Scientists reactivate memory in rats with light

Researchers from University of California-San Diego have found more evidence that strong connections between neurons in the brain are crucial for developing memories. And they were able to deactivate and reactivate fear memories in rats by using a flalshing light. Published in the journal Nature, the findings presented the first scientific evidence that long-term potentiation (LTP), which strengthens connections between neurons, can help form memories.

The scientists used a laser to control specific circuits within rats. When the rats received a shock accompanied by a sound, researchers triggered stimulation by lighting up a group of neurons associated with auditory fear memory. Varying the patterns of that stimulation increased LTP, thus strengthening neuron connections. They were also able to weaken neuron connections through long-term depression (LTD). So when a rat was shocked a second time, they would or wouldn’t be scared of the sound, depending on the strength of the neuron connections.

Therefore, they could end a memory by using LTD and bring a memory back by using LTP. When the rats died, the scientists were able to analyze the brain more closely. They found that the targeted neurons in the experiment exhibited signs of chemical sensitivity. This confirms the connection between the level of neuron strength and memory.

This new information could be used to better understand Alzheimer’s and other memory illnesses, such as post-traumatic stress disorder.

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