title: Descending control of swim posture by a midbrain nucleus in zebrafish.
abstract: The reticular formation in the brainstem controls motor output via axonal projections to the hindbrain and spinal cord. It remains unclear how individual groups of brainstem neurons contribute to specific motor functions. Here, we investigate the behavioral role of the nucleus of the medial longitudinal fasciculus (nMLF), a small group of reticulospinal neurons in the zebrafish midbrain. Calcium imaging revealed that nMLF activity is correlated with bouts of swimming. Optogenetic stimulation of neurons in the left or right nMLF activates the posterior hypaxial muscle and produces a graded ipsilateral tail deflection. Unilateral ablation of a subset of nMLF cells biases the tail position to the intact side during visually evoked swims, while sparing other locomotor maneuvers. We conclude that activity in the nMLF provides postural control of tail orientation and thus steers the direction of swimming. Our studies provide an example of fine-grained modularity of descending motor control in vertebrates.
authors: Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany.
authors: Tod R
authors: TR
authors: Thiele
authors: Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany; Program in Neuroscience, University of California at San Francisco, San Francisco, CA 94143, USA.
authors: Joseph C
authors: JC
authors: Donovan
authors: Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany. Electronic address: hbaier@neuro.mpg.de.
authors: Herwig
authors: H
authors: Baier
mesh_terms: D000818:Animals; D008636:Mesencephalon / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology*; D009474:Neurons / Q000166:cytology*; D011187:Posture / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D013550:Swimming; D015027:Zebrafish / Q000502:physiology*