By using a flash of light, scientists have reportedly been able to first erase and then restore a memory in genetically engineered rats. The research study, which was backed by the National Institutes of Health, is the first known evidence which shows reinforced connections between neurons are what memories are actually made of.
Dr. Roberto Malinow, who works at the University of California, San Diego and one of the researchers on the study, explained that the results his team found has added to increasing evidence that the brain signifies a memory by creating clusters of neurons that have fortified synapses (connections). The findings also propose that fading synapses most likely disassemble any neuronal assemblies in order to deactivate a memory.
The study report is printed up in the newest edition of the science journal Nature.
He explained that even past possible applications in disorders of memory loss, such as dementia, this improved understanding of how memory works might help show clues as to how to take control of runaway emotional memories which sometimes rage with mental illnesses, such as post-traumatic stress disorder.
Neuroscientists have long believed that connections among neurons which had been strengthened, triggers the formation of memories. This is known as long-term potentiation or LTP but proof had remained intangible, until now.
Dr. Malinow and his group were able to gain the evidence they were looking for by identifying LTP when they were forming memories in rodents. They removed the memory by using a procedure that is known to reverse LTP, and then they brought the memory back again. This was all done by adjusting the strength of the synapses in a memory gathering.
In order to gain the exact control needed to show such a relationship, Malinow’s crew turned to one of neuroscience’s best new powerful tools known as optogenetics. This adapts the exact cellular equipment which lets primitive organisms such as algae to be controlled by sunlight. It allows certain brain circuit components to instantly be stimulated by a laser, even in a working animal.
In normal rat conditioning experiments, some sort of tone is paired up with a shock to the foot to produce a fear memory of the tone. If the memory is active, the animal will freeze and shows lessened reward seeking activities when it hears the tone again. Instead of using a tone sound, Malinow’s group combined the shock with direct optogenetic stimulus, and lit up a certain group of neurons in an auditory fear memory circuit. Before this, there was never such detailed targeting with previous electrical stimulation techniques. The brain had mostly always been considered a jungle. There were just too many nerve cells coming and going in any single place.
However upon closer optogenetic probing in postmortem brains, the battered circuit neurons displayed revealing changes in sensitivity of brain chemical messenger systems. These deviations confirmed the conjectured idea of firming and weakening synaptic links in the switching on and off of the memory.
Dr. Malinow stated that his team was able to show the harmful products which build up in the brains of patients suffering from Alzheimer’s disease can weaken synapses the identical way that declining synapses remove a memory. He added that in addition to eradicating any hesitation about a connection between LTP and LTP with memories, such experiments show the amazing potential of meticulousness targeting and manipulation of circuits for improving maladaptive memories.
The scientists used a flash of light and have reportedly been able to first inactivate and then reactivate a memory in genetically engineered rats.
By Kimberly Ruble