Lacunar amnesia

Lacunar amnesia is the loss of memory about a specific event. This specific form of amnesia is caused by brain damage in the limbic system which is responsible for our memories and emotions. When the damage occurs it leaves a lacuna, or a gap, in the record of memory within the cortex region of the brain.There is a general belief that certain emotions from the lost memory may be triggered without the recollection of the event.

Lacunar amnesia
SpecialtyPsychology

Characteristics

Daniel Goleman, in his book Vital Lies, Simple Truths, defines a lacuna as:

...the sort of mental apparatus that diversionary schemas represent. A lacuna is, then, the attentional mechanism that creates a defensive gap in awareness. Lacunas, in short, create blind spots.[1]

Lacunar amnesia has also been known to be attributed to alcoholism, drug treatment, and withdrawal in some cases. After using these substances a person may experience a loss of memory of a specific event temporarily or even permanently.[2]

Steven Johnson, (the author of Mind Wide Open: Your Brain and the Neuroscience of Everyday Life) also states that:

"Scientists believe memories are captured and stored by two separate parts of the brain, the hippocampus, the normal seat of memory, and the amygdala, one of the brain's emotional centers. People who, due to hippocampus damage, are incapable of forming long-term memories can still form subconscious memories of traumatic events if their amygdala is intact."This may be related to erasure or reconsolidation of memories. Attempts have been made to remember memories that have been consolidated and reconsolidate them under desired conditions.[3]

According to Alex Chadwick speaking on NPR:

Some scientists now believe that memories effectively get rewritten every time they're activated. Studies on rats suggest that if you block a crucial chemical process during the execution of a learned behavior - pushing a lever to get food, for instance - the learned behavior disappears. The rat stops remembering. Theoretically, if you could block that chemical reaction in a human brain while triggering a specific memory, you could make a targeted erasure. Think of a dreadful fight with your girlfriend while blocking that chemical reaction, and zap! The memory's gone.[4]

This idea of the reconsolidation of memories has also been used in cases of PTSD to lessen or alleviate some of the symptoms associated with the illness.[5]

Criminal cases

This condition is often claimed in the instance of criminal cases. The victim or assailant will insist that they have lost their memory about the event in question, but the remainder of their memory, both anterograde and retrograde, remain intact. There is only one specific memory or recollection of an event that is impaired.[2] This is normally paired or in conjunction with the claim of insanity.

This type of amnesia is used as a plot element in the 2004 movie Eternal Sunshine of the Spotless Mind, in which a company named Lacuna offers the removal of all memories of a specific person from someone's memory. The plot of the film suggests that the brain is designed to preserve emotionally strong memories. Though the main characters attempt to forget one another, they eventually find their way back together due to their strong emotions. The film claims that even amnesiacs, under the right circumstances, can remember their past feelings.

Another movie that references this condition is called Memento. In this film, the main character suffers from anterograde amnesia but still feels an emotional component when faced with scenarios or people he has encountered previously. The film claims that someone suffering from this condition would likely have a feeling of general unease encountering a person who had harmed them in the past, though they wouldn't be able to say exactly why.

Both of the amnesiac conditions in these movies represent gaps in the memory instead of long-term or short-term loss.

References
  1. Goleman, Daniel (1985). Vital Lies, Simple Truths-The Psychology of Self-Deception. Bloomsbury.
  2. Benezech, M. "Lacunar amnesia and criminal behavior: Realities and medicolegal consequences in 7 cases". Annales Médico-Psychologiques. 136: 918–931.
  3. Przybyslawski, Jean; Sara, Susan J. (March 1997). "Reconsolidation of memory after its reactivation". Behavioural Brain Research. 84 (1–2): 241–246. doi:10.1016/s0166-4328(96)00153-2. ISSN 0166-4328. PMID 9079788.
  4. Analysis: Concepts in memory-loss movies not so far-fetched, NPR Special; 3/23/2004; Alex Chadwick.
  5. Lee, Jonathan L.C. (August 2009). "Reconsolidation: maintaining memory relevance". Trends in Neurosciences. 32 (8): 413–420. doi:10.1016/j.tins.2009.05.002. ISSN 0166-2236. PMC 3650827. PMID 19640595.

[1]

  1. Johnson, Steven, 1968- (2004). Mind wide open : your brain and the neuroscience of everyday life. New York: Scribner. ISBN 0-7432-4165-7. OCLC 53289868.CS1 maint: multiple names: authors list (link)
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