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Models of Memory
Introduction to Cognitive Science Lecture 7: Memory/Sleep September 29, 2009
Lecture Overview
• The Modal Model (Atkinson & Shiffrin)• ACT* Model (Anderson)• Working Memory Model (Baddeley)• Change Blindness• The Hippocampus• Sleep & Memory
MODELS OF MEMORY
RETRIEVAL
Short-term Memory
Long-term Memory
Sensory Memory
STIMULUS INPUT
The Modal Model (Atkinson & Shiffrin)
Figure 5.3, p 134 in text
RESPONSE OUTPUT
ENCODING
e.g. Visual (iconic)Auditory (echoic), etc.
Some Control Processes: Rehearsal, Coding, Decisions, Retrieval Strategies
ACT* Model: Adaptive Control of Thought (Anderson)
Working Memory
DeclarativeMemory
Production Memory
External Environment
Encoding Performance
Storage Match
ExecutionRetrieval
Figure 5.4, p 136 in text
The Working Memory Model (Baddeley)
Visuo-spatial Sketchpad
Processing of Visual Information
Executive Control System
Supervises and controls processes
Articulatory Loop
Rehearsal and processing of auditory information
Figure 5.5, p 138 in text
Occurs when major changes to a visual scene go unnoticed by the observer.
TESTING THE CAPACITY OF VISUAL WORKING MEMORY:
CHANGE BLINDNESS
Pay Attention….
Change Blindness
Differences between the two images can be detected only if we attend to one of the changing objects.This experiment demonstrates that we memorize only very little information from visual scenes.We typically use visual scenes as our “external memory” rather than filling our working memory with a large amount of scene information.
The Hippocampus
Long-Term Memory LearningNavigation
THE HIPPOCAMPUS =Dentate Gyrus, CA1-CA3, & Subiculum
Marjor input from Entorhinal Cortex which is other brain areas such as the Prefrontal Cortex
Information Flow:Entorhinal Cortex Dentate Gyrus CA3CA1 Subiculum
Neurogenesis: birth of new neurons
Highly active throughout development
Also adult hippocampal neurogenesis (dentate gyrus)!
What might this mean for learning and memory?
Hippocampal Damage
• Retrograde Amnesia: loss of memories before damage to the hippocampus
• Anterograde Amnesia: inability to form new memories
• Some causes: aging, Alzheimer’s disease, stress, temporal lobe epilepsy
Patient H.M.Patient H.M.
http://images.google.com/imgres?imgurl=http://dspace.mit.edu/bitstream/handle/1721.1/45580/9-10Spring-2004/NR/rdonlyres/Brain-and-Cognitive-Sciences/9-10Spring-2004/8AFEA93F-9C52-42E5-B967-211CCD2AA287/0/chp_9_10_hip_enc.jpg&imgrefurl=http://dspace.mit.edu/bitstream/handle/1721.1/45580/9-10Spring-2004/OcwWeb/Brain-and-Cognitive-Sciences/9-10Spring-2004/CourseHome/index.htm&usg=__baapQ1i44dpgT7ZDQuuBuOVnwnw=&h=307&w=350&sz=26&hl=en&start=2&um=1&tbnid=n5pajUYXebb7tM:&tbnh=105&tbnw=120&prev=/images%3Fq%3Dcoronal%2Bhippocampal%2Bhuman%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DG%26um%3D1
Anterograde Amnesia:Intact working and procedural memoryCould not commit to long-term
SOME Retrograde Amnesia:Couldn’t remember 3–4 -day prior to surgery, + some events up > 11 years prior
Able to commit new motor skills to long-term memory without actually remembering learning them
After Surgery for Temporal Lobe Epilepsy
Sleep & Memory Consolidation
• Born & Marshall The contribution of sleep to hippocampus-dependent memory consolidation
• MP Walker• Stickgold
Matthew P. Walker* and Robert Stickgold* Sleep-Dependent Learningand Memory Consolidation Neuron, Vol. 44, 121–133, Sept 30, 2004
Relaxed Wakefulness
NREM Stage 1
NREM Stage 2
NREM Stage 3, 4/Slow Wave SleepDelta Waves
REM
Sleep Can Be Divided Into:
•NREM (Stages 1-4)
•REM
Different stages are identified using EEG
SLEEP: Overview
NREM & REM cycle about every 90 minutes
Early in the night: NREM 3 & 4 dominate
Later in the night: Stage 2 and REM dominate
Neurobiology of Sleep Regulation
Many subcortical regions are involved:•Thalamus•Hypothalamus•Pons
Dreaming also involves:•Cortical: Prefrontal and Posterior (vision)•Subcortical: limbic (emotion)
Some key neurotransmitters:•Serotonin (5-HT) •Noradrenaline (NA)•Acetylcholine (Ach)
3, 679-693 (September 2002) Hobson & Pace-Schott
Influence of sleep on a motor skill task (A-C) and a visual skill task (D-F)
(A)Motor performance increase after sleep
(B) Such performance increase is not strengthened during subsequent wake phase
(C) Performance improve is strongly correlated with amount of stage 2 NREM sleep.
(D) Increased level of visual performance after one night of sleep.
(E) Performance iprovement with regular sleep periods (red) and no improvement after sleep deprivation during first night after training (green).
(F) Improvement is correlated with amount of slow-wave sleep and REM sleep.
Replay of hippocampal firing during sleep
Rodent Running path
Hippocampal cells and location-specific firing during running
Timecourse of firing patterns of 10 cells (rows) during running
Timecourse of firing patterns of 10 cells (rows) during REM
Louie & Wilson. Temporally Structured Replay of Awake Hippocampal Ensemble Activity during Rapid Eye Movement Sleep . Volume 29, Issue 1, January 2001, Pages 145-156