Memory

Dementia robs our loved ones of their memories because the brain is experiencing cell death at a faster rate than new cells are produced.  This lead me to wonder how memories are formed.

New brain cells are created each day.  Those cells are integrated into existing neural pathways and are active for several weeks during which time, they behave like a time stamp, recording events or associations which happen during the new cells time of peak activity.  You experience a stimulus through any of your senses.  Your brain processes that stimulus and decides to encode it or not.  Encoding is the process by which the brain converts that stimulus into the construct which is stored in the neural pathway.  During encoding, a synapse is strengthened when a new connection with another synapse is created.

In 2008, scientists were able to record individual brain cells recalling memory.  The study showed that memories occur when the same neurons which were active at the creation of the memory are stimulated. If the neural pathways are damaged when the individual cells within die and are not replaced, then the memories cannot be recalled.  By the time it is noticeable, the individual may have already lost 50% of the cells needed for memory recall. 

Additional Resources:
Memories Are Made of This: Uncovering the Key to How We Learn and Remember

How memories form, fade, and persist over time

Glimpse into how the brain forms memories could hold hope for Alzheimer's treatment

Tangentally Related:

Ted Talk: Allan Jones: A Map of the Brain
Ted Talk: Daniel Kahneman: The riddle of experience vs. memory