NIH. US: It’s no secret that many of
our memories are associated with feelings, some good and some
not-so-good. Why is this?
In 2014, as part of an ongoing quest to
explore how memories are shaped and reshaped, researchers were able to
identify the brain circuits that link memories to both positive and
negative emotions, at least in mice. In a technical tour de force, the
researchers went on to use a technique that uses light to control the
activity of brain cells, called optogenetics, to change the emotions
associated with the mice’s memories from negative to positive (in this
case, fearful to pleasant) and vice versa.
And there are many other examples from 2014 of neuroscientists making
progress in understanding the molecular mysteries of memory. For
example, another group recently used optogenetics to silence a subset of
neurons in the brains of mice, preventing the animals from recalling a
frightening event and effectively erasing their memory of it.
Although optogenetics is too invasive to use in humans, what is learned
from such research could help point the way to more effective treatments
for a range of mental illnesses, including depression, anxiety, and
post-traumatic stress disorder.
Bidirectional switch of the valence associated with a hippocampal contextual memory emgram. Redondo RL, Kim J, Arons AL, Ramirez S, Liu X, Tonegawa S. Nature. 2014 Sep 18;513(7518):426-30.
Cortical Representations Are Reinstated by the Hippocampus during Memory Retrieval. Tanaka KZ, Pevzner A, Hamidi AB, Nakazawa Y, Graham J, Wiltgen BJ. Neuron. 2014 Oct 22;84(2):347-54.