Isaac Bianco

Wednesday 13th September 2017

Time: 4.00pm

Ground Floor Seminar Room

25 Howland Street, London, W1T 4JG

Sensorimotor circuits controlling innate behaviours in larval zebrafish

We are interested in the structure and function of sensorimotor circuits, in particular those controlling innate visually guided behaviours of larval zebrafish. In this talk, I will discuss how activity in the midbrain optic tectum relates to perception of prey-like visual stimuli and the generation of hunting behaviour. Downstream of tectal activity, premotor circuits orchestrate behavioural responses. I will focus on our investigations of how supraspinal neural activity controls distinct locomotor outputs, which are selectively deployed in different behavioural contexts. Across vertebrates, it is clear that locomotor circuitry in the spinal cord generates the rhythmic and coordinated patterns of neural activity that directly control muscles, but less is known about the descending supraspinal commands that instruct these distinct locomotor responses. We are investigating activity of the reticulospinal complex – a stereotyped and compact population of projection neurons in the mid/hind-brain tegmentum, which represent a site of convergence for descending commands from the brain to spinal cord. 2-photon calcium imaging is combined with tethered behavioural assays, where larval fish are presented with a range of stimuli to evoke a diversity of motor outputs. A combination of machine learning and linear regression methods are used to analyse reticulospinal population activity and build encoding models for individual neurons. I will present our recent findings in relation to two main questions: (1) What are the reticulospinal population activity patterns associated with distinct locomotor outputs? (2) Can the activity of individual reticulospinal cells be linked to specific motor kinematics? We hope that this project will uncover principles concerning how supraspinal circuits generate locomotor diversity in vertebrates.