@article {47380, title = {Brain-wide mapping of neural activity controlling zebrafish exploratory locomotion.}, journal = {eLife}, year = {2016}, month = {2016 Mar 22}, abstract = {

In the absence of salient sensory cues to guide behavior, animals must still execute sequences of motor actions in order to forage and explore. How such successive motor actions are coordinated to form global locomotion trajectories is unknown. We mapped the structure of larval zebrafish swim trajectories in homogeneous environments and found that trajectories were characterized by alternating sequences of repeated turns to the left and to the right. Using whole-brain light-sheet imaging, we identified activity relating to the behavior in specific neural populations that we termed the anterior rhombencephalic turning region (ARTR). ARTR perturbations biased swim direction and reduced the dependence of turn direction on turn history, indicating that the ARTR is part of a network generating the temporal correlations in turn direction. We also find suggestive evidence for ARTR mutual inhibition and ARTR projections to premotor neurons. Finally, simulations suggest the observed turn sequences may underlie efficient exploration of local environments.

}, doi = {10.7554/eLife.12741}, url = {http://dx.doi.org/10.7554/eLife.12741}, author = {Dunn, Timothy W. and Mu, Yu and Narayan, Sujatha and Randlett, Owen and Naumann, Eva A. and Yang, Chao-Tsung and Schier, Alexander F. and Freeman, Jeremy and Engert, Florian and Ahrens, Misha B.} } @article {5840, title = {Identification of nonvisual photomotor response cells in the vertebrate hindbrain.}, journal = {The Journal of Neuroscience}, volume = {33}, year = {2013}, month = {2013 Feb 27}, pages = {3834-43}, abstract = {

Nonvisual photosensation enables animals to sense light without sight. However, the cellular and molecular mechanisms of nonvisual photobehaviors are poorly understood, especially in vertebrate animals. Here, we describe the photomotor response (PMR), a robust and reproducible series of motor behaviors in zebrafish that is elicited by visual wavelengths of light but does not require the eyes, pineal gland, or other canonical deep-brain photoreceptive organs. Unlike the relatively slow effects of canonical nonvisual pathways, motor circuits are strongly and quickly (seconds) recruited during the PMR behavior. We find that the hindbrain is both necessary and sufficient to drive these behaviors. Using in vivo calcium imaging, we identify a discrete set of neurons within the hindbrain whose responses to light mirror the PMR behavior. Pharmacological inhibition of the visual cycle blocks PMR behaviors, suggesting that opsin-based photoreceptors control this behavior. These data represent the first known light-sensing circuit in the vertebrate hindbrain.

}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.3689-12.2013}, author = {Kokel, David and Dunn, Timothy W. and Ahrens, Misha B and Alshut, R{\"u}diger and Cheung, Chung Yan J. and Saint-Amant, Louis and Bruni, Giancarlo and Mateus, Rita and van Ham, Tjakko J. and Shiraki, Tomoya and Fukada, Yoshitaka and Kojima, Daisuke and Yeh, Jing-Ruey J. and Mikut, Ralf and von Lintig, Johannes and Engert, Florian and Peters, Randall T.} } @article {6222, title = {Spinal projection neurons control turning behaviors in zebrafish.}, journal = {Current Biology}, volume = {23}, year = {2013}, month = {2013 Aug 19}, pages = {1566-73}, abstract = {

Discrete populations of brainstem spinal projection neurons (SPNs) have been shown to exhibit behavior-specific responses during locomotion [1-9], suggesting that separate descending pathways, each dedicated to a specific behavior, control locomotion. In an alternative model, a large variety of motor outputs could be generated from different combinations of a small number of basic motor pathways. We examined this possibility by studying the precise role of ventromedially located hindbrain SPNs (vSPNs) in generating turning behaviors. We found that unilateral laser ablation of vSPNs reduces the tail deflection and cycle period specifically during the first undulation cycle of a swim bout, whereas later tail movements are unaffected. This holds true during phototaxic [10], optomotor [11], dark-flash-induced [12], and spontaneous turns [13], suggesting a universal role of these neurons in controlling turning behaviors. Importantly, we found that the ablation not only abolishes turns but also results in a dramatic increase in the number of forward swims, suggesting that these neurons transform forward swims into turns by introducing turning kinematics into a basic motor pattern of symmetric tail undulations. Finally, we show that vSPN activity is direction specific and graded by turning angle. Together, these results provide a clear example of how a specific motor pattern can be transformed into different behavioral events by the graded activation of a small set of SPNs.

}, issn = {1879-0445}, doi = {10.1016/j.cub.2013.06.044}, author = {Huang, Kuo-Hua and Ahrens, Misha B and Dunn, Timothy W. and Engert, Florian} }