Web page: Allen Institute for Brain Science
Dipl. Chem. Eng. ETH Zurich
Ph.D. Imperial College London
computational neuroscience, biophysics, large-scale simulations, computation, systems neuroscience, translational neuroscience
Costas Anastassiou holds the position of senior scientist at the Allen Institute for Brain Science (Seattle, USA) concurrently with the position of adjunct professor at UBC. After completing his undergraduate studies in the department of chemical engineering at ETH Zurich, Anastassiou conducted his doctoral work in the department of bioengineering at Imperial College London, under the supervision of Danny O’Hare and Kim H. Parker, on techniques to analyze nonlinear data collected in electrochemical experiments. From 2007 until 2013 he was postdoctoral fellow at the laboratory of Christof Koch at the California Institute of Technology (Caltech) where his work was supported by a number of national and international research funding agencies. Before joining Caltech he also worked at the Massachusetts Institute of Technology in the department of mathematics with Martin Bazant on modeling reaction-(electro)diffusion processes occurring in the vicinity of charged surfaces.
My research explores how neurons in the mammalian brain integrate information and how such cooperative activity gives rise to percepts and concepts. Our approach is best described by the triptych “signals, systems and psyche”: by detailed comprehension of signals elicited by the brain, we seek to understand computation during a behavioral task (systems) and how such processing gives rise to a high-level, behavioral readout (psyche). We pursue such work at different levels of granularity – from lower-level biophysics of neurons and small networks to higher-level functions such as visual processing and behavior (perception, etc.)
How do neurons and circuits encode sensory input and how is it decoded in downstream areas? Which part is internally generated vs. which part is generated upstream? Furthermore, processing such as oscillatory functioning and nonlinear dendritic integration have been suggested as a means for different brain regions to communicate. To what extent is this true and what type/mode of communication can such processing support? These are some of the biophysics-related questions we seek to address in my laboratory.
With regards to higher level functioning, we focus on visual cortex processing where a number of theories have been suggested to explain how fundamental response properties such as orientation tuning of neurons and networks arise. Since the revolutionary work of Hubel and Wiesel, many classes of theories have been proposed attempting to explain the emergence of such properties. How many of these theories are plausible given what we know about synapses and neurons in visual cortex? Which of these postulations are most feasible and robust? These questions can be extended to more conceptual models of visual processing and object recognition where it remains unknown which aspects of the suggested computations can be realized based on the detailed biophysics of neurons and networks. Here, the aim of our work is to bridge the gap between computational vision and cellular biophysics and suggest bio-inspired strategies linking both worlds.
Finally, an important aim of my lab is to study the emergence of conscious processing and the minimal biophysical structures that support it. In particular, we pursue simulation work combined with slice and in vivo experiments to unravel the relationship between the recorded EEG-signal, the underlying neural and synaptic mechanisms eliciting it and the behavioral readout in rodents. Initial efforts focus on the cortical EEG-signature of evoked potentials spanning ~40 ms in rodents (~120 ms in humans). Interestingly, the fact that the brain can infer the category of, say, a picture (e.g., animal vs. animal-free pictures) does not necessarily mean this information is consciously accessible at such short period as so-called ‘masking’ experiments have revealed. Such experience, for example for visual stimuli, and the formation of percepts is accompanied by robust neural activities such as sustained activity in cortical areas, amplification of perceptual processing, emergence of correlations across distant regions, joint parietal, frontal, and cingulate activation, gamma-band oscillations, and, finally, late components of the EEG- waveform. What is the biophysics involved and the flow of information during cognitive processing, what are the critical hubs and how is their activity related to the EEG? Formulating hypotheses of how to selectively suppress or enhance activity in these hubs both is key in the research pursued in my lab.
To unravel how micro- (synapses, etc.) and meso-scale (single neurons, neural ensembles) brain processing gives rise to high-level, behavioral functioning we heavily rely on the development of comprehensive, data-driven, biophysically realistic simulations to emulate system-level brain dynamics constrained by in vitro and in vivo experiments. Such simulations help us formulate scientific questions, test various hypotheses on the emergence of specific cellular and network dynamics as well as assess a multitude of time-series analysis tools.
Though primarily theoretical/computational, our lab is collaborating with a number of external partners to define questions, design experiments and acquire data to test our hypotheses and elaborate our ideas on cortical computation. In the past we have heavily relied on brain slice and in vivo electrophysiology (whole cell patch-clamping, parallel extracellular voltage recordings, etc.) and optical monitoring techniques (Ca-imaging).
Interested graduate students and postdoctoral fellows should contact Dr. Anastassiou for current lab openings and employment opportunities.
Schaub*, M T; Billeh*, Y N; Anastassiou, C A; Koch, C; Barahona, M. Emergence of slow activity in structured networks PLoS Computational Biology (in press)
Anastassiou, C A; Koch, C (2015). Ephaptic coupling to endogenous field activity: bug or feature? Current Opinion in Neurobiology 31(1): 95-103. (Opinion article)
Shai, A S; Anastassiou, C A; Larkum, M; Koch, C (2015) Physiology of layer 5 pyramidal neurons in mouse primary visual cortex: a biophysical mechanism for cortical coincidence detection through bursting PLoS Computational Biology, Mar 13;11(3):e1004090
Schomburg*, E W; Fernandez-Ruiz*, A; Berenyi, A; Mizuseki, K; Anastassiou, C A; Koch, C; Buzsa?ki, G (2014) Theta phase segregation of input-specific gamma patterns in entorhinal-hippocampal networks Neuron, 84(2), 470-485.
Reimann*, M W; Anastassiou*, C A; Perin, R; Hill, S; Markram, H; Koch, C (2013). A biophysically detailed model of neocortical local field potentials predicts the critical role of active membrane currents Neuron, 79(2): 375-390.
Schomburg, E W; Anastassiou, C A; Buzsa?ki, G; Koch, C (2012). The spiking component of oscillatory extracellular potentials in the rat hippocampus Journal of Neuroscience, 32(34): 11798-11811.
Buzsa?ki, G; Anastassiou, C A; Koch, C (2012). Origin of extracellular fields and currents: EEG, ECoG, LFP and spikes Nature Reviews Neuroscience, 13: 403-420 (Review article)
Anastassiou*, C A; Perin*, R; Markram, H; Koch, C (2011). Ephaptic communication in cortical neurons Nature Neuroscience, 14(2): 217-223.
Anastassiou, C A; Montgomery, S M; Barahona, M; Buzsa?ki, G; Koch, C (2010) The effect of spatially inhomogeneous extracellular electric fields on neurons Journal of Neuroscience, 30(5): 1925-1936.