Memory consolidation and reconsolidation [videos]

Consolidation

Memory consolidation is the stabilization of a memory after it has been acquired.  This progressive process usually refers to its two types – synaptic consolidation and system consolidation. (1)

Coined by Muller & Pilzecker in 1900, consolidation or konsolidierung is a process that requires training. During recall, however, there is retroactive inhibition in which intervening stimuli distort the old memory. (1)

What is Memory Consolidation and Reconsolidation? by Misophonia International, on YouTube

Consolidation enables memories to persist. Any experience that begins as short-term memory will not turn into long-term unless that is consolidated. In other words, this is the process that converts short-term into long-term memory. (2)

Such memory retention process occurs when the brain undergoes protein synthesis – when brain cells transmit chemical signals at each other through a synapse…

One STEP Closer to Curing Alzheimer’s Disease. Animation by The Art of the Cell by: Medical & Scientific 3D Animation by John Liebler, on YouTube

Synapse is a tiny gap between two neurons in the brain where neurotransmitters are diffused in order to pass electrical signals – an important memory process. (3) In order for short-term memories to be converted into long-term, synapses have to be strengthened.

Burnham (1903), “There must be time for the processes of organization and assimilation (of memory) to take place. There must be time for nature to do her part…. Hurry defeats its own end.”

Two types of consolidation

There are two types: synaptic consolidation and system consolidation. (1)

  1. Synaptic consolidation – short-term consolidation
  2. System consolidation – long-term consolidation

In system consolidation, sometimes referred to as slow consolidation, it “takes weeks, months or even years to be accomplished. It is believed to involve reorganization over time of the brain circuits, or the systems, that encode the memory, and in the course of this the trace may spread to new locations in the brain while at the same time relinquishing its dependence on parts of the circuits that have subserved its acquisition.” (1)

Consolidation during sleep

According to first-century-AD Roman rhetoric teacher, Quintillian, “the interval of a single night will greatly increase the strength of the memory” and that in order to remember such a memory, it will have to “ripen” and “mature” during the passage of time. (1)

One implication of memory is that your memory is only as good as your last memory of that experience.

Joseph E. LeDoux, What is Memory Consolidation and Reconsolidation? [Youtube]

Reconsolidation

While a fresh memory need to consolidate, old memories need to reconsolidate.

Reconsolidation is the process that maintains, strengthens or modifies previously consolidated memories. This theory suggests that when an old memory is retrieved, it becomes subject to changes such that a new memory is formed and stabilized.

When recalling a memory that has already been fully consolidated, it has to go to another protein synthesis in order for that memory to persist. In reconsolidation, there is a continuous update of a retrieved information from the long-term memory storage. So every time you take a memory out, it is updated into a new memory. (4)

Reconsolidation blockade

If you block protein synthesis right after retrieval, it prevents that storage process thereby disrupting the memory. But why do you have to disrupt that natural process? Why do we sometimes choose to distort a biological system that updates such a memory? (4)

Reconsolidating blockage primarily affects the unconscious memories such as those in the amygdala that are detecting and responding to threats that are producing arousal.  It does not exactly erase your memory nor the conscious content of your memory but it dampens the impact of the memory so it is less troubling when you remember it later. (4)

Short-term to long-term memory

Two things we need to understand… The trace of short-term memory may decay or it will mature into long-term.


References:
(1) Dudai, Yadin. (2004, February 4). The Neurobiology of Consolidations, Or, How Stable is the Engram? Annual Review of Psychology, 55, 51-86. Retrieved from http://www.weizmann.ac.il/neurobiology/labs/dudai/PDFs/Dudai2004.pdf.
(2) Misophonia International. (2017, November 9). What is Memory Consolidation and Reconsolidation? [Video file]. Retrieved from https://www.youtube.com/watch?v=JKiV3FNpXhk.
(3) Cherry, Kendra. (2018, November 22). Synapses in the Nervous System. Retrieved from https://www.verywellhealth.com/what-is-a-synapse-2795867.
(4) Tronson & Taylor. (2007, April 01). Molecular mechanisms of memory reconsolidation. Nature Reviews Neuroscience, 8, 262–275. Retrieved from https://www.nature.com/articles/nrn2090.