Motor behavior is generated by specific neural circuits. Those producing locomotion are located in the spinal cord, and their activation depends on descending inputs from brain or sensory inputs. In this study, we have used an <i>in vitro</i> brainstem-spinal cord preparation adult zebrafish to localize a region where stimulation of can induce sustained locomotor activity. We show that brief at junction between brainstem induces long-lasting swimming The frequencies induced remarkably...

In vertebrates, spinal circuits drive rhythmic firing in motoneurons the appropriate sequence to produce locomotor movements. These become active early during development and mature gradually acquire flexibility necessary accommodate increased behavioral repertoire of adult animals. The focus here is elucidate how different pools are organized recruited membrane properties contribute their mode operation. For this purpose, we have used <i>in vitro</i> preparation zebrafish. We show that...

Neural circuits in the spinal cord transform instructive signals from brain into well-coordinated locomotor movements by virtue of rhythm-generating components. Although evidence suggests that excitatory interneurons are essence rhythm generation, their molecular identity and assessment necessity have remained unclear. Here we show, using larval zebrafish, V2a represent an intrinsic source excitation necessary for normal expression rhythm. Acute selective ablation these increases threshold...

Neural networks in the spinal cord can generate locomotion absence of rhythmic input from higher brain structures or sensory feedback because they contain an intrinsic source excitation. However, molecular identity interneurons underlying excitatory drive within locomotor circuit has remained unclear. Using optogenetics, we show that activation a molecularly defined class ipsilateral premotor elicits locomotion. These represent module and are sufficient to produce coordinated swimming...

Significance Spinal neural networks generate locomotion. An adjustment of the locomotion speed entails a precise order recruitment excitatory interneurons (e.g., V2a interneurons) within these networks. We show, using adult zebrafish spinal cord, that is not topographic and does conform to input resistance. The incremental determined by scaling drive with also show locomotor are composed multiple microcircuits recruited in continuum. Thus, we provide insights into mechanisms ensure optimal...

The spinal locomotor central pattern generator (CPG) generates rhythmic activity with alternating flexion and extension phases. This is likely to result from inhibitory interactions between neural populations representing flexor extensor half-centers. However, it unclear whether the flexor-extensor CPG has a quasi-symmetric organization both half-centers critically involved in rhythm generation, features an asymmetric flexor-driven rhythmogenesis, or comprises pair of intrinsically There are...

The circuit organization within the mammalian brainstem respiratory network, specifically and between pre-Bötzinger (pre-BötC) Bötzinger (BötC) complexes, roles of these circuits in pattern generation are continuously debated. We address issues with a combination optogenetic experiments modeling studies. used transgenic mice expressing channelrhodopsin-2 under VGAT-promoter to investigate perturbations activity by site-specific photostimulation inhibitory neurons pre-BötC or BötC....

A series of recent studies identified key structures in the mesencephalic locomotor region and caudal brainstem mice involved initiation control slow (exploratory) fast (escape-type) locomotion gait. However, interactions these centers with each other spinal circuits are poorly understood. Previously we suggested that commissural long propriospinal interneurons main targets for inputs adjusting gait (Danner et al., 2017). Here, by extending our previous model, propose a connectome...

Studying the neural components regulating movement in human locomotion is obstructed by inability to perform invasive experimental recording circuits. Neuromechanical simulations can provide insights modeling locomotor Past neuromechanical models proposed control of either driven central pattern generators (CPGs) with simple sensory commands or a purely reflex-based network regulated state-machine mechanisms, which activate and deactivate reflexes depending on detected gait cycle phases....

SUMMARY Pymetrozine is a neuroactive insecticide but its site of action in the nervous system unknown. Based on previous studies symptoms locust, feedback loop controlling femur–tibia joint middle leg was chosen to examine possible targets insecticide. The femoral chordotonal organ, which monitors position and movement, turned out be primary pymetrozine action, while interneurons,motoneurons central motor control circuitry general did not noticeably respond organs associated with wing hinge...

ABSTRACT Spatially invariant feature detection is a property of many visual systems that rely on information provided by two eyes. However, how across both eyes integrated for not fully understood. Here, we investigated spatial invariance looming responses in descending neurons (DNs) Drosophila melanogaster. We found multiple responsive DNs integrate eyes, even though their dendrites are restricted to single hemisphere. One DN, the giant fiber (GF), responds invariantly stimuli tested...

Abstract Studying the neural components regulating movement in human locomotion is obstructed by inability to perform invasive experimental recording. Neuromechanical simulations can provide insights modeling locomotor circuits. Past neuromechanical models proposed control of either driven central pattern generators (CPGs) with simple sensory commands or a purely reflex-based network regulated state-machine mechanisms. However, physiological interpretation these state-machines remains...

The sensory system plays a key role in the generation of behavior by providing nervous with information about environment and feedback body movements such that motor output can continuously be adapted to changing circumstances. Although effects organs on function have been demonstrated many systems, impact activity has rarely studied conditions which interact as they do behaving animals. In situations, emergent properties may surface govern characteristics system. We dynamics sensorimotor...

Abstract Central pattern generators are circuits generating rhythmic movements, such as walking. The majority of existing computational models these produce antagonistic output where all neurons within a population spike with broad burst at about the same neuronal phase respect to network output. However, experimental recordings reveal that many fire sparsely, sometimes rarely once cycle. Here we address sparse firing and develop model replicate behavior individual rhythm-generating...

Locomotion is a complex process involving specific interactions between the central neural controller and mechanical components of system. The basic rhythmic activity generated by locomotor circuits in spinal cord defines limb movements their coordination. operation these modulated sensory feedback from limbs providing information about state body. However, role contribution control gait posture remain poorly understood. We use biomechanical data on quadrupedal locomotion mice recent...

Synapses are often precisely organized on dendritic arbors, yet the role of synaptic topography in integration remains poorly understood. Utilizing electron microscopy (EM) connectomics we investigate Drosophila melanogaster looming circuits, focusing retinotopically tuned visual projection neurons (VPNs) that synapse onto descending (DNs). a given VPN type project to non-overlapping regions DN dendrites. Within these spatially constrained clusters, synapses not organized, but instead adopt...

Abstract Locomotion is a complex process involving specific interactions between the central neural controller and mechanical components of system. The basic rhythmic activity generated by locomotor circuits in spinal cord defines limb movements their coordination. operation these modulated sensory feedback from limbs providing information about state body. However, role contribution control gait posture remain poorly understood. We use biomechanical data on quadrupedal locomotion mice...