Identified neurons and leech swimming behavior

Brodfuehrer, Peter D.; Thorogood, Maria Stella E.

doi:10.1016/s0301-0082(00)00048-4

Cited by 43 publications

(33 citation statements)

References 31 publications

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“…Swimming has been thoroughly described at the level of its patterngenerating neural networks (Brodfuehrer and Thorogood, 2001;Brodfuehrer et al, 1995a), gating cells (Kristan and Weeks, 1983), descending command-like cells (Brodfuehrer and Friesen, 1986;Brodfuehrer et al, 1995b;O'Gara and Friesen, 1995;Esch et al, 2002), and modulation by serotonin Crisp and Mesce, 2006). Insights into the neuronal bases of both these locomotor patterns can now be advanced by comparing their organization and regulation.…”

Section: Comparisons Between Crawling and Swimming In The Leechmentioning

confidence: 99%

Dopamine Activates the Motor Pattern for Crawling in the Medicinal Leech

Puhl¹,

Mesce²

2008

J. Neurosci.

120

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Locomotion in segmented animals is thought to be based on the coupling of "unit burst generators," but the biological nature of the unit burst generator has been revealed in only a few animal systems. We determined that dopamine (DA), a universal modulator of motor activity, is sufficient to activate fictive crawling in the medicinal leech, and can exert its actions within the smallest division of the animal's CNS, the segmental ganglion. In the entire isolated nerve cord or in the single ganglion, DA induced slow antiphasic bursting (ϳ15 s period) of motoneurons known to participate in the two-step elongation-contraction cycle underlying crawling behavior. During each cycle, the dorsal (DE-3) and ventral (VE-4) longitudinal excitor motoneurons fired ϳ180°out of phase from the ventrolateral circular excitor motoneuron (CV), which marks the elongation phase. In many isolated whole nerve cords, DE-3 bursting progressed in an anterior to posterior direction with intersegmental phase delays appropriate for crawling. In the single ganglion, the dorsal (DI-1) and ventral (VI-2) inhibitory longitudinal motoneurons fired out of phase with each DE-3 burst, further confirming that the crawl unit burst generator exists in the single ganglion. All isolated ganglia of the CNS were competent to produce DA-induced robust fictive crawling, which typically lasted uninterrupted for 5-15 min. A quantitative analysis indicated that DA-induced crawling was not significantly different from electrically evoked or spontaneous crawling. We conclude that DA is sufficient to activate the full crawl motor program and that the kernel for crawling resides within each segmental ganglion.

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Section: Comparisons Between Crawling and Swimming In The Leechmentioning

confidence: 99%

Dopamine Activates the Motor Pattern for Crawling in the Medicinal Leech

Puhl¹,

Mesce²

2008

J. Neurosci.

120

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“…In vertebrates, electrophysiological data on the neuronal activity related to the self-initiated voluntary behavior have accumulated extensively (Schultz, 2000;Schall, 2001;Maimon and Assad, 2006;Tanji and Hoshi, 2008). In contrast, there are only a few lines of physiological evidence for such self-initiated behavior in invertebrates (Brodfuehrer and Thorogood, 2001;Garcia-Perez et al, 2007), although they have been exploited for the investigation of neuronal mechanisms subserving a variety of stimulusevoked behavior (Clarac and Pearlstein, 2007).…”

