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Dive into the research topics where Frédéric Brocard is active.

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Featured researches published by Frédéric Brocard.


European Journal of Neuroscience | 2003

Nicotinic activation of reticulospinal cells involved in the control of swimming in lampreys

Didier Le Ray; Frédéric Brocard; Céline Bourcier-Lucas; François Auclair; Philippe Lafaille; Réjean Dubuc

In lampreys as in other vertebrates, brainstem centres play a key role in the initiation and control of locomotion. One such centre, the mesencephalic locomotor region (MLR), was identified physiologically at the mesopontine border. Descending inputs from the MLR are relayed by reticulospinal neurons in the pons and medulla, but the mechanisms by which this is carried out remain unknown. Because previous studies in higher vertebrates and lampreys described cholinergic cells within the MLR region, we investigated the putative role of cholinergic agonists in the MLR‐controlled locomotion. The local application of either acetylcholine or nicotine exerted a direct dose‐dependent excitation on reticulospinal neurons as well as induced active or fictive locomotion. It also accelerated ongoing fictive locomotion. Choline acetyltransferase‐immunoreactive cells were found in the region identified as the MLR of lampreys and nicotinic antagonists depressed, whereas physostigmine enhanced the compound EPSP evoked in reticulospinal neurons by electrical stimulation of this region. In addition, cholinergic inputs from the MLR to reticulospinal neurons were found to be monosynaptic. When the brainstem was perfused with d‐tubocurarine, the induction of swimming by MLR stimulation was depressed, but not prevented, in a semi‐intact preparation. Altogether, the results support the hypothesis that cholinergic inputs from the MLR to reticulospinal cells play a substantial role in the initiation and the control of locomotion.


Neuroscience | 2007

Modulation of respiratory activity by locomotion in lampreys

J. Gravel; Frédéric Brocard; Jean-François Gariépy; James P. Lund; Réjean Dubuc

In vertebrates, locomotion is associated with changes in respiratory activity, but the neural mechanisms by which this occurs remain unknown. We began examining this in lampreys using a semi-intact preparation of young adult Petromyzon marinus, in which respiratory and locomotor behaviors can be recorded simultaneously with the activity of the underlying neural control systems. Spontaneous fictive respiration was recorded with suction electrodes positioned over the glossopharyngeal or the rostral vagal motor nucleus. In this preparation, locomotor activity, characterized by symmetrical tail movements (electromyogram recordings), was evoked by mechanical stimulation of the skin. During locomotion, the mean respiratory frequency and the mean area of the motor bursts were significantly increased (81.6+/-28.6% and 62.8+/-25.4%, respectively; P<0.05). The frequency returned to normal 92+/-51 s after the end of locomotion. There were fluctuations in the instantaneous respiratory and locomotor frequencies that were rhythmical but antiphasic for the two rhythmic activities. The changes in respiratory activity were also examined during bouts of locomotion occurring spontaneously, and it was found that a modification in respiratory activity preceded the onset of spontaneous locomotion by 3.5+/-2.6 s. This suggests that the early respiratory changes are anticipatory and are not caused by feedback generated by locomotion. The increase in respiratory frequency during locomotion induced by sensory stimulation persisted after removal of the mesencephalon. When both the mesencephalon and spinal cord were removed, resulting in the isolation of the rhombencephalon, changes in the respiratory activity were also present following skin stimulations that would have normally induced locomotion. Altogether, the results suggest that respiratory changes are programmed to adjust ventilation prior to motor activity, and that a central rhombencephalic mechanism is involved.


Journal of Neurophysiology | 2003

Differential Contribution of Reticulospinal Cells to the Control of Locomotion Induced By the Mesencephalic Locomotor Region

Frédéric Brocard; Réjean Dubuc


Journal of Neurophysiology | 2006

Emergence of Intrinsic Bursting in Trigeminal Sensory Neurons Parallels the Acquisition of Mastication in Weanling Rats

Frédéric Brocard; Dorly Verdier; Isabel Arsenault; J.P. Lund; Arlette Kolta


Journal of Neurophysiology | 2005

Modulatory effect of substance P to the brain stem locomotor command in lampreys

Frédéric Brocard; Cedric Bardy; Réjean Dubuc


Archives of Oral Biology | 2007

A review of burst generation by trigeminal main sensory neurons

Arlette Kolta; Frédéric Brocard; Dorly Verdier; James P. Lund


Journal of Neurophysiology | 2004

Muscarinic Modulation of the Trigemino-Reticular Pathway in Lampreys

Didier Le Ray; Frédéric Brocard; Réjean Dubuc


Archive | 2016

Pathway in Lampreys Muscarinic Modulation of the Trigemino-Reticular

Frédéric Brocard; Réjean Dubuc


Archive | 2015

Potential Oscillations in Lamprey Spinal Neurons Intracellular QX-314 Causes Depression of Membrane

Russell H. Hill; Sten Grillner; Sabrina Tazerart; Jean-Charles Viemari; Pascal Darbon; Laurent Vinay; Frédéric Brocard; Andrew D. McClellan; Mykola O. Kovalenko; Jessica A. Benes; David J. Schulz; Dimitri Ryczko; Vanessa Charrier; Auke Jan Ijspeert; Jean-Marie Cabelguen


Archive | 2015

Generator for Locomotion and Regulates the Locomotor Rhythm The Persistent Sodium Current Generates Pacemaker Activities in the Central Pattern

Sabrina Tazerart; Laurent Vinay; Frédéric Brocard; Alex C. Kwan; Shelby B. Dietz; Watt W. Webb; Ronald M. Harris-Warrick

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Laurent Vinay

Centre national de la recherche scientifique

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Arlette Kolta

Université de Montréal

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Dimitri Ryczko

Université de Montréal

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Dorly Verdier

Université de Montréal

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Didier Le Ray

Université de Montréal

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