Learning and memory

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Our memories shape who we are. Whenever we come across new information, like hearing an interesting fact or trying out a new sport, we learn something new. Information that is relevant or associated with strong emotions can be turned into memories in a process called consolidation. Different types of memory can be defined based on how long the information is stored for and the type of information the memory contains. The brain structures involved in creating and storing memories differ between types of memory.

Based on storage duration, memories can be divided into:

• Short-term memory; up to a few minutes
• Long-term memory; months or longer, up to a lifetime

The information in the short term memory is accessed by the working memory located in the prefrontal cortex for daily activities like having a conversation, looking for a lost item or crossing the street.

Based on the type of information contained, memories can be divided into:

• Explicit (or declarative) memory; facts or events that can be recalled consciously. These memories are consolidated in the hippocampus and in the medial temporal lobe, and stored in the sensory cortex that processed the original sensation. The amygdala plays a role in memories with high emotional content. The hippocampus and the prefrontal cortex appear to be involved in the retrieval of declarative memories.
• Implicit (or non-declarative) memory; skills, habits and procedures that are mostly unconscious. Motor tasks fall into this category. The main structures involved are the basal ganglia, cerebellum, motor cortex and the amygdala.

Memories are consolidated by strengthening the connections between neurons through long-term potentiation (or LTP). The glutamate released by the presynaptic neuron binds to AMPA receptors on the post-synaptic neuron. Sodium ions flow into the cytoplasm and depolarize the cell, facilitating the flow of Calcium ions through NMDA channels. The increased intracellular concentration of Calcium increases the amount of glutamate released by the presynaptic cell and improves the flow of ions through the membrane of the postsynaptic neuron. This strengthened synaptic connection between neurons forms pathways in the brain that store and retrieve memories.

Find out more about how our brains learn and retain new information in the video below.

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Different brain structures are involved in the formation, storage and retrieval of declarative and non-declarative memories.

Neurons in the hippocampus consolidate declarative memories by strengthening synaptic connections via long-term potentiation.

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Summary