A new study reported in the prestigious journal Cell (June 18, 2015) has found evidence that neurons break their own DNA to enable us to learn and to form memories. Up till know it has widely been assumed that a breakage in the DNA means damage and if the breakage remains then the DNA’s own repair systems are defective.
These researchers have found that “damage” is necessary to allow the expression of the so-called “early response” which are actually responsible for the regulation of processes crucial for the formation of long-lasting memories. The astounding conclusion to be drawn from this research is not only that this break in the DNA of neurons is not “damage” in the normal sense of the word, but also it is the routine process that results in the storage of the memory. The fact that the DNA is altered in this way clearly indicates that the memories are actually stored in the DNA and not in the neural network as has always been assumed.
These lesions or breaks in the DNA are immediately repaired, and what’s more it has been found that these repair systems become less effective in aging subjects which again clearly affirms that it is actually the DNA and not the neurons which are responsible for the storage of memory and thus accounts for the common loss of memory capability later in life. Earlier studies have actually foreshadowed this research when they found that the DNA of mice with Alzheimer’s disease had a significantly large occurrence of these unrepaired breaks or lesions. These earlier studies conducted by Li-Huei Tsai at the Massachusetts Institute of Technology (MIT) found the unrepaired lesions occurred specifically in the hippocampus of these mice which is known precisely to be a region of the brain responsible for learning and memory.
To further test this link between the breakage of the DNA and memory storage the researchers actually isolated neurons in a petri dish and exposed them to an agent that caused these double strand breaks in the DNA. When they examined the DNA in these isolated neurons they found that while the expression of the genes in general had been reduced, astoundingly expression had increased in these early-response genes responsible for memory storage, which would indicate that the DNA had committed this experiment to memory in these dead and lifeless neurons.
The early response genes are known to be rapidly expressed after neuronal activity and the researchers set out to ascertain whether the breaks in the DNA where a part of this process. When an organism is exposed to a new experience information flows across the gaps in the neural network known as the synapse. The scientists exposed the neurons to a substance which mimics the flow of this information after a new experience. “Sure enough, we found that the treatment very rapidly increased the expression of those early response genes, but it also caused DNA double strand breaks,” Tsai said in a statement. That is to say a false memory had been stored in the DNA of the organism.
The researchers used computers that scrutinized the DNA sequences adjacent to these breaks. When the DNA is intact there are minute kinks in the DNA caused by the binding of an architectural protein. These kinks prevent crucial signaling with distant DNA regions, and thus inhibits the expression of the early response genes. The breaks in the DNA remove this barrier to gene expression thus enabling the memory to be stored.
It has been known all along that aging results in a decline in the expression of the genes involved in learning processes as well as the storage of memories, and it would now appear that the problem is actually caused by the DNA repair processes becoming defective with age which means that these breaks in the DNA tend to accumulate thus hindering the retrieval of the information.
In another article on this website Memory Storage in the DNA you can learn how the expression of genes can be controlled by our brain waves, thus indicating that ultimately the occurrence of these breakages in the DNA must come from the mental image of the memory to be stored. These scientists have found a breakage in the chemical structure of the DNA but it must be obvious to all that the breakage cannot of itself explain the storage of a memory. Rather the breakage withdraws the barrier that enables the early response genes to pick up a certain precise frequency of brain wave which obviously would be capable of transmitting a precise mental image. A certain precise frequency of brain waves would most certainly be generated by the specific firing of a precise cluster of neurons, thus explaining all stages of the process from the formulation of a mental image to its ultimate storage as data in the DNA.