scholarly journals Evolution of central pattern generators and rhythmic behaviours

2016 ◽  
Vol 371 (1685) ◽  
pp. 20150057 ◽  
Author(s):  
Paul S. Katz
Keyword(s):  
Large Scale ◽  
Neural Circuits ◽  
Motor Pattern ◽  
Parallel Evolution ◽  
Central Pattern Generators ◽  
Neural Mechanism ◽  
Rhythmic Movements ◽  
Biological Organization ◽  
Gradual Evolution ◽  
Pattern Generators

Comparisons of rhythmic movements and the central pattern generators (CPGs) that control them uncover principles about the evolution of behaviour and neural circuits. Over the course of evolutionary history, gradual evolution of behaviours and their neural circuitry within any lineage of animals has been a predominant occurrence. Small changes in gene regulation can lead to divergence of circuit organization and corresponding changes in behaviour. However, some behavioural divergence has resulted from large-scale rewiring of the neural network. Divergence of CPG circuits has also occurred without a corresponding change in behaviour. When analogous rhythmic behaviours have evolved independently, it has generally been with different neural mechanisms. Repeated evolution of particular rhythmic behaviours has occurred within some lineages due to parallel evolution or latent CPGs. Particular motor pattern generating mechanisms have also evolved independently in separate lineages. The evolution of CPGs and rhythmic behaviours shows that although most behaviours and neural circuits are highly conserved, the nature of the behaviour does not dictate the neural mechanism and that the presence of homologous neural components does not determine the behaviour. This suggests that although behaviour is generated by neural circuits, natural selection can act separately on these two levels of biological organization.

Intersegmental Coordination of Walking Movements in Stick Insects

2005 ◽  
Vol 93 (3) ◽  
pp. 1255-1265 ◽  
Author(s):  
Björn Ch. Ludwar ◽  
Marie L. Göritz ◽  
Joachim Schmidt
Keyword(s):  
Motor Pattern ◽  
Central Pattern Generators ◽  
Stick Insect ◽  
Neural Mechanisms ◽  
Chordotonal Organ ◽  
Adjacent Segment ◽  
Body Segments ◽  
Stick Insects ◽  
Pattern Generators ◽  
Leg Movements

Locomotion requires the coordination of movements across body segments, which in walking animals is expressed as gaits. We studied the underlying neural mechanisms of this coordination in a semi-intact walking preparation of the stick insect Carausius morosus. During walking of a single front leg on a treadmill, leg motoneuron (MN) activity tonically increased and became rhythmically modulated in the ipsilateral deafferented and deefferented mesothoracic (middle leg) ganglion. The pattern of modulation was correlated with the front leg cycle and specific for a given MN pool, although it was not consistent with functional leg movements for all MN pools. In an isolated preparation of a pair of ganglia, where one ganglion was made rhythmically active by application of pilocarpine, we found no evidence for coupling between segmental central pattern generators (CPGs) that could account for the modulation of MN activity observed in the semi-intact walking preparation. However, a third preparation provided evidence that signals from the front leg's femoral chordotonal organ (fCO) influenced activity of ipsilateral MNs in the adjacent mesothoracic ganglion. These intersegmental signals could be partially responsible for the observed MN activity modulation during front leg walking. While afferent signals from a single walking front leg modulate the activity of MNs in the adjacent segment, additional afferent signals, local or from contralateral or posterior legs, might be necessary to produce the functional motor pattern observed in freely walking animals.

scholarly journals Augmenting Flexibility: Mutual Inhibition Between Inhibitory Neurons Expands Functional Diversity

2020 ◽  
Author(s):  
Belle Liu ◽  
Alexander James White ◽  
Chung-Chuan Lo
Keyword(s):  
Dynamical Systems ◽  
Bifurcation Theory ◽  
Neural Circuits ◽  
Feedback Inhibition ◽  
Central Pattern Generators ◽  
Recurrent Network ◽  
Inhibitory Neurons ◽  
Mutual Inhibition ◽  
Input Type ◽  
Pattern Generators

