The study found the mechanism by which the fruit fly rhythm neurons gate memory fades

In classical conditional reflexes, a neutral stimulus coupled with a non-conditional stimulus with a reward or punishment effect can become a conditional stimulus that can trigger a reward or punishment reaction alone, creating a memory of "conditional stimulation foreshadowing the ongoing non-conditional stimulus".
After memory formation, if repeated conditional stimuli occur alone without non-conditional stimulation, then the foreshadowing effect of conditional stimulation on non-conditional stimuli is re-evaluated, and even the forming of a regressive memory (memory memory) where "conditional stimulation indicates that non-conditional stimuli will not occur", and memory recedes occurs.
-receding memory can affect the predicted intensity of conditional stimulation for non-conditional stimuli, play an important role in adaptive behavior in animals according to environmental changes, and is also used in "exposure therapy" to treat post-traumatic stress disorder and drug addiction.
receding memory has two remarkable characteristics: first, it requires multiple trainings to form, and second, it lasts longer than the original memory, causing spontaneous recovery of the original memory after a period of inhibition.
these properties make memory-based exposure therapies expensive and not guaranteed long-term effective.
, understanding the mechanism behind "multiple training but only short-term maintenance of memory subsidion" is of great significance for improving the therapeutic effect of exposure therapy.
hungry fruit flies can form olfactory memories by mesolytic odors and sucrose, and a single concilink can form long-term memories that last more than 24 hours.
However, to form a regressive memory for a 24-hour reward memory, it is necessary to give the fruit fly a separate conditional stimulation several times, and the form of a regressive memory is maintained for less than 24 hours, after which the reward memory is spontaneously restored.
Such findings make it possible to study the formation and maintenance mechanisms of receding memory using the rewarding long-term memory of fruit flies, and the ability to form receding memory has been found to have circadian fluctuations, so that the relatively clear rhythmic neural networks of fruit flies and a wealth of genetic tools can be used to study their effects on memory decline by briefly manipulating the activity of rhythmic neurons.
the rhythmic neurons of fruit flies can be divided into sub-groups, including DN1 neurons, according to location and cytospheric morphology, and this study found that there are a small number of DN1 neurons expressing Cryptochrome, which play a role in the formation of gate-controlled receding memory.
researchers found that regressive memories formed by multiple retreats depend on increased activity of DN1 rhythm neurons, because if this increase is suppressed, memory decline cannot be observed even after multiple training sessions.
At the same time, a single retreat training that could not have stabilized the formation of a receding memory, accompanied by the brief activation of the DN1 rhythm neurons in fruit flies, can steadily form a receding memory sufficient to last more than 3 hours and disappear after 24 hours, similar to the results of multiple retreat training (Figure 1).
researchers then used two experiments to further confirm and explore the gate-controlled effect of DN1 rhythm neurons on memory decline: first, functional calcium imaging data showed that 1 to 3 DN1 rhythm neurons in each half of the brain of fruit flies had multiple retreat training in specific responses;
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