title: The dorsal raphe modulates sensory responsiveness during arousal in zebrafish.
abstract: During waking behavior, animals adapt their state of arousal in response to environmental pressures. Sensory processing is regulated in aroused states, and several lines of evidence imply that this is mediated at least partly by the serotonergic system. However, there is little information directly showing that serotonergic function is required for state-dependent modulation of sensory processing. Here we find that zebrafish larvae can maintain a short-term state of arousal during which neurons in the dorsal raphe modulate sensory responsiveness to behaviorally relevant visual cues. After a brief exposure to water flow, larvae show elevated activity and heightened sensitivity to perceived motion. Calcium imaging of neuronal activity after flow revealed increased activity in serotonergic neurons of the dorsal raphe. Genetic ablation of these neurons abolished the increase in visual sensitivity during arousal without affecting baseline visual function or locomotor activity. We traced projections from the dorsal raphe to a major visual area, the optic tectum. Laser ablation of the tectum demonstrated that this structure, like the dorsal raphe, is required for improved visual sensitivity during arousal. These findings reveal that serotonergic neurons of the dorsal raphe have a state-dependent role in matching sensory responsiveness to behavioral context.
authors.affiliation: Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.
authors.forename: Tohei
authors.initials: T
authors.lastname: Yokogawa
authors.forename: Markus C
authors.initials: MC
authors.lastname: Hannan
authors.forename: Harold A
authors.initials: HA
authors.lastname: Burgess
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D030801:Animals, Genetically Modified; D001143:Arousal / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics; D053148:Caspase 3; D004558:Electric Stimulation; D020287:In Situ Nick-End Labeling; D007814:Larva; D008164:Luminescent Proteins / Q000235:genetics; D009043:Motor Activity / Q000235:genetics / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010812:Physical Stimulation; D011903:Raphe Nuclei / Q000166:cytology* / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology; D012701:Serotonin / Q000378:metabolism; D013477:Superior Colliculi / Q000502:physiology; D013997:Time Factors; D014365:Tryptophan Hydroxylase / Q000235:genetics; D014732:Vibration; D015027:Zebrafish
chemical_list: D002352:Carrier Proteins; D008164:Luminescent Proteins; D009419:Nerve Tissue Proteins; D012701:Serotonin; D014365:Tryptophan Hydroxylase; D053148:Caspase 3; D002118:Calcium