Validating the Role of Inhibitory Interneurons in Memory
Have you ever wondered how our memories are formed and recalled? Well, it turns out that inhibitory interneurons, a type of brain cell, play a crucial role in this process. Let’s dive into the fascinating world of memory and explore the latest research on the subject.
Unveiling the Local Synaptic Connections
Memory, a fundamental tool for our survival, is closely linked with how we encode, recall, and respond to external stimuli. Over the past decade, extensive research has focused on memory-encoding cells, known as engram cells, and their synaptic connections. Most of this research has centered on excitatory neurons and the neurotransmitter glutamate, emphasizing their interaction between specific brain regions.
But what about inhibitory interneurons? To expand our understanding of memory, a research team led by KAANG Bong-Kiun (Seoul National University, Institute of Basic Science) developed a groundbreaking technology called LCD-eGRASP (local circuit dual-eGRASP). This technology allows scientists to label synapses of neural circuits within a specific brain region, shedding light on the role of inhibitory interneurons in memory expression.
The Fear Memory Connection
The researchers focused their study on the basolateral amygdala (BLA), a brain region responsible for controlling positive and negative emotions, especially fear. When a fear-related event occurs, specific neurons activated during that time become engram cells, encoding the fear memory.
These engram cells in the BLA play a crucial role in fear memory recall, leading to a fear response. The communication between these engram cells happens through synapses, which act as functional units in our brain, similar to individual transistors in semiconductor devices.
Advancing Synaptic Labeling Technology
Dr. Kaang, a leading expert in memory and engram research, previously developed Dual-eGRASP technology, which selectively labels synapses between engram cells. However, this technology was limited to examining changes between excitatory neurons and long-distance brain regions.
To overcome this limitation, the researchers enhanced Dual-eGRASP and developed LCD-eGRASP, a modified version that can mark local synaptic connections between neurons within a single brain region. This breakthrough allowed them to delve deeper into the role of inhibitory interneurons in memory.
Unveiling the Role of Inhibitory Interneurons
The research team conducted experiments using mice and the fear conditioning paradigm to form fear memories. They discovered that a specific population of inhibitory neurons in the BLA, called somatostatin (SOM) interneurons, was activated during fear memory formation.
By applying LCD-eGRASP, the researchers revealed that these activated SOM interneurons formed more synapses with the fear engram cells in the BLA. Additionally, these specific interneurons showed higher cellular excitability, indicating the suppression of fear expression by inhibiting fear engram.
During fear memory recall, the excitability of these interneurons further decreased. The artificial activation or inhibition of these activated SOM interneurons resulted in direct and indirect changes in fear memory expression and behavioral responses, highlighting the crucial role of inhibitory interneurons in proper memory recall.
Conclusion
The intricate dance of memory formation, unveiled through LCD-eGRASP technology, highlights the pivotal role of inhibitory interneurons in fear recall. Dr. Kaang’s team’s breakthrough showcases how specific interneurons, when activated during fear memory formation, regulate fear expression by influencing synapses with engram cells. Their modulation of fear recall emphasizes the delicate balance these interneurons maintain. This research not only enriches our comprehension of memory but also unveils potential avenues for therapeutic interventions targeting these interneurons, offering hope for managing conditions linked to memory dysregulation. The revelations brought forth by this study not only redefine our understanding of memory mechanisms but also pave the way for innovative approaches in neuroscience and cognitive health.
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