Jiannis Taxidis

After extensive training in Physics and Applied Mathematics, Jiannis Taxidis turned to Neuroscience. During his PhD at the University of Nottingham, UK, under the supervision of Professors Markus R. Owen and Robert Mason and during his first postdoctoral position at Caltech, CA, under the supervision of Prof. Christof Koch, he worked on complex computational modelling of cortico-hippocampal networks and intricate mathematical analyses of electrophysiological data. In his second postdoctoral position at UCLA in Professor Peyman Golshani’s lab, he made a radical transition to active experiments, specifically two-photon calcium imaging, voltage imaging and optogenetic manipulation in the hippocampus brain region of awake behaving mice. He joined SickKids in August 2022 as Scientist in the Neurosciences & Mental Health Program. He is also appointed as an Assistant Professor at the Department of Physiology, University of Toronto. His laboratory combines cutting-edge imaging experiments and computational modelling, focusing on network mechanisms underlying learning and memory consolidation in health and brain disorders. His goal is to understand how neuronal circuits collectively encode experiences and the temporal intervals between them, how they store those as memory and how these processes are disrupted in conditions associated with memory deficits.

Research

How does our brain turn our sequence of experiences into memory while also keeping track of their temporal relationships? How are sensory and time representations shaped and influenced by learning of a context or by memory recall? How are disrupted neuronal networks associated with memory deficits in brain disorders, like Alzheimer’s disease or schizophrenia? In his laboratory, Dr. Taxidis addresses these questions by combining (i) in vivo calcium and voltage imaging and optogenetic manipulations during complex behavioral assays in mice and (ii) computational modelling of neuronal network interactions and oscillations. He focuses mainly on recording, manipulating and modeling activity from neural circuits in the hippocampus while mice learn and perform olfactory-driven behavioral tasks which involve memory mechanisms.

Education and experience

• 2020–2022: Associate Project Scientist. Department of Neurology, University of California Los Angeles, Los Angeles, CA, USA.
• 2017–2020: Assistant Project Scientist. Department of Neurology, University of California Los Angeles, Los Angeles, CA, USA.
• 2013–2017: Postdoctroal Fellow. Department of Neurology, University of California Los Angeles, Los Angeles, CA, USA.
• 2011–2013: Postdoctroal Fellow. California Institute of Technology, Pasadena, CA, USA.
• 2007–2011: PhD in Mathematical Sciences. School of Mathematical Sciences, University of Nottingham, Nottingham, UK.
• 2005–2007: Master of Science (MSc) in Mathematical Sciences. Department of Mathematics, Utrecht University, Utrecht, The Netherlands.
• 2000–2005: Ptychion (Diploma) in Physics. Department of Physics, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece.

Achievements

• 2020: Scheibel Project Scientist Award, University of California Los Angeles, Los Angeles, CA , USA.
• 2016: Helmsley Interdisciplinary Fellowship, Cold Spring Harbor Laboratoy, Cold Spring Harbor, NY, USA.
• 2007–2010: Marie Curie Fellowship for Early Stage Research Training, Marie Curie Actions, University of Nottingham, Nottingham, UK.
• 2005–2006: Utrecht Excellence Scholarship, Utrecht University, Utrecht, The Netherlands.
• 2005: Huygens Scholarship, Nuffic Organization, Utrecht University, Utrecht, The Netherlands.

1. Taxidis J., Pnevmatikakis E., Dorian C.C., Mylavarapu A.L., Arora J.S., Samadian K.D., Hoffberg E.A., Golshani P. Differential emergence and stability of sensory and temporal representations in context-specific hippocampal sequences. Neuron. 108: 984–998, 2020.
2. *Lazaro M.T., *Taxidis J., Shuman T., Bachmutsky I., Ikrar I., Ikrar T., Santos R., Marcello G.M., Mylavarapu A., Chandra S., Foreman A., Goli R., Tran D., Sharma N., Azhdam M., Dong H., Choe K.Y., Peñagarikano O., Masmanidis M., Racz B., Xu X., Geschwid D., Golshani P. Reduced prefrontal synaptic connectivity and disturbed oscillatory population dynamics in the CNTNAP2 model of autism. Cell Reports, 27: 2567–2578, 2019. 
*Equal contribution.
3. Taxidis J., Anastassiou C.A., Diba K., Koch C. Local field potentials encode place cell ensemble activation during hippocampal sharp wave-ripples, Neuron, 87: 590–604, 2015.
4. Taxidis J., Mizuseki K., Mason R., Owen M.R. Influence of slow oscillation on hippocampal activity and ripples through cortico-hippocampal synaptic interactions, analyzed by a cortical-CA3-CA1 network model, Frontiers in Computational Neuroscience, 7: 1–19, 2013.
5. Taxidis J., Coombes S., Mason R., Owen M.R. Modeling sharp wave-ripple complexes through a CA3-CA1 network model with chemical synapses, Hippocampus, 22: 995–1017, 2012.

See a full list of Jiannis Taxidis' publications

Funding

• 2020–2022: Multiplexing working memory and timing: Encoding retrospective and prospective information in transient neural trajectories. Co-Investigator, NIH/NINDS Brain Initiative RO1, $1,841,418 USD