The Effects of noise of Zebrafish (Danio rerio) memory
Date
2023-06-28
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
Abstract
Ever since the start of the industrial revolution anthropogenic disturbances have increased in severity. Anthropogenic noise is one such example, which has deleterious effects on organisms in both terrestrial and aquatic habitats. The range of effects may vary from interruptions in behavioural functions such as communication, feeding, breeding, and prey-predator interactions to physiological alterations in hormones levels or even severe damages to internal organs. In this study, I investigated the effects of white noise on the cognitive performance of zebrafish (Danio rerio) and its possible mechanism of action, focusing on GABA neurotransmitter levels in the brain. To this end, adult zebrafish were exposed to four sound treatments: a medium intensity sound presented in either a regular and irregular pattern, or a high intensity sound presented with either a regular or irregular pattern for 30 min. Subsequently, alterations in cognitive performance were evaluated using a plus maze associative learning paradigm and novel object recognition paradigm. The first experiment results showed a significant drop in the total travelling distance in noise-exposed treatments compared to controls without supplementary noise. Moreover, in the noise treatments, there was a trend towards fewer visits to the target arm of the maze in comparison to the control group. Although the total time spent in the target arm among noise-exposed treatments was significantly different compared to control, only the High-Irregular treatment was significantly different from the Medium-Regular and High-Regular treatments. In the second test, no significant difference was observed in the total travelling distance except for Medium-Irregular and High-Irregular groups that showed reduced movement. Fish in the High-Irregular treatment had the lowest visiting frequency and accumulated time around the novel object, and the highest latency to visit the novel object, which can be an indicator of developing neophobia in this group. Furthermore, the High-Irregular treatment had a significant difference compared to other noise-exposed treatments. The noise intensity and predictability did not reveal a significant difference between treatments. However, slight changes were noticeable in some of the behavioural variables. Our results indicated that noise exposure can affect zebrafish performance, and different patterns of noise may result in different outcomes. However, whether these changes are the results of a direct effect of noise on memory requires more studies.
Description
Keywords
Noise, Zebrafish, Memory, Associative memory, Novel object recognition, Neurotransmitter
Citation
Degree
Master of Science (M.Sc.)
Department
Biology
Program
Biology