Taiwan – Chang Gung University has recently seen its strong biomedical research efforts bear fruit a the tiny fruit fly. A research team on campus, led by Associate Professor Chia-Lin Wu, found a new mechanism of memory formation in the fly’s brain. The findings, published in Nature Communications on 15 May 2017, provide brand new scope that may challenge our understanding of memory.
The research team deprived water from Drosophila melanogaster, the fruit flies, to produce the sense of thirst. By utilising an unique water-reward system, one can observe memory formation and degradation over time. Their results showed that water-reward memory can last for more than one day, and is not easily decayed. Therefore, they defined this form of memory the water-reward long-term memory.
The team also identified a specific group of dopaminergic neurons in fruit flies’ brain called PAM-β´1 that are responsible for conveying the reward signal to the learning and memory centre in insects named mushroom body, and form long-term memory. Other neural circuit responsible for short-term memory formation is also characterised. When the circuit was blocked, flies lost their short-term memory while long-term memory remained intact, and vice versa. This notion was confirmed independently by genetically activating neurons for either memory, upon which the flies only form the corresponding type of memory.
Chia-Lin Wu stated that, while people previously thought the short-term memory and long-term memory are formed sequentially, the results of the current study pointed out that these memories are formed independently after learning via different neural circuits.
The results of this paradigm-shifting study provides a reasonable insight into understanding memory loss due to some neurological disorders. For example, Alzheimer’s patients who suffer from memory loss only have their short-term memory impaired, with long-term memory remaining intact. This is very likely due to the fact that the two different memories are handled by two neural circuits completely independent of one another. The research was funded by the Ministry of Science and Technology and the Chang Gung Memorial Hospital, Taiwan.