CART Celebration May 2010

How Learning Changes the Physiology and Structure of

the Brain Ahmed M. Abdelal, Ph.D., CCC-SLPAssistant Professor of Communication

Sciences & DisordersDepartment of Special Education &

Communication Disordersaabdelal@bridgew.edu

Brain Function and Neuroal Transmission

Basic Brain LandmarksPresynaptic neuronsPostsynaptic neuronsSynaptic cleftNeural 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/implicitLearned 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 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 changesBirth 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 HippocampusAmygdalaMedial temporal lobe

PF cortex Association cortices

© A. Abdelal, Ph.D., CCC-SLP

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

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

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? 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)

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

Proteins C-Kinase Synapsin 1

Role of Hippocampus in Encoding

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

Occupies the first 20 minutes of learning

Newly born neurons immediately enter the memory pathways individually Enter Exit Re-enter and stay

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

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: 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

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 multiple-choice 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 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

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

Retrieval …

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 …

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.

Consolidation

Mostly occurs during sleep Facilitated by frequent

retrieval/rehearsal Starts one week after information

is delivered Lasts for up to 2 years

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

• 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 re-configure 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