AbstractOne of the most intriguing observations of recurrent neural circuits is their flexibility. Seemingly, this flexibility extends far beyond the ability to learn, but includes the ability to use learned procedures to respond to novel situations. Here, we report that this flexibility arises from the synergistic interplay between recurrent mutual excitation and recurrent mutual inhibition. Specifically, we show that mutual inhibition is critical in expanding the functionality of the circuit, far beyond what feedback inhibition alone can accomplish. By taking advantage of dynamical systems theory and bifurcation analysis, we show mutual inhibition doubles the number of cusp bifurcations in the system in small neural circuits. As a concrete example, we build a simulation model of a class of functional motifs we call Coupled Recurrent inhibitory and Recurrent excitatory Loops (CRIRELs). These CRIRELs have the advantage of being multi-functional, performing a plethora of functions, including decisions, switches, toggles, central pattern generators, depending solely on the input type. We then use bifurcation theory to show how mutual inhibition gives rise to this broad repertoire of possible functions. Finally, we demonstrate how this trend also holds for larger networks, and how mutual inhibition greatly expands the amount of information a recurrent network can hold.

scholarly journals Central pattern generators in the turtle spinal cord: selection among the forms of motor behaviors

2018 ◽  
Vol 119 (2) ◽  
pp. 422-440 ◽  
Author(s):  
Paul S. G. Stein
Keyword(s):  
Spinal Cord ◽  
Motor Pattern ◽  
Central Pattern Generators ◽  
Knee Extensor ◽  
Motor Patterns ◽  
Motor Behaviors ◽  
Multiple Behaviors ◽  
Pattern Generators ◽  
Electrical Stimuli

Neuronal networks in the turtle spinal cord have considerable computational complexity even in the absence of connections with supraspinal structures. These networks contain central pattern generators (CPGs) for each of several behaviors, including three forms of scratch, two forms of swim, and one form of flexion reflex. Each behavior is activated by a specific set of cutaneous or electrical stimuli. The process of selection among behaviors within the spinal cord has multisecond memories of specific motor patterns. Some spinal cord interneurons are partially shared among several CPGs, whereas other interneurons are active during only one type of behavior. Partial sharing is a proposed mechanism that contributes to the ability of the spinal cord to generate motor pattern blends with characteristics of multiple behaviors. Variations of motor patterns, termed deletions, assist in characterization of the organization of the pattern-generating components of CPGs. Single-neuron recordings during both normal and deletion motor patterns provide support for a CPG organizational structure with unit burst generators (UBGs) whose members serve a direction of a specific degree of freedom of the hindlimb, e.g., the hip-flexor UBG, the hip-extensor UBG, the knee-flexor UBG, the knee-extensor UBG, etc. The classic half-center hypothesis that includes all the hindlimb flexors in a single flexor half-center and all the hindlimb extensors in a single extensor half-center lacks the organizational complexity to account for the motor patterns produced by turtle spinal CPGs. Thus the turtle spinal cord is a valuable model system for studies of mechanisms responsible for selection and generation of motor behaviors. NEW & NOTEWORTHY The concept of the central pattern generator (CPG) is a major tenet in motor neuroethology that has influenced the design and interpretations of experiments for over a half century. This review concentrates on the turtle spinal cord and describes studies from the 1970s to the present responsible for key developments in understanding the CPG mechanisms responsible for the selection and production of coordinated motor patterns during turtle hindlimb motor behaviors.

Intrinsic and Extrinsic Modulation of a Single Central Pattern Generating Circuit

2000 ◽  
Vol 84 (3) ◽  
pp. 1186-1193 ◽  
Author(s):  
Peter T. Morgan ◽  
Ray Perrins ◽  
Philip E. Lloyd ◽  
Klaudiusz R. Weiss
Keyword(s):  
Neural Circuits ◽  
Central Pattern Generators ◽  
Motor Program ◽  
Pattern Generator ◽  
Motor Programs ◽  
Appetitive Behavior ◽  
Protraction Phase ◽  
Pattern Generators ◽  
Rhythmic Behaviors ◽  
Appetitive Behaviors

