HOW DO WE STORE OUR MEMORIES?
Henry G. Molaison, popularly known as patient HM used to suffer from epileptic seizures since he was 10 years old. The seizures kept worsening till no available anticonvulsant were effective enough to stop them; so in 1953, he underwent a neurosurgery performed by W. B. Scoville in which portions of the medial temporal lobes were cut out. The operation was successful but it left him with severe memory loss; he had become amnesic.
Within each temporal lobe laid a sea-horse shaped brain structure called the Hippocampus. The neural basis of the link between context and memory involves it. New memories are stored, structured and coded by the Hippocampus and then they are eventually transferred to the frontal lobes for long term storage. This process is called memory consolidation which might happen during our sleep.
Now memory can be of two types- Long term memories and Short term memories. Long term memories aren't stored in just one part of the brain but they are widely distributed throughout the cortex. They are stored as a group of neurons that are primed to fire together in the same pattern as they had in the original experience.
During memory encoding, a few neurons (called engrams) give rise to new connections and after that, memory consolidation stabilizes those new connections. This is marked by the permanent increase in synaptic strength essential for memory retrieval. These synaptic connectivities are the basis of memory storage and potentiation of the synapses is required for memory retrieval.
Memories can also be encoded redundantly so that if one engram is erased there will be duplicate pathways to retrieve the memory.
So. how come we start to lose our memories as we age?
As we age the Brain starts to lose its connections and the hippocampus also starts to deteriorate which increases forgetfulness. The graph which is shown below depicts how our performance and memory deteriorates as we age.
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| Ref: http://www.rise.duke.edu/apep/pages/001006.html |
Within each temporal lobe laid a sea-horse shaped brain structure called the Hippocampus. The neural basis of the link between context and memory involves it. New memories are stored, structured and coded by the Hippocampus and then they are eventually transferred to the frontal lobes for long term storage. This process is called memory consolidation which might happen during our sleep.
Now memory can be of two types- Long term memories and Short term memories. Long term memories aren't stored in just one part of the brain but they are widely distributed throughout the cortex. They are stored as a group of neurons that are primed to fire together in the same pattern as they had in the original experience.
During memory encoding, a few neurons (called engrams) give rise to new connections and after that, memory consolidation stabilizes those new connections. This is marked by the permanent increase in synaptic strength essential for memory retrieval. These synaptic connectivities are the basis of memory storage and potentiation of the synapses is required for memory retrieval.
So. how come we start to lose our memories as we age?
As we age the Brain starts to lose its connections and the hippocampus also starts to deteriorate which increases forgetfulness. The graph which is shown below depicts how our performance and memory deteriorates as we age.
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| STM = Short term memory, WM = Working memory; Ref: J. K. Hartshorne, Psychological Science 2015
There are a few ways you can improve your memory though- by giving your brain a workout, get on a regular sleep schedule, involve as many senses as possible, have a healthy diet and use mnemonic devices to memorize easily.
Until next time, stay healthy, stay curious and keep your neurons firing.
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