Manipulating Memory

Manipulating Memory

By: Olajumoke Bamgbose

Memory is a key part of survival, especially fear learning. While being scared is not the ideal situation, our brain is still able to use that to learn and then later keep us away from harms way. Without fear learning, we would not know to run away from a tiger, which is important for survival. Fear is not the best emotion to feel at the time, but there is no doubt that most times having an appropriate fear response is necessary. While most fear memories are good for longevity some fear memories, like the ones seen in PTSD patients, can actually make life harder. According to a study done at the University of California: Riverside, researchers may have found a way to erase parts of fear memory that are not necessary for survival in mice while still keeping parts of that memory needed for survival in tact.

The researchers looked in the amygdala, which is responsible for fear learning and memory, and they saw that the fear conditioning training led to stronger connections in the synapses of neurons in the amygdala. The mice learned to fear different tones that were accompanied by a footshock and those tones began to have really strong synaptic connections in the amygdala. The researchers at UC-Riverdale then used optogenetics to manipulate this memory system. They were able to stimulate only the cells that responded to the sound by weakening the signal in the neurons, while leaving the fear response of the footshock alone. They were able to erase the fear of the tone from the mice without erasing the fear of a footshock. The researchers manipulated memory in a way that weakened connections in the amygdala which gave more insight on how fear memory is encoded.

 This is somewhat similar to the work of Joel Voss, who also manipulated memory but in an opposite direction. Voss’s work used TMS and MRI to strengthen communication between parts of the hippocampal network. TMS was used on the lateral parietal cortex and they found that the excitation of that area was able to indirectly stimulate the hippocampus, by waking up that network. This stimulation was able to cause an increase in performance of a memory task that participants took. Voss and his team were able to strengthen connections in the hippocampal network through rTMS and continual stimulation of the hippocampal network. They were able to improve memory by up to 30% which can be a big deal, especially for people with different types of memory deficits. Both studies give a lot of insight to memory and can both lead to changing the way we deal with different disorders that include memory deficits.  

References:

1.         University of California - Riverside. "How particular fear memories can be erased: Findings have therapeutic implications in PTSD and phobias." ScienceDaily, August 17, 2017 https://www.sciencedaily.com/releases/2017/08/170817131130.htm

2.         Jane X. Wang, Lynn M. Rogers, Evan Z. Gross, Anthony J. Ryals, Mehmet E. Dokucu, Kelly L. Brandstatt, Molly S. Hermiller, Joel L. Voss (2014) “Targeted enhancement of cortical-hippocampal brain networks and associative memory” Science, 345 pg. 1054-1057

3.         Woong Bin Kim, Jun-Hyeong Cho. “Encoding of Discriminative Fear Memory by Input-Specific LTP in the Amygdala” Neuron, 2017