Module 11 Flashcards
(148 cards)
Who was H.M. and what procedure did he undergo?
H.M. was a man who underwent a bilateral medial temporal lobectomy in 1953 at the age of 27 to treat severe epilepsy.
The surgery successfully reduced H.M.’s seizures, but it resulted in devastating amnesic effects.
What is retrograde amnesia, and how did it affect H.M.?
Retrograde amnesia is the inability to recall events that occurred before brain damage or surgery. H.M. had mild retrograde amnesia for events preceding his surgery but retained memory for remote events.
H.M. had an almost total inability to form new long-term memories after the surgery. He became suspended in time and could not remember events or people he encountered after the surgery.
What is the digit-span + 1 test, and how did H.M. perform on it?
The digit-span + 1 test assesses verbal long-term memory by having the participant repeat a sequence of digits with an additional digit added each trial. H.M. performed poorly on this test, failing to repeat an 8-digit sequence after 25 trials.
Describe H.M.’s performance on the mirror-drawing test.
H.M. showed improvement over three days on the mirror-drawing test, indicating retention of the task. However, he could not recall ever having completed the task before.
What were three influential contributions of H.M.’s case to the study of memory?
Challenging the view of memory as diffusely distributed throughout the brain.
Supporting the theory of different modes of storage for short-term, long-term, and remote memory.
Revealing the distinction between explicit and implicit long-term memories.
What are explicit and implicit long-term memories, and how did H.M.’s case contribute to their distinction?
Explicit memories are consciously recalled memories, while implicit memories are demonstrated through improved performance without conscious awareness.
H.M.’s performance on tasks like mirror-drawing and incomplete-pictures tests showed evidence of implicit memories despite lacking conscious recollection, leading to the distinction between explicit and implicit memories.
What is the significance of having both explicit and implicit memory systems?
The implicit memory system provides simple, unconscious memory processes, while the explicit memory system allows for flexible use of information, leading to greater adaptability.
What are semantic and episodic memories, and how do they differ in individuals with medial temporal lobe amnesia?
Semantic memories are for general facts or information, while episodic memories are for specific events in one’s life.
Individuals with medial temporal lobe amnesia often have difficulty with episodic memories but retain their semantic memory.
Describe the case of transient global amnesia and its relevance to understanding medial temporal lobe amnesia.
Transient global amnesia is characterized by sudden onset anterograde amnesia and moderate retrograde amnesia, typically lasting 4 to 6 hours. Abnormalities in the hippocampus suggest ischemia-induced damage, offering insights into the pathology of medial temporal lobe amnesia.
What is Korsakoff’s syndrome, and what are its symptoms?
Korsakoff’s syndrome is a disorder of memory commonly seen in heavy alcohol consumers, often associated with thiamine deficiency. Symptoms include sensory and motor problems, confusion, personality changes, and a risk of death from related disorders.
How does the amnesia of Korsakoff’s syndrome progress, and what types of memory are affected?
Initially, there is anterograde amnesia for explicit episodic memories, progressing to retrograde amnesia extending back into childhood. Deficits in implicit memory are less severe and depend on the test used.
What part of the brain is often implicated in the memory deficits of Korsakoff’s syndrome, and why is it challenging to identify the specific cause of amnesia?
Damage to the mediodorsal nuclei of the thalamus is often observed, but the diffuse brain damage complicates pinpointing a single cause of amnesia in Korsakoff’s syndrome.
Describe Alzheimer’s disease and its effects on memory.
Alzheimer’s disease is a progressive disorder characterized by memory deterioration, leading to severe dementia and inability to perform daily activities. Memory deficits include both explicit and implicit memory impairments.
What are the characteristics of memory deficits in predementia Alzheimer’s patients?
Predementia Alzheimer’s patients display general memory deficits, including anterograde and retrograde deficits in explicit memory tests, as well as deficiencies in short-term and certain types of implicit memory.
What role does acetylcholine depletion play in Alzheimer’s amnesia, and what other brain areas are affected?
Acetylcholine depletion, resulting from basal forebrain degeneration, is thought to contribute to Alzheimer’s amnesia. However, the brain damage associated with Alzheimer’s disease is diffuse, affecting areas like the medial temporal lobes and prefrontal cortex.
What is posttraumatic amnesia, and what are its characteristics following a closed-head traumatic brain injury (TBI)?
Posttraumatic amnesia follows a closed-head TBI and involves permanent retrograde amnesia for events leading up to the injury and anterograde amnesia for events during the period of confusion after regaining consciousness.
How do memory deficits following a closed-head TBI often puzzle friends and relatives of the patient?
Patients may seem lucid during interactions because short-term memory is intact, but they later have no recollection of the conversation due to anterograde amnesia.
Improved test performance without conscious awareness, as in the case of H.M.’s mirror-drawing task, exemplifies long-term memories which became known as _______ memories.
implicit
Explicit long-term memory is broadly divided in two main categories: episodic and _______.
semantic
Ischemia in the _______ could result in transient global amnesia.
hippocampus
Amnesia due to Korsakoff’s syndrome is typically associated with large lesions to the _______.
medial diencephalon
_______ amnesia refers to the loss of memories that took place before the brain injury.
Anterograde
_______ depletion resulting from damage to the basal forebrain may contribute to Alzheimer’s amnesia.
Acetylcholine
Memory consolidation is studied using _______ shock, which induces seizures using large electrodes.
electroconvulsive