L5 - How the Brain Retrieves Information Flashcards
What did Montaldi et al. (2006) test about brain activity during retrieval?
PPS had to select 3 options for each item they saw, after looking at items during an encoding phase.
Pressed buttons signalling that they thought the item was new, old, or familiar.
What did Montaldi et al., (2006) find about brain activity during retrieval?
The parahippocampal gyrus showed decreased activity with items reported as familiar. Parahippocampal gyrus activity dropped off completely during the recollection experience - was only active for new items.
The hippocampus was more active for recollected items, that pps saw before - and was not interested in items that seemed familiar.
How did Staresina, Cooper and Henson (2013) test the role of the MTL in retrieval?
PPS were presented with object-scene pairs which they had to learn. During the test phase, PPS had to recall the scene if they were shown the object, and had to recall the object if they were shown the scene.
What did Staresina, Cooper and Henson (2013) find about the role of the MTL in retrieval?
Hippocampus was equally active for both recall conditions.
Perirhinal cortex showed greater activity when recalling the object (after being shown the scene)
Parahippocampal cortex more active when recalling scenes (after being shown the object)
What is mnemonic competition?
The ability to remember is often compromised by competition from irrelevant memories
How is the PFC brought into action by mnemonic competition?
The PFC is involved in making decisions on the correct and relevant memory that should be accessed, when several competing memories are activated.
What does the cortical reinstatement hypothesis suggest?
Retrieval involves the cortical reinstatement of the pattern of neural activity that was present at the time that an experience was first encoded into memory.
What did Tulving (1982) theorise about retrieval?
‘Ecphory’ is a term to describe the correlation of cues with information in the associated memory trace(s).
There are two steps to retrieval:
- presence of ecphoric information (that which provides cues that associate with a full memory trace)
- conversion of that information into an accessible form for the rememberer.
What was Moscovitch’s (2008) model/quote about retrieval by the hippocampus?
The hippocampus records all of our conscious experiences. Retrieval is subsequently fast, automatic and therefore “stupid”, as memories will be retrieved without confirmation of its relevance.
How did Wheeler, Peterson and Buckner (2000) study cortical reinstatement with sensory regions?
They simply presented items in either a visual or auditory domain, and recorded brain activity.
During retrieval, PPS had to state whether the item was old or new, and whether it was a picture or sound
What did Wheeler, Peterson and Buckner (2000) find about cortical reinstatement in sensory regions?
During encoding, visual and auditory regions were active for visual and auditory stimuli respectively.
During retrieval, small amounts of activity was found in those same regions - i.e. if a previously seen visual cue was presented, activity could be seen in visual regions.
Suggests that retrieval requires the reactivation of sensory information that was specific to the encoding phase, supporting the idea of cortical reinstatement.
Wimber et al., (2012) studied what, in relation to cortical reinstatement, and how did she do this?
Tested the question of whether cortical reinstatement precedes, (and potentially causes) memory retrieval, or whether retrieval precedes (and potentially causes) cortical reinstatement.
Used a standard encoding-retrieval task, but presented items with either a 6Hz or 10Hz flicker in the background/behind the item.
What did Wimber et al., (2012) find in relation to cortical reinstatement?
Found that neural activity at retrieval matched activity at encoding, even for the flicker frequency (Hz).
Found that cortical reinstatement occurred very early, (before 300ms), without access to contextual information.
Supports Tulving’s (1983) idea of ecphonic information eliciting an automatic and stupid retrieval of a memory.
Which analysis/neuroimaging techniques are used to measure ‘natural’ brain activity during encoding and retrieval?
Pattern fMRI
What does pattern fMRI analyse that’s different to standard fMRI?
Pattern fMRI is a multivariate analysis technique, whereas standard fMRI is univariate. This means pattern fMRI can analyse multiple areas of difference, rather than a single difference between two regions.
For example, standard fMRI could not reveal differences between activity for encoding of ‘rah’ and ‘lah’, but pattern fMRI could.
