Learning & Memory Flashcards
• The Case of H.M. • Types & Stages of Memory • Memory Capacity • Memory Disorders • Neural Basis & Brain Regions Involved
Learning
process of acquiring new information.
Memory
the outcome of learning
The Case of H.M.
- Had Epilepsy from childhood
- 1950s: He was a young adult, couldn’t work.
• Surgical treatment:
remove bilateral medial temporal lobes (seizure foci).
• After surgery, HM could no longer form new long-term memories (anterograde amnesia)
– Could remember things from before surgery
– Could remember things for a few min (short‐term memory)
– Could learn new procedural/implicit memories
– Intact intelligence/personality
H.M.
Lessons
• Hippocampus/MTL critical for forming new explicit memories
• Different types of memory
supported by different structures
HM Revolutionized our
understanding of memory!
Memory
Types/Stages
• Time scale of storage: – Sensory memory – Short term memory (STM), working memory – Long term memory (LTM)
• Types of memory (knowledge)
– Declarative/explicit
– Procedural/implicit
• Stages of memory
– Encoding
– Storage
– Retrieval
Time scale of storage
– Sensory memory
– Short term memory (STM),
working memory
– Long term memory (LTM)
Time Scale:
Sensory Memory
• Available for brief periods, overridden
– Visual: iconic (<200 ms)
– Auditory: echoic
(several seconds)
• High capacity
Sensory Memory:
Iconic Memory
Full/partial report technique.
• Sperling’s partial report
-‐ flashed very briefly
-‐ tones used to indicate line to report
-‐ performance much better than
expected from full report
-‐ evidence for brief, high-capacity iconic
memory
Short‐term Memory
vs
Long‐term Memory
• H.M. had intact short-term memory (STM) but impaired long-term memory (LTM)
• What’s the relationship/difference
between STM & LTM?
– Hypothesis I:
Info first in STM then transferred to
LTM
– Hypothesis II: STM and LTM are the “same” memory system; LTM simply places greater demands on the memory system.
– Hypothesis III:
STM and LTM are relatively
independent learning and memory systems
Patient KF
– 28 years old
– LH damage to cortical areas:
parieto-‐occipital
(motorbike accident age 17)
– Normal IQ
– Poor STM:
Digit span = 1-‐2 (controls 5-8)
– Normal LTM
HM and KF
Both had a double dissociation of STM/LTM
• What’s the relationship/difference between STM & LTM?
– LTM is not just a harder version of STM
Working Memory
active maintenance of information
– Limited capacity – Short-‐term – Information that can be acted on and processed (e.g., backward digit span test) – Maintenance and Manipulation
Types of Memory
knowledge
– Declarative/explicit
– Procedural/implicit
Stages of Memory
– Encoding
– Storage
– Retrieval
Baddeley-‐Hitch’s Working
Memory Model
– Central executive controls
2 subordinate systems:
• Phonological loop (acoustical)
• Visuospatial sketchpad (visual)
Are there multiple WM systems?
Are they independent?
Can you store both visual and auditory info simultaneously?
yes, independent systems
Evidence for multiple WM systems:
PET study
Verbal & spatial memory tasks
activate different brain networks.
Long-‐term Memory
• Declarative memory:
knowledge with conscious access (a question you can answer explicitly)
– Episodic memory:
events we recall about own lives
(“where did you live when you were 5 years old?”)
– Semantic memory: facts/world knowledge
(“who is the president?”)
• Non-‐declarative memory: knowledge with no conscious access (implicit) – Procedural memory: motor/cognitive skills – Perceptual priming – Conditioned learning
Declarative Memory
knowledge with conscious access (a question you can answer explicitly)
– Episodic memory: events we recall about own lives (“where did you live when you were 5 years old?”) – Semantic memory: facts/world knowledge (“who is the president?”)
Non-‐declarative memory
knowledge with no conscious access (implicit)
– Procedural memory:
motor/cognitive skills
– Perceptual priming
– Conditioned learning
Revisiting H.M.
Procedural
vs.
Declarative Memory
Mirror-‐drawing = procedural
– HM demonstrated clear learning/memory
– But no recollection of having seen task before
Non-‐declaratve Memory:
Procedural
Implicit learning without explicit awareness
- ‐ Performance improves for repeated sequences
- ‐ Most subjects don’t report noticing repetitions
Procedural memory / motor skill learning:
involves Basal Ganglia
Non-‐declarative Memory:
Priming
Priming:
The change in the response to a stimulus or in the ability to identify a stimulus as the result of prior exposure to that stimulus.
-‐ Explicit test:
which of these words did you see before:
animal or house?
(H.M. would fail)
-‐ Implicit test:
word fragment completion»
What word is this: A_I_A_?
(H.M. would show perceptual priming for previously seen words, like ANIMAL)
This is behavioral priming; can also see neural priming (smaller neural responses to a repeated stimulus).
Priming
The change in the response to a stimulus or in the ability to identify a stimulus as the result of prior exposure to that stimulus.
