The primary goal of the laboratory is to better understand the neuronal circuitry of the hippocampus, which is known to play crucial roles in certain learning and memory functions. In particular we are interested in the cellular interface between the dentate gyrus and CA3 regions and the integration of neuronal information within the dentate gyrus. The mossy fibres (the axon of dentate gyrus granule cells) introduce certain novel information about the environment in the CA3 network, and this incoming excitation is correlated with previously acquired memories that are represented by the interconnected synaptic network of local pyramidal cells. This interaction essential in the ability to distinguish novel situations from previously acquired memories. Our research questions focus on the elementary components of this interaction: the synaptic projections from the DG to CA3. The second research direction of the group investigates the essential neuronal mechanisms of the granule cells that link their exceptional and universal electrophysiological and synaptic properties to their specific physiological functions. An important methodology of the laboratory is the in vitro patch clamp electrophysiology of unitary synaptic connections, during which we directly record from single small presynaptic axons and postsynaptic neurons. Furthermore, we use the patch clamp method to analyze the elementary electrophysiological properties of small axonal and dendritic structures. These recordings are combined with anatomy, immuno-histochemistry, calcium-imaging, computational modelling and virus labelling. Combination of these methods allow us to investigate how inputs are translated and processed into neuronal output within individual neurons and what are the fundamental mechanisms of synaptic communications between individual neurons.
The laboratory started its operation in July 1st 2009 after a new young investigator position was created by the institute with the support of the Network of the European Neuroscience Institutes (ENI-Network). The current projects of the laboratory are funded by the Wellcome Trust, by the “Momentum” Young Investigator Program from the Hungarian Academy of Sciences and by the Hungarian Brain Research Program.
The diversity of GABAergic neurons is manifested at several functional levels. One of these functionally defining properties is the cell-type specific innervations of GABAergic cells by excitatory pathways which enables pathway specific activation of distinct inhibitory circuits. We obtain simultaneous recordings from presynaptic mossy fibre terminals and synaptically coupled CA3 neurons which are identified with post hoc immuno-histochemistry and morphological analysis to directly study monosynaptic connections between distant dentate gyrus granule cells and CA3 neurons, and thus, providing novel opportunities to better understand the neuronal circuitry of the hippocampus. Specifically, we are interested in how physiologically relevant activity patterns influence the neuronal output of individual hippocampal mossy fibres (#4 on the summary cartoon). Other major interests of the group are the mechanisms of the input integration in granule cells (#5: published 2014). To directly measure the propagation of signals along the dendritic arbors of granule cells we employ dendritic recordings, optical stimulation and calcium imaging, and verification of the obtained data by multicompartmental modelling. Similar question is asked on the input integration of the CA3 GABAergic cells (#3), which are the major targets of the mossy fibres, where we focus on the cell type specific modulation of the input integration by potassium conductances. We also investigate the potential cellular consequences of the unique capability of the dentate gyrus to generate new neurons throughout the life of the animals by using a specific retroviral labelling method to birth-date adult born granule cells (#7: published 2016). Altogether, these projects will reveal fundamental components of the cellular interface between the dentate gyrus and CA3 regions, thus, provide novel insights into the machinery of higher order neuronal functions.
mta.hu – 2016, Dec 14: “Az idegsejtek dendritjei analóg/digitális hibrid jeleket használnak“