Section: Introductionmentioning

confidence: 99%

Readiness Discharge for Spontaneous Initiation of Walking in Crayfish

Kagaya¹,

Takahata²

2010

J. Neurosci.

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Animals initiate behavior not only reflexively but also spontaneously in the absence of external stimuli. In vertebrates, electrophysiological data on the neuronal activity associated with the self-initiated voluntary behavior have accumulated extensively. In invertebrates, however, little is known about the neuronal basis of the spontaneous initiation of behavior. We investigated the spike activity of brain neurons at the time of spontaneous initiation of walking in the crayfish Procambarus clarkii and found neuronal signals indicative of readiness or preparatory activities in the vertebrate brain that precede the onset of voluntary actions. Those readiness discharge neurons became active Ͼ1 s before the initiation of walking regardless of stepping direction. They remained inactive at the onset of mechanical stimulus-evoked walking in which other descending units were recruited. These results suggest that the parallel descending mechanisms from the brain separately subserve the spontaneous and stimulus-evoked walking. Electrical stimulation of these different classes of neurons caused different types of walking. In addition, we found other descending units that represented different aspects of walking, including those units that showed a sustained activity increase throughout the walking bout depending on its stepping direction, as well as one veto unit for canceling out the output effect of the readiness discharge and three termination units for stopping the walking behavior. These findings suggest that the descending activities are modularized in parallel for spontaneous initiation, continuation, and termination of walking, constituting a sequentially hierarchical control.

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“…Within the Protostomia, individually identiWable neurons have been shown to be present in the nervous systems of, e.g. Arthropoda (Burrows 1996;Harzsch et al 2005;Harzsch 2006), Annelida (Stuart et al 1987;Huang et al 1998, Gilchrist et al 1995Brodfuehrer and Thorogood 2001;Orrhage and Müller 2005;Müller 2006), Nemathelminthes/Cycloneuralia (White et al 1986;Walthall 1995), basal Mollusca (Friedrich et al 2002;Voronezhskaya et al 2002), Plathelminthes (Halton and Gustafsson 1996;Reuter et al 1998;Reuter and Halton 2001), and Gnathifera (Müller and Sterrer 2004). The presence of at least some individually identiWable neurons in basal deuterostomes such as tunicates (Meinertzhagen 2004;Stach 2005;Meinertzhagen et al 2004;Imai and Meinertzhagen 2007;Soviknes et al 2007), and the lancelet (Wicht and Lacalli 2005) indicates that the potential to establish individual identities may not only be present in the ground pattern of Protostomia; but may even date back to the ground pattern of Bilateria.…”

Section: Introductionmentioning

confidence: 99%

Fine structure of the ventral nerve centre and interspecific identification of individual neurons in the enigmatic Chaetognatha

et al. 2008

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The enigmatic arrow worms (Chaetognatha) are marine carnivores and among the most abundant planktonic organisms. Their phylogenetic position has been heavily debated for a long time. Most recent molecular studies still provide a diverging picture and suggest arrow worms to be some kind of basal protostomes. In an eVort to understand the organization of the nervous system in this clade for a broad comparison with other Metazoa we analysed the ultrastructure of the ventral nerve centre in Spadella cephaloptera by transmission electron microscopy. We were able to identify six diVerent types of neurons in the bilateral somata clusters by means of the cytoplasmic composition (regarding the structure of the neurite and soma including the shape and eu-/heterochromatin ratio within the nucleus) as well as the size and position of these neurons. Furthermore, our study provides new insights into the neuropil composition of the ventral nerve centre and several other Wne structural features. Our second goal was to examine if individually identiWable neurons are present in the ventral nerve centres of four chaetognath species, Sagitta setosa, Sagitta enXata, Pterosagitta draco, and Spadella cephaloptera. For that purpose, we processed whole mount specimens of these species for immunolocalization of RFamiderelated neuropeptides and analysed them with confocal laser-scanning microscopy. Our experiments provide evidence for the interspeciWc homology of individual neurons in the ventral nerve centres of these four chaetognath species suggesting that the potential to generate serially arranged neurons with individual identities is part of their ground pattern.

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Identified neurons and leech swimming behavior

Cited by 43 publications

References 31 publications

Dopamine Activates the Motor Pattern for Crawling in the Medicinal Leech

Dopamine Activates the Motor Pattern for Crawling in the Medicinal Leech

Readiness Discharge for Spontaneous Initiation of Walking in Crayfish

Fine structure of the ventral nerve centre and interspecific identification of individual neurons in the enigmatic Chaetognatha

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