Yukta Kulkarni ’22
Some of the most important topics covered by neuroscience research encompass memory retention. This type of research helps explain how much information brains can retain and how easily it is learned. However, does prior learning affect the ability to learn in the future? To answer this, Cole et al. blocked protein-kinase A (PKA) and extracellular signal-related mitogen-activated protein-kinase (ERK/MAPK) within the basolateral amygdala (BLA) using designer receptors exclusively activated by designer drugs (DREADDs). This was done to determine the effect of fear conditioning on primed learning after an extended amount of time.
To test this hypothesis, 126 adult rats were used. Three basic behavioral tests were conducted: baseline startle, fear conditioning, and fear memory testing. All of the rats experienced the baseline startle of listening to 30 95dB white noise surges, each 50 ms with 30 seconds between them, to determine the starting point of their fear responses. During the fear conditioning test, the rats were placed into a shock cage where they learned to associate light with shocks, inducing fear. They first tested the role of BLA in forming a priming effect by inhibiting neural activity during or immediately after the shock trial. They then tested the roles of PKA and MAPK inhibitors before or immediately after the shock trial. When the fear conditioning was no longer in the rat’s short-term memory, the rats were tested to see if their recollection of the previous test had primed them to not be as startled. The rats both moved less and had less of a reaction to shock in the second trial. It was discovered that neural activity in the BLA was necessary only before or during the conditioning test to have a priming effect on fear. Even if it is inhibited after the initial conditioning, the brain will be primed for the future.
These conclusions suggest that priming is a reason why after exposure to a fear-inducing stimulus, the effects of future experiences aren’t as substantial. This could be a way that fear is overcome. For instance, viewing a horror movie may cause fear; however, that movie may not persist in long-term memory. Instead, the individual is primed to be cautious in watching horror movies in the future and to not let it scare them as much. This is one way in which the brain copes with fears and tries to control them.
- K. Cole, et al., Subthreshold fear conditioning produces a rapidly developing neural mechanism that primes subsequent learning. ENuero 6(3), 113-119 (2019). Doi: https://doi.org/10.1523/ENEURO.0113-19.2019
- Image received from: https://www.needpix.com/photo/382432/fear-embrace-clouds-sky