The Structure and Timescales of Heat Perception in Larval Zebrafish

Abstract

SUMMARY Avoiding temperatures outside the physiological range is critical for animal survival, but how temperature dynamics are transformed into behavioral output is largely not understood. Here, we used an infrared laser to challenge freely swimming larval zebrafish with “white-noise” heat stimuli and built quantitative models relating external sensory information and internal state to behavioral output. These models revealed that larval zebrafish integrate temperature information over a time-window of 400 ms preceding a swimbout and that swimming is suppressed right after the end of a bout. Our results suggest that larval zebrafish compute both an integral and a derivative across heat in time to guide their next movement. Our models put important constraints on the type of computations that occur in the nervous system and reveal principles of how somatosensory temperature information is processed to guide behavioral decisions such as sensitivity to both absolute levels and changes in stimulation.

Probabilistic Models of Larval Zebrafish Behavior: Structure on Many Scales

“…Together, the anatomy and movement patterns of larval zebrafish simplify behavioral analyses and allow each swim bout to be represented as a point in a high dimensional posture or kinematic parameter space. Several studies have taken advantage of these properties to analyse and categorize swim bouts, and the most comprehensive 14 effort to date identified 13 basic types of swims used during hunting 30,31 , taxis behaviors 32,33,34,35 , escape maneuvers 36,37,38 , social interactions 39 , and spontaneous 40 swimming in the light and dark.…”

Multiple overlapping hypothalamus-brainstem circuits drive rapid threat avoidance

“…To address these challenges, we chose to investigate fast-timescale encoding of environmental stressors in the larval zebrafish. Adult and larval zebrafish demonstrate both slow endocrine adaptations and fast behavioral avoidance in response to environmental stressors, including heat, salinity, and acidity, among others (Wendelaar Bonga, 1997;Hoshijima & Hirose, 2007;Yeh et al, 2013;De Marco et al, 2014;Kwong et al, 2014;Schulte, 2014;Haesemeyer et al, 2015;Schreck & Tort, 2016;vom Berg-Maurer et al, 2016;Takei & Hwang, 2017;Wee et al, 2019). The structure and function of the hypothalamus is conserved across fish and mammals (Chiu & Prober, 2014;Biran et al, 2015), and larval zebrafish possess a number of experimental advantages over rodents.…”

Imaging, manipulation and optogenetics in zebrafish

“…They also have small brains that are well suited to studies FIGURE 1.1: Top and side view of a 6 days post-fertilization (dpf) larvae zebrafish using light-based techniques. Despite the brain's size, larvae at 5 days postfertilisation (dpf) have functioning sensory systems for visual [11][12][13], auditory [14][15][16], somatory [17,18], water flow [19][20][21], and vestibular stimuli [22,23]. This makes them an ideal system in which to use light based tools to study the details of sensory neural circuits.…”

“…To correct for this I calculated the convolution of the Monte Carlo ray distribution (once all the ray trajectories have been calculated) in a plane with the focal spot of the unscattered beam calculated using wave theory. For the numerical aperture considered here, the paraxial formula is sufficiently accurate [51], giving a Gaussian focal spot intensity: 17) where w 0 is the beam waist defined as: 18) and: 19) where z r is the Raleigh range, or distance over which the beam radius spread with a factor of 2, which can be expressed as:…”

“…Even though the behavioural responses observed and shown cannot be from heat, it does not prove the absence of heat sensation and heat information processing in the brain. Noxious heat has been studied in zebrafish [18,139,140], and multiple brain regions show activity in response to noxious heat. With those results, we know that we need to differentiate brain activity in responses to heat and acceleration.…”