Intrinsic and extrinsic neuromodulation are both thought to be responsible for the flexibility of the neural circuits (central pattern generators) that control rhythmic behaviors. Because the two forms of modulation have been studied in different circuits, it has been difficult to compare them directly. We find that the central pattern generator for biting in Aplysia is modulated both extrinsically and intrinsically. Both forms of modulation increase the frequency of motor programs and shorten the duration of the protraction phase. Extrinsic modulation is mediated by the serotonergic metacerebral cell (MCC) neurons and is mimicked by application of serotonin. Intrinsic modulation is mediated by the cerebral peptide-2 (CP-2) containing CBI-2 interneurons and is mimicked by application of CP-2. Since the effects of CBI-2 and CP-2 occlude each other, the modulatory actions of CBI-2 may be mediated by CP-2 release. Although the effects of intrinsic and extrinsic modulation are similar, the neurons that mediate them are active predominantly at different times, suggesting a specialized role for each system. Metacerebral cell (MCC) activity predominates in the preparatory (appetitive) phase and thus precedes the activation of CBI-2 and biting motor programs. Once the CBI-2s are activated and the biting motor program is initiated, MCC activity declines precipitously. Hence extrinsic modulation prefacilitates biting, whereas intrinsic modulation occurs during biting. Since biting inhibits appetitive behavior, intrinsic modulation cannot be used to prefacilitate biting in the appetitive phase. Thus the sequential use of extrinsic and intrinsic modulation may provide a means for premodulation of biting without the concomitant disruption of appetitive behaviors.

Altered Gravity Highlights Central Pattern Generator Mechanisms

2008 ◽  
Vol 100 (5) ◽  
pp. 2819-2824 ◽  
Author(s):  
Olivier White ◽  
Yannick Bleyenheuft ◽  
Renaud Ronsse ◽  
Allan M. Smith ◽  
Jean-Louis Thonnard ◽  
...  
Keyword(s):  
Neural Networks ◽  
Resonant Frequency ◽  
Parabolic Flight ◽  
Central Pattern Generators ◽  
Arm Movement ◽  
Rhythmic Movements ◽  
Earth Environment ◽  
Major Interest ◽  
Microgravity Conditions ◽  
Pattern Generators

In many nonprimate species, rhythmic patterns of activity such as locomotion or respiration are generated by neural networks at the spinal level. These neural networks are called central pattern generators (CPGs). Under normal gravitational conditions, the energy efficiency and the robustness of human rhythmic movements are due to the ability of CPGs to drive the system at a pace close to its resonant frequency. This property can be compared with oscillators running at resonant frequency, for which the energy is optimally exchanged with the environment. However, the ability of the CPG to adapt the frequency of rhythmic movements to new gravitational conditions has never been studied. We show here that the frequency of a rhythmic movement of the upper limb is systematically influenced by the different gravitational conditions created in parabolic flight. The period of the arm movement is shortened with increasing gravity levels. In weightlessness, however, the period is more dependent on instructions given to the participants, suggesting a decreased influence of resonant frequency. Our results are in agreement with a computational model of a CPG coupled to a simple pendulum under the control of gravity. We demonstrate that the innate modulation of rhythmic movements by CPGs is highly flexible across gravitational contexts. This further supports the involvement of CPG mechanisms in the achievement of efficient rhythmic arm movements. Our contribution is of major interest for the study of human rhythmic activities, both in a normal Earth environment and during microgravity conditions in space.

scholarly journals Asymmetric and transient properties of reciprocal activity of antagonists during the paw-shake response in the cat

2021 ◽  
Vol 17 (12) ◽  
pp. e1009677
Author(s):  
Jessica R. Parker ◽  
Alexander N. Klishko ◽  
Boris I. Prilutsky ◽  
Gennady S. Cymbalyuk
Keyword(s):  
Activity Patterns ◽  
Central Pattern Generators ◽  
Emg Activity ◽  
Rhythmic Movements ◽  
Related Activity ◽  
Fast Transient Response ◽  
Hindlimb Muscles ◽  
Pattern Generators ◽  
A Current

