Amnesia (6)

Amnesia Overview

• Definition of Amnesia: A deficit in memory that can have various causes and manifestations.

Types of Amnesia

• Retrograde Amnesia

  • Definition: Loss of memories that were formed before the disruption occurred.

• Anterograde Amnesia

  • Definition: Inability to form new long-term memories after the onset of the condition.

  • eg. Clive Wearing- both anterograde and retrograde amnesia; total loss of short term memory ; this condition prevents him from retaining any new information for longer than a few seconds, illustrating the profound impact of anterograde amnesia on daily life.

Causes of Amnesia

• Damage to brain structures, including:

  • Hippocampus (and other components of the limbic system)

  • Medial temporal lobes

  • Frontal lobes

• Additional factors leading to amnesia:

  • Closed head injuries

  • Anoxia (lack of oxygen)

  • Stroke

  • Korsakoff’s syndrome (associated with chronic alcoholism and vitamin deficiency)

• Note: Damage is rarely restricted to a specific location in the brain.

Timecourse of Amnesia Following Injury

• Post-Traumatic Amnesia:

  • Duration: Can last from minutes to months. May not develop immediately.

  • Symptoms:

  • Confused state and disorientation

  • Loss of memory relating to the event of the injury

  • Potential difficulty in recognizing familiar objects or people

• Retrograde Amnesia:

  • Observation of a consistent pattern where the period of memory loss shrinks over time. From ‘I can’t remember’, but as recovery progresses, you may remember more and more events leading up to it

  • Failure to recover memories of events just prior to the injury.

• Long-term Effects:

  • Cognitive problems: Such as difficulty concentrating and fatigue.

  • Emotional problems: Including irritability and altered personality traits.

Pure Amnesia Cases

• Case Example: HM (Henry Molaison)

  • Characteristics: No formation of new explicit memories while preserving implicit memory and learning capabilities.

• Korsakoff’s Syndrome:

  • Characteristics: Normal conversational abilities observed, although individuals may conceal their memory problems.

  • Short-term memory span remains intact.

  • Recency effect intact – the ability to recall recently learned information.

  • eg. Patient EP - Intact short term memory, but no long-term memory for new events due to hippocampus damage. Anything new does not get recorded in memory. But he has long-term memory for events before infection (childhood locations, etc.)

Amnesia and Everyday Life

• Observation: Many diagnostic tests for amnesia do not correlate with real-life impairments.

• Example of unrealistic tasks: Learning lists of unrelated words is not frequently a real-world scenario.

• Issue: Difficulty getting amnesic patients to effectively record data.

Assessment Tools

• Rivermead Behavioural Memory Test (RBMT):

  • Purpose: Evaluates both immediate and delayed memory.

  • Components:

  • Tests for names and faces

  • Stories and pictures

  • Prospective memory tasks (planning for the future)

  • Spatial memory (route following)

  • Orientation in time and space

• Pricing Information:

  • Currently in its third version, with costs outlined as follows:

  • Fall 2022: $960.75

  • Winter 2024: $1,079.20

  • Winter 2025: $1,154.80

  • Winter 2026: $1,212.60

What is Preserved in Amnesia?

• Areas where memory capabilities remain unaffected:

  • Skill learning

  • Priming in stem/fragment completion tasks

  • Classical conditioning techniques

  • Evaluative conditioning (associative learning)

  • Non-associative learning tasks (including artificial grammar and jigsaw puzzles)

  • Overall ability to utilize remaining declarative memory via mnemonics

• Techniques in memory assistance:

  • Visual Imagery: Employ visual techniques to enhance recall.

  • Name Mnemonic: Use mnemonic devices related to names for improved memory performance.

  • Vanishing Cues: Implement techniques that progressively reduce prompts to aid memory retrieval.