Long-term memory Flashcards
LTM processes
- Encoding: Initial creation of memory traces in the brain from incoming information
- Consolidation: Continued organization and stabilization of memory traces over time
- Storage: Retention of memory traces over time
- Retrieval: Accessing/using stored information from memory traces
- Reconsolidation?: Possible reorganization and restabilization of memory traces after retrieval
Long-term vs. short term memory
STM: extremely limited capacity, lasts seconds, based on sustained activation of neurons
LTM: massive capacity, lasts minutes, hours, days, years, based on number & strength of synapses
Single dissociation
- performance difference across two tasks of one case compared to controls
- A single dissociation does not necessarily demonstrate separable systems, different brain regions, or distinct cognitive processes
Double dissociation
- two opposing single dissociations put together
- provides strong evidence for separable systems that depend on different brain regions and distinct cognitive processes
Types of LTM
Implicit memory and explicit memory
Implicit long-term memory
- Non-declarative
- Independent of conscious
awareness - Procedural, conditioning,
nonassociative, or priming - Timescale: minutes, hours, days, years
- Capacity: massive (e.g. ~1,000s of skilled motor sequences)
- Neural basis: number & strength of synapses
Explicit long-term memory
- Declarative
- Available to conscious
awareness - Semantic or episodic
- Timescale: minutes, hours, days, years
- Capacity: massive (e.g. ~20,000 word families in adult vocabulary)
- Neural basis: number & strength of synapses
Non-associative memory
- A type of implicit memory
- A change in responce to an unchanging stimulus
- Habituation
● Reduced response to an unchanging stimulus - Sensitization
● Increased response to an unchanging stimulus - Primarily involves sensory-motor reflex pathways
Changes from habituation & sensitization
- Short-term changes: lasts minutes, changes in. amount of neurotransmitter released
- Long-term changes: lasts for hours, days and weeks, changes in number of synapses
Types of implict memory
- Procedural (motor and cognitive skills)
- Perceptual priming
- Classical conditioning
- Non associative learning
Stimuli and responses in classical conditioning
An initially neutral conditioned stimulus (CS) comes to elicit a conditioned
response (CR) due to pairing
with an appetitive or aversive unconditioned stimulus (US) which reflexively elicits an unconditioned response (UR)
Procedural memory (reinforcement learning)
- In the basal ganglia
- Unexpected rewards generate dopamine signals from the substantia nigra pars compacta (SNc)
- This excites the direct
pathway (via D 1 receptors)
and inhibits the indirect
pathway (via D 2 receptors) - This allows modification of
behavior based on reward
Priming
- Change in stimulus processing due to prior exposure to the same or related stimulus without conscious awareness
- Depends on region of cortex processing relevant representations
- Perceptual priming: Sensory cortices (occipital lobe)
- Conceptual/semantic priming: Unimodal & multimodal association cortices (anterior temporal, prefrontal cortex)
Semantic memory
- A type of explicit memory
- Memory for concrete word meanings activates areas of
cortex involved in relevant processing
Sensory/functional theory
- Organization of semantic
representations is based on
relevant sensory and motor
features - E.g.: Action words activate
region of primary motor
cortex for specific body part
