Neuron Imaging Lab uses cutting-edge optoelectrophysiological techniques to understand the functional organization of inhibitory circuits in the hippocampus

Information processing within neural networks is determined by a dynamic partnership between principal

neurons and local circuit inhibitory interneurons. GABAergic interneurons represent the dominant inhibitory cell type throughout the mammalian central nervous system. This population of neurons is extremely heterogeneous and comprises, in many brain regions, cells with divergent morphological and physiological properties and highly specialized functions.

During the past two decades, GABAergic inhibitory interneurons have been studied extensively, espe-

cially in the hippocampus, a relatively simple cortical structure. Different types of hippocampal inhibitory interneurons control the spike initiation (e.g., axo-axonic and basket cells) and synaptic integration [e.g., bistratified and oriens-lacunosum moleculare (O-LM) interneurons] within pyramidal neurons and synchronize local network activity, providing a means for functional segregation of neuronal ensembles and proper routing of hippocampal information. Thus, it is thought that, at least in the hippocampus, GABAergic inhibitory interneurons represent critical regulating elements at all stages of information processing, from synaptic integration and spike generation to large-scale network activity. However, it remains largely unknown what mechanisms control the activity of inhibitory interneurons themselves.

In search of answer to this fundamental question, we use a combination of two-photon laser scanning

microscopy, whole-cell patch clamp electrophysiology, pharmacology, immunocytochemistry and genetic approaches in brain slices from mice. An emphasis is placed on the examining of the inhibitory control of inhibitory interneurons and interneuron dendritic integration.

Current research program encompasses two themes:

Cellular Basis of Synaptic Communication between Inhibitory Interneurons in the Hippocampus
Functional biochemical compartmentalization in aspiny dendrites of inhibitory interneurons