Long-term memory Flashcards
Long-term memory is measured how ?
days and years
What is long-term memory also referred to as?
qualitative memory
What are the two major divisions of long-term memory?
Declarative and nondeclarative memory
What is declarative memory?
is knowledge that we have conscious access to
What is declarative memory also known as?
explicit memory
What does declarative memory require?
deliberate recall of information
What are the two subdivisions of declarative memory?
Semantic and Episodic memory
What is semantic memory?
knowledge about the world
What is episodic memory?
knowledge that we recall about he events of our own lives
What is nondeclarative memory?
encompasses several forms of knowledge and is revealed when an individual performs a task that does not require intentional recollection of previous experience
What are the 4 subdivisions of nondeclarative memory?
- Procedural memory
- Priming
- Classical conditioning
- Non-associative learning
What is procedural memory?
memory that involves the learning of motor and cognitive skills
What is priming?
memory that involves a change in response to a stimulus or the ability to identify a stimulus as a result of previous exposure to that stimulus
What is classical conditioning?
a conditioned (neutral) stimulus is paired with an unconditioned stimulus (one that evokes a response) which results in an evoked response to the conditioned stimulus
What is another name for classical conditioning?
Pavlovian conditioning
What is non-associative learning require ?
simple forms of learning
What are included in simple forms of learning (non-associative learning?
- Habituation
- Sensitization
What is habituation? (non-associative learning)
decrease in response to a stimulus following repeated exposure
What is sensitization? (non-associative learning)
Increase in response to a stimulus following repeated exposure
What happened to patient H.M?
had a severe temporal lobe epilepsy and underwent bilateral medial temporal lobectomy
- his seizures ceased and his intelligence and motor abilities remained intact
What issues did patient H.M post lobectomy?
Resulted in amnesic effects: total anterograde amnesia (including episodic and semantic memory) –> could not form new declarative memories
- Partial retrograde amnesia
- Could not recall information learned following his surgery
- Was able to demonstrate improved performance on a task that did not require conscious access to information
What did we learn about patient H.M?
- Functioning of the medial temporal lobe (MTL) was necessary for memory
- The process underlying storage of short-term and long-term memory are different
- Two distinct categories of long-term memory exists (explicit and implicit)
What is explicit and implicit memory?
other names for the subdivisions of long-term memory
- explicit –> declarative
- implicit –> nondeclarative
What is retrograde amnesia?
loss of information/memories for a period of time prior to the event causing the amnesia
- long-term memories and memory from the period following the event are often intact
What is anterograde amnesia?
loss of information/memories for a period following the causal event
- memory prior to the event is often retained
What are the divisions of declarative (explicit) memory mediated by?
- divisions = Semantic and Episodic
- Mediated by the medial temporal lobe (MTL)
Is declarative memory flexible?
yes, can adapt to contextual changes
Rat experiment involving the importance of the medial temporal lobe & declarative memory
Rats given spatial task to find a platform in a tank filled with opaque water –> able to find platform faster each timee
- Naive rats with hippocampal lesion were unable to find platform
- Rats that learned to find the platform before lesion were able to find platform at the same level as before
What did the rat experiment teach us?
Neurons of the hippocampus are needed for formation but not necessarily storage or retrieval of declarative memories
What is the role of the medial temporal lobe related to learning & memory?
it is thought to be a “switchboard” that binds and keeps track of all relevant circuits selected (utilized) by working memory
- also directs the consolidation of info into long-term storage by maintaining linkage of all relevant networks (able to activate as a group/recall later)
What do neurons of the MTL utilize?
Glutamate
What are the 3 major structures involved in memory with the MTL?
Hippocampus, amygdala, and the rhinal cortex
What is the role of the hippocampus in the MTL?
- Mediates spatial memory
specifically the parahippocampal cortex
What is the role of the amygdala in the MTL?
- Modulates the encoding and storage of hippocampal-dependent memories
What are the two regions that divide the Rhinal cortex?
- Perirhinal cortex (PR)
- Entorhinal cortex (EN)
What is the role of the perirhinal cortex (PR) in MTL related learning and memory?
controls object recognition
What is the role of the entorhinal cortex (ER) in MTL related learning and memory?
Serves as the interface between the neocortex and the hippocampus
- plays an important role in the formation & consolidation of episodic and spatial memories
Where does the entorhinal cortex (ER) project to?
sends projections to the dentate gyrus (part of the hippocampal formation)
- also aids in the formation of episodic memories
Medail temporal lobe (MTL) pathway related to learning and memory
5 SSDNs –> Thalamic ARAS (Iln & TRn) –>hippocampus + rhinal cortex + amygdala
What is thought to be the underlying mechanism of declarative memory?
