Associative Learning in Zebrafish

点击翻译按钮获取中文摘要

Learning and memory are important and complex functions of the brain. While significant discoveries have been made about the psychological, neurobiological and molecular mechanisms underlying learning and memory, most scientists agree, we have only started to scratch the surface. The overwhelming majority of the studies in this research area have been conduced with laboratory rodents. However, a new laboratory species, the zebrafish, may offer some advantages and may allow us to discover fundamental aspects of learning and memory faster. Here, we propose a program for the analysis of learning and memory using the zebrafish. Specifically, we will first investigate what motivates zebrafish in learning tasks. Without proper motivators (reward or punishment) learning does not occur. Zebrafish is a newcomer in learning and memory research and we will investigate how to avoid fast satiation in food rewarded tasks. Also, we will optimize computer-presented social cues that highly motivate zebrafish, a social species. We will also investigate the motivational value of natural environmental stimuli. Second, the biggest issue in zebrafish memory research is human handling induced stress. We will develop home-tank based learning tasks to avoid this stress, a development that will substantially increase one's ability to study complex learning processes in the zebrafish. Our third goal is to characterize simple and complex forms of associative learning. The complex forms (called relational learning and memory) are particularly interesting as they are similar to what allows us, human beings, to form episodic/declarative or consciously recallable memories. In a pioneering study, we have shown that zebrafish could form relational memories. Here, we will study this type of memory using our home-tank paradigm with experimentally controlled presentation of a series of visual stimuli whose order and co-occurrence will have to be learned by the fish to obtain reward. Our fourth goal is to determine how long fish remember simple and complex memories and whether these memories are prone to disruption or modification by experimental manipulations. That is, we will study how stable or modifiable simple and complex forms of memories are in the zebrafish. At the end of the 5-year grant, we will have understood fundamental behavioural mechanisms of learning and memory in zebrafish, which will be crucial to the next phase of our program: the analysis of molecular and neurobiological mechanisms underlying memory processes. We are excited about our proposal because numerous evolutionarily conserved features have been identified in the zebrafish, ranging from nucleotide sequences of its genes through its neurotransmitter systems to how its brain responds to drugs developed for humans. Thus, these similarities between human and zebrafish features suggest that what we will discover with zebrafish will be translatable to a variety of other vertebrates.