Division of Neural Dynamics
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Unravelling the functional roles of neural dynamics
The brain can be regarded as a dynamical system, which is composed of a number of connected nonlinear elements (e.g., neurons and glial cells) and exhibits a wide variety of nonlinear dynamics in its activity. For instance, depending on the brain state, the human brain exhibits transient oscillations and synchronization at various frequency bands. We investigate functional roles of nonlinear neural dynamics such as oscillation, synchrony, metastability, and noise-induced phenomena in perception, cognition, motor, and social functions from a computational neuroscience perspective. We measure and analyze scalp electroencephalographic (EEG) signals in humans while human participants are engaged in cognitive tasks, at rest, or during noninvasive brain stimulation such as transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES). We also analyze electrocorticographic (ECoG), magnetoencephalographic (MEG), and functional magnetic resonance imaging (fMRI) data in humans, as well as imaging and electrophysiological data in distinct modalities in animals. We promote computational studies by data analysis and mathematical modeling based on nonlinear dynamical systems theory, information theory, signal processing theory, complex network analysis, and statistical machine learning theory. We also analyze clinical data for stroke and epilepsy patients obtained from collaborators and try to understand clinical symptoms in terms of altered neural dynamics and explore brain-machine interface applications. Moreover, we investigate the relationships between neural dynamics and modulating factors such as autonomic nervous activity and excitation/inhibition balance in neural circuits to understand the functional roles of neural dynamics from an integrative perspective.
We measure neural activity in humans by the TMS-EEG concurrent recording paradigm. Then we analyze the EEG data and mathematically model the neural dynamics to understand the functional roles of the neural dynamics.
Selected publications
*Ueda K, Nishiura Y, Kitajo K (2020) Mathematical mechanism of state-dependent phase resetting properties of alpha rhythm in the human brain. Neuroscience Research, 4387, 1-13*Okazaki YO, Mizuno Y, T. Kitajo K (2020) Probing dynamical cortical gating of attention with concurrent TMS-EEG. Scientific Reports, 10, 4959, 1-10.
*Glim S. Okazaki Y, Nakagawa Y, Mizuno Y, Hanakawa T. Kitajo K (2019) Phase-amplitude coupling of neural oscillations can be effectively probed with concurrent TMS-EEG. Neural Plasticity, 6263907, 1-14
*Kawano T et al. (2017) Large-scale phase synchrony reflects clinical status after stroke: An EEG study. Neurorehabilitation & Neural Repair, 31, 6, 561-570
*Kajihara T, Anwar MN, Kawasaki M, Mizuno Y, Nakazawa K, Kitajo K (2015) Neural dynamics in motor preparation: From phase-mediated global computation to amplitude-mediated local computation. NeuroImage 118, 445-455.