2. Memory Flashcards
What are the two key tools for understanding human memory?
Neuropsychology (Causal) & Neuroimaging (Correlational)
Neuropsychology, Single dissociation:
- Patients with brain damage can show SELECTIVE deficits (impaired in ONE task but not another)
Neuropsychology, Double dissociation:
Two patients can show DOUBLE dissociation
- Patient A: impaired on task A (not B)
- Patient B: impaired on task B (not A)
Neuroimaging & memory: two tasks show different regions active.
This supports the idea that…
given tasks measure distinct forms of memory
Neuroimaging is correlational!
What is conscious memory?
- Available to conscious retrieval
- Can be declared (I remember this…)
e. g.:
- What phone number did I just give you (STM)
- What’s the capital of France (semantic)
- What did I eat for breakfast? (episodic)
What is non-conscious memory?
- Change in behaviour
following experience - Cannot be declared
e. g.:
- How to drive a car (procedural learning)
- Phobias (conditioning)
- Subliminal advertising (priming)
Episodic memory test: Free recall
Encoding:
Cat, Train
Retrieval:
? (Recall anything you can)
Episodic memory test: Cued recall
Encoding:
Cat, Train
Retrieval:
Ca.., Tr.. (part of the memoranda is cued)
Episodic memory test: Paired associate
Encoding:
Cat-Train
Retrieval:
Cat-… (completing the pair)
Episodic memory test: Recognition
Encoding:
Cat, Train
Retrieval:
Cat (old), Dog (new) (deciding whether the memorandum appeared at encoding)
Episodic memory test: Source memory
Encoding:
Cat (written in bold), Train (written in italics)
Retrieval:
Cat (bold), Train (italics) (deciding in what form the memorandum appeared at encoding)
Amnesia
Deficit in memory
Retrograde amnesia
Inability to retrieve information BEFORE trauma
Anterograde amnesia
Inability to encode NEW information
Scoville & Milner (1957):
HM case
Surgery to alleviate epileptic seizures:
- Removed medial temporal lobes bilaterally
- Severe retro/anterograde amnesia
BUT…
STM intact
What part of the brain did a virus damage in Clive Wearing
Wearing developed a profound case of total amnesia as a result of his illness. Because of damage to the hippocampus, an area required to transfer memories from short-term to long-term memory, he is completely unable to form lasting new memories – his memory only lasts between 7 and 30 seconds
Vargha-Khadem et al (1997):
Developmental Amnesia
- describe it
- Selective bilateral hippocampal damage early in life
- Anterograde amnesia
- Still bale to learn semantic info as hippocampi are selectively involved in episodic memory
What lobes show activity during encoding/retrieval memory tasks?
Neuropsychology (HM, Clive, Developmental amnesia) points to hippocampi as the key structure but these regions are also involved:
- Frontal
- Parietal
- Medial Temporal
What is familiarity?
Recognition in the absence of recalling source information
What is recollection?
Recognition combined with retrieval of source information
Davachi et al (2003):
Recollection vs Familiarity (fMRI)
Placed people in a scanner, and shown them words at encoding. (Scanning during learning)
- There were 2 encoding tasks:
1. Imagine a scene which could be described by that word (place encoding task)
- ## Try to imagine the word being said backwards in your head (read encoding task)At test:
- Recollection task (have you seen the word or not? - old/new)
- Do you remember the source? (Using which task was the word encoded?)
Looking at activity in Perirhinal Cortex vs Hippocampus…
- Perirhinal is more active if the given word is recognised (compared to if the word was forgotten)
- For the recognised words, the hippocampus is more active when participants recall the source of the item (the way in which it was encoded)
!- Hippocampus = source/context
!- Perirhinal = Recognition as Old/New
This evidence is in the favour of dual source accounts (recollection & familiarity is processed separately)
Horner et al (2012):
Neuropsychology of Recollection vs familiarity
Patients with selective damage to hippocampus vs healthy participants:
- Both equally good at the Old/new recognition task (familiarity)
- Patients significantly worse (performing at chance level) at associative memory task (remembering what scene was associated with recognised words - source; Recollection)
What is the problem with dual-process accounts of episodic memory?
They largely ignore the idea of representations
What are the place cells? (O’Keefe & Dostrovsky, 1971)
Fire in specific location (‘place field’ - where neuron fires on a heat map) in an environment
(hippocampus cares about space)
What are the grid cells? (Hafting et al., 2005)
Fire in multiple locations, in a regular hexagonal pattern
hippocampus cares about space
What are the concept cells? (Quian Quiroga et al., 2005)
Fire when presented with a famous person regardless of modality (Face, name, etc.) or perspective
Doeller et al (2010):
Grid cells in humans (fMRI)
Greater fMRI response in Grid cells when moving on axis (across more grid points) compared to off axis (where you cross grid points less frequently)
- First evidence humans might have grid cells as found in rodents
(hippocampus cares about space)
Horner et al (2016):
Space and imagery (in fMRI)
- Grid cells are as active when imagining navigating in a virtual environment as when actually navigating through it
(Hippocampus might be involved in planning navigation)
Bird et al (2010):
Space and imagery
- 5 ‘lego’ blocks
- some columns
- some barriers (horizontal)
Greater fMRI response as the number of imagined boundaries increases in the hippocampus
Hartley et al (2007):
Space perception/memory
- Target picture (scene) of four digital mountains shown
- Then 3 pictures of similar scene and 1 of the same scene appear with a view from a different perspective
The participant has to select which of the subsequent four mountain scenes is the same as the target one
The task is testing the ability to know where mountains are in relation to each other
Patients with selective hippocampal damage could not do this task
(Hippocampus might be critical in tasks that are not episodic in nature… critical for spatial tasks involving STM and landscape perception)
Horner et al (2015):
Episodic memory & events (fMRI study)
Hippocampus might be critical to binding features of a particular event together to form a coherent representation which you might retrieve later
At encoding, participants had to try and vividly imagine a combination of:
- object (e.g. hammer)
- location (e.g. kitchen)
- person (e.g Obama)
At encoding, there was activity specific in areas specific to these 3 components outside of the hippocampus
- medial areas (people)
- parahippocampal gyrus (place area - cares about scenes)
- ## Lateral occipital (objects)!!!!!These elements seem to be bound in the anterior hippocampus
!!!!At retrieval the hippocampus is also active (leading to outflow of information to the areas which were active for the constituent elements)
To provide evidence for a double dissociation in neuropsychology, you would require:
Two patients, each with lesions to different brain regions
A common measure of episodic memory is:
A source memory task
The ‘butcher on the bus’ phenomenon refers to the feeling of:
Seeing your local butcher on the bus, feeling you’ve met him before but not recalling where
you’ve met him (this is FAMILIARITY)
The distinction between familiarity and recollection originates from
A dual-process account of recognition memory
A computational account of episodic memory proposes that recollection results from
The retrieval of a complete event engram in the hippocampus, followed by reinstatement of
all event elements in the neocortex
