherence potentials form in analogy to action potentials at the single neuron level, suggestive of computational building blocks at the network level. The organization of coherence potentials translates into weighted, directed small-world networks built on the principle of integrated neighborhood. These functional networks share unique aspects with gene networks and human social and communication networks. All three dynamical features are found in the ongoing activity of normal neocortex whether recorded in the dish or in awake monkeys suggesting they constitute a robust framework of mammalian brain function.