22 December 2020
The study by Petrazzini et al (2020) used the Zantiks AD unit to perform a light-dark preference test as a measure of anxiety. This test utilises an animals natural preference for dark environments and is widely taken as a valid low-cost tool for assessing anxiety.
Zebrafish were singly inserted into an experimental tank for 15 min and were free to explore the environment. After 5 min of acclimation, in which the bottom of the tank was black, half of the floor became white while the other half remained black. After 5 min, the position of the light and dark floors was switched to ensure that zebrafish choice was not affected by any existing laterality bias in the environment. The proportion of time spent in the dark compartment and the proportion of movements made in the dark compartment were recorded and automatically output by the AD unit.
Two experiments were performed. First using wild type Zebrafish, followed by Zebrafish with reversed epithalamic asymmetry. Half of the subjects with left parapineal (Left-PP) and half with right parapineal (Right-PP).
Figure: Proportion of time spent in the darker area and proportion of movement in the darker area for Right-PP and Left-PP subjects. Errorbars represent the standard error of the mean.
Overall, zebrafish spent a larger proportion of time in the darker area. There was no correlation between the degree of behavioural lateralization of fish and the proportion of time spent in the darker area, nor was there a correlation between degree of lateralization and the proportion of movement in the darker area. A positive correlation was found between the proportion of time spent and the proportion of movementin the darker compartment. No significant difference was observed between Left-PP and Right-PP subjects in either the proportion of time in the darker compartment or the proportion of movements in the darker area.
The full article can be found here:
