Joyce Chen ’23
One of the most fascinating things about the brain is its malleability. When humans learn, whether it be in the classroom or from an experience, the brain produces new neurons so that the information can be recalled in the future. This is a process known as neuronal plasticity. Although there is plenty of research surrounding this area, there is still much more to learn about the effect of prior learning on the brain’s reaction to future learning. Stony Brook University professor Dr. Ryan Parsons and a group of researchers looked deeper into the role of the basolateral amygdala (BLA) in learning and memory by using designer receptors exclusively activated by designer drugs (DREADDs) on model rats.
Drugs were administered to the amygdalas of the rats in order to activate the DREADD receptors. Afterwards, the research team initiated the behavioral procedures: baseline startle responses and fear conditioning. During the baseline startle procedure, the rats were exposed to bursts of white noise to test their startle responses. In the fear conditioning procedure, the rats were introduced to a light and a shock. The light and shock were either paired together or unpaired depending on the trial being conducted. After being injected with a drug that inhibited BLA activity, the rats underwent another trial. Data analysis revealed that the paired light and shock trial aided in priming long-term memory (LTM) while the unpaired trial did not have as big of an impact. Furthermore, rats that received the inhibitor of BLA had little to no levels of LTM during their test trials. However, if the rats were injected with the drug right after the first trial and before the second trial, their LTM was not affected. Thus, the studies showcase how neurons can form and enhance learning directly from the first experience.
Dr. Parsons and his colleagues’ study highlights the rapid development of neurons within the BLA. Future studies will be conducted to focus on trials that are separated in time in order to understand how the LTM from the first trial affects that of future learning.
 K.E. Cole, et al., Subthreshold fear conditioning produces a rapidly developing neural mechanism that primes subsequent learning. eNeuro 6(3), (2019). Doi: 10.1523/eneuro.0113-19.2019
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