Research areas

The research we carry out in our laboratory can be divided into four broad areas: “systems neuroscience,” “formulating theories of motor learning,” “creating neuro-connect technology and applying it to neurorehabilitation,” and “primate research on neuroregeneration using common marmosets.” However, these research areas are not kept separate. In reality, we mix multiple themes to varying degrees until they crystallize into individual research topics. For example, we approach problems in systems neuroscience by using electrophysiological methods and neuroimaging techniques to describe physiological phenomena. On the other hand, to uncover the processes by which the brain learns to move the body in line with changes in the external environment or the physical condition of the body, we also need an approach in which systems are described based on control theory, with the brain serving as the controller and the limbs as plants. We are working to develop our experimental and theoretical knowledge into research that aims to create a new form of therapy: neuro-connect technology. We are also working on model animal research using common marmosets that aims to gain a true understanding of the mechanisms of the nervous system—mechanisms that research on human subjects can only let us guess at.

Research areasystems neuroscience

We have precise control over the limb movements that we usually execute without thinking, because feedback information from sensory receptors situated throughout the entire body constantly influences the movement commands that are generated by the countless neurons in the brain and the spinal cord. We use electrophysiological methods and neuroimaging techniques to study not only the motion control mechanisms that are part of this sensorimotor loop, but also the mechanisms that allow the nervous system to adapt flexibly to the external environment. For example, we measure the electrical activity in the brain and the muscles, then analyze it through time series modeling and frequency transfer functions. That allows us to uncover how nervous information inside the brain and the body is processed, and also to detect changes in neural structure due to exercise training (by using MRI images to determine the routes formed by the nerve bundles and the volume of the brain). Examining “function” and “structure” in an integrated way should allow us to get a full view of the brain system that is involved in physical exercise for the first time. We apply the findings and analytical techniques obtained in the course of our work to clinical research in an attempt to improve our understanding of various pathophysiologies that cause motor and sensory impairments, including strokes and dystonia.

 

EEG measurement systems, EMG measurement systems, transcranial magnetic stimulation devices, electrical stimulation devices

Research areaformulating theories of motor learning

Why does our motor function improve when we practice in order to become proficient at a sport or a musical instrument, or when we undergo rehabilitation after our motor function is impaired through an injury or nervous system disorder? We use control theory to describe the mechanisms through which the brain learns the optimal ways to move the body in line with changes in the external environment or the physical condition of the body, confirm these mechanisms through behavioral experiments, and explain the results of these experiments using mathematical models. For example, we conduct behavioral experiments that involve a robot manipulandum executing reaching tasks. In these experiments, we artificially manipulate the information that is fed back to the brain, which functions as the controller, as well as the mechanical properties of the arm, which functions as the plant. In this way, we introduce errors that allow us to observe how the motion learning system responds. Analyzing the resulting data from a control engineering perspective may enable us to uncover the essence of the system by looking at its input-output relations. Another one of our goals is to use the findings we obtain to predict learning conditions in pathological models in which part of the system is damaged, then develop more effective rehabilitation methods.

 

Robotic manipulanda for upper-limb exercise (KINARM, PHANTOM), transcranial magnetic stimulation devices, EMG measurement systems, MRI devices

Research area creating neuro-connect technology and applying it to neurorehabilitation

When part of the nervous system is damaged through injury or illness, this has a negative impact on the flow of nervous information, leading to somatosensory and motor impairments. We work on developing medical treatment devices that can fix damage inflicted on the flow of nervous information. These devices include a headset that can monitor the status of the movement commands generated by the brain, and a robotic device that can amplify the somatosensory sensations that are generated when hands or feet move. The Brain-Machine Interface (BMI), for example, involves a machine helping a paralyzed hand move in response to brain activity. Even when someone suffers from severe motor impairment as a result of nervous system injuries or illness, the BMI assists the patient in practicing voluntary movements, helping the brain re-learn the patterns of neural activity that are needed to bring about movement. This allows the patient to recover motor functions. Besides the BMI, we are also working on a glove that strengthens functional connections between cooperating muscles at brain level to efficiently adjust the smooth movement of the hand, and on an orthotic device that uses nerve stimulation functions to stimulate the rhythm generators that are present in the nervous system. In this form of therapy, machines help recover lost nerve functions, setting it apart from prosthetic therapies that seek to use machines to substitute for lost physical functions. We want to create more of these new technologies of the future. Neuro-connect technology, which reconnects functionally disconnected neurons, gives us hope that we can create next-generation therapies inside the science and engineering department. In 2017, a hospital in Tokyo finally opened a smart rehab room that will gradually introduce and use a combination of the therapeutic devices that we have developed. Our research approach is truly unique in the sense that we can let basic and clinical research stimulate each other, and we have high hopes for our future output.

 

EEG measurement systems, EMG measurement systems, electrical muscle stimulation devices, electric harnesses, upper-limb exercise assistance robots

Research areaRprimate research on neuroregeneration using common marmosets

When motor functions improve as a result of rehabilitation, what kind of changes occur in the brain and the spinal cord? Genes that work to repair injured nerves, molecules involved in nerve growth that are secreted as a result of gene switching, networks that are reconstructed by restored and surviving nerves, the conductivity of nervous information flowing through networks, regaining ways to generate nervous information itself… To gain a comprehensive understanding of these mechanisms of “brain healing” across hierarchical divides within the field of neuroscience, we began conducting research on model animals that have suffered strokes or spinal cord injuries, using applied molecular biological methods in conjunction with electrophysiological methods, biomechanical methods, and more. We recently succeeded in establishing a highly unique experimental system for simultaneously recording the activity of individual neurons in units of 100 under ambulatory conditions. By using animal models to conduct detailed studies, we can uncover information that can never be gained when only human subjects are used for research. We believe that this will help lead us to true understanding of the changes that occur in the sensory-motor system as a result of injuries and disorders of the central nervous system, and the processes that lead to recovery. Every day, we work hard to reach our goal of using cutting-edge basic science to create new rehabilitation techniques.

 

Neural potential recording systems, motion capture systems, microendoscopes