Stimulating different parts of the brain can dial up or down a specific memory's emotional oomph, study shows Source: Boston University New research shows memories are pliable if you know which regions of the brain's hippocampus to stimulate, a finding that could someday enable personalized treatment for people with PTSD, depression and anxiety.
Inside our brains, a cashew-shaped structure called the hippocampus stores the sensory and emotional information that makes up memories, whether they be positive or negative ones.
No two memories are exactly alike, and likewise, each memory we have is stored inside a unique combination of brain cells that contain all the environmental and emotional information associated with that memory
The hippocampus itself, although small, comprises many different subregions all working in tandem to recall the elements of a specific memory.
Now, a team of collaborators have shown just how pliable memory is if you know which regions of the hippocampus to stimulate, which could someday enable personalized treatment for people haunted by particularly troubling memories.
Using a technique called optogenetics, scientists mapped out which cells in the hippocampus were being activated when male mice made new memories of positive, neutral, and negative experiences.
A positive experience, for example, could be exposure to a female mouse. In contrast, a negative experience could be receiving a startling but mild electrical zap to the feet.
Then, identifying which cells were part of the memory-making process (which they did with the help of a glowing green protein designed to literally light up when cells are activated), they were able to artificially trigger those specific memories again later, using laser light to activate the memory cells.
Their studies reveal just how different the roles of the top and bottom parts of the hippocampus are.
Activating the top of the hippocampus seems to function like effective exposure therapy, deadening the trauma of reliving bad memories
But activating the bottom part of the hippocampus can impart lasting fear and anxiety-related behavioral changes, hinting that this part of the brain could be overactive when memories become so emotionally charged that they are debilitating.