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Faculty Biography For:

Jokubas Ziburkus
Associate Professor
Louisiana State University Health Sciences Center, PhD 2001

Biology and Biochemistry Department
University of Houston
Houston, Texas 77204-5001

Office: SR2 242G
Phone: (713) 743-0659
jziburkus@uh.edu

____________________________
The long-term goal of my laboratory is to understand the mechanisms of neuronal interactions in health and disease. We employ a multi-disciplinary approach that synthesizes in vitro neurophysiology, imaging, molecular biology, immunohistochemistry, and computational neuroscience. Using these techniques we are trying to understand alterations in single cells and neural networks that lead to epileptic seizures, abnormal excitability in Alzheimer's disease, or occur following a traumatic brain injury.

Inhibitory and excitatory cell network interactions underlying normal behavior and epileptic seizure formation
Cortical circuits are comprised of diverse populations of inhibitory and excitatory subtypes of neurons. During normal animal behavior these distinct cell subtypes get activated in a precise sequence. Recently, we showed that in epileptic tissue inhibitory and excitatory cells also get activated during distinct phases of seizure-like events (Ziburkus et al., 2006). Currently we are continuing our studies on additional subtypes of interneurons in dissecting their role in the mechanics of seizure dynamics. We perform simultaneous multiple whole-cell recordings in identified neuronal subtypes in the hippocampus and neocortex. Pharmacological manipulations include the use of adrenergic receptor and other channel modulators, and gap junction blockers.

Fast imaging of neuronal activity
Concurrently with the extracellular or whole-cell electrical recordings we perform voltage-sensitive dye measurements of neuronal activity. This rare combination of techniques allows to monitor single or few cell participation in larger spatio-temporal network dynamics. We are interested in how typical epileptic activity emerges and propagates in anatomically distinct structures, like the hippocampus and neocortex?
In traumatic brain injury, we study how neural activity transmission in cortical layers in altered following a severe brain injury. In Alzheimer's disease, we study hippocampal excitability and neural networks involved in memory encoding.

Adrenergic modulation of single cell and network excitability
Neocortex receives strong neuromodulatory inputs from the basal forebrain, the ventral tegmental area, and a number of brainstem nuclei. Cortical interneurons are a major target of the diffuse neuromodulator projections. Using electrophysiology and imaging we currently study adrenergic receptor's role in mediating single cell excitability and regional network synchrony.

Changes in synaptic plasticity in acute and chronic seizure models
Although synaptic plasticity is widely studied, little is known how short-term plasticity (STP, facilitation and depression) in specific cell subtypes changes as a function of epileptiform activity. Furthermore, little is known about spatio-temporal patterns of short-term plasticity. We address these questions by studying cellular facilitation and depression in acute and chronic seizure models and its impact on the spatio-temporal patterns of neuronal network activation.

Activity-dependent molecular changes
Some of our preliminary studies using micro RNA microarrays and RT PCRs show that in an acute model of ictogenesis fast (90 min) differential mRNA and miRNA expression occurs in the hippocampal areas. With these studies we seek to correlate changes in molecular markers with the functional electrophysiological changes in neuronal activity. We are currently exploring the role of miRNA as a homeostatic regulator of voltage-gated potassium channels and as an alternative regulator of adrenergic receptor activated intracellular pathways.

Mathematical models of inhibitory, excitatory and glial cell networks
Immersion of the experimental data into a computationally sound and testable model is essential to complete understanding and further prediction of physiological processes, such as neuronal network dynamics. Through collaborations with the computational neuroscientists, mathematicians, and phycisists we have recreated interneuron and pyramidal cell activity patterns using conductance based single cell and network activity models. Additionally, one of the currently proposed inhibitory-excitatory network activity models indicate that we search for activity-dependent dynamical synapses in epileptiform neuronal activity. The neurophysiological normal activity-dependent or epileptic plasticity paradigm could then be well related with a robust mathematical cell network model.
See Cressman JR et al. 2009 J comp Neurosci
Ulah G et al. 2009 J Comp Neurosci

Collaborators:
Steven J. Schiff (Center for Neural Engineering, The Pennsylvania State University)
John R. Cressman (Krasnow Institute, George Mason University).
Preethi Gunaratne (UH Biology and Biochemistry)
Kresimir Josic (UH Mathematics)
Bernhard Bodmann (UH Mathematics)


Ziburkus J, Dilger EK, Lo FS, Guido W. (2009) LTD and LTP at the developing retinogeniculate synapse. J Neurophysiol. 102:3082-90.

Cressman JR Jr, Ullah G, Ziburkus J, Schiff SJ, Barreto E.(2009) The influence of sodium and potassium dynamics on excitability, seizures, and the stability of persistent states: I. Single neuron dynamics. J Comput Neurosci. 26:159-70 Accompanying paper: Ullah G, Cressman JR Jr, Barreto E, Schiff SJ. (2009) The influence of sodium and potassium dynamics on excitability, seizures, and the stability of persistent states. II. Network and glial dynamics. J Comput Neurosci.

Schiff, SJ, Cressman, JR, Ziburkus, J, Towards a Dynamics of Seizure Mechanics, Book chapter in Computational Neuroscience in Epilepsy, Edited by Drs. Soltesz I and Staley K, Estimated publication date: Nov. 2007, Copyright year: 2008.

Seol GH*, Ziburkus J*, Huang SY, Song L, Kim IT, Takamiya K, Huganir RL, Lee H-K, and Kirkwood A. *Equally contributing authors. (2007) Neuromodulators control the polarity of spike-timing dependent synaptic plasticity. Neuron, 55:919-29.

Ziburkus, J. and Guido W (2006) Loss of binocular responses and reduced retinal convergence during the period of retinogeniculate axon segregation. J Neurophysiology, 96:2775-84

Ziburkus, J., Cressman, J.R., Barreto, E. and Schiff, S.J. (2006) Inhibitory and excitatory interplay during in vitro hippocampal seizures. J Neurophysiology, 95:3948-54.

Ziburkus, J., Lo, F.-S., and Guido, W. (2003) Nature of inhibitory postsynaptic activity in developing relay cells of the lateral geniculate nucleus. J. Neurophysiology, 90:1063 - 1070.

Lo, F.-S., Ziburkus, J., and Guido, W. (2002) Synaptic mechanisms regulating the activation of a Ca2 -mediated plateau potential in developing relay cells of the lateral geniculate nucleus. J. Neurophysiology 87: 1175-1185

Carden, W.B., Guido, W., Ziburkus, J., Datskovskaia, A., Godwin, D.W., Bickford, M.E. (2000) A novel means of Y cell identification in the developing lateral geniculate nucleus of the cat. Neuroscience Letters 295: 5-8

Ziburkus, J., Bickford, M.E., and Guido, W. (2000) NMDAR-1 staining in the lateral geniculate nucleus of normal and visually deprived cats. Visual Neuroscience 17, 1-10.