Transcript CART Presentation

CART Celebration May 2010
How Learning Changes the Physiology
and Structure of the Brain
Ahmed M. Abdelal, Ph.D., CCC-SLP
Assistant Professor of Communication Sciences & Disorders
Department of Special Education & Communication Disorders
[email protected]
Brain Function and Neuroal Transmission
 Basic
Brain Landmarks
 Presynaptic neurons
 Postsynaptic neurons
 Synaptic cleft
 Neural transmission
http://www.youtube.com/watch?v=4cDbY7Jf31I
DISTINCTION
BETWEEN
MEMORY & LEARNING
Memory
Memory refers to “A number of
different brain functions. The
common feature of these functions is
the re-creation of past experiences by
the synchronous firing of neurons
that were involved in the original
experience.”
(Carter, et al 2009, 154)
Our Memories Are Always Subjective
“Our memories are
personal and evocative,
intertwined with emotion,
and they provide us with a
sense of who we are.”
(Squire & Kandel 2010, 75)
Learning
“Learning is the process in which neurons that
fire together to produce a particular experience
are altered so that they have a tendency to fire
together again. The subsequent combined
firing of the neurons reconstructs the original
experience, producing a ‘recollection’ of it. The
act of recollecting makes the neurons involved
even more likely to fire again in the future.”
(Carter, et al 2009, 154)
Relationship Between Learning & Memory
Leaning is “the process by
which we acquire knowledge
about the world, while memory
is the process by which that
knowledge is encoded, stored,
and later retrieved”
(Kandel, Schwartz, & Jessell, 2000, p. 1227)
Types of Memory: Type of Experience
 Procedural/implicit
 Learned
actions (routines & procedures)
 Declarative/explicit
 Episodic
 Sensations
& emotions (personal)
 Semantic
 Factual,
non-personal information
Types of Memory Based on Duration

Immediate memory
Capacity of 7 items
 Only 30 seconds, if info not rehearsed

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Working Memory (WM)
Phonological loop (verbal info)
 Visuospatial sketch pad (faces, images, spatial layouts)

WM sustains info for 0.5 sec. to 10 min.
 Long-term memory

Neural Plasticity
“The ability of the nervous
system to form new synaptic
connections and reconfigure
old connections in response to
experience or injury”
(Byrnes 2001, p. 192)
Neural Plasticity …
Means that brain wiring is not constant
 Includes any type of brain changes
 Occurs throughout the lifespan
 Makes new learning possible
 Makes it possible to eliminate undesired
behavior
 Makes it possible to unlearn and forget

How Learning Changes Brain Structure
 Any
type of learning must result in
physical changes in brain structure:
 Cellular
changes
 Birth of new neurons (Neurogenesis)
 Expansion of existing networks
 Creation of new circuits
How Learning Changes Brain Structure

Cellular changes in the existing neurons:
Strengthening existing synaptic connections
 Growth of new synaptic branches and production
of neurotransmitter components in presynaptic
neurons
 Translation and transcription of specific genes
 Production of new receptor proteins and inserting
them along the membrane of the postsynaptic
neuron

Primary Centers of Learning
 Hippocampus
 Amygdala
 Medial
temporal
lobe
 PF cortex
 Association
cortices
© A. Abdelal, Ph.D.,
Hippocampus &
Amygdala
Phases of Learning
For information to be retained in LT
memory, it has to be processed in phases
 Each phase involves specific neural
pathways, and structural modifications

Perception
 Pre-encoding
 Encoding
 Transfer
 Imprinting
 Storage
 Retrieval
 Consolidation

Setting the Stage for Learning
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Motivation and emotional response direct
our attention
Information cannot enter into the memory
system unless it is attended to
Attend to a piece of info for about 0.2 sec.
Attention intensifies the experience by
triggering neurons to fire more frequently

The more a neuron fires the stronger its
connections are with other neurons
Preparatory Phase: Pre-encoding Mechanism
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There are specific areas “pre-prepared to store
new information, even before the stimuli are
collected and coded”
If these areas are activated in time for
encoding, encoding & recall will efficient
This pre-encoding circuit is activated by:
Good self-esteem
 Strong motivation
 Positive attitude

(Atlas of Human Physiology, 2009, 166-167)
Working Memory & Executive Functions

Executive functions: location?

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Develop, pursue & focus on goals; sustain
attention, allocate attentional resources, monitor
our own work toward the goal; regulate our
behavior, etc.
Behavioral inhibition suppresses distractions
Working Memory: PFC Sensory center


Holds material to guide on-going behavior and cognition
Info gets shuttled back and forth from frontal cortex to
the sensory cortex that initially registered it.
Encoding

The process by
which new
information is
attended to and
processed when it is
first encountered
(Kandel et al., 2000)
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Mediated by the
hippocampus & PFC
New info reaching the
hippocampus induces
activation of pathways
to previous info
What Happens During Encoding
 Activation
of previous information
 Evaluation of the new information
 Analysis
 Organization
 Integration
 Reassembling and synthesis
Encoding Mechanisms

Neurotransmitters
Noreadrenaline/Norepinephrine
 Acetylcholine
 Serotonin
 Dopamine