Mutually inhibitory populations of neurons, half-center oscillators (HCOs), are commonly involved in the dynamics of the central pattern generators (CPGs) driving various rhythmic movements. Previously, we developed a multifunctional, multistable symmetric HCO model which produced slow locomotor-like and fast paw-shake-like activity patterns. Here, we describe asymmetric features of paw-shake responses in a symmetric HCO model and test these predictions experimentally. We considered bursting properties of the two model half-centers during transient paw-shake-like responses to short perturbations during locomotor-like activity. We found that when a current pulse was applied during the spiking phase of one half-center, let’s call it #1, the consecutive burst durations (BDs) of that half-center increased throughout the paw-shake response, while BDs of the other half-center, let’s call it #2, only changed slightly. In contrast, the consecutive interburst intervals (IBIs) of half-center #1 changed little, while IBIs of half-center #2 increased. We demonstrated that this asymmetry between the half-centers depends on the phase of the locomotor-like rhythm at which the perturbation was applied. We suggest that the fast transient response reflects functional asymmetries of slow processes that underly the locomotor-like pattern; e.g., asymmetric levels of inactivation across the two half-centers for a slowly inactivating inward current. We compared model results with those of in-vivo paw-shake responses evoked in locomoting cats and found similar asymmetries. Electromyographic (EMG) BDs of anterior hindlimb muscles with flexor-related activity increased in consecutive paw-shake cycles, while BD of posterior muscles with extensor-related activity did not change, and vice versa for IBIs of anterior flexors and posterior extensors. We conclude that EMG activity patterns during paw-shaking are consistent with the proposed mechanism producing transient paw-shake-like bursting patterns found in our multistable HCO model. We suggest that the described asymmetry of paw-shaking responses could implicate a multifunctional CPG controlling both locomotion and paw-shaking.

scholarly journals Behavioral evidence for nested central pattern generator control of Drosophila grooming

2020 ◽  
Author(s):  
Primoz Ravbar ◽  
Neil Zhang ◽  
Julie H. Simpson
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Neural Circuits ◽  
Central Pattern Generators ◽  
Repetitive Behaviors ◽  
Short Time Scale ◽  
Behavioral Experiments ◽  
Behavioral Evidence ◽  
Pattern Generators ◽  
Short Time

AbstractCentral pattern generators (CPGs) are neurons or neural circuits that produce periodic output without requiring patterned input. More complex behaviors can be assembled from simpler subroutines, and nested CPGs have been proposed to coordinate their repetitive elements, simplifying control over different time-scales. Here, we use behavioral experiments to establish that Drosophila grooming may be controlled by nested CPGs. On the short time-scale (5-7 Hz), flies execute periodic leg sweeps and rubs. More surprisingly, transitions between bouts of head cleaning and leg rubbing are also periodic on a longer time-scale (0.3 - 0.6 Hz). We examine grooming at a range of temperatures to show that the frequencies of both oscillations increase – a hallmark of CPG control – and also that the two time-scales increase at the same rate, indicating that the nested CPGs may be linked. This relationship also holds when sensory drive is held constant using optogenetic activation, but the rhythms decouple in spontaneously grooming flies, showing that alternative control modes are possible. Nested CPGs simplify generation of complex but repetitive behaviors, and identifying them in Drosophila grooming presents an opportunity to map the neural circuits that constitute them.

FMRFamide-like peptides in the crayfish (Procambarus clarkii) stomatogastric nervous system: distribution and effects on the pyloric motor pattern.

1997 ◽  
Vol 200 (24) ◽  
pp. 3221-3233 ◽  
Author(s):  
A J Tierney ◽  
J Blanck ◽  
J Mercier
Keyword(s):  
Nervous System ◽  
Procambarus Clarkii ◽  
Motor Pattern ◽  
Central Pattern Generators ◽  
Projection Neurons ◽  
Inhibitory Effects ◽  
Stomatogastric Nervous System ◽  
Whole Mount ◽  
Cycling Frequency ◽  
Pattern Generators

