Dr. Katalin Tóth

My laboratory is interested in the basic principles of neuronal communication in the hippocampal network. We aim to better understand how spatial information is processed and coded by hippocampal cells. We pay particular attention to the properties of synaptic interactions between mossy fibers and CA3 pyramidal cells during burst activity. Granule cells fire in bursts when the animal is in a particular spatial location, suggesting that this form of communication is a key element of spatial information processing. We investigated pre- and postsynaptic responses to high frequency stimulation. We investigated how granule cell bursting triggers large postsynaptic calcium waves and how this type of activity leads to the mobilization of different vesicle pools, and how these subsets of vesicles contribute to various forms of release, short-term facilitation and information coding. Work in my laboratory is focused on the simultaneous monitoring of optical and electrophysiological signals in hippocampal neurons.

Information processing by single MF terminals (Collaboration with Drs Kirill Volynski, UCL and Yulia Timofeeva, U. Warwick)

Recently, we discovered that MFBs transmit information by effectively counting the number of spikes in physiological bursts (counting logic), which represents a new alternative mechanism to rate coding. Using a simplified model, we showed that the counting of spikes by MFBs could be explained by the interplay among endogenous Ca2+ buffer dynamics, Ca2+ extrusion and SV priming. Building on this model, next we aim to determine how structural and functional diversity among active zones contribute to intraterminal calcium dynamics and the coding strategy exhibited by MF terminals.

Information processing by the dentate gyrus - CA3 network

Dentate GCs have a low average firing rate and typically they discharge brief bursts of action potentials that are separated by several seconds long silent periods. How does the CA3 network decode this incoming information? We aim to identify the pre- and postsynaptic factors and molecular players that underlie these two distinct types of information transfer strategies. To achieve this, we will use KO animals, calcium imaging, glutamate uncaging and computational modelling.

Implications of feed-forward inhibition on network-level information processing (Collaborative work with Dr Richard Naud)

Combining our expertise in experimental and theoretical network analysis, we aim to develop a computational framework with experimentally constrained parameters to understand the effect of MF coding strategies on the CA3 network.

Experimental approaches

Patch-clamp recording, two-photon imaging, electron microscopy

V. Villette, M. Chavarha, I. K. Dimov, L. Pradhan, S. W. Evans, D. Shi, R. Yang, S. Chamberland, J. Bradley, B. Mathieu, F. St-Pierre, J. M. J. Schnitzer, G. Bi, K. Tóth, Jun Ding, Stéphane Dieudonné, Michael Z. Lin* (2019) Fast two-photon volumetric imaging of an improved voltage indicator reveals electrical activity in deeply located neurons in the awake brain. Cell 2019 Dec 12;179(7):1590-1608.e23. doi: 10.1016/j.cell.2019.11.004.
Y. Mircheva, M. R. Peralta III and K. Tóth (2019) Recruitment of feedforward inhibition in the molecular layer of the dentate gyrus drives long lasting hyperpolarization in granule cells and alters the entorhinal input integration. 2019 Aug 14;39(33):6399-6413. doi: 10.1523/JNEUROSCI.2976-18.2019

S. Chamberland, Y. Timofeeva, A. Evstratova, K.Volynski, K. Tóth (2018) . Proc Natl Acad Sci U S A.2018 Jul 10;115(28):7434-7439.

J. Khlghatyan, A Evstratova, S Chamberland, A Marakhovskaia, A Bahremand, K Tóth, JM Beaulieu (2018) Mental Illnesses-Associated Fxr1 and Its Negative Regulator Gsk3β Are Modulators of Anxiety and Glutamatergic Neurotransmission. Front Mol Neurosci. 2018 Apr 12;11:119. doi: 10.3389/fnmol.2018.00119. eCollection 2018.

S. Chamberland, H. H. Yang, M. Pan, S.W. Evans, M. Chavarha, Y. Yang, C. Salesse, H. Wu, J. C. Wu, T. R. Clandinin,*, K. Tóth,*, M. Z. Lin, F. St-Pierre* (2017) Fast two-photon imaging of subcellular voltage dynamics in neuronal tissue with genetically encoded indicators. eLife 2017 Jul 27;6. pii: e25690. doi: 10.7554/eLife.25690.

S. Chamberland, A. Evstratova and K. Tóth (2017) Short-term facilitation at a detonator synapse requires the distinct contribution of multiple types of voltage-gated calcium channels. 2017 May 10;37(19):4913-4927. doi: 10.1523/JNEUROSCI.0159-17.2017 J. Neuroscience

S. Chamberland and K. Tóth (2015) Functionally heterogeneous synaptic vesicle pools support diverse synaptic signalling. J Physiol. 2015 Nov 28. doi: 10.1113/JP270194

Evstratova, S. Chamberland, V. Faundez and K. Tóth (2014) Vesicles derived via AP-3-dependent recycling contribute to asynchronous release and influence information transfer. Nat Commun. 2014 Nov 20;5:5530. doi: 10.1038/ncomms6530.

Sood A, DV Jeyaraju, J Prudent, A Caron, P Lemieux, HM McBride, M Laplante, K Tóth, L Pellegrini* (2014) A Mitofusin-2-dependent inactivating cleavage of Opa1 links changes in mitochondria cristae and ER contacts in the postprandial liver. Proc Natl Acad Sci U S A. 2014 Nov 11;111(45):16017-22. doi: 10.1073/pnas.1408061111.

S. Chamberland, A. Evstratova and K. Tóth (2014) Interplay between synchronization of multivesicular release and recruitment of additional release sites support short-term facilitation at hippocampal mossy fiber to CA3 pyramidal cells synapses. J Neuroscience 2014 Aug 13;34(33):11032-47. doi: 10.1523/JNEUROSCI.0847-14.2014.

and K. Tóth (2014) Information processing and synaptic plasticity at hippocampal mossy fiber terminals. Frontiers in Cellular Neuroscience., 04 February 2014 | doi: 10.3389/fncel.2014.00028

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Profile

Biography

Information processing by single MF terminals (Collaboration with Drs Kirill Volynski, UCL and Yulia Timofeeva, U. Warwick)

Information processing by the dentate gyrus - CA3 network

Implications of feed-forward inhibition on network-level information processing (Collaborative work with Dr Richard Naud)

Experimental approaches

Research interests