Whisker motor cortex ablation and whisker movement patterns

Gao, Peng; Hattox, Alexis M.; Jones, Lauren M.; Keller, Asaf; Zeigler, H. Philip

doi:10.1080/08990220310001622924

Cited by 56 publications

(50 citation statements)

References 26 publications

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“…Like CPGs, this system does not rely on cortical inputs (Gao et al 2003;Lovick 1972;Semba and Komisaruk 1984) or sensory feedback (Welker 1964) to generate rhythmic output. However, whereas mammalian CPGs are typically composed of networked interneurons that generate the motor pattern and subsequently drive motoneurons, in the vibrissa system, our results suggest that rhythmic movements are generated by the motoneurons themselves in response to tonic input from serotonergic premotoneurons.…”

Section: Discussionmentioning

confidence: 99%

“…These rhythmic movements, or whisking, persist after sensory denervation (Welker 1964), cortical ablation (Gao et al 2003;Semba and Komisaruk 1984), or decerebration (Lovick 1972), suggesting that the whisking motor pattern is produced subcortically by a CPG. We demonstrated previously that serotonin (5-HT) drives vibrissa motoneurons (vMNs) at whisking frequencies and that infusion of 5-HT receptor antagonists onto vMNs suppresses voluntary whisking .…”

Section: Introductionmentioning

confidence: 99%

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The Whisking Rhythm Generator: A Novel Mammalian Network for the Generation of Movement

Cramer

Liu²,

Keller³

2007

Journal of Neurophysiology

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. Using the rat vibrissa system, we provide evidence for a novel mechanism for the generation of movement. Like other central pattern generators (CPGs) that underlie many movements, the rhythm generator for whisking can operate without cortical inputs or sensory feedback. However, unlike conventional mammalian CPGs, vibrissa motoneurons (vMNs) actively participate in the rhythmogenesis by converting tonic serotonergic inputs into the patterned motor output responsible for movement of the vibrissae. We find that, in vitro, a serotonin receptor agonist, ␣-Me-5HT, facilitates a persistent inward current (PIC) and evokes rhythmic firing in vMNs. Within each motoneuron, increasing the concentration of ␣-Me-5HT significantly increases the both the magnitude of the PIC and the motoneuron's firing rate. Riluzole, which selectively suppresses the Na ϩ component of PICs at low concentrations, causes a reduction in both of these phenomena. The magnitude of this reduction is directly correlated with the concentration of riluzole. The joint effects of riluzole on PIC magnitude and firing rate in vMNs suggest that the two are causally related. In vivo we find that the tonic activity of putative serotonergic premotoneurons is positively correlated with the frequency of whisking evoked by cortical stimulation. Taken together, these results support the hypothesized novel mammalian mechanism for movement generation in the vibrissa motor system where vMNs actively participate in the rhythmogenesis in response to tonic drive from serotonergic premotoneurons.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Whisking Rhythm Generator: A Novel Mammalian Network for the Generation of Movement

Cramer

Liu²,

Keller³

2007

Journal of Neurophysiology

Self Cite

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“…As such, this procedure has enabled other difficult behavioral tasks (Gao et al, 2001;Bermejo et al, 2002;Gao et al, 2003b;Friedman et al, 2006) and intracellular (Crochet and Petersen, 2006) and extracellular (Sachdev et al, 2000;Kleinfeld et al, 2002;Melzer et al, 2006) recording studies. Yet it has been heretofore undocumented how head restraint may alter whisking behavior.…”

Section: Whisking In Head-fixed Versus Freely Exploring Animalsmentioning

confidence: 99%

“…Lesion studies have shown that whisking persists after sensory nerve transection (Welker, 1964;Gao et al, 2001;Berg and Kleinfeld, 2003;Berg et al, 2006), contralateral motor cortex ablation (Gao et al, 2003b), and extensive decerebration (Welker, 1964). These results argue for a brainstem central pattern generator to drive rhythmic whisking.…”

