Physiology of Learning

dr. Legiran, M.KesS1 FK Unsri PalembangS2 Anatomi PPs UGM YogyakartaPengajar Anatomi ManusiaKetua Bagian Anatomi FK UnsriKomisi III Unit Pengembangan dan Evaluasi Pendidikan (UPEP)

WHAT DO YOU THINK?Can your brain grow new cells?Does what you eat and drink affect your brain?Do colors influence emotion?Can knowledge of brain- based learning positively influence learning?How are you already using brain based approaches to learning in your lessons?

How is your brain like(?)A cabbageA raisinA pillowcaseA grapefruitString cheeseA walnut

Our BrainsAre like a jungle- nothing runs the jungleAll parts of the brain participate with each other, while each has its own functionThere is natural pruning or neural pruning that occurs when parts are not used (this may be why sounds not heard or used atrophy over time) LEARNING IS A DELICATE, BUT IS A POWERFUL DIALOGUE BETWEEN GENETICS AND THE ENVIRONMENT Robert Sylwester, A Celebration of Neurons

Brains ComplexityCellular level - three pints of liquid, three pounds of mass, tens of billions of nerve cells (or neurons), ten times more numerous glial cells that support, insulate and nourish the neuronsBrain cells - 30 thousand neurons (300,000 glial cells) fit into the space of a pinhead.

Parts of the BrainBrainstem (survival )Cerebellum ( autonomic nervous system)Limbic system (emotion)Cortex ( reason/logic)

BrainstemCerebellumCortex

Frontal lobe - CortexCreativity- Judgment- Optimism - ContextPlanning- Problem solving- Pattern makingUpper temporal lobe - Wernickes AreaComprehension - Relevancy - Link to past (experience) - Hearing - Memory - MeaningLower frontal lobe - Cortex Speaking/language - Brocas areaOccipital lobe - Spatial orderVisual processing - Patterns - DiscoveryParietal lobeMotor - Primary Sensory Area - Insights - Language functionsCerebellumMotor/motion- Novelty learning - cognition - balance - posture

BrocasareaParsopercularisMotor cortexSomatosensory cortexSensory associativecortexPrimaryAuditory cortexWernickesareaVisual associativecortexVisualcortexLanguage and ThoughtGrammar and word productionMovement and joint positionsCerebellum

NeuronsConnect to other neurons, to muscles, or glandsSend and receive chemical information (messages) for behaviorsCan be a millimeter in length or as long as a meterCells nucleus contains DNA (As long a meter)

Neurons contain tubular extensions that are designed to communicate quickly with specific cells in the body network - this is a transportation system, much like a phone system.

The brain has both nerve cells and glial cells. The neurons are cellular agents of cognition; the glial cells act as a scaffolding or insulation for impulses. (The insulation increases the speed of the neural (electrical) messages.)

MemoryPlace to store information, as in: How much memory does your hard drive have?

Information that gets stored, as in: I have fond memories of my summer vacation.

retention of learned information

Learning: acquisition of knowledge/information

MemoryThompsonmany structures involved in memory formation; memory depends on many mechanisms;classical conditioning of eyelid responses in rabbit response occurs in cerebellum - lateral interpositus nucleus (LIP)

The Modal Model of Human Memory

Memory stores

Processes

Four Theories of Forgetting from Long-Term Memory

Four Theories of Forgetting (contd)

Types of LTM

Memory and learning Types of memory:declarative facts and eventsconscious recollectioneasy come easy goprocedural learning to play an instrument, to ride a bike; no conscious recollection (usually); need repetition or training; longer retention

Memory and learningSubtypes of declarative memory:short-term memorytemporary, limited capacity, needs rehearsal (e.g. telephone number)long-term memory'permanent'greater capacity no continual rehearsal needed

Theories of memory storage Engram Engram was a hypothetical structure or feature inside of the neuron that stored information Grandmother cell the neuron that fired when you see your grandmother In computers, information (memories) stored in cells or slots of hard drive But this is not how the nervous system stores information!

