8.5 Memory Consolidation: Definition & Theory
Do You Remember?
Imagine that you witness a truck recklessly smash into a parked car on the side of the road. The driver of the truck zooms away, fleeing the scene of the crime. You see the license plate of the truck and repeat the license plate number over and over again to yourself. Then you dial 911 and report the incident.
Now imagine a different scene. Imagine that one day you are busily shopping in the mall when you walk past a clothing store. A fragrance from the store grabs your attention. The smell reminds you of a former romance. You remember emotions and events from years ago in vivid detail.
Both of these scenarios involve memories. Our brains work hard to record and store our experiences as both short-term and long-term memories.
Short-term memories are retained for only 20-30 seconds. It is theorized that memories are created in the synapse (or gap) between neurons in our brains. These connections between neurons can vary in strength. The level of strength held by each neural connection is one component of neural plasticity (or synaptic plasticity). (The study of neural plasticity involves the examination of neural pathways and the brain’s capacity to re-route those pathways.) Some behaviors (such as repetition) can increase the strength of a neural connection by providing less resistance between neurons. When a neuron forms a strong connection with another neuron it is called long-term potentiation. As memories are acquired, the synapse changes and protects the stored memory from interruption or interference as new memories are acquired. Synaptic consolidation occurs within hours after information is acquired. Sometimes synaptic consolidation is also referred to as memory maintenance.
Long-term memories are stored for weeks, months, years or even an entire lifetime. System consolidation occurs when memories that were previously dependent on the hippocampus are stored independently in the cortex. One of the first case studies that provided insight into this was in 1953. Due to severe epilepsy, a patient named H.M. had portions of his medial temporal lobe surgically removed. As a result, H.M. found that he could recall memories from years before the surgery, yet he struggled to recall simple and more recent memories. As a result of his surgery, researchers concluded that the medial temporal lobe helps to facilitate memory (or system) consolidation. System consolidation typically occurs during sleep. Each time a memory is recalled it must be reconsolidated for further retrieval.
The brain facilitates both short-term and long-term memory-making. Some suggest that the brain creates memories in the synapses between neurons. Synaptic consolidation or memory maintenance occurs hours after information is acquired. This is a process in which stored memories are protected from interruption or interference. Memories may be initially stored in the hippocampus and eventually move to more permanent storage in the cortex. The neurological process of moving a memory from short-term to long-term storage is called memory consolidation.