Long-term habituation of the C-start escape response in zebrafish larvae

Abstract

The cellular and molecular basis of long-term memory in vertebrates remains poorly understood. Knowledge regarding long-term memory has been impeded by the enormous complexity of the vertebrate brain, particularly the mammalian brain, as well as by the relative complexity of the behavioral alterations examined in most studies of long-term memory in vertebrates. Here, we demonstrate a long-term form of nonassociative learning—specifically, long-term habituation (LTH)—of a simple reflexive escape response, the C-start, in zebrafish larvae. The C-start is triggered by the activation of one of a pair of giant neurons in the zebrafish’s hindbrain, the Mauthner cells. We show that LTH of the C-start requires the activity of NMDA receptors and involves macromolecular synthesis. We further show that the long-term habituated reflex can by rapidly dishabituated by a brief tactile stimulus. Our results set the stage for rigorous, mechanistic investigations of the long-term memory for habituation of a reflexive behavioral response, one that is mediated by a relatively simple, neurobiologically tractable, neural circuit. Moreover, the demonstration of NMDAR and transcriptionally dependent LTH in a translucent vertebrate organism should facilitate the use of optical recording, and optogenetic manipulation, of neuronal activity to elucidate the cellular basis of a long-term vertebrate memory.

Brain-wide visual habituation networks in wild type and fmr1 zebrafish

“…Since zebrafish larvae undergo behavioral habituation 18,19 they have been used for experiments with tactile, visual, and acoustic stimuli, exploring the genetic and molecular mechanisms of specific circuits 20-24 . Furthermore, they share important molecular underpinnings of habituation with other species [25][26][27] . All together, these features make them an appealing platform for exploring brain-wide habituation circuitry.This approach requires a robust innate behavior that is subject to habituation.…”

Behavioral studies of stimulus learning in zebrafish larvae

“…The consensus to emerge is that more stimulus exposures and longer interstimulus intervals (ISIs) at t1 produce stronger learning effects at t2 (Rescorla and Holland, 1976). Data from the larval zebrafish are consistent with these outcomes (O'Neale et al, 2014;Roberts et al, 2011Roberts et al, , 2016Wolman et al, 2011). For example, O'Neale et al (2014) varied the number of 5-min presentations of the bouncing disk or the stationary control disk across different groups of 7 dpf larvae.…”

“…Remarkably, only a few studies have adopted the t1-t2 framework to demonstrate stimulus learning during early larval development (O'Neale et al, 2014;Roberts et al, 2011Roberts et al, , 2016Wolman et al, 2011). Roberts et al (2011) used a between-subject design and implemented the conventional no treatment control condition outlined in Table 1.…”

“…An alternative strategy to dishabituation is to demonstrate the persistence of the response decrement over a time period long enough to allow for the dissipation of any sensory adaptation or motor fatigue effects. Using both of these strategies, Roberts et al (2016) have demonstrated habituation of the C-start reflex to an auditory/vibrational stimulus detected 18 hours after exposure and the dishabituation of that response by the application of a novel stimulus, lightly touching the larva with a broom bristle, 15 min before testing.…”

Effects of Social Experience on the Habituation Rate of Zebrafish Startle Escape Response: Empirical and Computational Analyses

“…One form of learning is habituative learning, a well-characterized form of non-associative learning during which an animal decreases its responsiveness to repeated stimuli (Thompson and Spencer, 1966 ; Rankin et al, 2009 ). While habituation has been described in many organisms including Cnidarians (Rushforth et al, 1964 ), aplysia (Kandel, 2009 ), crayfish (Krasne and Woodsmall, 1969 ; Araki et al, 2013 ), zebrafish (Eaton et al, 1977a ; Marsden and Granato, 2015 ; Pantoja et al, 2016 ; Roberts et al, 2016 ) and humans (Davis, 1934 ), it remains unclear how social dominance leads to neural differences underlying habituation processes (Glanzman, 2009 ; Thompson, 2009 ).…”