ABOUT

Yasushi Kobayashi, Ph.D., Associate Professor

Osaka University Graduate School of Frontier Biosciences, Laboratories for Neuroscience Visual Neuroscience Group

1-4 Yamadaoka, Suita, Osaka 565-0871 JAPAN

Tel (direct): +81-6-6877-6805, 090-3924-2764, Fax: +81-6-6879-4438 yasushi@fbs.osaka-u.ac.jp

Dr. Kobayashi received a B.S. and M.C. degree in Neurophysiology from Osaka University in 1991, where he obtained training on neurophysiology by Dr. Fujio Murakami. Then, he worked for Panasonic Research Labs, where he worked with Dr. Tadayasu Mitsumata (biosensors), Dr. Keisuke Toyama (Kyoto Pref. Univ. Med.: Plasticity of primary visual cortex), Dr Kenji Kawano (ETL: Oculomotor control) and Dr. Mitsuo Kawato (ATR: Cerebellar motor learning). He received his Ph.D. degree in Neurophysiology in 1998 from Osaka University. From 1998, he worked as a research associate at National Institute for Physiological Sciences Okazaki with Dr. Tadashi Isa (Neural control of movement) and he worked with Dr. Doug Munoz (Neural control of saccades) at Queen’s University Canada. Since 2002, Dr. Kobayashi has been an associate professor in Osaka University Graduate school of Frontier Biosciences within the Laboratory of Visual Neuroscience Research Group. His laboratory (Prof. Izumi Ohzawa PhD) explores how the cerebral cortex processes visual information and how the brain converts visual information into eye movements.

Research Interests:

Cerebellar motor learning. Many theories of cerebellar motor learning propose that complex spikes (CS) provide essential error signals for learning and modulate parallel fiber inputs that generate simple spikes (SS). These theories, however, do not satisfactorily specify what modality is represented by CS or how information is conveyed by the ultra-low CS firing rate (1 Hz). To further examine the function of CS and the relationship between CS and SS in the cerebellum, CS and SS were recorded in the ventral paraflocculus (VPFL) of awake monkeys during ocular following responses (OFR) with Dr. Kenji Kawano (Kyoto University). Now, we (collaboration with Dr. Mitsuo Kawato) are deeply analyzing the data in relation to synchronization and de-synchronization of the CS and chaos and its motor learning effect.

Cholinergic signaling and sensory-motor control systems. The cholinergic pedunculopontine tegmental nucleus (PPTN) is one of the major ascending arousal systems in the brain stem, and is linked to motor and limbic systems. We hypothesize that PPTN is related to integrative control of movement in behaving animals, and present a new model of the PPTN's involvement in the control of arousal, attention and reinforcement aspects of motor behavior, with a focus on the control of saccades. We are investigating the relationship between the task performance and activity of PPTN neurons during visually guided saccade task and the effects of reward schedule on them.

Related papers:

Yamamoto K, Kobayashi Y, Takemura A, Kawano K, and Kawato M: Computational Studies on Acquisition and Adaptation of Ocular Following Responses Based on Cerebellar Synaptic Plasticity. J Neurophysiol 87: 1554-1571, 2002

Yamamoto K, Kobayashi Y, Takemura A, Kawano K, Kawato M: A mathematical analysis of the characteristics of the system connecting the cerebellar ventral paraflocculus and extraoculomotor nucleus of alert monkeys during upward ocular following responses. Neurosci Res 2000 Dec; 38(4):425-35

Kobayashi Y, Kawano K, Takemura A, Inoue Y, Kitama T, Gomi H, Kawato M: Temporal Firing Patterns of Purkinje Cells in the Cerebellar Ventral Paraflocculus During Ocular Following Responses in Monkeys. II. Complex Spikes. J. Neurophysiol, 80: 832-848, 1998

Yamamoto K, Kobayashi Y, Kawano K, Takemura A, Kawato M: A mathematical model that reproduces vertical ocular following responses from visual stimuli by reproducing by simple spike firing frequency of Purkinje cells in the cerebellum. Neurosci. Res 29: 161-169, 1997

Kobayashi Y, Inoue Y, Yamamoto M, Isa T and Aizawa H: Contribution of Pedunculopontine Tegmental Nucleus Neurons to Performance of Visually Guided Saccade Tasks in Monkeys. J Neurophysiol 88: 715-731, 2002.

Kobayashi Y and Isa T: Sensory-motor gating and cognitive control by the brainstem cholinergic system. Neural Networks　15: 731-41, 2002

Aizawa H, Kobayashi Y, Yamamoto M, and Isa T: Injection of Nicotine Into the Superior Colliculus Facilitates Occurrence of Express Saccades in Monkeys. J.Neurophysiol. 82: 1642-1646, 1999