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Cronin EM, Schneider AC, Nadim F, Bucher D. Modulation by Neuropeptides with Overlapping Targets Results in Functional Overlap in Oscillatory Circuit Activation. J Neurosci 2024; 44:e1201232023. [PMID: 37968117 PMCID: PMC10851686 DOI: 10.1523/jneurosci.1201-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 10/18/2023] [Accepted: 10/24/2023] [Indexed: 11/17/2023] Open
Abstract
Neuromodulation lends flexibility to neural circuit operation but the general notion that different neuromodulators sculpt neural circuit activity into distinct and characteristic patterns is complicated by interindividual variability. In addition, some neuromodulators converge onto the same signaling pathways, with similar effects on neurons and synapses. We compared the effects of three neuropeptides on the rhythmic pyloric circuit in the stomatogastric ganglion of male crabs, Cancer borealis Proctolin (PROC), crustacean cardioactive peptide (CCAP), and red pigment concentrating hormone (RPCH) activate the same modulatory inward current, I MI, and have convergent actions on synapses. However, while PROC targets all four neuron types in the core pyloric circuit, CCAP and RPCH target the same subset of only two neurons. After removal of spontaneous neuromodulator release, none of the neuropeptides restored the control cycle frequency, but all restored the relative timing between neuron types. Consequently, differences between neuropeptide effects were mainly found in the spiking activity of different neuron types. We performed statistical comparisons using the Euclidean distance in the multidimensional space of normalized output attributes to obtain a single measure of difference between modulatory states. Across preparations, the circuit output in PROC was distinguishable from CCAP and RPCH, but CCAP and RPCH were not distinguishable from each other. However, we argue that even between PROC and the other two neuropeptides, population data overlapped enough to prevent reliable identification of individual output patterns as characteristic for a specific neuropeptide. We confirmed this notion by showing that blind classifications by machine learning algorithms were only moderately successful.Significance Statement It is commonly assumed that distinct behaviors or circuit activities can be elicited by different neuromodulators. Yet it is unknown to what extent these characteristic actions remain distinct across individuals. We use a well-studied circuit model of neuromodulation to examine the effects of three neuropeptides, each known to produce a distinct activity pattern in controlled studies. We find that, when compared across individuals, the three peptides elicit activity patterns that are either statistically indistinguishable or show too much overlap to be labeled characteristic. We ascribe this to interindividual variability and overlapping subcellular actions of the modulators. Because both factors are common in all neural circuits, these findings have broad significance for understanding chemical neuromodulatory actions while considering interindividual variability.
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Affiliation(s)
- Elizabeth M Cronin
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, Newark, New Jersey 07102
| | - Anna C Schneider
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, Newark, New Jersey 07102
| | - Farzan Nadim
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, Newark, New Jersey 07102
| | - Dirk Bucher
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, Newark, New Jersey 07102
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Hutt A, Trotter D, Pariz A, Valiante TA, Lefebvre J. Diversity-induced trivialization and resilience of neural dynamics. CHAOS (WOODBURY, N.Y.) 2024; 34:013147. [PMID: 38285722 DOI: 10.1063/5.0165773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 01/01/2024] [Indexed: 01/31/2024]
Abstract
Heterogeneity is omnipresent across all living systems. Diversity enriches the dynamical repertoire of these systems but remains challenging to reconcile with their manifest robustness and dynamical persistence over time, a fundamental feature called resilience. To better understand the mechanism underlying resilience in neural circuits, we considered a nonlinear network model, extracting the relationship between excitability heterogeneity and resilience. To measure resilience, we quantified the number of stationary states of this network, and how they are affected by various control parameters. We analyzed both analytically and numerically gradient and non-gradient systems modeled as non-linear sparse neural networks evolving over long time scales. Our analysis shows that neuronal heterogeneity quenches the number of stationary states while decreasing the susceptibility to bifurcations: a phenomenon known as trivialization. Heterogeneity was found to implement a homeostatic control mechanism enhancing network resilience to changes in network size and connection probability by quenching the system's dynamic volatility.
