Engrams and Early-Life Neglect Alters Emotional and Cognitive Behavior reducing Neuronal Excitability in the PFC

Throughout the semester, one of our speakers, Dr. Stephanie Grella, presented her research on engrams, a neural substrate for storing and recalling memories. Prior to her lecture, we read the article, “Memory engrams: Recalling the past and imagining the future,” conducted by Sheena A. Josselyn and Susumu Tonegawa. The article introduced the concept of engrams and how neuronal excitability and synaptic plasticity are both vital components that contribute to forming them. The researchers found that silencing engrams can disrupt memory, while reactivating them can trigger recall. Neuronal activity is vital to reinforce neuronal pathways, making the memories more likely to be recalled. This led me to further explore other topics, discussing how neuronal excitability affects memory recall. An article I found discusses how early life neglect alters cognitive behavior in a sex dependent manner and reduces neuronal excitability in the prefrontal cortex, therefore affecting memory formation. 

 

In the article, “Early-Life Neglect Alters Emotional and Cognitive Behavior in a Sex-Dependent Manner and Reduces Glutamatergic Neuronal Excitability in the Prefrontal Cortex,” written by Xiuping Sun, Yu Zhang, and others. The article explores the possible influence of maternal separation with early weaning (MSEW) on glutamatergic neuronal excitability in the prefrontal cortex (PFC) in rats. In addition, the article discussed how neuronal intrinsic excitability plays a key role in information processing and storage in the brain. The article used MSEW to create an early-life neglect rat model, inducing long-lasting anxiety-like behavior in male rats to explore the influences of early-life stress on adult anxiety disorder and discuss potential therapies. The researchers found that reduced glutamatergic neuronal excitability may be associated with the emotional alteration induced by MSEW in male rats. Overall, MSEW affected memory formation in a sex-dependent manner. The researchers found that, “The reduced glutamatergic neuronal excitability may be associated with the emotional alteration induced by maternal separation with early weaning (MSEW) in male rats” (Sun et al., 2021,12). This means that neuronal intrinsic excitability does, in fact, play a significant role in information processing and storage in the brain. 

 

Both articles discuss the importance of neuronal excitability and how a decrease in excitability can influence memory recall. The understanding of engram formation and factors like early-life neglect may alter emotional and cognitive behavior in a sex-dependent manner, as we see in the article conducted by Sun and others. Furthermore, from Dr. Grella’s presentation, we learned that excitability-based competition guides the organization of multiple engrams in the brain and influences how these engrams interact. Similarly, in Sun’s experiment, they found that an experience is represented in specific connections with multiple engram ensembles distributed across multiple brain regions. It is interesting to see how recent engram studies have progressed and what future research could do to help facilitate memory recall.

 

References:

Josselyn, S. A., & Tonegawa, S. (2020). Memory Engrams: Recalling the Past and Imagining the Future. Science, 367(6473). https://doi.org/10.1126/science.aaw4325

Sun, X., Zhang, Y., Li, X., Liu, X., & Qin, C. (2021). Early-Life neglect alters emotional and cognitive behavior in a Sex-Dependent manner and reduces glutamatergic neuronal excitability in the prefrontal cortex. Frontiers in Psychiatry, 11. https://doi.org/10.3389/fpsyt.2020.572224 

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