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short term/working memory
memory where info is temporarily maintained in mind while it is being used to perform some task, but is rapidly lost when attention shifts elsewhere
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subcomponents of working memory
- visuospatial sketchpad: keeps visual images in mind
- phonological loop: keeps words, sentences, and numbers in mind
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long term memory
- encode, store, and retrieve information over long periods of time
- greater capacity than working memory
- divided into implicit and explicit
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implicit memory
- skills and learning that can occur without conscious awareness
- nondeclarative: can't verbally express these memories (e.g. playing piano or tying shoes)
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procedural memories
- implicit memory
- memories for how to perform skills or habits
- acquired through repition and practice
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priming
- implicit memory
- form of unconscious memory in which past experiences can influence a response to a sensory stimulus
- can be perceptual or conceptual
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classical conditioning
- implicit memory
- a form of memory in which a previously neutral stimulus gains the ability to elicit a behavioural response, after becoming associated with another stimulus that naturally elicits that response
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operant conditioning
- implicit memory
- a form of learning in which a behaviour is made more likely by providing a reinforce (reward) after it occurs or made less likely by providing a punishment after it occurs
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nonassociative learning
- long term strengthening or weakening of a response after repeated exposures to stimulus
- habituation and sensitisation
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explicit memory
- information that can be consciously recalled and expressed
- declarative: things you know you know, and can be talked about
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episodic memory
- explicit memory
- memories for past events in you life associated with spatial context (where), temporal context (when and sequence), perceptual detail (what things looked like, who was there, how felt)
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divisions of episodic memory
- recognition memory - ability to tell that you have seen or experienced something before
- recollection: retrieval of qualitative details realted to previous experience
- familiarity: sense of having seen something before, without an ability to bring to mind qualitative details about the prior experience
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semantic memory
- explicit memory memories for facts about the world
- memories for concepts rather than specific percepts
- semantic memories are independent of any particular sensory modality
- organised based on meaning
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disorders of explicit memory
- Alzheimer's disease (episodic memory before semantic memory)
- semantic dementia (semantic before episodic)
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amnesia
- damage to the hippocampus and surrounding medial temporal lobe cortex results in amnesia
- retrograde: inability to retrieve episodic memories for events that occurred prior to brain injury
- anterograde: inability to form new episodic memories after injury
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spatial memory
an extensive body of research on the hippocampus comes from non human animal models
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place cells
were discovered in the rodent hippocampus these are cells that fire when the animal is a particular location in its environment
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theories of hippocampal function
(what theories agree on)
- memories represented as a pattern of activity in the brain
- the system of brain regions active when memory is encoded
- hippocampus serves as a pointer to perceptual systems, indexing perceptual features of the memory
- some parts of the network active during memory encoding reactivated when memory retrieved
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declarative theory
- hippocampus critical for all forms of declarative memory
- hippo has time limited role in memory: involved initially but gradually memories become independent and consolidated into cortical areas
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multiple trace theory
- important for semantic and episodic memory
- only semantic memories become independent of the hippocampus over time
- true episodic memories accompanied by mental time travel always depend on hippocampus
- semantic and semanticised episodic memories gradually become supported by the cortex as a result of repeated retrieval and rehearsal
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dual process theory
- the hippocampus is critical for
- recollection: retrieval of specific details about the events of a particular memory, including where and when those events took place
- medial temporal lobe cortex critical for assessing familiarity in absence of recollection
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relational theory
hippocampus critical for storing relations/associations between elements of events in contrast to storing just individual items
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cognitive map theory
- hippocampus evolved to create and store spatial maps for navigation, orientation, finding resources
- this system has been co opted to create and store episodic memories as well (because they're spatial)
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prospection and amnesia
patients with amnesia not only have difficulty remembering the past, but also have difficulty imagining new experiences
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default mode network
- network of brain regions linked to episodic memory and imagine, but also active when people are resting quietly
- default mode involves memory retrieval, introspection, mind wandering, self reflection
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memory distortions
- Memory is falliable: we all make errors in remembering even when we are fairly confident
- memory is reconstructive
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confabulation
- unintentional production of false or distorted recollections or narratives, often in the face of contradictory evidence
- may be inability to inhibit currently irrelevant memories in favour of ones that are currently relevant
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provoked confabulation
healthy people, uninjured brains, when they're pressured to remember details of memory beyond their ability to recall it accurately
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spontaneous confabulations
- generated with no external cues, accompanied by strong conviction, may be acted upon
- constructed memories containing elements of the past but for the wrong situation at hand
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misattribution
attributing an idea or recollection to the wrong source (wrong time, place, or person)
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suggestibility
false memories can be created by providing a fictitious suggestion about a past experience, then encouraging elaboration of that false memory
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hebbian learning
- cells that fire together wire together
- evidence from synaptic connections can be modified as a result of the activity history of the cells involved
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long term potentiation
- long lasting increases in synaptic strength that are induced when a presynaptic cell consistently activates along with a postsynaptic cell
- many postsynaptic membranes contains NMDA receptors, which are glutamate receptors
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long term depression
long lasting decreased synaptic sgregnth that are induced when a presynaptic cell and postsynaptic cell are not consistently activated at the same time
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synaptic plasticity
- other mechanisms important for memeory formation
- neurogenesis: production of new neurons
- dentritic spines: tiny protrusions from dendrites, which may undergo structural changes with experience
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