Performance on innate behaviour during early development as a function of stress level

Abstract

What is the relationship between the level of acute stress and performance on innate behaviour? The diversity of innate behaviours and lack of sufficient data gathered under the same experimental conditions leave this question unresolved. While evidence points to an inverted-U shaped relationship between the level of acute stress and various measures of learning and memory function, it is unknown the extent to which such a non-linear function applies to performance on innate behaviour, which develops without example or practice under natural circumstances. The fundamental prediction of this view is that moderate stress levels will improve performance, while higher levels will not. Testing this proposition has been difficult because it entails an overall effect that must be invariant to the nature of the stressor, the behaviour under scrutiny and the stimulus that drives it. Here, we report new experimental results showing that developing zebrafish (Danio rerio) under moderate but not higher levels of stress improved their performance on instinctive activities driven by visual, hydrodynamic and thermal inputs. Our findings reveal, for the first time, the existence of an inverted-U shaped performance function according to stress level during early development in a series of innate behaviours.

Convergence on reduced stress behavior in the Mexican blind cavefish

“…Various stimuli such as predators, osmotic stress, and thermal alterations induce behavioral measures of stress, and lead to reduced exploration, prolonged immobility or freezing, and reduced social interaction (Facchin et al, 2015; Levin et al, 2007; Mateo, 2007; Ryu and De Marco, 2017; vom Berg-Maurer et al, 2016; Yeh et al, 2013). In fish, several behavioral assays exist for measuring stress in adults.…”

“…For example, in mammals, maternal deprivation or neglect in early life can lead to aberrant behaviors in adults such as increased aggression and increased anxiety. Moreover, the effect of environmental stressors on stress responses follows a characteristic inverted U-shaped curve, where both too much and too little stress in the environment can have debilitating effects in later life (Russo et al, 2012; Ryu and De Marco, 2017). The neuronal systems that lead to this environmental relationship are not well understood, but they are thought to involve synaptic plasticity of the forebrain and epigenetic modifications of the crh gene (Elliott et al, 2010; Murgatroyd et al, 2009).…”

Active behaviour during early development shapes glucocorticoid reactivity

“…The scheme of independent sampling has been described elsewhere 46 . Briefly, cortisol and behavioural measurements were made on different groups of equally treated larvae and therefore constitute fully independent samples.…”

Larval Zebrafish Use Olfactory Detection of Sodium and Chloride to Avoid Salt Water

“…Zebrafish, in particular, would benefit from the ability to detect and navigate NaCl gradients because the environments in which they likely evolved are characterized by dramatic changes in local salinity levels: the river basins that surround the Ganges River in India and Bangladesh, for example, 17,18 are characterized by soft, ion-poor water with NaCl concentrations as low as 1 part per trillion, which can increase locally by orders of magnitude during the dry season. 19 Importantly, such changes lead to elevated stress and cortisol levels and are ultimately lethal, [20][21][22] which makes neural mechanisms for detecting and avoiding salt gradients paramount for survival. Here, we show that zebrafish have evolved behavioral strategies to avoid highsalt environments and that this behavior is mediated by the olfactory system through a subset of olfactory sensory neurons that detect the combined presence of sodium and chloride.…”