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Affiliation(s)
- Axel Hutt
- MLMS, MIMESIS, Université de Strasbourg, CNRS, Inria, ICube, 67000 Strasbourg, France
| | - Daniel Trotter
- Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
- Krembil Brain Institute, University Health Network, Toronto, Ontario M5T 0S8, Canada
| | - Aref Pariz
- Krembil Brain Institute, University Health Network, Toronto, Ontario M5T 0S8, Canada
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Taufik A Valiante
- Krembil Brain Institute, University Health Network, Toronto, Ontario M5T 0S8, Canada
- Department of Electrical and Computer Engineering, Institute of Medical Science, Institute of Biomedical Engineering, Division of Neurosurgery, Department of Surgery, CRANIA (Center for Advancing Neurotechnological Innovation to Application), Max Planck-University of Toronto Center for Neural Science and Technology, University of Toronto, Toronto, Ontario M5S 3G8, Canada
| | - Jérémie Lefebvre
- Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
- Krembil Brain Institute, University Health Network, Toronto, Ontario M5T 0S8, Canada
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
- Department of Mathematics, University of Toronto, Toronto, Ontario M5S 2E4, Canada
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Goolsby BC, Smith EJ, Muratore IB, Coto ZN, Muscedere ML, Traniello JFA. Differential Neuroanatomical, Neurochemical, and Behavioral Impacts of Early-Age Isolation in a Eusocial Insect. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.29.546928. [PMID: 37425857 PMCID: PMC10326991 DOI: 10.1101/2023.06.29.546928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Social experience early in life appears to be necessary for the development of species-typical behavior. Although isolation during critical periods of maturation has been shown to impact behavior by altering gene expression and brain development in invertebrates and vertebrates, workers of some ant species appear resilient to social deprivation and other neurobiological challenges that occur during senescence or due to loss of sensory input. It is unclear if and to what degree neuroanatomy, neurochemistry, and behavior will show deficiencies if social experience in the early adult life of worker ants is compromised. We reared newly-eclosed adult workers of Camponotus floridanus under conditions of social isolation for 2 to 53 days, quantified brain compartment volumes, recorded biogenic amine levels in individual brains, and evaluated movement and behavioral performance to compare the neuroanatomy, neurochemistry, brood-care behavior, and foraging (predatory behavior) of isolated workers with that of workers experiencing natural social contact after adult eclosion. We found that the volume of the antennal lobe, which processes olfactory inputs, was significantly reduced in workers isolated for an average of 40 days, whereas the size of the mushroom bodies, centers of higher-order sensory processing, increased after eclosion and was not significantly different from controls. Titers of the neuromodulators serotonin, dopamine, and octopamine remained stable and were not significantly different in isolation treatments and controls. Brood care, predation, and overall movement were reduced in workers lacking social contact early in life. These results suggest that the behavioral development of isolated workers of C. floridanus is specifically impacted by a reduction in the size of the antennal lobe. Task performance and locomotor ability therefore appear to be sensitive to a loss of social contact through a reduction of olfactory processing ability rather than change in the size of the mushroom bodies, which serve important functions in learning and memory, or the central complex, which controls movement.
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Affiliation(s)
- Billie C. Goolsby
- Department of Biology, Boston University, Boston, MA, 02215, USA
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - E. Jordan Smith
- Department of Biology, Boston University, Boston, MA, 02215, USA
| | - Isabella B. Muratore
- Department of Biology, Boston University, Boston, MA, 02215, USA
- Department of Biological Sciences, New Jersey Institute of Technology, NJ, 07102, USA
| | - Zach N. Coto
- Department of Biology, Boston University, Boston, MA, 02215, USA
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More-Potdar S, Golowasch J. Oscillatory network spontaneously recovers both activity and robustness after prolonged removal of neuromodulators. Front Cell Neurosci 2023; 17:1280575. [PMID: 38162002 PMCID: PMC10757639 DOI: 10.3389/fncel.2023.1280575] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 11/08/2023] [Indexed: 01/03/2024] Open
Abstract
Robustness of neuronal activity is a property necessary for a neuronal network to withstand perturbations, which may otherwise disrupt or destroy the system. The robustness of complex systems has been shown to depend on a number of features of the system, including morphology and heterogeneity of the activity of the component neurons, size of the networks, synaptic connectivity, and neuromodulation. The activity of small networks, such as the pyloric network of the crustacean stomatogastric nervous system, appears to be robust despite some of the factors not being consistent with the expected properties of complex systems, e.g., small size and homogeneity of the synaptic connections. The activity of the pyloric network has been shown to be stable and robust in a neuromodulatory state-dependent manner. When neuromodulatory inputs are severed, activity is initially disrupted, losing both stability and robustness. Over the long term, however, stable activity homeostatically recovers without the restoration of neuromodulatory input. The question we address in this study is whether robustness can also be restored as the network reorganizes itself to compensate for the loss of neuromodulatory input and recovers the lost activity. Here, we use temperature changes as a perturbation to probe the robustness of the network's activity. We develop a simple metric of robustness, i.e., the variances of the network phase relationships, and show that robustness is indeed restored simultaneously along with its stable network activity, indicating that, whatever the reorganization of the network entails, it is deep enough also to restore this important property.
