L49 - Learning and memory Flashcards
Define learning and memory?
Learning = acquisition of new information; observed as a change in behavior
Memory = retention of the learned information; categorized based on the duration of its retention
2 ways to investigate which brain areas are involved in diff. types of learning and memory?
- Measure neuronal activity in the brain while the subject is performing a particular task
- Examine selective memory deficits in patients with different brain lesions
Classify memory types.
Immediate memory (fractions of a second to seconds)
Short-term memory (seconds to minutes)
Long-term memory (days to years)
2 outcomes in retention of short-term memories?
1) Consolidation into long-term memories (stable)
2) Lost if information is trivial/ meaningless = forget
What drives consolidation of selective memories?
Motivation, reward, or association with pre-existing information
Function of Working Memory? Which brain area involved?
one type of short-term memory
- achieve a behavioral goal (e.g. remembering a phone number)
- used in planning
• Depends on frontal lobe especially prefrontal cortex**
Name the cognitive test used to test working memory?
Wisconsin card-sorting test
Define the 2 types of amnesia following trauma.
- Retrograde amnesia: memory loss for events prior to trauma
- Anterograde amnesia: failure to from new memory after the trauma
Define Engram?
physical representation of memory (trace) in brain
= synapses that are activated/formed during memory acquisition
How is memory affected if medial temporal lobe is resected?
Intact perception and cognition
Problems in memory formation:
- Normal working memory
- Severe anterograde amnesia in all kinds of memory
- Temporary graded retrograde amnesia (intact remote memory)
Divide long-term memory into 2 types?
based on whether it requires conscious awareness
1) Explicit (declarative, Requires conscious recall)
a) Episodic
b) Semantic
2) Implicit (nondeclarative)
Define the 2 subtypes of explicit memory?
- Episodic memory (memory for events)
• Personal experience in a specific spatial and temporal context - Semantic memory (memory for facts)
• General knowledge (word, objects, concepts); not associated with context
Compare the plasticity and stability between explicit and implicit memory?
Explicit:
- More flexible, more associations formed
- Easier to form and forgotten, less stable
Describe the formation of explicit memory. (4 processes)
- Encoding (acquire new information and link to existing one)
- Storage (retain the information in specific cortical areas)
- Consolidation (transform the newly-stored memory, which is labile and susceptible to disruption, to a more stable one)
- Retrieval (bring back the different kinds of information from different brain areas)
Which brain area is involved in encoding explicit memory?
prefrontal cortex and medial temporal lobe
Which brain area is involved in storage of explicit episodic memory?
stored in distinct areas of the cerebral cortex**
where the specific aspect of a concept is processed (e.g. image, sound, movement)
Widely stored, no single area
Describe the interconnection between hippocampus and cortex in forming explicit memory?
Hippocampal area @ medial temporal lobe:
- Receive sensory information
- Integrates various sensory information to build up memory
- outflow to association cortices for storage of information
** Repeated retrieval of information between hippocampus and cortices = consolidation of memory **
Describe the connection and function of the connection between visual cortex and frontal association cortex?
- Dorsal stream:
- Spatial information (e.g. position, motion)
- To parietal association cortex (also receives somatosensory input) - Ventral stream:
- Information about form (e.g. color, shape) + auditory, somatosensory input
- To temporal association cortex
»»> Where semantic information is stored ***
Both parietal, temporal association cortices project to frontal association cortex
Where is semantic information stored?
Temporal association area
Define the brain region for spatial memory and list the cells involved.
Hippocampus
constitutes a cognitive map for the surrounding environment
Place cells in the hippocampus + grid cells in the entorhinal cortex (which provides input to the hippocampus) are involved
Classify implicit memory types?
- Priming
- Procedural memory
- Habit learning
- Non-associative learning
- Associative learning
Define ‘priming’ in implicit memory and brain region involved?
Exposure to one stimulus influences the response to a subsequent stimulus unconsciously
Depends on neocortex*** (not medial temporal lobe)
Define procedural learning in implicit memory and brain region involved?
Skill learning includes:
a) Visuo-motor skills
b) Perceptual learning
Training and repeated stimulation causes shift from parietal cortex activity to inferior temporal cortex»_space; direct recognition
Not affected by medial temporal lobe or Hippocamus
Which patient retain ability for procedural learning: Amnesic patient (e.g. Alzheimer’s) with medial temporal lobe damage or Parkinsons patient?
Procedural learning requires parietal cortex + inferior temporal cortex, doesn’t involve medial temporal lobe or hippocampus
Alzheimer’s retain ability
Parkinson’s lose ability
Define habit learning in implicit memory and brain region involved?
Repeated stimulation and tasks form strong association
Depends on the striatum***
,NOT medial temporal lobe
deficit in Parkinson’s disease (PD) but not amnesic (AMN) patients
Define non-associative learning and Subtypes in implicit memory and brain region involved?
unconscious change in response to stimulus: includes:
- Habituation: decrease in response to a non-threatening stimulus (“learning to ignore”)
- Sensitization: increase in response to different stimuli after an intense or noxious event (startle reflex)
> > > Depends on reflex pathways
Define associative learning and Subtypes in implicit memory and brain region involved?
- Classical conditioning (e.g. fear conditioning): association of two stimuli
»> response by AMYGDALA - Operant conditioning: association of an action and the outcome (behavior is controlled by consequences)
»> response by CEREBELLUM
Describe the pathways involved in fear learning (a type of classical associative learning)?
2 neural pathways relay information (e.g. auditory, somatosensory) from thalamus to amygdala
- Rapid direct pathway (from somatosensory thalamus to lateral nucleus of amygdala)
- Slower indirect pathway (e.g. relay from thalamus to auditory cortex/ somatosensory cortex, then to lateral nucelus of amygdala)
Summarize the brain regions required for explicit memory?
Semantic
Episodic
Both go to medial temporal lobe
Semantic memory is stored at temporal association area
Summarize the brain regions required for implicit memory?
- Associative (classical, operant) = amydgala, cerebellum
- Non-associative (habituation, sensitization) = reflex pathways
- Procedural = Parietal and inferior temporal cortices
- Habit = Striatum
- Priming = neocortex
Describe the changes to synapses in Engram?
Experience-dependent change in synaptic strength = synaptic plasticity
Learning Increases synpatic strength (more receptors, structural change), stronger postsynaptic response