Theories of memory storage Long-Term Potentiation (LTP) Recent research indicates that memories are stored in the synapses between neurons Learning involves formation and modification of synapses Neurons that fire together wire together LTP takes days to complete learning spaced over several days more effective at inducing LTP than learning crammed into short period of timeMost research on LTP done on sea slug Aplysia

Memory and learning Plasticity paradigms:Associative mechanisms:classical conditioning pairing of 2 stimuli changes the response to one of them (Pavlov)conditioned stimulus (CS) - originally neutral (no response)unconditioned stimulus (UCS) - automatically evokes response unconditioned response (UCR) after repetitive pairing of CS and UCS presentation of CS evokes learned response - conditioned response (CR)operant conditioning - reinforcement and punishment

Memory and learningNonassociative mechanisms:habituation decrease in response to a repeated stimulus not accompanied by changes in other stimuli sensitisation an increase in response to a moderate stimuli as a result of a previous exposure to a strong stimulus

Memory and learningmemory consolidation - storing knowledge in the long-term memoryHebb - reverberating circuit - prolonged excitation leads to chemical or structural changesMemory of meaningful or emotional facts enhanced involvement of amygdala (stimulation of hippocampus and cortex)damage to amygdala impairs emotional enhancement of memories

Memory and learningworking memory - modification of the concept of short term memory memory consolidation may take place with or without use of the short-term memorya phonological loop a visuo-spatial sketchpad the central executive - directs attention towards stimuli; determines what will be stored in the working memoryworking memory test - delayed response task - higher activity in the prefrontal cortex during the delay

Physiology of Memory Types of amnesia Retrograde amnesia Loss of memories already formed due to brain damageBut can still form new LTMs Example: Patient has stroke and no longer recognizes family members. Common symptom of Alzheimers disease

Physiology of Memory Types of amnesia Anterograde amnesia Loss of ability to form new long-term memoriesPreviously stored memories may still be intactKorsakoffs syndrome You meet patient, tell him your name, he can repeat it You leave room, come back 2 minutes later, he doesnt know who you are.

Hippocampus Thought to play a role in encoding information from STM to LTM Case of H.M. Both hippocampi removed to control severe epilepsyNo problems with short-term memory Lost ability to form new long-term memories (anterograde amnesia) LTM intact for events until shortly before surgerySymptoms similar to Korsakoffs syndrome, but different area of brain affected

Memory and learningHippocampus H. M. - removal of hippocampus:Retrograde amnesia (loss of memory for events occurring shortly before brain damage)intact short-term/working memoryacute anterograde amnesia (declarative memory) (loss of memory for events happening after the brain damage)intact procedural memorybetter implicit than explicit memory

Memory and learningTheories of the hippocampal function:declarative, explicit memorysupported by the H.M. casehippocampal damage may impair implicit memoryit does not damage all the memory in nonhumans in tasks similar those requiring declarative memory from humansdependence on the experimental protocol in delayed matching-to-sample and delayed nonmatching-to-sample task experiments

Memory and learningspatial memoryrat maze experimentshippocampus is involved also in nonspatial aspects of the tasksconfigural learning the meaning of the stimulus depends on what other stimuli are paired with it, e.g. A + food; B + food; AB + no foodhippocampus is involved in nonconfigural learning if its sufficiently difficultbinding memoriesinput from many parts of cortex (secondary and tertiary areas)

Memory and learningBrain damage and memory Korsakoff's syndrome brain damage due to prolonged deficiency in thiamine (B1). Thiamine deficiency loss of neurons in dorsomedial thalamus damage to prefrontal cortexapathy, confusion, retrograde and anterograde amnesia;better implicit memory (good at priming tasks);impaired reasoning about own memories; confabulation;

Memory and learningAlzheimer's disease forgetfulness, proceeding into serious memory loss confusion, depression, restlessnesshallucinations sleeplessness, loss of appetiteimpaired procedural memory, explicit memory, attention.Genetic involvement; excessive accumulation of beta-amyloid plaques atrophy of cerebral cortex (esp. entorhinal), hippocampusformation of neurofibrillary tangles

