Wk4 - Explicit Long-Term Memory Flashcards
What is the difference between explicit and implicit memory?
Explicit memory is conscious, intentional recollection
Implicit memory is non-conscious, unintentional retention
What do circular definition problems refer to?
Depends on the way that types of memory are measured.
We have to be certain that the kind of task we are using is actually measuring the type of memory that we think we are measuring.
What is another word for explicit memory?
Declarative
What is another word for implicit memory?
Non-declarative
What are 2 examples of explicit long-term memory?
Recalling facts
Recalling events
What are 4 types of implicit long-term memory?
Priming
Procedural
Associative
Non-associative
What is the term given to the type of memory that refers to recalling events from one’s past?
Episodic memory
or autobiographical memory
What brain region mediates explicit memory (recollection of facts or events)?
Medial temporal lobe
What does procedural long-term memory refer to?
Habits or sequence learning
What is associative learning?
Conditioning (learning to associate a stimulus with an emotional response or a movement)
What is non-associative learning?
An automatic reflex
What is priming?
Prime someone by giving them a letter or a word before completing a task. Participants will be more likely to give that letter or word as a response in the task (sub-conscious priming)
How does priming relate to consciousness?
Priming is a sub-conscious process. It makes something more available to our consciousness to then act on.
What brain region mediates priming?
Neocortex
What brain region mediates procedural memory?
Striatum
What pathways mediate non-associative learning?
Reflex pathways
What brain regions mediate emotional associative responses?
Amygdala (e.g., fear conditioning, avoidance conditioning)
What brain regions mediate skeletal musculature associative memory?
Cerebellum
What parts of the medial temporal lobe does explicit memory depend on?
Hippocampus
Para hippocampal gyrus
What is the type of memory for names and facts?
Semantic memory
What happens if the medial temporal lobe is damaged?
Explicit memory will be destroyed
What patient had a large part of their medial temporal lobe and hippocampi removed?
H.M
What happened to the memory of patient H.M after brain surgery of the medial temporal lobe/hippocampi?
STM unchanged
Unable to make any new memories (anterograde amnesia)
What can we conclude from patient H.M case study about STM and LTM?
STM and LTM are separate. There is a definite division between STM and LTM.
What can we conclude from patient H.M case study about necessity?
The roles of the medial temporal lobe and the hippocampi are necessary to make new memories.
How can start-it experiments demonstrate the role of the hippocampus?
If we stimulate the hippocampus we can evoke memories.
What is an advantage of stop-it and start-it experiments compared to generic brain imaging tasks?
Can see more causation with stop-it and start-it experiments, rather than simple correlation.
What is a limitation of generic brain imaging tasks?
Can generally just get an idea of a simple correlation. NOT causation.
What happens if we stimulate the temporal lobe?
Recall old memories
Explain the stimulation study by Jacobs et al. (2012)
Patient underwent cortical stimulation whilst performing a memory task
What type of stimulation did Jacobs et al. (2012) use?
ECoG monitoring (ElectroCorticoGraphic monitoring)
What did Jacobs et al. (2012) study allow you to see?
Could see what would happen at the stimulated site and then see if that site was activated during normal memory processing.
What did Jacobs et al. (2012) find when they stimulated the left ventral temporal cortex?
Caused spontaneous recall of vivid high school memories in patients
How does ElectroCorticoGraphic (ECoG) monitoring work?
ECoG stimulation temporarily inhibits neuronal activity
What did Jacobs et al. (2012) find?
Spontaneous recall of high-school memories can be caused by mimicking the activity that occurs during natural recall of these memories
Found lower neuronal activity for retrievals of high-school memories compared to non-high-school memories
What study supports the localisation of memory?
Jacobs et al. (2012) - lower neuronal activity in the left ventral temporal cortex caused spontaneous recall of high school memories
Localised parts of the temporal lobe relate to memories from high-school
Who did the Jennfier Aniston and the concept cell study?
Quiroga et al. (2005)
Briefly explain the Quiroga et al. (2005) Jennifer Aniston study
8 patients with epilepsy
Implanted electrodes into temporal lobes
Subjects were shown pictures of various animals, objects, landmarks
Responses of neurons surrounding the hippocampus were recorded
What does implanted electrodes allow?
Localisation of the focus of seizure onset
What unit of the medial temporal gyrus fired in response to Jennifer Aniston?
A single unit in the left posterior hippocampus
What unit fired in response to Halle Berry?
Single unit in the right anterior hippocampus of a different patient
What does the findings of Quiroga et al. (2005) suggest?
Suggests that there are particular neurons which respond to specific concepts
What did Quiroga et al. (2005) find?
