Thanos Tzounopoulos

Ph.D., Oregon Health Sciences University, 1997

Assistant Professor, Cell and Developmental Biology

Assistant Professor, Behavioral Neuroscience, OHSU

Research Assistant Professor, Vollum Institute

It is generally accepted that formation of new memories involves changes in the strength of synaptic transmission. The most widely studied cellular model of learning and memory is the phenomenon referred to as long term potentiation (LTP), in which brief repetitive stimulation results in a long lasting enhancement of excitatory synaptic responses. We use in vitro slice preparations of the hippocampus, a brain structure that plays a key role in memory, to understand the mechanisms that modulate this phenomenon. Additionally, in collaboration with Dr. Robert Stackman, we investigate the behavioral consequences of this modulation in memory and learning.

We are investigating the role of the afterhyperpolarization (AHP) in the induction of synaptic plasticity. By using genetic (knockout mice) and pharmacological approaches, we found that the AHP, by affecting the degree of activation of NMDA receptors and subsequent Ca⁺² entry, modulates the induction of synaptic plasticity, in CA1 but not in the mossy fibre synapse. We are also investigating the behavioral consequences of this modulation.

In another project, we have found that hypoxia, through induction of hypoxia-induced potentiation, changes the threshold for the induction of synaptic plasticity (LTP and LTD). We are currently investigating whether this finding may explain why perinatal hypoxia results in poor performance in behavioral tasks that require memory and learning.

To contact Dr. Tzounopoulos directly: tzounopo@ohsu.edu