Whole-mount immunocytochemistry was used to map the location of FMRFamide-like peptides in the crayfish (Procambarus clarkii) stomatogastric nervous system. This system contains the pyloric and gastric mill central pattern generators, which receive modulatory inputs from projection neurons with somata located primarily in other ganglia of the stomatogastric nervous system. Our studies revealed stained somata in the commissural and esophageal ganglia. A pair of stained somata was located in the inferior ventricular nerve, and another pair of somata was located in the stomatogastric nerve where it is joined by the two superior esophageal nerves. The stomatogastric ganglion contained no stained somata, but the neuropil was brightly stained and 2-4 axons projected laterally in small nerves directly from the ganglion. These results indicate that FMRFamide or related peptides may act as neuromodulators in the crayfish stomatogastric nervous system. To test this hypothesis, we studied the effects of FMRFamide and four related peptides (DF2, NF1, F1 and LMS) on the pyloric motor pattern. DF2, NF1 and F1 all excited certain pyloric cells, especially the lateral pyloric (LP) and ventricular dilator (VD) neurons, and enhanced pyloric cycling frequency in most actively rhythmic preparations. FMRFamide had no detectable effects on pyloric cells, and LMS had inhibitory effects, causing disruption of the pyloric rhythm in actively cycling preparations and reducing tonic activity in non-rhythmic preparations.

scholarly journals An optimality principle for locomotor central pattern generators

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hansol X. Ryu ◽  
Arthur D. Kuo
Keyword(s):  
Internal Model ◽  
Sensory Feedback ◽  
Motor Pattern ◽  
Central Pattern Generators ◽  
Optimal Estimation ◽  
Legged Locomotion ◽  
Energetic Cost ◽  
Fictive Locomotion ◽  
Cost Of Transport ◽  
Pattern Generators

AbstractTwo types of neural circuits contribute to legged locomotion: central pattern generators (CPGs) that produce rhythmic motor commands (even in the absence of feedback, termed “fictive locomotion”), and reflex circuits driven by sensory feedback. Each circuit alone serves a clear purpose, and the two together are understood to cooperate during normal locomotion. The difficulty is in explaining their relative balance objectively within a control model, as there are infinite combinations that could produce the same nominal motor pattern. Here we propose that optimization in the presence of uncertainty can explain how the circuits should best be combined for locomotion. The key is to re-interpret the CPG in the context of state estimator-based control: an internal model of the limbs that predicts their state, using sensory feedback to optimally balance competing effects of environmental and sensory uncertainties. We demonstrate use of optimally predicted state to drive a simple model of bipedal, dynamic walking, which thus yields minimal energetic cost of transport and best stability. The internal model may be implemented with neural circuitry compatible with classic CPG models, except with neural parameters determined by optimal estimation principles. Fictive locomotion also emerges, but as a side effect of estimator dynamics rather than an explicit internal rhythm. Uncertainty could be key to shaping CPG behavior and governing optimal use of feedback.

scholarly journals Cortical Control of a Whisking Central Pattern Generator

2006 ◽  
Vol 96 (1) ◽  
pp. 209-217 ◽  
Author(s):  
Nathan P. Cramer ◽  
Asaf Keller
Keyword(s):  
Motor Control ◽  
Motor Cortex ◽  
Serotonin Receptor ◽  
Motor Pattern ◽  
Central Pattern Generators ◽  
Motor Units ◽  
Activity Level ◽  
Active Motor ◽  
Pattern Generators ◽  
Serotonin Receptor Antagonist

Whether the motor cortex regulates voluntary movements by generating the motor pattern directly or by acting through subcortical central pattern generators (CPGs) remains a central question in motor control. Using the rat whisker system, an important model system of mammalian motor control, we develop an anesthetized preparation to investigate the interaction between the motor cortex and a whisking CPG. Using this model we investigate the involvement of a serotonergic component of the whisking CPG in determining whisking kinematics and the mechanisms through which drive from the CPG is converted into movements by vibrissa motor units. Consistent with an action of the vibrissa motor cortex (vMCx) on a subcortical CPG, the frequency of whisking evoked by intracortical microstimulation (ICMS) of vMCx differed significantly from the stimulation frequency, whereas whisking onset latencies correlated negatively with stimulation intensity. Further, ICMS-evoked whisking was suppressed by a serotonin receptor antagonist, supporting previous findings that the whisking CPG contains a significant serotonergic component. The amplitude of ICMS-evoked whisking was correlated with the number of active motor units—isolated from vibrissal EMGs or recorded directly from vibrissa motoneurons—and their activity level. In addition, whisking frequency was correlated with the firing rate of these motoneurons. These findings support the hypothesis that vMCx regulates whisking through its actions on a subcortical CPG.

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