Section: Motor Control Of Exploratory Whiskingmentioning

confidence: 99%

Biomechanics of the Vibrissa Motor Plant in Rat: Rhythmic Whisking Consists of Triphasic Neuromuscular Activity

Hill¹,

Bermejo²,

Zeigler³

et al. 2008

J. Neurosci.

138

188

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The biomechanics of a motor plant constrain the behavioral strategies that an animal has available to extract information from its environment. We used the rat vibrissa system as a model for active sensing and determined the pattern of muscle activity that drives rhythmic exploratory whisking. Our approach made use of electromyography to measure the activation of all relevant muscles in both head-fixed and unrestrained rats and two-dimensional imaging to monitor the position of the vibrissae in head-fixed rats. Our essential finding is that the periodic motion of the vibrissae and mystacial pad during whisking results from three phases of muscle activity. First, the vibrissae are thrust forward as the rostral extrinsic muscle, musculus (m.) nasalis, contracts to pull the pad and initiate protraction. Second, late in protraction, the intrinsic muscles pivot the vibrissae farther forward. Third, retraction involves the cessation of m. nasalis and intrinsic muscle activity and the contraction of the caudal extrinsic muscles m. nasolabialis and m. maxillolabialis to pull the pad and the vibrissae backward. We developed a biomechanical model of the whisking motor plant that incorporates the measured muscular mechanics along with movement vectors observed from direct muscle stimulation in anesthetized rats. The results of simulations of the model quantify how the combination of extrinsic and intrinsic muscle activity leads to an enhanced range of vibrissa motion than would be available from the intrinsic muscles alone.

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“…Lesion studies first indicated a persistence of whisking after decortication [8]. More recent studies demonstrated alterations in whisking after cortical lesions [62,63], but the induced deficits were often subtle and did not immediately indicate a specific cortical function. All in all, the function of VMC is still very much unclear, in part, also because of the lack of understanding of the overall significance of whisker movements.…”

Section: Organization Of the Vibrissa Motor Cortexmentioning

confidence: 99%

Cellular mechanisms of motor control in the vibrissal system

Brecht

Grinevich

Jin

et al. 2006

Pflugers Arch - Eur J Physiol

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In this article we discuss the experimental advantages that the vibrissal motor system offers for analysis of motor control and the specializations of this system related to the unique characteristics of whisker movements. Whisker movements are often rhythmic, fast, and bilateral. Movements of individual whiskers have simple characteristics, whereas, movements of the entire vibrissae array are complex and sophisticated. In the last few years, powerful methods for high precision tracking of whisker movements have become available. The whisker musculature is arranged to permit forward movements of individual whiskers and consists-depending on the species -mainly or exclusively of fast contracting, fast fatigable muscle fibers. Whisker motor neurons are located in the lateral facial nucleus and their cellular properties might contribute to the rhythmicity of whisking. Numerous structures provide input to the lateral facial nucleus, the most mysterious and important one being the putative central pattern generator (CPG). Although recent studies identified candidate structures for the CPG, the precise identity and the functional organization of this structure remains uncertain. The vibrissa motor cortex (VMC) is the largest motor representation in the rodent brain, and recent work has clarified its localization, subdivisions, cytoarchitectonics, and connectivity. Single-cell stimulation experiments in VMC allow determining the cellular basis of cortical motor control with unprecedented precision. The functional significance of whisker movements remains to be determined.

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Whisker motor cortex ablation and whisker movement patterns

Cited by 56 publications

References 26 publications

The Whisking Rhythm Generator: A Novel Mammalian Network for the Generation of Movement

The Whisking Rhythm Generator: A Novel Mammalian Network for the Generation of Movement

Biomechanics of the Vibrissa Motor Plant in Rat: Rhythmic Whisking Consists of Triphasic Neuromuscular Activity

Cellular mechanisms of motor control in the vibrissal system

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