Neurobiology: Reconstructing the Neural Control of Leg Coordination

Zill, Sasha N.; Keller, Bridget R.

doi:10.1016/j.cub.2009.03.044

Cited by 3 publications

(2 citation statements)

References 18 publications

(22 reference statements)

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“…However, the fictive pattern is generally not identical to the pattern in the behaving animal, partly due to the absence of sensory input in the isolated nervous system [7][8][9][10][11][12][13]. Sensory inputs often have phase-specific actions, but they can also have longer-term actions on rhythmic motor systems, including activating or terminating motor patterns and modulating ongoing motor activity [2][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Neural circuit flexibility in a small sensorimotor system

Blitz

Nusbaum

2011

Current Opinion in Neurobiology

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Neuronal circuits underlying rhythmic behaviors (central pattern generators: CPGs) can generate rhythmic motor output without sensory input. However, sensory input is pivotal for generating behaviorally relevant CPG output. Here we discuss recent work in the decapod crustacean stomatogastric nervous system (STNS) identifying cellular and synaptic mechanisms whereby sensory inputs select particular motor outputs from CPG circuits. This includes several examples in which sensory neurons regulate the impact of descending projection neurons on CPG circuits. This level of analysis is possible in the STNS due to the relatively unique access to identified circuit, projection, and sensory neurons. These studies are also revealing additional degrees of freedom in sensorimotor integration that underlie the extensive flexibility intrinsic to rhythmic motor systems.

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Section: Introductionmentioning

confidence: 99%

Neural circuit flexibility in a small sensorimotor system

Blitz

Nusbaum

2011

Current Opinion in Neurobiology

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“…In order to coordinate body segments and limbs for movement, animals rely on both central mechanisms and sensory inputs (Skinner and Mulloney, 1998; Friesen and Cang, 2001; Yu and Friesen, 2004; Borgmann et al, 2009; Zill and Keller, 2009; Puhl and Mesce, 2010). The former includes endogenously rhythmic and centrally coupled central pattern generator neural networks (CPGs) that generate alternating activity in antagonistic motor neurons (MNs).…”

Section: Introductionmentioning

confidence: 99%

Intersegmental coordination of cockroach locomotion: adaptive control of centrally coupled pattern generator circuits

Fuchs

Holmes

Kiemel

et al. 2010

Front. Neural Circuits

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Animals’ ability to demonstrate both stereotyped and adaptive locomotor behavior is largely dependent on the interplay between centrally generated motor patterns and the sensory inputs that shape them. We utilized a combined experimental and theoretical approach to investigate the relative importance of CPG interconnections vs. intersegmental afferents in the cockroach: an animal that is renowned for rapid and stable locomotion. We simultaneously recorded coxal levator and depressor motor neurons (MN) in the thoracic ganglia of Periplaneta americana, while sensory feedback was completely blocked or allowed only from one intact stepping leg. In the absence of sensory feedback, we observed a coordination pattern with consistent phase relationship that shares similarities with a double-tripod gait, suggesting central, feedforward control. This intersegmental coordination pattern was then reinforced in the presence of sensory feedback from a single stepping leg. Specifically, we report on transient stabilization of phase differences between activity recorded in the middle and hind thoracic MN following individual front-leg steps, suggesting a role for afferent phasic information in the coordination of motor circuits at the different hemiganglia. Data were further analyzed using stochastic models of coupled oscillators and maximum likelihood techniques to estimate underlying physiological parameters, such as uncoupled endogenous frequencies of hemisegmental oscillators and coupling strengths and directions. We found that descending ipsilateral coupling is stronger than ascending coupling, while left–right coupling in both the meso- and meta-thoracic ganglia appear to be symmetrical. We discuss these results in comparison with recent findings in stick insects that share similar neural and body architectures, and argue that the two species may exemplify opposite extremes of a fast–slow locomotion continuum, mediated through different intersegment coordination strategies.

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