Distributed Plasticity Drives Visual Habituation Learning in Larval Zebrafish

Habituation is a simple form of learning where animals learn to reduce their responses to repeated innocuous stimuli [1]. Habituation is thought to occur via at least two temporally and molecularly distinct mechanisms, which lead to short-term memories that last for seconds to minutes and long-term memories that last for hours or longer [1, 2]. Here, we focus on long-term habituation, which, due to the extended time course, necessitates stable alterations to circuit properties [2–4]. In its simplest form, long-term habituation could result from a plasticity event at a single point in a circuit, and many studies have focused on identifying the site and underlying mechanism of plasticity [5–10]. However, it is possible that these individual sites are only one of many points in the circuit where plasticity is occurring. Indeed, studies of short-term habituation in C. elegans indicate that in this paradigm, multiple genetically separable mechanisms operate to adapt specific aspects of behavior [11–13]. Here, we use a visual assay in which larval zebrafish habituate their response to sudden reductions in illumination (dark flashes) [14, 15]. Through behavioral analyses, we find that multiple components of the dark-flash response habituate independently of one another using different molecular mechanisms. This is consistent with a modular model in which habituation originates from multiple independent processes, each adapting specific components of behavior. This may allow animals to more specifically or flexibly habituate based on stimulus context or internal states. [Display omitted] •High-throughput behavioral analysis of dark-flash habituation in larval zebrafish•Multiple components of the response adapt with different habituation kinetics•Controlled by multiple circuit loci with different molecular requirements•Modular habituation selectively tunes behavioral components based on context Animals habituate to repeated stimuli, learning to ignore potential distractions. Randlett et al. show that multiple components of the larval zebrafish dark-flash response habituate independently using different molecular mechanisms. This reveals that habituation learning is a modular process that selectively adapts specific components of behavior.