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Title

CHANGES OF ZEBRAFISH BEHAVIORAL RESPONSES TO ODORANTS BY OLFACTORY IMPRINTING AND LEARNING

Creator

Deng, Xin

Date

2014, 2014-12

Description

This study reports the improved behavioral responses to odorants due to olfactory imprinting and learning. Learning is a process thereby an...
Show moreThis study reports the improved behavioral responses to odorants due to olfactory imprinting and learning. Learning is a process thereby an individual obtains the information from the environment and the retained information facilitates the subsequent reactions to the same or related information. Olfactory imprinting is a special form of learning in that it occurs in a specific stage of life such as development, and the learned information has a life long influence on animal behavior or physiology when animals encounter the same stimuli later in their life. Olfactory imprinting is an important physical process for many species. Studies in our laboratory have shown that zebrafish can be imprinted by amino acids and bile acids. Here, I studied the influence of olfactory imprinting and learning on olfactory detection sensitivity of zebrafish using behavioral tests. The experimental zebrafish included the following groups: the BA group, imprinted by two bile acids, deoxycholic acid and taurocholic acid (TCA); the AA group, imprinted by two amino acids, L-arginine and L-cysteine, and the control group without odorant stimuli. Odorant exposure for imprinting was completed on 40 days post-fertilization and behavioral tests were conducted in adult fish of one year old. TCA and lithocholic acid (LCA) were used in the adult fish behavioral tests. My results showed that zebrafish from the BA group had significant lower detection thresholds to both TCA and LCA compared with the corresponding detection thresholds in the control group of zebrafish. In contrast, the AA group of fish did not show lower detection threshold to TCA compared with the control fish. The results indicated that imprinting can increase the sensitivity of BA fish to bile acids, while imprinting of amino acids did not improve the sensitivity of the AA fish to bile acids. Learning tests were conducted in my study because the data indicated that learning might also be responsible for the lowered detection thresholds in the BA and control groups due to repeated exposure to TCA in behavioral tests. Age matched naive zebrafish were used in behavioral tests from low concentration to high concentration of TCA. Then the behavioral tests were conducted in the opposite direction, from high to low concentrations.The detection threshold obtained in the former experiments was one log unit higher than that from the later experiments. Thus, it appears that learning can also increase the sensitivity of zebrafish to bile acids. Taken together, my data indicate that the improved sensitivity to TCA in the BA group might result from a combination of both olfactory imprinting and learning.
M.S. in Biology, December 2014
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