New research decodes the brain's forgetting mechanisms

scientists have long explored memory to avoid the topic of "forgotten": people think that "forgotten" is the disappearance of memory, "preventing forgetting" is the best way to enhance memory.But with the neuroscience community's research on the mechanism of forgetting in recent years, a complex picture has emerged: forgetting is not simply "elimination of memory". The phenomenon of "words in the mouth" is an example: suddenly forgotten names, birthdays, cell phone numbers, will suddenly appear in our minds after a period of time.In a study published January 21 in Nature, three neuroscientistes from the Scripps Institution in Florida unveiled this unique mechanism.The "happy molecule" that drives forgetting, dopamine, is thought to be the brain's release of "fast-splitting music", a common neurotonic condition that transmits complex and diverse global messages to different regions of the brain. In recent years, dopamine's role in oblivion has gradually emerged. In a series of experiments, the researchers not only confirmed the importance of dopamine for endogenetic forgetting, but also found dopamine neurons responsible for promoting forgetting, and even dopamine-likes responsible for performing forgetting functions. All this, thanks to the black belly fruit fly.Fruit flies have about 100,000 neurons in their brains -- far less than the 86 billion neurons in the human brain, but the brains of fruit flies are complex enough for us to explore biological memory and forgetfulness. The 100,000 neurons make up an area of the brain called the "post-outer frontal brain region 1" (PPL1), which contains 12 dopamine neurons. Many of these 12 dopamine neurons send information to the mushroom body (the sensory information processing center of the fruit fly) and release dopamine on the ad altrues of various neurons in the mushroom body (the primary location where the neurons receive information), thus regulating signal integration of the mushroom body neurons.Neuroscientistes have long divided the mushroom body into many regions based on the gene expression and anatomical position of various neurons in the mushroom body. Among them, the mushroom body neurons receive information from PPL1 dopamine neurons and mediat endogenous (long-term) oblivion. Past studies have supported the role of dopamine-mediated forgetting, which provides a valuable cornerstone for this study.In the study,Ronald Davis of the Scripps Institute, along with doctoral student John Sabandar and postdoctoral researcher Jacob Berry, tried to uncover the mysterious mechanism of instant forgetting by sending PPL1 to the mushroom body.Davis and others trained fruit flies in aversion to olfactory condition reflexes. Put the trained fruit flies in a T-word maze and place "bad smells" (representing the smell of electric shock) and "neutral smells" (smells not connected to electric shocks) on both sides of the intersection to see which way they go. The results were the same as expected: trained fruit flies were more likely to avoid "bad smells" and move in the direction of "neutral smells".Next, to study instant forgetting, Davis et al. briefly jetted, electrocuted, or blue-lighted fruit flies before choosing "left or right." The results were not surprising: the fruit flies were dizzy under the influence of disturbing stimuli and stopped avoiding "bad smells" at all. Interestingly, if fruit flies were tested again an hour after the disturbance, they could recall which one was a "bad smell" and actively avoid choosing another path.By directly stimulating dopamine neurons in PPL1, the researchers succeeded in suppressing the memory of fruit flies, which, if they inhibited the output of these dopamine neurons, did not produce instantaneous forgetting under interference. Among them, dopamine neurons from PPL1 to mushroom body alpha 2'2 are the most important. This suggests that there is a "memory memory" in the mushroom body alpha-2 alpha'2 neurons, while dopamine acts as a "gate".However, one thing is important in instant forgetting: it is short-lived, and after minutes to hours, the ability to recall is restored. This suggests that instant forgetting (the activity of PPL1-alpha2 alpha'2 dopamine neurons) does not destroy memory storage, but simply disconnects the "circuit" of memory. This can also be proved by experiments: in fruit flies where dopamine neurons are active, the "memory neurons" in mushrooms are actually as active as when dopamine neurons are inactive. In other words, dopamine neurons block memory extraction, but do not destroy the memory itself.(According to Global Science) (Source: Science and Technology Daily)