Specific neurons in the medial temporal lobe fired in response to a photo of Jennifer Aniston
Specific neurons in the medial temporal lobe fired in response to the concept of Halle Berry (photo, writing, voice recording)
These neurons did not fire in response to other famous or non-famous faces, animals, objects, or landmarks
When does the firing of recognition in medial temporal lobe occur?
With conscious recognition. E.g., the participant has to know that they are looking at Jennifer Aniston before their Jennifer Aniston neuron cell will fire
What is the hierarchy of the medial temporal lobe?
Sensory input
Parahippocampal/Perirhinal cortices
Entorhinal cortex
Hippocampus
How does specificity of neuronal firing in recognition to particular stimuli relate to the hierarchy of the medial temporal lobe?
Specificity of neuronal firing in recognition to particular stimuli increases along the hierarchy of the medial temporal lobe
What does specificity of neuronal firing in response to a stimulus depend on?
Subjective opinion (think of the Sydney Opera House and the Bahai Temple). The same neuron will fire if the participants think both images are of the Sydney Opera House, for example.
Do concept cells act in isolation?
No. Concept cells act as part of sparse cell assemblies
What might the association of related concepts rely on?
Rely on overlaps in the networks of neurons that represent them
How do sparse cell assemblies work?
Assemblies of cells represent particular concepts. Parts of these assemblies of cells would overlap with related concepts and will share related neurons.
What is the neuronal basis of explicit memory creation?
Long-term potentiation in the hippocampus is involved in explicit memory
What is LTP?
Long-lasting enhancing signal transmission between 2 neurons after repeated stimulation
LTP is an enhancement of post-synaptic response
When does LTP occur?
When two neurons are activated simultaneously
What is the saying of LTP?
Neurons that fire together wire together
What causes LTP?
A brief period of high frequency stimulation
Where does LTP occur?
Hippocampus
What is an example of an excitatory neurotransmitter?
Glutamate
What is glutamate essential for?
LTP
Where is the hippocampus located?
Medial temporal lobe
What receptors are on the post-synaptic cell in LTP?
NMDA and AMPA receptors
What binds to NMDA and AMPA receptors in LTP?
Glutamate
What happens when glutamate binds to AMPA receptors in LTP after a high frequency action potential?
Large amount of glutamate binding to AMPA receptors causes a greater depolarisation event.
AMPA receptors are open for longer due to increased concentration of glutamate. More Na+ enters through the AMPA receptors.
Influx of lots of Na+ causes a large depolarisation event in the post-synaptic cells.
Mg2+ blockade is repelled and Na+ and Ca2+ enter through NMDA receptors.
What is the name of the process in which Mg2+ blockade on NMDA receptors is repelled?
Electrostatic repulsion
What are the 2 phases of LTP?
Early phase
Late phase
What happens during the early phase?
Ca2+ binds to its respective binding proteins and causes the insertion of new AMPA receptors onto the post-synaptic cell membrane
How long does the early phase last?
A few hours
What happens during the late phase?
A prolonged influx of Ca2+ causes an increase in protein synthesis. More AMPA receptors inserted into the post-synaptic cell membrane. Increase in growth factors too.
What are growth factors involved in?
Involved in the formation of new synapses, which is the basis for synaptic plasticity
How long can late phase changes last?
From 24 hours to a lifetime
What does LTP result in?
Increase in AMPA receptors and synaptic connections, which allows the low frequency action potential to cause a greater depolarisation event in the post-synaptic terminals. This is the foundation of memory.
What is LTP the foundation of?
Memory
How are neural pathways strengthened?
Continuous activation of the same pathways creates high-frequency pre-synaptic and post-synaptic action potentials in those paths. These events strengthen the connections in the specific pathway.
What contributes to the ability to recall material and memorise things?
The strengthening of neural pathways
What are a likely site for LTP?
Small dendritic spines of pyramidal neurons in the hippocampus
Glutamate enlarges these dendritic spines during LTP
What might large dendritic spines of pyramidal neurons in the hippocampus represent?
The physical trace of long-term memory.
LTP makes physical changes in the neurons.
What does the cell assembly theory suggest?
Suggests that the internal representation of objects consists of all cortical cells activated by the stimulus
What makes up the cell assembly?
A group of simulataneously active neurons
What happens during consolidation of information?
Internal representations of objects will be held in STM
Activity reverberates through these connections between the cells
If activity persists, there will be consolidation
The reciprocal connections are made more effective by LTP
How does the cell assembly theory work?
If only some or one of the cells of the assembly become activated by a stimulus, the whole assembly will become activated
What theory underlies the development of neural networks?
Cell assembly theory
What is the opposite of LTP?
Long-term depression
What is LTD?
A long-lasting reduction in synaptic transmission
What is the saying for LTD?
Neurons that fire out of synch lose their link
What happens in LTD?
Neurons that stop being active synchronously start to lose those connections with each other
