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Yukari OHKI
Ph.D. (Tokyo University)Associate Professor in 1st Department of Physiology, Kyorin University School of Medicine
Sensory-motor control of human finger movements
Research theme:
The goal of our research is to reveal how humans' central nervous system (CNS) supports our extraordinary ability to manipulate external objects with hands, where the objects may have various physical properties and must be operated under different situations and for different purposes. Because our hands have many degrees of freedom, CNS would control tens of hand muscles separately to manipulate a novel object with unknown properties. However we are not very dexterous in such a case. Indeed for CNS to calculate control commands for each muscles should be rather energy- and time-consuming. In contrast when we handle familiar objects, or unfamiliar objects whose properties can be predicted, our hands behave very smoothly. In the situation CNS might control the muscles in groups based on sensory-motor memories. Recently it is suggested that we acquired multiple such memories in CNS, and select the most appropriate one(s) depending on current object and situation. Our research theme is to prove function of sensory-motor memories in human motor control and reveal parts of CNS which involve in them.
Experimental approach:
For analyzing manipulative movements of human during multi-digit manipulative task, we use specially designed instrumentation with multiple grip plates (objects). With the instrumentation we recorded multidimensional fingertip forces and movements, and control behaviors (timing, direction, speed, amplitude etc.) of the objects individually by laboratory computer. In addition we monitor motoneuronal signals with multichannel EMG, and CNS signals with multi channel EEG. In some experiments, we use transcranial magnetic stimulation to simulate or inhibit cortical cells during the task. We also analyze manipulative behaviors of neurological patients to reveal nervous areas which are essential for the task.
Current research projects:
- Evaluation of sensory-motor memory selection by observing reflexive (possibly transcortical) movements
- Time course of switching between acquired sensory-motor memories
- Involvement of cerebral cortices in sensory-motor memories by using magneto-cortical stimulation techniques
- Analysis of motor behavior by neurological patients to reveal brain areas which involve in sensory-motor memories
Collaborators:
Roland S. Johansson (Umeå University, Sweden)
Benoni B. Edin (Umeå University, Sweden)
Kanae Watanabe (Shinshu University)
Satoshi Shibuya (Ph.D. student in Tokyo Gakugei University)
Spinal system for motor command integration
Bror Alstermark (Umeå University, Sweden)
Tadashi Isa (NIPS)
Contact Info:
contact person:Yukari Ohki
address: Department of Physiology, Kyorin University School of Medicine, Shinkawa, Mitaka, Tokyo 181-8611
tel: +81 422 47 5511 ext. 3445
fax: +81 422 44 1816
e-mail: ohkiy@kyorin-u.ac.jp
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