Memory and learningPhysiology of learning and memory Hebbian learning a cell A that successfully stimulated cell B in the past becomes more successful in the stimulation of B in the futureHebbian learning and classical conditioningSingle cell mechanisms of invertebrate plasticityAplysia

Memory and learninghabituation depends on a change in synapse between the sensory and motor neuron

Memory and learningSensitisationstrong skin stimulationexcitation of facilitating interneuron serotonine release on presynaptic terminals of sensory neurons metabotropic effectsprolonged action potentiallonger opening of voltage-gated calcium channelsgreater transmitter release per action potential

Memory and learningassociative learningsimilar to the sensitisation pairing the CS (conditioned stimulus) and UCS (unconditioned stimulus) increases presence of calcium in the presynaptic terminal (due to CS) Intensified metabotropic effectsMore transmitter released than in sensitisation

Memory and learningPhysiology of vertebrate plasticitylong term potentiation (LTP) a response enhancement at certain synapses due to rapid intensive stimulus delivered simultaneously to a neuron by several axonsunderlying mechanisms vary between the brain areasprominent in hippocampusattractive as a cellular basis of learning and memory:Specificity only the active synapses become strengthenedCooperativity simultaneous (almost) stimulation produces LTPAssociativity LTP is hebbian (no need for action potential depolarisation sufficient)

Memory and learning Biochemistry of LTP main actors:Glutamate receptorsAMPA opens sodium channelsNMDA allows sodium and calcium ions to enter the neuronresponds to glutamate ONLY when the membrane is partly depolarisedremoval of magnesium ions blocking NMDA receptors glutamate excitation of NMDA receptors opens NMDA-dependent calcium channels

Memory and learninglarge influx of calcium activates protein kinases: protein kinase C (PKC) CaMKII (calcium calmodulin-dependent protein kinase) alteration the structure (phosphorylation) of AMPA receptorsconversion of some NMDA receptors into AMPA receptorscreation of more AMPA receptorsincreased dendritic branch growth increased dendritic responsiveness to subsequent incoming of glutamate

Memory and learningLong term depression (LTD) a prolonged decrease in response to synaptic input repeatedly paired to another input at a low frequencyLTP (LTD) may be involved in memory formation - recently questioned

Memory and learningPotential problems with LTP/LTD as correlates of memory formation:Importance of protein phosphorylation Protein phosphorylation is not permanentprotein molecules are not permanent (app. 2 weeks lifetime)

Memory and learning Alternative mechanisms: continual phosphorylation of proteinsmain suspect: persistently active protein kinases (PKC) large elevation of calcium activates calpain (enzyme)breaking the peptide bond between regulatory and catalytic parts of PKC freeing the catalytic region (remains active) leading to continual proteins phosphorylationproblem with PKC solution limited time (minutes to hours but Bruces work)

Memory and learningprotein synthesisevidence from experiments with protein synthesis inhibitors animals injected with these inhibitors learn normally but fail to recall during later testingstructural changeschange in the number of synapsesmorphological reorganisation

Techniques to Help MemoryDefine the gist - OVERVIEWSequence eventsPlot out pictorially the informationTell the information to others in own words - TALKPeer teaching/tutoringAmplify by giving examplesUse multiple parts of the brain (emotional, factual, physical)Auditory, Visual, Kinesthetic, TalkCombineUse color effectivelyYellow and orange as attention-getters

The Brain is a Social Brain12 The brain develops better in concert with others When students have to talk to others about information, they retain the information longer and more efficiently! Make use of small groups, discussions, teams, pairings, and question and answer situations.

A cabbage - weight, stemA raisin -convolutions (membrane)A pillowcase - size - unfoldedA grapefruit - skin, thickness of cortex; high % of waterString cheese - corpus colosum - bundle of axons, fibersA walnut - two sides, skull covering; lobes534