冠動脈バイパス術患者における術前アスピリン投与中止時期の検討

研究科: 千葉大学大学院医学薬学府学位:千大院医薬博甲第医1081号博士(医学)千葉大

COP Fixed Floor

COP data of human subjects on a fixed floor

COP Rotational Floor

COP data of human subjects on a rotational floor

Tilting Floor Motion

COP and Floor motion of subjects on slowly tilting floo

Rotational Floor Motion

COP position of subjects on rotational floo

Fixed Floor Motion

COP position of subjects on fixed floo

Simple analytical model reveals the functional role of embodied sensorimotor interaction in hexapod gaits

<div><p>Insects have various gaits with specific characteristics and can change their gaits smoothly in accordance with their speed. These gaits emerge from the embodied sensorimotor interactions that occur between the insect’s neural control and body dynamic systems through sensory feedback. Sensory feedback plays a critical role in coordinated movements such as locomotion, particularly in stick insects. While many previously developed insect models can generate different insect gaits, the functional role of embodied sensorimotor interactions in the interlimb coordination of insects remains unclear because of their complexity. In this study, we propose a simple physical model that is amenable to mathematical analysis to explain the functional role of these interactions clearly. We focus on a foot contact sensory feedback called phase resetting, which regulates leg retraction timing based on touchdown information. First, we used a hexapod robot to determine whether the distributed decoupled oscillators used for legs with the sensory feedback generate insect-like gaits through embodied sensorimotor interactions. The robot generated two different gaits and one had similar characteristics to insect gaits. Next, we proposed the simple model as a minimal model that allowed us to analyze and explain the gait mechanism through the embodied sensorimotor interactions. The simple model consists of a rigid body with massless springs acting as legs, where the legs are controlled using oscillator phases with phase resetting, and the governed equations are reduced such that they can be explained using only the oscillator phases with some approximations. This simplicity leads to analytical solutions for the hexapod gaits via perturbation analysis, despite the complexity of the embodied sensorimotor interactions. This is the first study to provide an analytical model for insect gaits under these interaction conditions. Our results clarified how this specific foot contact sensory feedback contributes to generation of insect-like ipsilateral interlimb coordination during hexapod locomotion.</p></div

Leg movement based on oscillator phase.

<p><b>A</b>: Oscillator phase. <b>B</b>: Desired leg movement. AEP and PEP represent the anterior extreme position and the posterior extreme position, respectively.</p

Interlimb phase relationships for locomotion speed.

<p><b>A</b>: Ipsilateral relative phases (fore leg–hind leg) for dogs and sheep versus Froude number (where the locomotion speed increases as the Froude number increases) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192469#pone.0192469.ref003" target="_blank">3</a>]. Dogs change their phase relationship suddenly at a Froude number of approximately 0.5, while sheep change their phase relationship smoothly based on locomotion speed. <b>B</b>: Ipsilateral relative phases ((fore leg–hind leg)/2) of stick insects for gait cycle (where the locomotion speed decreases as the gait cycle increases) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192469#pone.0192469.ref004" target="_blank">4</a>]. Data points and error bars show the average values and the errors of the mean values of the measured results, respectively. Stick insects change their phase relationships smoothly based on locomotion speed in a manner similar to sheep.</p

Evolution of the oscillator phases as a result of sensory feedback at each event.

<p>The sensory feedback provided at each event changes the relative phases.</p