Kutatás: Befejezett munkáink
A DG and CA3 agyterületek közötti kapcsolat sejtes elemeiről
Mossy fibres (the axon of DG GCs) 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 CA3 pyramidal cells. This interaction essential in the ability to distinguish novel situations from previously acquired memories. Our research questions addressed the elementary components of this interaction: the synaptic projections from the DG to CA3 and the essential neuronal mechanisms of GCs 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.
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. Specifically, we investigated how physiologically relevant activity patterns influence the neuronal output of individual hippocampal mossy fibres (published in 2018, 2017) and what are the elementary rules of the wiring of feedforward inhibition. Other major interests of the group are the mechanisms of the input integration in granule cells (published in 2016, 2013). 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 (published in 2020), 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 investigated 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 (published in 2014). Altogether, these projects revealed fundamental components of the cellular interface between the DG and CA3 regions, thus, provided novel insights into the machinery of higher order neuronal functions.