Relationship Between Autonomous and Evoked Activities in a Living Neuronal Network of a Neurorobot, 'Vitaenoid'.

摘要

Toward neuroprostheses, establishing a model system for bi-directional communication between a living neuronal circuit and electrical devices is critical. We developed a neu-rorobot with a dissociated hippocampal culture system. Small neuronal circuits on a culture dish with planar microelectrode arrays were used to detect the electrical activity patterns of a neuronal circuit. Responses of neurons against an input fluctuate by internal autonomous activity. If this fluctuation includes certain information, the interface should detect such embedded information. Thus, handling such fluctuation of autonomous activity is critical, which is the focus of this research. In this study, we proposed neurorobot system as a model system for bidirectional communication between a living neuronal circuit and a robot body. We call this system " Vitaenoid, " which means the robot like (-oid) livs (Vitae) with Neuron (N). To illustrate Vitaenoid, we attempted a self-organizing map (SOM) based method for generating robot behavior. SOM was designed so that the distribution of winner nodes reflected the trend of spatiotemporal electrical patterns. We confirmed that the SOM-based " Vitaenoid " performed a collision avoidance behavior, and the distribution of winner node revealed that some parts of spontaneous activity shared the patterns with evoked responses and suggested that the spontaneous activity and evoked responses were not strictly discriminated. In addition, the ratio of winners shared with spontaneous activity tended to decrease during a 60-min-robot-run. Inputs from outer world to a living neuronal circuit are considered not to be tightly coupled to their response patterns, instead of that, they loosely coupled with the specific activity pattern, which is also expressed as spontaneous activity. We propose this hypothesis as "the loose-coupling hypothesis in input-and-output relationship of the neuronal circuit".