Hirokazu Takahashi was born in Sendai, Japan, in 1975. He received B.S., M.S., and Ph.D. degrees in mechanical engineering from the University of Tokyo, Tokyo, Japan, in 1998, 2000, and 2003, respectively. After working as a research associate in Department of Engineering Synthesis, the University of Tokyo, he has joined Department of Mechano-Informatics, the Graduate School of Information Science and Technology, the University of Tokyo, as an assistant professor since 2004. In 2006, he has joined the Research Center for Advanced Science and Technology. His current research interests include areas of biomedical engineering ranging from rehabilitation engineering for restoring lost functions to experimental neurophysiology for understanding fundamental brain functions.
|How does intelligence emerge from a neuronal network in the brain? To address
this fundamental question, dissociate neuronal culture may inspire us.
In the dissociate culture, neurons seeded onto a petri dish form a network
in a self-organizing manner. In addition, this neural network flexibly
alters the activities depending on external stimuli and developmental age.
Such spatio-temporal activity pattern must be helpful to reveal the design
principle of these networks.
Various innovative technologies are easily applicable in the dissociate culture. For example, we demonstrated that a high-dense CMOS array with 10,000 recording sites within 2 x 2 mm2 is able to track the propagation of action potentials within the network. The dissociate culture can be also genetically modified such that photoreceptors and odorant receptors are extrinsically expressed within the network. Such a network may be used as a bio-silicon hybrid sensor.
Inspired by recent theoretical advances in the field of reservoir computing, we also attempt to use the neuronal culture as a reservoir. A robot embodied by reservoir computing sometimes exhibits complex, living-organism-like behaviors.
|Dissociate neuronal culture
High-dense CMOS array
|How does the brain differ from computers when representing external world?
How does our conscious perception emerge in the brain, but not in computers?
Unlike transistors in computers, each neuron exhibits heterogeneous characteristics.
Now, the largest missing link is how such heterogeneous information is
integrated. To address this question, we gather "big data" from
the cortex in rats with various microelectrode arrays, and analyze them
using information theory and machine learning techniques. We also employ
behavior experiments to reveal how subjective information such as ongoing
conscious perception, preference, emotion, saliency, valence, etc., are
encoded in the neural activity patterns of animals.
Owing to cutting-edge, high-density mapping of neural activities, we are able to characterize precise, local synchrony patterns in the auditory cortex, and are able to investigate the thalamo-cortical interaction in terms of information transfer. Such 'state' of the brain emerging from interaction between top-down and bottom-up activities are more informative than we thought, offering a future direction in a research field of sensory computation.
|Epileptic seizure is a disorganized state of the brain. We would like to
understand how and why seizures occur, and establish treatments to avoid
and control seizures.
Taking advantage of intra-cortical, high-density mapping, we are investigating functional networks within the brain of epileptic patients and epileptic model of animals. The network properties exhibit long-term fluctuation, which may be critical to predict seizures and to understand pathological conditions of seizure. Of our particular interest is the vagus nerve stimulation (VNS), which may exert modulation in the cortical synchronous activities. VNS is effective not only for seizure inhibition, but also for enhancement of cognitive performance. Thus, by better understanding the mechanism of actions of VNS as well as the mechanisms of seizure, we may gain insights into cortical computation.
