The Human Memory - what it is, how it works and how it can go wrong
The Human Memory - what it is, how it works and how it can go wrong

Memory Disorders
  Age Associated
  Alzheimer's Disease
     Anterograde Amnesia
     Retrograde Amnesia
     Psychogenic Amnesia
     Post-Traumatic Amnesia
  Huntington's Disease
  Korsakoff's Syndrome
  Parkinson's Disease
  Tourette Syndrome


??? Did You Know ???
The “lost in the mall” experiments of Elizabeth Loftus, part of her ground-breaking research into confabulation, showed that fully 25% of participants claimed to be able to remember, and even embellish, supposed childhood events that never actually occurred.
It should also be noted that some patients of repressed memory syndrome claim to have had false memories of childhood sexual abuse suggested or prodded by their psychotherapists.
For example, certain psychiatrists have been shown to have an inordinate amount of patients with the same type of repressed memory (e.g. many of one psychiatrist’s patients had been abducted by aliens, another's had all been molested, etc).
In the same way, memory recovery that has been directed by dreams or hypnosis is also notoriously unreliable.
Psychogenic amnesia, also known as functional amnesia or dissociative amnesia, is a disorder characterized by abnormal memory functioning in the absence of structural brain damage or a known neurobiological cause. It results from the effects of severe stress or psychological trauma on the brain, rather than from any physical or physiological cause. It is often considered to be equivalent to the clinical condition known as repressed memory syndrome.

There are two main types of psychogenic amnesia: global amnesia and situation-specific amnesia. Global amnesia, also known as fugue state, refers to a sudden loss of personal identity lasting a few hours or days, often accompanied by severe stress or depression and often involving extended periods of wandering and confusion. It is very rare, and usually resolves over time (although memory of the fugue episode itself may remain lost), often helped by therapy. Situation-specific amnesia is a type of psychogenic amnesia that occurs as a result of a severely stressful event, as part of post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) is a severe anxiety disorder that can develop after exposure to any event that results in psychological trauma, which manifests itself in constant re-experiencing of the original trauma through flashbacks or nightmares and avoidance of any stimuli associated with the trauma, as well as increased arousal (such as difficulty falling or staying asleep, anger and hypervigilance).

It is most commonly associated with traumatic events or violent experiences involving emotional shock, such as being mugged or raped or involved in car crash. Those at increased risk include those sexually or physically abused during childhood, those who have experienced domestic violence, natural disasters, terrorist acts, etc, soldiers who have experienced combat, and essentially anyone who has experienced any sufficiently severe psychological stress, internal conflict or intolerable life situation.

Freudian psychology suggests that psychogenic amnesia is an act of self-preservation, where the alternative might be overwhelming anxiety or even suicide. Unpleasant, unwanted or psychologically dangerous memories are repressed or blocked from entering the consciousness as a kind of subconscious self-censorship, but they remain in the unconscious. Neurologically, normal autobiographical memory processing is blocked by an imbalance of stress hormones such as glucocorticoids and mineralocorticoids in the brain, particularly in the regions of the limbic system involved in memory processing.

Such repressed memories may be recovered spontaneously, years or decades after the event, triggered by a particular smell, taste or other identifier. Because it is due to psychological rather than physiological causes, psychogenic amnesia can also sometimes be helped by therapy. Repressed memories may be accessed by psychotherapy, hypnotism or other techniques, although it is often difficult to distinguish a true repressed memory from a false one without corroborating evidence.

Those who suffer from psychogenic amnesia tend to lose their biographical or episodic memories, (to the extent of not even being able to remember their own names and addresses), particularly of the events leading up to the trigger event, but usually preserve their semantic and procedural memories, and the ability to create new memories. Episodes of psychogenic amnesia can last from a few hours to several days, or sometimes even months, although severe cases are very rare.

The constant remembering and re-imagining of traumatic events causes them to be reinforced and re-consolidated time after time, and the memory is so strong and realistic that it is encoded almost as a new current event each time, rather than as an old memory. Thus, the memories need to be “re-filed” in their proper place (in the past), and recent advances in the understanding of neuroplasticity (the brain's ability to rewire and reconfigure itself) have led to some promising treatments. One example is the use of beta blockers, such as propanolol, while repeatedly reading a detailed account of the traumatic event, thus chemically blocking neurons so that, over time, the account becomes just another story without the old traumatic personal associations.

Back to Top of Page
Home | Contact | Search
Introduction | Types of Memory | Memory Processes | Memory Disorders | Memory & the Brain | Sources & References
© 2010 Luke Mastin

what is memory, what is human memory