Memory: How Our Minds Store, Recall, and Forget
- voicesofbraininjur
- Apr 6
- 3 min read
Updated: 3 days ago
What is memory?
Memory is the process of retaining information to guide future actions, primarily taking place in the brain’s hippocampus. It can be divided into two main types:
Explicit (declarative) memory: involves the conscious recall of facts and events requiring intentional effort (e.g., remembering a birthday or a historical fact).
Implicit (procedural) memory: refers to the unconscious storage of skills and habits, like riding a bike or typing on a keyboard, which don’t require active awareness to perform.
How do we form and consolidate memories?
Memory formation begins with encoding, where excitable neurons are recruited based on their ability to fire. Neurons with higher excitability, influenced by proteins like CREB, are more likely to encode memories. This process creates a physical change in the nervous system called an engram, which stores the memory.
Memories are consolidated (transformed into long-term storage) through changes in synaptic connections, with proteins like CaMKII and PP1 balancing memory memory retention and forgetting. Persistent learning activates pathways (e.g., PKA and MAPK) that promote gene expression and synaptic plasticity, strengthening useful connections. Over time, mechanisms like DNA methylation help preserve long-term memories.
Reconsolidation allows stored memories to be updated, showing that memory is dynamic. Emotionally charged events tend to be remembered better than neutral ones.
How do we retrieve memories?
Memory retrieval depends on the encoding specificity principle, meaning that retrieval is easier when the context matches the original encoding. Research using advanced techniques, like tagging active neurons, shows that retrieving a memory reactivates the same neurons used during encoding. Silencing these neurons prevents recall, while activating them restores it. This confirms the critical role of engram reactivation in memory retrieval.
Who do we forget?
Forgetting happens when a memory is no longer available or accessible, often because it no longer serves a useful purpose. According to some theories, this may result from:
Synaptic remodeling, such as weakening old connections or forming new ones, which disrupts the memory’s neural network.
Interference, where new information overrides old memories (retroactive) or old memories block new ones (proactive).
The forgetting curve, showing that memories fade over time without reinforcement.
While forgetting reduces recall, memories are not always permanently erased; stimulating engram neurons can sometimes restore them.
Amnesia
Amnesia is a condition that affects memory. It can take two main forms:
Anterograde amnesia: Difficulty forming new memories.
Retrograde Amnesia: Difficulty remembering past events or information.
Amnesia can result from various factors, including:
Traumatic Brain Injury (TBI)
Diseases like Korsakoff’s syndrome
Surgery involving the brain
Infections, such as herpes simplex encephalitis
These factors disrupt areas of the brain that process memory, especially the hippocampus and medial temporal lobes. In some cases, amnesia may be permanent. However, treatments often focus on addressing the underlying cause to improve memory function. The severity and affected brain regions determine the impact of amnesia.
Written by Aleksija Milovanovic
References
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