LTP
What are the two forms of LTP found in experimental studies within the neurons of the hippocampus? (declarative memory)
early long-term potentiation (E-LTP)
late long-term potentiation (L-LTP)
Which LTP form (E-LTP or L-LTP) is stimulated by short period of stimulation? prolonged stimulation?
E-LTP = short period L-LTP = prolonged period
Characteristics of E-LTP
Synaptic changes last for several minutes to ~3 hours
- No new protein synthesis within the neurons was observed
- No synaptic morphology changes were observed
Characteristics of L-LTP
Synaptic changes last for ~3 to > 24hours
- New proteins created within the neurons
- Synaptic morphology changes were observed
(LTP): What is associativity?
the induction of LTP by the stimulation of two sets of synapses that are activated concurrently
- thought to strengthen the connections between relevant information
(LTP): What is specificity?
refers to the phenomenon in which LTP is elicited at one set of synapses on a postsynaptic cell, whereas adjacent synapses that were not activated do not exhibit LTP-like changes
- exclude non-relavent connections
What is the example of associativity and specificity? (sight and smell of rose)
When the sight and the smell of a rose are presented to an individual several times, eventually the networks involved in the processing of this “sight” and “smell” information will fire simultaneously (associativity)
- Once LTP mechanisms have “bound” these networks, the sight or smell of a rose alone will activate the other network
- Conversely, if subjects were exposed to the smell of an onion, only the onion network would be activated due to specificity of LTP mechanism
Non-declarative memory characteristics
- Memory without recall or awareness
- Experience alters behavioral performance unconsciously
- Evidence for implicit memories can be found in preferences, habits, and disposition that are inaccessible to conscious recall (both during and after acquisition)
- Implicit memory is not dependent on the MTL
Once again, what are the 4 subtypes of nondeclarative memory?
- procedural/habit or skill memory
- priming
- classical conditioning
- non-associative
Procedural/habit or skill memory involves what?
involves the learning of a variety of motor skills (i.e riding a bike) and cognitive skills (i.e reading)
- Repeated rehearsal improves the skill performance unconsciously
- context specific/inflexible
What is the associated brain region with the Procedural (skills and habits) portion of nondeclarative memory?
striatum
What is priming in nondeclarative memory?
a change in response to a stimuli or the ability to recognize a stimulus as the result of prior exposure to that stimulus
Previous exposure or experiance activates specific circuits making it ______ to reactivate the same circuit?
easier
Can a single exposure to a cognitive item lead to unconscious improvement in performance when tested?
Yes
Classical conditioning responses can include what?
Skeletal muscle responses
Emotional responses
What controls skeletal muscle response in classical conditioning?
motor control controlled by the cerebellum
What controls emotional response in classical conditioning?
controlled by the amygdala, nAc, and orbital/medial PFC
Which subtype of nondiscrimative learning is considered to be the most primitive form of learning and is found in organisms with basic nervous systems?
Non-associative learning
What are the subtypes of non-associative learning?
Sensitization and Habituation
Sensitization activates STP or STD?
STP –> enhanced release of NT from the presynaptic termina
Habituation activates STP or STD?
STD –> suppression of NT release from the presynaptic terminal
Recent research suggests what about the implicit memory process involving emotion and “intuition”?
These play a crucial role in an individual’s ability to make decisions
Does conscious or unconscious emotion factor in first when making a decision?
Unconscious may factor in 1st
What mediates the process of implicit memory and emotional response?
ventro-medial PFC (VM PFC)
What is the ventro-medial PFC responsible for?
storage of personal information about past rewards and punishments
Which region is proposed to be triggered with non-conscious (implicit) emotional responses that individuals describe as “intuition”?
Ventro-medial PFC
What do individuals with VM PFC lesions display?
- Little emotion in social situations and no empathy towards others
- Perform well on IQ and memory tests but exhibit poor decision making ability
- Have intact factual knowledge but emotional memories are absent
- Exhibit dissociation of socially appropriate goal-directed (reward) behavior and willful behavioral action
A PET scan of violent criminals and those exhibiting sociopathology showed abnormal low cerebral blood flow (rCBF) in what areas of the brain?
ventro-medial PFC
What region of the brain is credited for housing Theory of Mind ability & empathy?
ventro-medial PFC