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Affiliation(s)
| | - Jorge Golowasch
- Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ, United States
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Shen X, Sun T, Li Z, Wu Y. Generation of locomotor‑like activity using monopolar intraspinal electrical microstimulation in rats. Exp Ther Med 2023; 26:560. [PMID: 37941590 PMCID: PMC10628655 DOI: 10.3892/etm.2023.12259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/17/2023] [Indexed: 11/10/2023] Open
Abstract
Severe spinal cord injury (SCI) affects the ability of functional standing and walking. As the locomotor central pattern generator (CPG) in the lumbosacral spinal cord can generate a regulatory signal for movement, it is feasible to activate CPG neural network using intra-spinal micro-stimulation (ISMS) to induce alternating patterns. The present study identified two special sites with the ability to activate the CPG neural network that are symmetrical about the posterior median sulcus in the lumbosacral spinal cord by ISMS in adult rats. A reversal of flexion and extension can occur in an attempt to generate a stepping movement of the bilateral hindlimb by either reversing the pulse polarity of the stimulus or changing the special site. Therefore, locomotor-like activity can be restored with monopolar intraspinal electrical stimulation on either special site. To verify the motor function regeneration of the paralyzed hindlimbs, a four-week locomotor training with ISMS applied to the special site in the SCI + ISMS group (n=12) was performed. Evaluations of motor function recovery using behavior, kinematics and physiological analyses, were used to assess hindlimb function and the results showed the stimulation at one special site can promote significant functional recovery of the bilateral hindlimbs (P<0.05). The present study suggested that motor function of paralyzed bilateral hindlimbs can be restored with monopolar ISMS.
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Affiliation(s)
- Xiaoyan Shen
- School of Information Science and Technology, Nantong University, Nantong, Jiangsu 226019, P.R. China
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226019, P.R. China
| | - Tinghui Sun
- School of Information Science and Technology, Nantong University, Nantong, Jiangsu 226019, P.R. China
| | - Zhiling Li
- School of Information Science and Technology, Nantong University, Nantong, Jiangsu 226019, P.R. China
| | - Yan Wu
- School of Information Science and Technology, Nantong University, Nantong, Jiangsu 226019, P.R. China
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Pirtle TJ. A review of the circuit-level and cellular mechanisms contributing to locomotor acceleration in the marine mollusk Clione limacina. Front Neurosci 2022; 16:1072974. [PMID: 36620465 PMCID: PMC9815461 DOI: 10.3389/fnins.2022.1072974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
The pteropod mollusk, Clione limacina, is a useful model system for understanding the neural basis of behavior. Of particular interest are the unique swimming behavior and neural circuitry that underlies this swimming behavior. The swimming system of Clione has been studied by two primary groups-one in Russia and one in the United States of America-for more than four decades. The neural circuitry, the cellular properties, and ion channels that create and change the swimming locomotor rhythm of Clione-particularly mechanisms that contribute to swimming acceleration-are presented in this review.
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Affiliation(s)
- Thomas J. Pirtle
- Department of Biology, The College of Idaho, Caldwell, ID, United States
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Marder E, Kedia S, Morozova EO. New insights from small rhythmic circuits. Curr Opin Neurobiol 2022; 76:102610. [PMID: 35986971 DOI: 10.1016/j.conb.2022.102610] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/20/2022] [Accepted: 06/28/2022] [Indexed: 11/30/2022]
Abstract
Small rhythmic circuits, such as those found in invertebrates, have provided fundamental insights into how circuit dynamics depend on individual neuronal and synaptic properties. Degenerate circuits are those with different network parameters and similar behavior. New work on degenerate circuits and their modulation illustrates some of the rules that help maintain stable and robust circuit function despite environmental perturbations. Advances in neuropeptide isolation and identification provide enhanced understanding of the neuromodulation of circuits for behavior. The advent of molecular studies of mRNA expression provides new insight into animal-to-animal variability and the homeostatic regulation of excitability in neurons and networks.
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Affiliation(s)
- Eve Marder
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA
| | - Sonal Kedia
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA. https://twitter.com/Sonal_Kedia
| | - Ekaterina O Morozova
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA.
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Tamvacakis AN, Lillvis JL, Sakurai A, Katz PS. The Consistency of Gastropod Identified Neurons Distinguishes Intra-Individual Plasticity From Inter-Individual Variability in Neural Circuits. Front Behav Neurosci 2022; 16:855235. [PMID: 35309684 PMCID: PMC8928192 DOI: 10.3389/fnbeh.2022.855235] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 02/07/2022] [Indexed: 11/13/2022] Open
Abstract
Gastropod mollusks are known for their large, individually identifiable neurons, which are amenable to long-term intracellular recordings that can be repeated from animal to animal. The constancy of individual neurons can help distinguish state-dependent or temporal variation within an individual from actual variability between individual animals. Investigations into the circuitry underlying rhythmic swimming movements of the gastropod species, Tritonia exsulans and Pleurobranchaea californica have uncovered intra- and inter-individual variability in synaptic connectivity and serotonergic neuromodulation. Tritonia has a reliably evoked escape swim behavior that is produced by a central pattern generator (CPG) composed of a small number of identifiable neurons. There is apparent individual variability in some of the connections between neurons that is inconsequential for the production of the swim behavior under normal conditions, but determines whether that individual can swim following a neural lesion. Serotonergic neuromodulation of synaptic strength intrinsic to the CPG creates neural circuit plasticity within an individual and contributes to reorganization of the network during recovery from injury and during learning. In Pleurobranchaea, variability over time in the modulatory actions of serotonin and in expression of serotonin receptor genes in an identified neuron directly reflects variation in swimming behavior. Tracking behavior and electrophysiology over hours to days was necessary to identify the functional consequences of these intra-individual, time-dependent variations. This work demonstrates the importance of unambiguous neuron identification, properly assessing the animal and network states, and tracking behavior and physiology over time to distinguish plasticity within the same animal at different times from variability across individual animals.
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Affiliation(s)
| | | | - Akira Sakurai
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| | - Paul S. Katz
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, United States
- *Correspondence: Paul S. Katz,
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9
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McKenna KE. What Is the Trigger for Sexual Climax? ARCHIVES OF SEXUAL BEHAVIOR 2022; 51:383-390. [PMID: 34664153 DOI: 10.1007/s10508-021-02164-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 08/27/2021] [Accepted: 09/20/2021] [Indexed: 06/13/2023]
Abstract
A model is proposed to consider sexual climax in men, women, and animals as a unitary phenomenon. Sexual climax is a stereotyped rhythmic pattern of spinally generated neural activity in the autonomic and somatic nerves innervating pelvic organs. A column of neurons in the spinal cord of the male rat is strongly activated by ejaculation (sexual climax in the male). These neurons project to the thalamus and are therefore called lumbar spinothalamic cells (LSt cells). Comprehensive studies have demonstrated that the LSt cells constitute a central pattern generator of ejaculation. These findings have been extended to female animals. Further studies identified LSt cells in the lumbar spinal cord of men and women. Strong evidence indicates that the LSt cells mediate ejaculation in men. The climax model generalizes and extends these studies. It postulates that LSt cells in the lumbar spinal cord of humans and animals of both sexes generate climax. The LSt cells generate the neural activity driving the pelvic contractions and other responses of climax. The activity is transmitted to supraspinal sites to activate orgasm. The LSt cells receive excitatory and inhibitory projections from supraspinal sites. The descending projections reflect subjective arousal and inhibitions. Spinal sensory neurons from the genitals provide excitatory and inhibitory innervation to the LSt cells. These represent pleasurable and noxious sensations. The supraspinal and spinal excitatory and inhibitory inputs are integrated by the LSt. When the sum of the excitatory inputs, minus the sum of the inhibitory inputs reaches a threshold, the LSt cells generate sexual climax.
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Affiliation(s)
- Kevin E McKenna
- Departments of Neuroscience and Urology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave., Chicago, IL, 60611, USA.
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10
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Neural implant for the treatment of multiple sclerosis. Med Hypotheses 2020; 145:110324. [PMID: 33038587 DOI: 10.1016/j.mehy.2020.110324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/06/2020] [Accepted: 09/26/2020] [Indexed: 11/20/2022]
Abstract
The methods used to treat various neurological diseases are evolving. The facilities provided by the technology have led to creation of new treatment opportunities. Neuromodulation is one of these important methods. By definition, the neuromodulation is a change in neural activity which occurs by stimulating a specific area of nervous system. The mentioned stimulation can be electrical, magnetic, or chemical. This method is used in various diseases, such as stroke, Parkinson's, Alzheimer's, and amyotrophic lateral sclerosis (ALS). Multiple sclerosis (MS) is no exception in this regard and methods including the neurofeedback and transcranial magnetic stimulation (TMS) are used to treat various complications of the MS. One aspect of neuromodulation is the use of neural implant, which is applied nowadays, especially in the Parkinson's disease, and the use of microchips and prostheses to treat various symptoms in different neurological diseases has received significant attention. Although neural implant has been exploited to improve the symptoms of MS, they appear to have much greater potential to improve the condition of patients with MS. It seems that more attention to the symptoms of MS, on the one hand, and a new approach to the pathogenesis of this disease and considering it as a connectomopathy, on the other hand, can provide new opportunities for application of this method in the treatment of MS.
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Northcutt AJ, Schulz DJ. Molecular mechanisms of homeostatic plasticity in central pattern generator networks. Dev Neurobiol 2019; 80:58-69. [PMID: 31778295 DOI: 10.1002/dneu.22727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 10/09/2019] [Accepted: 11/22/2019] [Indexed: 01/27/2023]
Abstract
Central pattern generator (CPG) networks rely on a balance of intrinsic and network properties to produce reliable, repeatable activity patterns. This balance is maintained by homeostatic plasticity where alterations in neuronal properties dynamically maintain appropriate neural output in the face of changing environmental conditions and perturbations. However, it remains unclear just how these neurons and networks can both monitor their ongoing activity and use this information to elicit homeostatic physiological responses to ensure robustness of output over time. Evidence exists that CPG networks use a mixed strategy of activity-dependent, activity-independent, modulator-dependent, and synaptically regulated homeostatic plasticity to achieve this critical stability. In this review, we focus on some of the current understanding of the molecular pathways and mechanisms responsible for this homeostatic plasticity in the context of central pattern generator function, with a special emphasis on some of the smaller invertebrate networks that have allowed for extensive cellular-level analyses that have brought recent insights to these questions.
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Affiliation(s)
- Adam J Northcutt
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri
| | - David J Schulz
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri
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Berkowitz A. Expanding our horizons: central pattern generation in the context of complex activity sequences. J Exp Biol 2019; 222:222/20/jeb192054. [DOI: 10.1242/jeb.192054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
ABSTRACT
Central pattern generators (CPGs) are central nervous system (CNS) networks that can generate coordinated output in the absence of patterned sensory input. For decades, this concept was applied almost exclusively to simple, innate, rhythmic movements with essentially identical cycles that repeat continually (e.g. respiration) or episodically (e.g. locomotion). But many natural movement sequences are not simple rhythms, as they include different elements in a complex order, and some involve learning. The concepts and experimental approaches of CPG research have also been applied to the neural control of complex movement sequences, such as birdsong, though this is not widely appreciated. Experimental approaches to the investigation of CPG networks, both for simple rhythms and for complex activity sequences, have shown that: (1) brief activation of the CPG elicits a long-lasting naturalistic activity sequence; (2) electrical stimulation of CPG elements alters the timing of subsequent cycles or sequence elements; and (3) warming or cooling CPG elements respectively speeds up or slows down the rhythm or sequence rate. The CPG concept has also been applied to the activity rhythms of populations of mammalian cortical neurons. CPG concepts and methods might further be applied to a variety of fixed action patterns typically used in courtship, rivalry, nest building and prey capture. These complex movements could be generated by CPGs within CPGs (‘nested’ CPGs). Stereotypical, non-motor, non-rhythmic neuronal activity sequences may also be generated by CPGs. My goal here is to highlight previous applications of the CPG concept to complex but stereotypical activity sequences and to suggest additional possible applications, which might provoke new hypotheses and experiments.
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Affiliation(s)
- Ari Berkowitz
- Department of Biology and Cellular & Behavioral Neurobiology Graduate Program, University of Oklahoma, Norman, OK 73019, USA
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