From Medical Xpress:

A singe dopamine neuron (yellow) in the mushroom body of the fruit fly Drosophila. Glenn Turner and colleagues trained flies to avoid certain odors by pairing them with stimulations of dopamine neurons signaling punishment. They found that this form of associative learning is driven by changes in synaptic strength between mushroom body neurons that process odors and downstream neurons that generate behavioral responses. Credit: Turner Lab, CSHL

Scientists at Cold Spring Harbor Laboratory (CSHL) have resolved a decades-long debate about how the brain is modified when an animal learns.

Using newly developed tools for manipulating specific populations of , the researchers have for the first time observed direct evidence of synaptic plasticity—changes in the strength of connections between neurons—in the fruit fly brain while flies are learning.

“We showed something that people have been hoping to see for a long time,” says the team leader, CSHL Associate Professor Glenn Turner, “and we showed it quite definitively.” The results appear online today in the journal Neuron.

Due to the relative simplicity of fruit fly neural anatomy—there are just two synapses separating odor-detecting antenna from an olfactory-memory brain center called the mushroom body—the diminutive insects have provided a powerful model organism for studying learning.

Historically, researchers have monitored neurons in the mushroom body, as well as others to which they send signals, using a technique called calcium imaging. This approach enabled previous researchers to observe changes in neural activity that accompany learning. However this technique doesn’t reveal precise how the…

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