Brainstem pathways controlling the versatility and selection of motor actions in the zebrafish Danio rerio

• Applicant: Dr. Eva Berg
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2016 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 324960069

The versatility of behaviors that is shown throughout the animal kingdom is overwhelming. Yet, how this versatility is organized and how the selection of behaviors is achieved in the nervous system is only beginning to be understood. I will address this question in the context of neural circuits controlling locomotion, specifically locomotor speed, in a vertebrate, the zebrafish Danio rerio.Behaviors are planned in the cortex and basal ganglia and are then executed by neural circuits in the brainstem and spinal cord. These circuits transform the planned behaviors into motor actions with the right parameters, like speed, force, and timing, for the surrounding circumstances. Traditionally, the vertebrate spinal locomotor circuit is seen as one single network providing uniform drive to the motor neurons. Accordingly, the descending drive from higher brain centers is thought to uniformly activate the neurons of the spinal locomotor circuit. The versatility of locomotor speeds is thus encoded in the number and frequency of action potentials conveyed by the (uniform) descending pathway.Recent results in the zebrafish indicate that this view might not be detailed enough. In this work, the spinal locomotor circuit is shown to be organized in ensemble sub-circuits that preferably activate slow, intermediate, and fast motor units, respectively. These premotor sub-circuits are engaged at different swimming speeds.These results raise the question whether also descending inputs may be modular and channeled in distinct descending paths that preferably activate the slow, intermediate, and fast spinal sub-circuits. Thus, already the descending paths would be engaged in a task-dependent manner related to the locomotor speed. This hypothesis will be tested in the current project. For this purpose, I will test the connectivity of descending neurons to the different spinal sub-circuits both anatomically and functionally and test the impact of certain groups of descending neurons on behavior.

• DFG Programme: Research Fellowships
• International Connection: Sweden
• Host: Professor Dr. Abdel El Manira