While remembering your telephony telephone number or what sentence you made dinner reservations for tomorrow dark may not glut you with feelings , many computer memory have emotion attached to them ; your first Clarence Shepard Day Jr. at school , your nuptials twenty-four hour period , losing your pet .
It ’s been get it on for some time that these worked up associations , or valency , aremalleable . Therapists even take advantage of this intrinsic property of memory in social club to plow patients with weather condition such as post - traumatic stress disorder . However , the neural mechanism that enable us to flip emotional associations have long been a mystery . Now , in a newMIT study , neuroscientist have discover the neuronal electrical circuit that is critical for the connection of emotion with retentivity . what is more , they have demonstrate that they can reverse the valence of a memory by activate specific populations of encephalon cells . The study has been published inNature .
Two brain structures are known to be decisive in the formation of new memories : the genus Hippocampus and the amygdala . Thehippocampusis affect in memory formation , organization and storage . Theamygdalais demand in emotional processing and computer memory storage . However , until now , scientists did n’t know at what stagecoach in the head circuit that valences became assigned to memories , or engrams .
To find out more , the researcher used a technique calledoptogeneticsto manipulate the activity of neuron . This involved using a light - sensitive protein to label a population of cells in either the dorsal dentate gyrus of the genus Hippocampus or the amygdala . The nerve cell they tagged were those that were touch off during a rewarding experience ( male mice socializing with female person ) or during fearfulness ( a mild electric shock ) .
The squad then placed the mouse in a two - zone arena and observe which side they exhibit a druthers for . Next , they used blue light tostimulate the pronounce neuronsin the fear stipulate mice whenever they entered their preferred side of the arena . The mice quickly started to ward off the area that they had in the first place preferred , suggesting the care memory had been reactivated .
They then did the same for the mice that were reward - condition , but instead stimulated their neurons when they entered the side they did not favour . for certain enough , the mice started to accede this side more frequently , suggesting they wererecalling the pleasant memory .
Next , the researcher attempted to reverse the valence of a memory by subjecting the condition mouse to theopposite condition — i.e. they activated the neuron in the mice that originally get payoff conditioning while they received galvanising shocks , and vice versa .
When they come in the shiner back in the box , those that were earlier fear qualify and avoiding one side of the field while their hippocampal neurons were trigger now began to favor this area , suggesting the computer memory valency had been switched . This switch also took place in mice that were originally reward - conditioned . However , this did not occur in shiner that had their amygdala trigger off as fight back to the genus Hippocampus .
rent together , this studysuggeststhat valency are encoded in the circuit that connect the dentate gyrus to the amygdala . Furthermore , the neurons carry memories in the dentate convolution are plastic , intend the valence can be reversed by reassociating memory with a stimulus of an paired valency . Cells of the amygdala , on the other hand , are pre - committed to encode a positive or damaging retentivity andcannot throw .
The researchers are now adopt this work forward by examine whether reactivating pleasant computer storage can positively touch depression .
