W7.2 (N): Cellular and system level memory consolidation Flashcards
(14 cards)
What are the two main types of memory consolidation?
Cellular (synaptic) and system level (whole brain)
What did Mueller and Pilzecker (1900) investigate and find about new memories and syllable learning?
New memories are initially fragile, but soon start to become resistant to interference
Ppts learnt a list of paired associate syllables and were tested in a cued recall using the first syllable
Interpolating another list e.g. (CD) impaired the memory of the first list (AB). They found a temporal gradient, where the closer in time the interfering list to the target list, the stronger the amnestic effect
What did Mueller and Pilzecker’s (1900) research reveal about interference and memory?
Memories require time to consolidate
Retroactive interference compromises the integrity of recently formed but not yet consolidated memories
Interference is ‘nonspecific’ i.e. the interfering material does not have to be similar to the target material i.e. AB, CD
Mental exertion is the interfering force
What is the continuous reduction in the forgetting rate a sign of?
Consolidation- along with the principle that we forget less as time goes on
What is the ‘clay sculpture’ metaphor (Wixted and Cai, 2014) and what does this fit well with?
Memory initially at its finest but fragile; over time, it becomes resistant to interference and shows less potential for damage
Fits well with forgetting curves as the rate at which we forget is not constant
Describe cellular memory consolidation
Occurs at the neuron level rather than the whole brain systems level
Takes place during the first hours (and perhaps days) after initial memory formation in the hippocampus
Fits well with the idea of a trace-hardening physiological process put forward
Corresponds to the discovery of long term potentiation
What is long term potentiation?
Long lasting enhancement of synaptic efficacy induced by a tetanus (short burst of high frequency stimulation) to the presynaptic neuron, observed before or after training
What is retrograde facilitation?
If subsequent encoding (mental exertion) interferes with memory consolidation, then factors blocking new encoding should promote memory stabilisation
Includes alcocohol, drugs and slow wave sleep
So, resulting anterograde amnesia is accompanied with retrograde facilitation: memories formed prior to drug/intake sleep are forgotten o a lesser degree, counter intuitively
What is anterograde amnesia?
The inability to form new declarative memories
What is temporally graded retrograde amnesia?
An impairment of memories formed prior to surgery, stronger for young than old memories
What is ‘systems consolidation’ defined as?
Declarative memories becoming independent from the hippocampus and more dependent on the neocortex
What is the significance of the shift in activation from the medial temporal lobe to the neocortex?
Fragments of declarative memories stored in the neocortex from the outset e.g. sensory and semantic areas, as they travel through it
The hippocampus acts as a relay station and binds these fragments together
Over time, cortical associations develop such that these memories become independent of the hippocampus
What are the two complementary learning systems?
Fast system that holds information only temporarily (medial temporal lobe, hippocampus)
Slow learning system that serves as a long term store i.e. the neocortex
What are the main ideas for the complementary learning systems?
Information is initially stored in the hippocampus and is progressively fed back into the neocortex via ‘neural replay’ so that pre-existing knowledge can accommodate newly learnt information- the hippocampus is seen as the internal sparring partner of the neocortex
As both systems are used to encode new learning, this reactivation/redistribution has to occur offline e.g. during sleep
