lecture 6: memory 3 Flashcards
multiple trace theory
In this view, hippocampal ensembles are always involved in storage and retrieval of episodic information, but semantic (gist) information can be established in neocortex, and will survive damage to the hippocampal system if enough time has elapsed.
standard consolidation theory
The traditional view, as articulated in standard consolidation theory (SCT), is that (episodic and semantic) memories initially depend on the hippocampus, but eventually become consolidated in their original forms in other brain regions.
mutiple trace vs standard consolidation
A) The standard consolidation theory proposes that, over time, memories become independent of the hippocampus.
B) The multiple trace theory proposes that semantic or context-free memories become independent of the hippocampus over time, but that episodic or contextually-rich memories always depend on the hippocampus.
activation likelihood estimation (ALE)
comprehensive meta analysis of fMRI studies of episodic autobiographical memories
tests for above chance clustering of activation peaks across different studies
procedural learning in amnesics
Motor skills: HM showed intact learning on a mirror tracing task
Basal Ganglia play an important role in procedural memory
Procedural learning is impaired in patients with basal ganglia damage,
including patients with Huntington’s disease and Parkinson’s disease, who
have relatively intact explicit memory
Basal Ganglia
a group of subcortical nuclei linked to the thalamus in the base of the brain and involved in coordination of movement.
is amnesic syndrome a failure of consolidation or retrieval
Amnesic patients showed normal memory performance on word fragment and word completion tests, along with poor performance on
free recall and recognition tests, suggesting to Warrington and weiskrantz that amnesics could consolidate new memories but could not retrieve them
During the 1980s, it became clear that amnesics showed intact performance when word stem and fragment completion were given as implicit tests (provide the first word that comes to mind) but not when given as explicit tests (try to recall the
word from the list that fits the stem or fragment)
priming effect
The priming effect occurs when an individual’s exposure to a certain stimulus subconsciously influences his or her response to a subsequent stimulus
Priming and the perceptual representation system
Medial temporal lobe amnesics show robust, often intact, perceptual priming
Priming reduced by perceptual changes such as study-test modality change
Priming relatively unaffected by semantic vs. nonsemantic encoding tasks
Priming unaffected by one hour vs. one week delay
Longevity of Perceptual Priming
Mitchell & Brown (1988) reported that priming on the picture
fragment identification test persisted with little change across
six weeks
17 years later, Mitchell (2006) tracked down 12 of the 48 participants in the original study and tested them again (mailed participants the picture fragments from their previous test and
asked them to try to identify each item)
Priming-related activation decreases
Reduced activation (indicating
priming) for repeated objects in
multiple regions, including:
Left anterior inferior frontal
cortex (BA 47, 45)
* Bilateral fusiform, extending
into parahippocampal cortex
(BA 37, 19)
“DRM” Paradigm
The Deese, Roediger and McDermott (DRM) task is a false memory paradigm in which subjects are presented with lists of semantically related words (e.g., nurse, hospital, etc.) at encoding. After a delay, subjects are asked to recall or recognize these words
Some DRM lists yield more false memories than others,
e.g., “SLEEP” list below produces very high levels of false
memories, but “BUTTERFLY” list produces hardly
any false memories
SLEEP: bed, rest, awake, tired, dream, night comfort, eat,
sound, slumber, snore, deep.
BUTTERFLY: moth, insect, wing, bird, fly, yellow, net,
pretty, flower, bug, cocoon, summer
Temporal pole
as been called
“semantic hub” of the brain; thought to be important
for representing
semantic information.
Left temporal pole
implicated in Semantic
Dementia
linked to increase susceptibility to false memories due to semantic knowledge distorting memory
Semantic Representation and DRM False Memories study
*Used a type of multi-voxel pattern analysis (MVPA) that measures
similarity in neural patterns between pairs of stimuli as a basis for
inferring similarity in underlying representations.
*Measured neural overlap between each set of DRM words and
their associated critical lure when all words were presented during
a semantic encoding task. Each set associated with a different
probability of a false memory for the lure.
Past/Future fMRI Paradigm
