Inspiratory and expiratory rhythms in mammals are thought to be generated by pacemaker-like neurons in 2 discrete brainstem regions: pre-Bö tzinger complex (preBö tC) and parafacial respiratory group (pFRG). How these putative pacemakers or pacemaker networks may interact to set the overall respiratory rhythm in synchrony remains unclear. Here, we show that a pacemakers 2-way ''handshake'' process comprising pFRG excitation of the preBö tC, followed by reverse inhibition and postinhibitory rebound (PIR) excitation of the pFRG and postinspiratory feedback inhibition of the preBö tC, can provide a phase-locked mechanism that sequentially resets and, hence, synchronizes the inspiratory and expiratory rhythms in neonates. The order of this handshake sequence and its progression vary depending on the relative excitabilities of the preBö tC vs. the pFRG and resultant modulations of the PIR in various excited and depressed states, leading to complex inspiratory and expiratory phase-resetting behaviors in neonates and adults. This parsimonious model of pacemakers synchronization and mutual entrainment replicates key experimental data in vitro and in vivo that delineate the developmental changes in respiratory rhythm from neonates to maturity, elucidating their underlying mechanisms and suggesting hypotheses for further experimental testing. Such a pacemakers handshake process with conjugate excitation-inhibition and PIR provides a reinforcing and evolutionarily advantageous fail-safe mechanism for respiratory rhythmogenesis in mammals.entrainment ͉ parafacial respiratory group ͉ postinhibitory rebound ͉ preBö tzinger complex ͉ rhythm P acemaker bursting and beating are profound emergent behaviors at the single-cell level that are fundamental to a myriad of biological rhythms (1, 2). How distinct oscillators may synchronize at the network level to produce an ensemble rhythm in unison is an important question for many periodic phenomena in nature (3-5). In mammalian respiration, pacemaker-like neurons have been identified in 2 discrete regions in the rostral ventrolateral medulla (VLM): the pre-Bötzinger complex (preBötC) (6) and parafacial respiratory group (pFRG) (7-9). The demonstrated plurality of respiratory-related pacemakers has led to divergent hypotheses regarding the mechanism of respiratory rhythmogenesis in mammals: (i) the preBötC and pFRG rhythmogenic populations represent coupled inspiratory and expiratory rhythm generators (IRG, ERG) that separately drive inspiration and expiration (10-13); and (ii) pFRG neurons represent the master rhythm generator that not only sets the expiratory rhythm but also entrains inspiratory bursts (9,14).Both hypotheses appear to be well-founded and supported by relevant experimental data. Yet, both leave major questions unanswered. For one, how can the IRG and ERG synchronize without a master rhythm generator? Conversely, if the pFRG is a master rhythm generator, then why does breathing persist after its lesioning (9, 15)?To resolve the dilemma, we propose a mathematical model...

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A version of this paper with color figures is available online at http://dx.doi.org/10.1162/ artl_a_00088. Subscription required.Abstract Anthropomimetic robotics differs from conventional approaches by capitalizing on the replication of the inner structures of the human body, such as muscles, tendons, bones, and joints. Here we present our results of more than three years of research in constructing, simulating, and, most importantly, controlling anthropomimetic robots. We manufactured four physical torsos, each more complex than its predecessor, and developed the tools required to simulate their behavior. Furthermore, six different control approaches, inspired by classical control theory, machine learning, and neuroscience, were developed and evaluated via these simulations or in small-scale setups. While the obtained results are encouraging, we are aware that we have barely exploited the potential of the anthropomimetic design so far. But, with the tools developed, we are confident that this novel approach will contribute to our understanding of morphological computation and human motor control in the future.

Abstract-Anthropomimetic robotics differ from conventional approaches by capitalizing on the replication of the inner structures of the human body, such as muscles, tendons, bones and joints [1]. Prominent examples for this class of robots are the robots developed at the JSK laboratory of the University of Tokyo and the robots developed by the EU-funded project Embodied Cognition in a Compliantly Engineered Robot (Eccerobot). However, the high complexity of these robots as well as their lack of sensors has so far failed to provide the desired new insights in the field of control.Therefore, we developed the simplified but sensorized robot Anthrob. The robot replicates the human upper limb and features 13 compliant tendon driven uni-and biarticular muscles as well as a spherical shoulder joint. Whenever possible, Selective Laser Sintering (SLS) was used for the production of the robot parts to reduce the production costs and to implement cutting-edge technologies, such as tendon canals or solid-state joints.