Classical Conditioning
Conditioned stimulus (CS) is paired with the unconditioned stimulus (US) to eventually give a response on its own
Stages of Memory
• Encoding: Processing of incoming information to be stored
– Acquisition (registering sensory inputs)
– Consolidation
(creating a stronger stored representation)
• Storage: Permanent record of the information
• Retrieval:
Utilizing stored information to recall conscious memory or execute learned behavior.
Encoding
Processing of incoming information to be stored.
– Acquisition (registering sensory inputs)
– Consolidation (creating a stronger stored representation)
Memory
Capacity
• What is typical memory capacity?
– “magic number 7”?
– ~4 “chunks”?
• Individual differences
(high‐capacity vs low-‐capacity)
• Eidetic/photographic memory
hmp://www.youtube.com/watch?v=A4ugfCjqlZ4
• Strategies for improving memory capacity
– Chunking
– Mnemonics
– Memory mapping:
hmp://artofmanliness.com/2011/09/30/how-‐to-‐
memorize-‐anything-‐you-‐want-‐a-‐quick-‐primer-‐on-‐mental-‐
mapping/
– hmp://www.youtube.com/watch?v=V8S8V9VEFyI
Strategies for improving memory capacity
– Chunking
– Mnemonics
– Memory mapping
False Memories
• Parallels between attention & memory:
– What we perceive is not necessarily what we see;
– What we remember is not necessarily what we saw
• Problem for eye-witness testimony
Why Do We Form False Memories?
• Failure in encoding:
– Insufficient memory separation
• Failure in retrieval:
– Low criteria for accepting a memory as veridical (truthful).
• “Forgotten” memories:
also failures of storage
– Decay or interference of representations
False Memories
fMRI studies show that the Hippocampus responds to false memories as if the where true
Remembering
and
Forgetting
“Remembering is not simply a process of passively activating stored information. Instead, people’s
expectations, metamemorial beliefs, even how they are instructed to examine their memory, influence the
kind and amount of information that is remembered.”
Dodson & Schacter, 2001
Memory
Disorders
- Amnesia
- Korsakoff’s
- Alzheimer’s
Amnesia
Amnesia = deficit in memory as a function of brain damage, disease, or psychological trauma
• Retrograde amnesia:
loss of previous knowledge from before event
• Anterograde amnesia:
inability to form new memories after event
Caused by damage to Bilateral Medial Temporal
lobe (MTL)
Which type of amnesia did H.M. have?
?
Retrograde
amnesia
loss of previous knowledge from before event
Korsakoff’s
• Amnesia associated with alcoholism
• Long term alcohol abuse»_space;> vitamin B deficiency
»> brain damage
• Degeneration of thalamus & mammillary bodies
• Anterograde & retrograde amnesia
Alzheimer’s
• Degenerative brain disorder
• Formation of plaques & tangles
– Tau concentrated in medial temporal lobe
• Progressive dementia – Short-‐term memory loss – Repetive behaviors/conversations – Difficulty remembering names – Difficulty performing familiar tasks – Misplacing items / putting items in inappropriate places – Difficulty remembering words – Disorientation, paranoia – Inability recognizing family/friends – Loss of basic functions, death
- Not same as “normal aging”
- Medication can slow, but not stop progression
- Preventative “treatment”: staying mentally active
Memory & Learning:
Where in the brain?
• Hippocampus/MTL
– Encoding & retrieval
– Consolida\on, ability to acquire long term memories
– NOT the ultimate storage site (which is located elsewhere in the neocortex)
• Information encoded in relevant parts of cortex
• Projected to parahippocampal regions
(perirhinal, parahippocampal, entorhinal)
- Projected to hippocampus; consolidated
- Fed back to original relevant cortical areas for storage/retrieval
Where is information encoded?
“Subsequent memory paradigm”
– Present list of items while measuring brain activity
– Afterwards,
test memory
for items
– Sort neural data as a function of whether items were later remembered or forgotten
– Hippocampus & MTL more active during successful encoding
Recollection vs familiarity task
– Do you actually remember seeing this item before, or does it just feel familiar?
• Scanned during retrieval phase
• Hippocampus is active during successful retrieval
(of full episodic memory)
Retrieval:
recollection
vs
familiarity
• Binding of items & contexts
– Perirhinal Cortex represents info about specific items (what, who)
– Parahippocampal represents info about context (where, when)
– Bound together in hippocampus
- Familiarity: Perirhinal is sufficient
- Full episodic memory: Need hippocampus
Where is information stored?
- Re-activation during long-term memory retrieval
- Learned sets of sounds & pictures
- Retrieval of pictures re-activated visual cortex (green)
- Retrieval of sounds reactivated auditory cortex (orange)
- Content of memories stored in content-specific regions
Perceptual Activation
Memory Test
Other
brain
areas
involved
• Frontal lobes
– Executive functions: Working memory
(lateral PFC, planning, goal monitoring, task switching)
– Encoding and Retrieval
• Parietal lobes
– Attentional processes, etc.
