Mushrooms aid total recall

Drosophila: offers clues to how we keep memories in mind.(C) SPL.

Learning to love putrid pongs must take some nerve. But flies can learn smells even when critical nerve connections in their brains are blocked, researchers have found although recalling the scents needs cells that are fully switched on1. The findings offer clues on how the mind keeps track of its memories.

Flies like dung because of a brain nodule called the mushroom body. This knot of nerves is involved in learning and remembering smells but whether it makes the memories, stores them or recalls them was unknown.

By silencing synapses, Adidas Ultra Boost AQ8257 Men Black White Malaysia Price the connections between nerve cells, Josh Dubnau and his colleagues at Cold Spring Harbor Laboratory in New York found that the fruitflies’ ability to memorize smells is not affected when the mushroom body is switched off. “I was very surprised that electrical activity is not required for learning,” says Dubnau.

The team used a heat sensitive switch to silence the nerves. Putting the flies in a hot room overheated dynamin, Adidas Pure Boost BA8893 Men White Grey Malaysia Online the synapse protein found in the cells of the mushroom body. For a few minutes at a time, these hot nerve cells could receive but not send signals. Meanwhile the flies learnt to choose between two smells: liquorice and sweaty tennis shoes.

Memories formed by the flies when they were hot could still be recalled when the insects were cooled down. But if the flies were heated up while remembering, Adidas NMD X Bape Unisex Camouflatge White 2017 Malaysia they could not recall a thing.

The findings challenge a long standing idea that memories are formed by persistent electrical signals echoing around the brain, says Randolf Menzel, who works on bee learning at Freie Universit Berlin. “If such a circulating activity does exist, it does not involve the part of the network responsible for reading out the information,” he says.

The mushroom body: may be responsible for learning smells.

Instead, Dubnau’s team speculates that electrical activity entering nerve cells in the mushroom body stops there, creating biochemical changes that store the memory. “The cells can learn this information without communicating with other neurons,” says Dubnau.

But Scott Waddell of the Massachusetts Institute of Technology, Cambridge, who also works on fly memory, thinks that other brain areas may also have been affected by the synaptic knockout. “I don’t think you can pin it down to the mushroom body,” he says.

Nevertheless, he notes that “understanding information processing and storage in any animal relates to others”. The mushroom body is a simple neural network, and the way it works relates to other networks, such as our own hippocampus and cortex.