Hunting for proprioception in larval zebrafish: does age matter?

Zebrafish (Danio rerio) are an important vertebrate model for neuroscience research. Much is known about zebrafish development and neuroanatomy, but less is known about how specific their behavior is affected by cell-type specific ablations which is important for understanding the function of their neural circuitry. Behavioral analysis of the sensorimotor behavior of zebrafish following cell-specific ablations addresses this gap. This study investigated proprioceptive function of the lateral line, one of the major sources of sensory input from the trunk, in larval zebrafish. Proprioception is a key mechanism for coordinating motor behaviors in response to self-generated cues. The study investigated the effect of removing the lateral line sensory input on the swimming behavior of larval zebrafish. An established method for evoking reflexive motor behavior in zebrafish, the Optomotor Response (OMR), was used to quantify swimming ability. Lateral line mechanosensory hair cells were ablated by bath application of neomycin. The experiments were replicated in two separate clutches of zebrafish larvae, raised to ages 11-12 dpf (days post-fertilization). Clutch 1 (n = 47) did not show an effect on swim distance (OMR gain) or speed from the lateral line ablation, whereas Clutch 2 (n = 27) did. This may be due to the larvae compensating for the lack of neuromast sensory input with other trunk sensory input, such as from the Dorsal Root Ganglion sensory neurons.