Flexible circuit mechanisms for context-dependent song sequencing

Many sequenced behaviors, including locomotion, reaching, and vocalization, are patterned differently in different contexts, enabling animals to adjust to their current environments. However, how contextual information shapes neural activity to flexibly alter the patterning of actions is not yet understood. Prior work indicates such flexibility could be achieved via parallel motor circuits, with differing sensitivities to sensory context [1, 2, 3]; instead we demonstrate here how a single neural pathway operates in two different regimes dependent on recent sensory history. We leverage the Drosophila song production system [4] to investigate the neural mechanisms that support male song sequence generation in two contexts: near versus far from the female. While previous studies identified several song production neurons [5, 6, 7, 8], how these neurons are organized to mediate song patterning was unknown. We find that male flies sing 'simple' trains of only one syllable or mode far from the female but complex song sequences consisting of alternations between modes when near to her. We characterize the male song circuit from the brain to the ventral nerve cord (VNC), and find that the VNC song pre-motor circuit is shaped by two key computations: mutual inhibition and rebound excitability [9] between nodes driving the two modes of song. Weak sensory input to a direct brain-to-VNC excitatory pathway (via pC2 brain and pIP10 descending neurons) drives simple song far from the female. Strong sensory input to the same pathway enables complex song production via simultaneous recruitment of P1a neuron-mediated disinhibition of the VNC song pre-motor circuit. Thus, proximity to the female effectively unlocks motor circuit dynamics in the correct sensory context. We construct a compact circuit model to demonstrate that these few computations are sufficient to replicate natural context-dependent song dynamics. These results have broad implications for neural population-level models of context-dependent behavior [10] and highlight that canonical circuit motifs [11, 12, 13] can be combined in novel ways to enable circuit flexibility required for dynamic communication.

Extrasynaptic signaling enables an asymmetric juvenile motor circuit to produce a symmetric mature gait.

Bilaterians generate motor patterns with symmetries that correspond to their body plans. This is thought to arise from wiring symmetries in their motor circuitries. We show that juvenile C. elegans larva has an asymmetrically wired motor circuit, but they still generate bending pattern with dorsal-ventral symmetry. In this juvenile circuit, wiring between excitatory and inhibitory motor neurons drives and coordinates contraction of dorsal muscles with relaxation of ventral muscles, producing dorsal bends. Ventral bending is not driven by its own circuitry. Instead, ventral muscles are excited uniformly by premotor interneurons through extrasynaptic signaling, and ventral bends occur in entrainment to the activity of motor neurons for dorsal bends. During maturation, the juvenile motor circuit is replaced by two homologous motor circuits that separately generate dorsal and ventral bending. Our modeling reveals that the juvenile circuit configuration provides an adequate solution for an immature motor circuit to drive functional gait long before the animal matures.

PLC Based DC Motor Speed Monitoring and Controlling System

PLC using rensans microcontroller for speed control of DC Gear Motor. in this project we will use rensans PLC for controlling the speed of operation of DC gear motor DC gear motor we can control with the help of pwm technique pulse width modulation. in this modulation we will very the weed width and control the DC gear motor speed. we will give 12 volt supply to DC motor and for controlling the speed we will put one circuit with the help of transistor between Rensans PLC and DC gear motor circuit used for pwm purpose the microcontroller give the pulses through transistor to the DC motor depending upon the pulses speed will vary in this pulses we will vary the on time and off time of the DC speed water if the on time is larger than the of time the speed of motor is increases and if the of time is larger than of time then speed will decreases this is a pwm technique pulse width modulation we will use in the project.

Influence of Flow Divider on Overall Efficiency of a Hydrostatic Drivetrain of a Skid-Steer All-Wheel Drive Multiple-Axle Vehicle

The efficiency of a skid-steer, all-wheel drive, multiple-axle vehicle with a hydrostatic drivetrain equipped with low-speed motors when it operates on soft terrain was studied. A flow divider enables a single pump to simultaneously power more than one motor circuit with different pressures in each. It prevents kinematic discrepancy and improves vehicle mobility. There are two types of flow divider: spool type and gear type, where each type has its own set of performance characteristics, such as flow range, pressure drop, accuracy and application parameters. In the present work, the influence of the characteristics of both types of flow divider on overall vehicle driveline efficacy is described.

Aberrant dynamics of cognitive control and motor circuits predict distinct restricted and repetitive behaviors in children with autism

Restricted and repetitive behaviors (RRBs) are a defining clinical feature of autism spectrum disorders (ASD). RRBs are highly heterogeneous with variable expression of circumscribed interests (CI), insistence of sameness (IS) and repetitive motor actions (RM), which are major impediments to effective functioning in individuals with ASD; yet, the neurobiological basis of CI, IS and RM is unknown. Here we evaluate a unified functional brain circuit model of RRBs and test the hypothesis that CI and IS are associated with aberrant cognitive control circuit dynamics, whereas RM is associated with aberrant motor circuit dynamics. Using task-free fMRI data from 96 children, we first demonstrate that time-varying cross-network interactions in cognitive control circuit are significantly reduced and inflexible in children with ASD, and predict CI and IS symptoms, but not RM symptoms. Furthermore, we show that time-varying cross-network interactions in motor circuit are significantly greater in children with ASD, and predict RM symptoms, but not CI or IS symptoms. We confirmed these results using cross-validation analyses. Moreover, we show that brain-clinical symptom relations are not detected with time-averaged functional connectivity analysis. Our findings provide neurobiological support for the validity of RRB subtypes and identify dissociable brain circuit dynamics as a candidate biomarker for a key clinical feature of ASD.