Intracortical electrode array for ECoG recording
- Prof. Kenske Kawai (NTT Kanto Hospital) (link)
- Dr. Naoto Kunii (Univ. Tokyo)
Hirokazu Takahashi, Masayuki Nakao, Yataro Kikuchi, and Kimitaka Kaga: “Alaryngeal speech aid using an intra-oral electrolarynx and a miniature fingertip switch.” Auris Nasus Larynx 32 (2): pp. 157-162, 2005 (link)
Hirokazu Takahashi, Masayuki Nakao, and Kimitaka Kaga: “Accessing ampli-tonotopic organization of rat auditory cortex by microstimulation of cochlear nucleus.” IEEE Transactions on Biomedical Engineering 52 (7): pp. 1333-1344, 2005 (link)
Hirokazu Takahashi, Takayuki Ejiri, Masayuki Nakao, Naoya Nakamura, Kimitaka
Kaga, and Thierry Hervé: “Microelectrode array on folding polyimide ribbon
for epidural mapping of functional evoked potentials.”IEEE Transactions
on Biomedical Engineering 50 (4): pp. 510-516, 2003 (link)
Takahiro Noda, and Hirokazu Takahashi: “Anesthetic effects of isoflurane on the topographic map and neuronal population activity in the rat auditory cortex.” European Journal of Neuroscience 42 (6): pp. 2298-2311, 2015 (doi: 10.1111/ejn.13007) (link)
Tomoyo I. Shiramatsu, Kazusa Takahashi, Takahiro Noda, Ryohei Kanzaki, Haruka Nakahara, and Hirokazu Takahashi: “Microelectrode mapping of tonotopic, laminar, and field-specific organization of thalamo-cortical pathway in rat.” Neuroscience 332: pp. 38-52, 2016 (doi: 10.1016/j.neuroscience.2016.06.024) (link)
Jun Suzurikawa, Hirokazu Takahashi, Ryohei Kanzaki, Masayuki Nakao, Yuzo Takayama, and Yasuhiko Jimbo: “Light-addressable electrode with hydrogenated amorphous silicon and low-conductive passivation layer for stimulation of cultured neurons.” Applied Physics Letters 90 (9): Art. No.093901 (3pp), 2007 (link)
Norio Tanada, Takeshi Sakurai, Hidefumi Mitsuno, Douglas J. Bakkum, Ryohei Kanzaki, Hirokazu Takahashi: “Dissociated neuronal culture expressing ionotropic odorant receptors as a hybrid odorant biosensor – proof-of-concept study –.” Analyst 137 (15): pp. 3452-3458, 2012 (link)
Douglas J. Bakkum, Urs Frey, Milos Radivojevic, Thomas L. Russell, Jan Müller, Michele Fiscella, Hirokazu Takahashi, Andreas Hierlemann: “Tracking axonal action potential propagation on a high-density microelectrode array across hundreds of sites.” Nature Communications 4: Art. No. 2181 (12 pp), 2013 (doi: 10.1038/ncomms3181) (link)
Hirokazu Takahashi, Masayuki Nakao, and Kimitaka Kaga: “Interfield differences
in intensity and frequency representation of evoked potentials in rat auditory
cortex.” Hearing Research 210 (1-2): pp. 9-23, 2005 (link)
Hirokazu Takahashi, Ryo Yokota, and Ryohei Kanzaki: “Response variance in functional maps: Neural Darwinism revisited.” PLOS ONE 8 (7): e68705 (7 pp), 2013 (doi:10.1371/journal.pone.0068705) (link)
Hirokazu Takahashi, Ryo Yokota, Akihiro Funamizu, Hidekazu Kose, Ryohei
Kanzaki: “Learning-stage-dependent, field-specific, map plasticity in the
rat auditory cortex during appetitive operant conditioning.”Neuroscience
199: pp. 243-258, 2011 (link)
Akihiro Funamizu, Ryohei Kanzaki, and Hirokazu Takahashi: “Pre-attentive, context-specific representation of fear memory in the auditory cortex of rat.” PLOS ONE 8 (5): e63655 (14 pp), 2013 (link)
Takahiro Noda, Ryohei Kanzaki, and Hirokazu Takahashi: “Stimulus phase locking of cortical oscillation for auditory stream segregation in rats.” PLOS ONE 8 (12): e83544 (14 pp), 2013 (link)
Tomoyo I. Shiramatsu, Ryohei Kanzaki, and Hirokazu Takahashi: “Cortical mapping of mismatch negativity with deviance detection property in rat.” PLOS ONE 8 (12): e82663 (10 pp), 2013 (link)
Hirokazu Takahashi, Shuhei Takahashi, Ryohei Kanzaki, Kensuke Kawai: “State-dependent precursors of seizures in correlation-based functional networks of electrocorticograms of patients with temporal lobe epilepsy.” Neurological Sciences 33 (6): pp. 1355-1364, 2012 (link)
Hirokazu Takahashi, Ph. D.
4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan