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Sillar KT, Simmers J, Combes D. From tadpole to adult frog locomotion. Curr Opin Neurobiol 2023; 82:102753. [PMID: 37549591 DOI: 10.1016/j.conb.2023.102753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/05/2023] [Accepted: 07/05/2023] [Indexed: 08/09/2023]
Abstract
The transition from larval to adult locomotion in the anuran, Xenopus laevis, involves a dramatic switch from axial to appendicular swimming including intermediate stages when the tail and hindlimbs co-exist and contribute to propulsion. Hatchling tadpole swimming is generated by an axial central pattern generator (CPG) which matures rapidly during early larval life. During metamorphosis, the developing limbs are controlled by a de novo appendicular CPG driven initially by the axial system before segregating to allow both systems to operate together or independently. Neuromodulation plays important roles throughout, but key modulators switch their effects from early inhibitory influences to facilitating locomotion. Temperature affects the construction and operation of locomotor networks and global changes in environmental temperature place aquatic poikilotherms, like amphibians, at risk. The locomotor control strategy of anurans differs from other amphibian groups such as salamanders, where evolution has acted upon the thyroid hormone pathway to sculpt different developmental outcomes.
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Affiliation(s)
- Keith T Sillar
- School of Psychology and Neuroscience, University of St Andrews, St Marys Quad., St Andrews, Fife KY16 9AP, Scotland.
| | - John Simmers
- Institut des Neurosciences Cognitives et Intégratives d'Aquitaine, CNRS UMR 5287, Université de Bordeaux, 33706 Bordeaux, France
| | - Denis Combes
- Institut des Neurosciences Cognitives et Intégratives d'Aquitaine, CNRS UMR 5287, Université de Bordeaux, 33706 Bordeaux, France
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2
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Wilson AC, Sweeney LB. Spinal cords: Symphonies of interneurons across species. Front Neural Circuits 2023; 17:1146449. [PMID: 37180760 PMCID: PMC10169611 DOI: 10.3389/fncir.2023.1146449] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/23/2023] [Indexed: 05/16/2023] Open
Abstract
Vertebrate movement is orchestrated by spinal inter- and motor neurons that, together with sensory and cognitive input, produce dynamic motor behaviors. These behaviors vary from the simple undulatory swimming of fish and larval aquatic species to the highly coordinated running, reaching and grasping of mice, humans and other mammals. This variation raises the fundamental question of how spinal circuits have changed in register with motor behavior. In simple, undulatory fish, exemplified by the lamprey, two broad classes of interneurons shape motor neuron output: ipsilateral-projecting excitatory neurons, and commissural-projecting inhibitory neurons. An additional class of ipsilateral inhibitory neurons is required to generate escape swim behavior in larval zebrafish and tadpoles. In limbed vertebrates, a more complex spinal neuron composition is observed. In this review, we provide evidence that movement elaboration correlates with an increase and specialization of these three basic interneuron types into molecularly, anatomically, and functionally distinct subpopulations. We summarize recent work linking neuron types to movement-pattern generation across fish, amphibians, reptiles, birds and mammals.
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Affiliation(s)
| | - Lora B. Sweeney
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Lower Austria, Austria
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Locascio A, Vassalli QA, Castellano I, Palumbo A. Novel Insights on Nitric Oxide Synthase and NO Signaling in Ascidian Metamorphosis. Int J Mol Sci 2022; 23:ijms23073505. [PMID: 35408864 PMCID: PMC8999111 DOI: 10.3390/ijms23073505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/11/2022] [Accepted: 03/20/2022] [Indexed: 02/05/2023] Open
Abstract
Nitric oxide (NO) is a pivotal signaling molecule involved in a wide range of physiological and pathological processes. We investigated NOS/NO localization patterns during the different stages of larval development in the ascidia Ciona robusta and evidenced a specific and temporally controlled pattern. NOS/NO expression starts in the most anterior sensory structures of the early larva and progressively moves towards the caudal portion as larval development and metamorphosis proceeds. We here highlight the pattern of NOS/NO expression in the central and peripheral nervous system of Ciona larvae which precisely follows the progression of neural signals of the central pattern generator necessary for the control of the movements of the larva towards the substrate. This highly dynamic localization profile perfectly matches with the central role played by NO from the first phase of settlement induction to the next control of swimming behavior, adhesion to substrate and progressive tissue resorption and reorganization of metamorphosis itself.
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Affiliation(s)
- Annamaria Locascio
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
- Correspondence: (A.L.); (A.P.)
| | - Quirino Attilio Vassalli
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
| | - Immacolata Castellano
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Via Pansini 5, 80131 Napoli, Italy;
| | - Anna Palumbo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
- Correspondence: (A.L.); (A.P.)
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Hachoumi L, Rensner R, Richmond C, Picton L, Zhang H, Sillar KT. Bimodal modulation of short-term motor memory via dynamic sodium pumps in a vertebrate spinal cord. Curr Biol 2022; 32:1038-1048.e2. [PMID: 35104440 PMCID: PMC9616794 DOI: 10.1016/j.cub.2022.01.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 11/12/2021] [Accepted: 01/06/2022] [Indexed: 01/10/2023]
Abstract
Dynamic neuronal Na+/K+ pumps normally only respond to intense action potential firing owing to their low affinity for intracellular Na+. Recruitment of these Na+ pumps produces a post-activity ultraslow afterhyperpolarization (usAHP) up to ∼10 mV in amplitude and ∼60 s in duration, which influences neuronal properties and future network output. In spinal motor networks, the usAHP underlies short-term motor memory (STMM), reducing the intensity and duration of locomotor network output in a manner dependent on the interval between locomotor bouts. In contrast to tonically active Na+ pumps that help set and maintain the resting membrane potential, dynamic Na+ pumps are selectively antagonized by low concentrations of ouabain, which, we show, blocks both the usAHP and STMM. We examined whether dynamic Na+ pumps and STMM can be influenced by neuromodulators, focusing on 5-HT and nitric oxide. Bath-applied 5-HT alone had no significant effect on the usAHP or STMM. However, this is due to the simultaneous activation of two distinct 5-HT receptor subtypes (5-HT7 and 5-HT2a) that have opposing facilitatory and suppressive influences, respectively, on these two features of the locomotor system. Nitric oxide modulation exerts a potent inhibitory effect that can completely block the usAHP and erase STMM. Using selective blockers of 5-HT7 and 5-HT2a receptors and a nitric oxide scavenger, PTIO, we further provide evidence that the two modulators constitute an endogenous control system that determines how the spinal network self-regulates the intensity of locomotor output in light of recent past experience. Short-term memory in a spinal locomotor network is controlled by dynamic Na+ pumps Na+ pumps mediate an underlying ultraslow AHP modulated by 5-HT receptors and NO 5-HT7Rs increase and 5-HT2aRs and NO decrease the usAHP and short-term motor memory Endogenous 5-HT and NO regulate the usAHP and short-term motor memory
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Iyer AA, Briggman KL. Amphibian behavioral diversity offers insights into evolutionary neurobiology. Curr Opin Neurobiol 2021; 71:19-28. [PMID: 34481981 DOI: 10.1016/j.conb.2021.07.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/16/2021] [Accepted: 07/27/2021] [Indexed: 11/18/2022]
Abstract
Recent studies have served to emphasize the unique placement of amphibians, composed of more than 8000 species, in the evolution of the brain. We provide an overview of the three amphibian orders and their respective ecologies, behaviors, and brain anatomy. Studies have probed the origins of independently evolved parental care strategies in frogs and the biophysical principles driving species-specific differences in courtship vocalization patterns. Amphibians are also important models for studying the central control of movement, especially in the context of the vertebrate origin of limb-based locomotion. By highlighting the versatility of amphibians, we hope to see a further adoption of anurans, urodeles, and gymnophionans as model systems for the evolution and neural basis of behavior across vertebrates.
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Affiliation(s)
- Aditya A Iyer
- Center of Advanced European Studies and Research (Caesar), Ludwig-Erhard-Allee 2, Bonn, Germany
| | - Kevin L Briggman
- Center of Advanced European Studies and Research (Caesar), Ludwig-Erhard-Allee 2, Bonn, Germany.
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Cappellini G, Sylos-Labini F, Dewolf AH, Solopova IA, Morelli D, Lacquaniti F, Ivanenko Y. Maturation of the Locomotor Circuitry in Children With Cerebral Palsy. Front Bioeng Biotechnol 2020; 8:998. [PMID: 32974319 PMCID: PMC7462003 DOI: 10.3389/fbioe.2020.00998] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/30/2020] [Indexed: 12/26/2022] Open
Abstract
The first years of life represent an important phase of maturation of the central nervous system, processing of sensory information, posture control and acquisition of the locomotor function. Cerebral palsy (CP) is the most common group of motor disorders in childhood attributed to disturbances in the fetal or infant brain, frequently resulting in impaired gait. Here we will consider various findings about functional maturation of the locomotor output in early infancy, and how much the dysfunction of gait in children with CP can be related to spinal neuronal networks vs. supraspinal dysfunction. A better knowledge about pattern generation circuitries in infancy may improve our understanding of developmental motor disorders, highlighting the necessity for regulating the functional properties of abnormally developed neuronal locomotor networks as a target for early sensorimotor rehabilitation. Various clinical approaches and advances in biotechnology are also considered that might promote acquisition of the locomotor function in infants at risk for locomotor delays.
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Affiliation(s)
- Germana Cappellini
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy.,Department of Pediatric Neurorehabilitation, IRCCS Santa Lucia Foundation, Rome, Italy
| | | | - Arthur H Dewolf
- Centre of Space Bio-medicine and Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - Irina A Solopova
- Laboratory of Neurobiology of Motor Control, Institute for Information Transmission Problems, Moscow, Russia
| | - Daniela Morelli
- Department of Pediatric Neurorehabilitation, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Francesco Lacquaniti
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy.,Centre of Space Bio-medicine and Department of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - Yury Ivanenko
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
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Janes TA, Fournier S, Chamberland S, Funk GD, Kinkead R. Respiratory motoneuron properties during the transition from gill to lung breathing in the American bullfrog. Am J Physiol Regul Integr Comp Physiol 2019; 316:R281-R297. [PMID: 30601705 DOI: 10.1152/ajpregu.00303.2018] [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] [Indexed: 12/23/2022]
Abstract
Amphibian respiratory development involves a dramatic metamorphic transition from gill to lung breathing and coordination of distinct motor outputs. To determine whether the emergence of adult respiratory motor patterns was associated with similarly dramatic changes in motoneuron (MN) properties, we characterized the intrinsic electrical properties of American bullfrog trigeminal MNs innervating respiratory muscles comprising the buccal pump. In premetamorphic tadpoles (TK stages IX-XVIII) and adult frogs, morphometric analyses and whole cell recordings were performed in trigeminal MNs identified by fluorescent retrograde labeling. Based on the amplitude of the depolarizing sag induced by hyperpolarizing voltage steps, two MN subtypes (I and II) were identified in tadpoles and adults. Compared with type II MNs, type I MNs had larger sag amplitudes (suggesting a larger hyperpolarization-activated inward current), greater input resistance, lower rheobase, hyperpolarized action potential threshold, steeper frequency-current relationships, and fast firing rates and received fewer excitatory postsynaptic currents. Postmetamorphosis, type I MNs exhibited similar sag, enhanced postinhibitory rebound, and increased action potential amplitude with a smaller-magnitude fast afterhyperpolarization. Compared with tadpoles, type II MNs from frogs received higher-frequency, larger-amplitude excitatory postsynaptic currents. Input resistance decreased and rheobase increased postmetamorphosis in all MNs, concurrent with increased soma area and hyperpolarized action potential threshold. We suggest that type I MNs are likely recruited in response to smaller, buccal-related synaptic inputs as well as larger lung-related inputs, whereas type II MNs are likely recruited in response to stronger synaptic inputs associated with larger buccal breaths, lung breaths, or nonrespiratory behaviors involving powerful muscle contractions.
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Affiliation(s)
- Tara A Janes
- Department of Pediatrics, Université Laval and Institut Universitaire de Cardiologie et de Pneumologie de Québec , Québec City, Québec , Canada
| | - Stéphanie Fournier
- Department of Pediatrics, Université Laval and Institut Universitaire de Cardiologie et de Pneumologie de Québec , Québec City, Québec , Canada
| | - Simon Chamberland
- Department of Neuroscience and Physiology and New York University Neuroscience Institute, New York University Langone Medical Center , New York, New York
| | - Gregory D Funk
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute, University of Alberta , Edmonton, Alberta , Canada
| | - Richard Kinkead
- Department of Pediatrics, Université Laval and Institut Universitaire de Cardiologie et de Pneumologie de Québec , Québec City, Québec , Canada
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Picton LD, Sillar KT, Zhang HY. Control of Xenopus Tadpole Locomotion via Selective Expression of Ih in Excitatory Interneurons. Curr Biol 2018; 28:3911-3923.e2. [PMID: 30503615 PMCID: PMC6303192 DOI: 10.1016/j.cub.2018.10.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/06/2018] [Accepted: 10/22/2018] [Indexed: 11/16/2022]
Abstract
Locomotion relies on the coordinated activity of rhythmic neurons in the hindbrain and spinal cord and depends critically on the intrinsic properties of excitatory interneurons. Therefore, understanding how ion channels sculpt the properties of these interneurons, and the consequences for circuit function and behavior, is an important task. The hyperpolarization-activated cation current, Ih, is known to play important roles in shaping neuronal properties and for rhythm generation in many neuronal networks. We show in stage 42 Xenopus laevis frog tadpoles that Ih is strongly expressed only in excitatory descending interneurons (dINs), an important ipsilaterally projecting population that drives swimming activity. The voltage-dependent HCN channel blocker ZD7288 completely abolished a prominent depolarizing sag potential in response to hyperpolarization, the hallmark of Ih, and hyperpolarized dINs. ZD7288 also affected dIN post-inhibitory rebound firing, upon which locomotor rhythm generation relies, and disrupted locomotor output. Block of Ih also unmasked an activity-dependent ultraslow afterhyperpolarization (usAHP) in dINs following swimming, mediated by a dynamic Na/K pump current. This usAHP, unmasked in dINs by ZD7288, resulted in suprathreshold stimuli failing to evoke swimming at short inter-swim intervals, indicating an important role for Ih in maintaining swim generation capacity and in setting the post-swim refractory period of the network. Collectively, our data suggest that the selective expression of Ih in dINs determines specific dIN properties that are important for rhythm generation and counteracts an activity-dependent usAHP to ensure that dINs can maintain coordinated swimming over a wide range of inter-swim intervals. Ih is strongly expressed in Xenopus locomotor-rhythm-generating dIN interneurons Ih is active at rest in dINs, contributing to their distinct electrical properties dINs normally lack a Na pump-dependent ultra-slow afterhyperpolarization (usAHP) Ih counterbalances dIN usAHPs to preserve tadpole rhythm generating capacity
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Affiliation(s)
- Laurence D Picton
- School of Psychology and Neuroscience, University of St Andrews, St Andrews KY16 9JP, UK
| | - Keith T Sillar
- School of Psychology and Neuroscience, University of St Andrews, St Andrews KY16 9JP, UK
| | - Hong-Yan Zhang
- Centre for Discovery Brain Sciences, Edinburgh Medical School, University of Edinburgh, Edinburgh EH16 4SB, UK.
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