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Proteins
C-Kinase
 Synapsin 1

Role of Hippocampus in Encoding
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LT Potentiation
Site for incoming
information
Directly connected with
emotional processing &
long-term storage sites
Determines what info to
be selected for LT
storage
Assembly site for info
being retrieved
Neurogenesis During Encoding

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Occupies the first 20 minutes of learning
Newly born neurons immediately enter the
memory pathways individually
Enter
 Exit
 Re-enter and stay
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They appear to imprint the new information
and integrate it with previous information
They mediate forgetfulness of irrelevant
information
Efficiency of Encoding
 Encoding
determines the efficiency
of retrieval.
 Efficiency
of retrieval depends on the
cues & strategies used while the info
is being encoded, rather than the
strategies used during the retrieval
process.
What Determines Efficiency of Encoding
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Emotional content of the info: happy vs sad
Motivation & level of interest cause deep
encoding and subconscious rehearsal
Effort learner puts into practicing recall of info
Novelty
(Carter et al, 2009, 154)
Extent to which the info is:
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Organized
Related to previous knowledge
Rehearsed after it has been presented
(Squire & Kandel 2009, 74)
Efficiency of Encoding: Elaborative Encoding
 Elaborative/deep
encoding is better
than shallow/superficial encoding
 Breaking
down info
 Discussing the meaning of each part
 Relating the info to previous knowledge
 Asking questions in the process
 Example
Implications for Teaching
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Testing promotes “better long-term retention
than restudying” (Squire & Kandel 2009, 77).
Students perform better when they know test
format ahead of time.
Focusing on concepts is best for essay tests
Focusing on details is best study for multiplechoice tests
Visual presentation is extremely powerful:
“Nearly half of the cortex is dedicated to processing visual information” (Squire & Kandel
2009, 77)
Transfer
Starts within about 20 minutes
 The medial prefrontal cortex directs the
information through a monodirectional
pathway: hippocampus  entorhinal
cortex  perirhinal cortex
 Neurotransmitters
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Serotonin, Norepinephrine, Acetylcholine, oxitocin
Imprinting and Storage

Storage: “The mechanisms and sites by
which memory is retained over time”
(Kandel et al., 2000)
Initiated around one hour post learning
 Imprinting is the initial step in the storage
process
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Imprinting starts one hour after learning,
and lasts 25 hours

Mediated by special neurons called Imprinting
Stimulus Neurons (IS neurons)
Retrieval

The process of recalling stored
information through reactivating the
pattern or pathways in which the
information was originally stored.
(Nelson, 2005)

Retrieval is a reconstructive process that
involves pulling pieces of info from
various storage sites and integrating
them into a coherent whole.
Retrieval …
Either involuntary or intentional
 Intentional retrieval is required for
adequate academic performance and
similar goal-directed behavior.
 Requires:

 Executive
functioning & WM
 Attentional resources
 Strategic memory searching
Retrieval …
Involves gene expression and protein
synthesis and insertion along pathways
 Any interruption of these cellular
processes (e.g., stress, alcohol, etc.)
prevents the formation of long-term
memories
 Info becomes temporarily unstable &
vulnerable to distortion
 Followed by re-writing of the new info.

Retrieval …
Reactivation of a verbal pathway takes
about one second
 Reactivation of a visual pathway takes 0.5
second
 Complex information may require several
minutes
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Retrieval …
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The more frequently the information is
retrieved, the stronger the pathway, and the
faster the activation
Information not retrieved for an extended
period of time might take longer to reactivate
or might be forgotten
Context & Strength of cues are related to
strength of retrieval

Retrieval is best when in same context and in
presence of initial cues used during encoding
Retrieval …
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Previous knowledge promotes efficient recall
of new information
Experts have superior abilities in
remembering info related to there area of
expertise, but “have no special gift for
recalling details that are not meaningful to
their area of expertise”
Memory exercises do not improve retrieval
(Squire & Kandel 2009, 77-78)
Consolidation
The process by which information
becomes stable and more resistant to
interference, or the enhancement of
the information through off-line
processing between training sessions.
(Robertson et
al., 2004; Walker 2005)
Consolidation
Long-lasting, dynamic process
 Involves integration of procedural and
declarative knowledge
 Requires gene expression and protein
synthesis
 Involves interactions among numerous
brain systems to organize, update, or
strengthen existing memories.
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Consolidation
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Mostly occurs during sleep
Facilitated by frequent retrieval/rehearsal
Starts one week after information is delivered
Lasts for up to 2 years
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The long duration provides time for cerebral
cortex to perform the required modifications
Newly consolidated information is flexible
and modified frequently
Consolidation of Learning
Mediated by
pathways
involving
 Medial temporal
lobe
 Hippocampus
 PFC
 Sensory centers
Conclusion
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Learning is a life-long, dynamic process
Any type of learning produces physical & structural
changes in the brain
Learning is encoded and stored in stages and requires time
The lengthy consolidation allows the brain time to reconfigure itself in response to the new information
Mood & Motivational states play a major role in determining
the efficiency of encoding and retrieval of new learning