What is dementia?
a neurological disorder caused by progressive cell death
What is dementia characterised by?
memory impairment, and one of the following:
- Aphasia: language impairment
- Apraxia: motor memory impairments
- Agnosia: sensory memory impairments
- Abstract thinking/ central executive impairments
What are examples of degenerative dementias and what does that mean?
- Alzheimer’s, Parkinson’s and Huntington’s
- Means they have a genetic aspect and are cortical/subcortical
What are non-degenerative dementias and what is an example of one?
- a group of disorders with diverse origin
- example is Korsakoff’s syndrome which originates from chronic alcohol or drug abuse
What is the difference between cortical and subcortical dementias?
cortical dementias cause impairments in cortical functions such as memory and language. subcortical dementias cause and impairment in subcortical functions such as abstraction, mood and strategy
What are early, middle and late symptoms of Alzheimer’s?
- early: needs reminders, concentration is difficult and loss of recent memories
- middle: changes in personality, gets lost easily
- late: severe confusion, doesn’t recognise one’s self or family
In Alzheimer’s, which cortical brain, structure demonstrates the most evidence for cell loss?
entorhinal cortex (located in the medial temporal lobe)
In Alzheimer’s, what type of memory is affected most?
declarative memory affected more than procedural memory (which is implicit)
In terms of language impairments, what skill is relatively preserved?
auditory comprehension
What are the two main categories of LTM?
Implicit/ non-declarative memory: skills and habits, , associative and non-associated learning, but can’t explicitly retrieve information
- Explicit/ declarative memory: consciously recalling facts and events in one’s knowledge
What types of of memory are declarative? (2)
semantic: general knowledge about the world
episodic: personal details about oneself and their experiences
What types of memory are non-declarative? (3)
procedural: skills, learning that occurs slowly and gradually
priming: repeated presentation of a stimulus makes it easier to process using less resources, e.g. reading the same word for a second time
conditioning: classical and operant
Which of implicit and explicit memory is top down and which is bottom up?
- Implicit = bottom up, person has a passive role, information is encoded the same way it is perceived
- Explicit = top down, person has an active role
What can amnesia be caused by? (4)
- Parkinson’s disease
- brain resection as a treatment for epilepsy
- physical accident
- Korsakoff’s syndrome
What procedure did Scoville perform on patient HM and why?
he performed a bilateral medial temporal lobe resection to remove the amygdala and hippocampal formation, which were causing him seizures
Following the surgery, what aspects of HM’s memory were impaired and what parts were in tact?
- no explicit memory of events that happened AFTER the surgery, but could still recall most events from before the surgery. performance Implicit memory tests was in tact
- His memory for new personal events and memory for knew facts = impaired
- But, his memory for new skills = intact
- his short term memory was intact, but he suffered from anterograde amnesia which is where he would forget everything after a few minutes
What are the prime structures associated with explicit memory?
- areas in the medial temporal region such as amygdala, hippocampus, entorhinal cortex, perirhinal cortex and parahippocampal cortex. (AHEPP)
- the frontal cortex, and reciprocal connections between frontal and temporal brain regions are also prime structures for explicit memory
What is double dissociation and how is it evidence for independent processes in LTM?
either when implicit memory is impaired and explicit memory is in tact, or vice versa
How is patient JK and example of double dissociation?
He developed Parkinson’s disease in his mid 70’s and had damage to his basal ganglia. He has impaired ability to perform tasks he’d done all his life such as turning on the radio, but could still recall explicit events. This shows that he had impaired implicit memory (skills) but intact explicit memory
What brain structures feature in Mishkin and colleagues neural circuit for IMPLICIT memory?
- basal ganglia
- ventral thalamus
- substantia nigra
- premotor cortex
(BVSP)
Which type of memory is attached to a specific time/ location?
episodic memory
What is semanticisation?
What was once an episodic memory can become a semantic memory; remember that both at the time of learning and at the time of retrieval the systems interact and are interdependent
How did Hodges at al demonstrate the possibility of a double dissociation between semantic and episodic memory
asked people with semantic dementia to recall facts about childhood, young adulthood and recent, and then relate them to personal experiences which were then scored for detail. Results demonstrated that the semantic part of the task had significantly low results, but the episodic part showed normal scores.
This is evidence that semantic memory can be impaired whilst episodic memory is intact
Is there evidence for a double dissociation where semantic memory is intact but episodic memory is impaired?
- Yes - patient KC suffered a brain injury from a motorcycle accident, and after could not produce a single episode from his past with a distinct time and place. When shown pictures of people he was still able to identify who each face was (semantic memory) but couldn’t relate the pictures to life events (episodic memory)
