We all have memories; but how does our brain actually make and store memories?
The difference between long-term and short-term memory.
We’ve all heard the terms long-term and short-term memory. Short-term memory is used to refer to our recollection of things that have happened recently and, while we may think that this covers a period of say the last hour, day or week, in actual fact short-term memory lasts a mere 15-30 seconds. Long-term memories are those memories that can be recalled after that period of time. Short-term memory is rather like the RAM of a computer in that is holds the information we’re currently using, and is supported by precise patterns of neuron activity in the prefrontal cortex.
Our long-term memories are like the hard drive of a computer. They have a physical presence in the brain and, rather than being dependent on specific patterns of neuron activity, the neurons make their own new permanent physical connections and synapses.
Our long-term memories can be divided into explicit and implicit memories, with implicit memories including automatic skills and habits such as walking or driving a car. Explicit memories are those which we make a point of remembering and of which we’re consciously aware. These memories are further split into the kind of events and things that have happened to us personally – known as episodic memories, and those events and facts which we choose to remember – known as semantic memories.
How does our brain make memories?
The region of the brain responsible for the formation of new memories is the hippocampus. Here new information is linked together and encoded into a new memory by forming new but permanent synapses. However, not all information is equal; the hippocampus will encode important things more quickly and effectively than routine or incomprehensible things. Events and things that have been practiced repeatedly in the short-term memory, or which have a strong emotional element, will be dealt with first.
Where are memories stored?
Once consolidated, the memories will stay in the hippocampus temporarily, but as new memories are formed; the older memories move further into the cortex, ultimately being stored throughout the brain. Similar memories are stored together, for example visual memories will be stored close to the visual cortex, and all our memories are constantly updated as we receive more relevant information.
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