It seems like we’re writing about fish a whole lot lately! Last week, we featured an article about goldfish learning to drive. This week, zebrafish, a species studied for their relatively long lifespans, are helping us understand how memories are made!
Let’s talk synapses!
Signals in the brain are passed between neurons through tiny gaps called synapses. Here, a chemical rapidly transfers from one side to another, allowing information to flow through the organ. It is widely accepted these structures play a key role in memory formation, the theory being that particular synapses are linked to particular memories. Therefore, the more a synapse is used the more the memory is reinforced.
Testing zebrafish memories
Scientists, from the University of California, have been able to add more key information to this theory through imaging the brains of zebrafish (Danio rerio). The reason these creatures were used was their convenient clear skin, giving scientists a see-through window into their organs without having to kill the animals, a research goldmine!
Previously, synapse structures have been too minuscule to image. Although, with the clever use of fluorescence molecules and lasers the group was able to image the live fish brains. Using neutral (light) and unpleasant (heat) stimuli, the researchers trained the associated memory of the fish and recorded their neurological activity.
What were the results?
The results, published in PNAS, were interesting, to say the least. The team actually found that the widely accepted strengthening idea is not entirely true! Instead, new synapse connections were seen forming in numerous parts of the brain and also disappearing while making memories. The updated theory may point towards memory being imprinted through changes in the number of synapses.
Further research needs to be carried out to strengthen the group’s idea. If proven true, it could change how we approach the brain and mental health treatment. For example, therapy for diseases such as PTSD, addiction, and memory loss therapies could be seeing an enormous upgrade.
Source study: PNAS – Regional synapse gain and loss accompany memory formation in larval zebrafish