Chapter 13: The Biology of Learning & Memory

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Look at the brain and memory, how the brain consolidates, stores, and retrieves memories as well as diseases of memory.

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Chapter 13: The Biology of Learning & Memory

  1. 1. The Biology of Learning & Memory
  2. 2. Localized Representations of Memory <ul><li>Classical Conditioning </li></ul><ul><li>UCS = UCR after repeated pairings of a CS </li></ul><ul><li>CS + UCS = CR </li></ul><ul><li>Operant Conditioning </li></ul><ul><li>Following a behavior with a reward increases the possibility of a repetition of that behavior </li></ul><ul><li>Punishment supresses the frequency of a response </li></ul>The ABCs of Operant Conditioning Anticedents Behavior Consequences
  3. 3. Localized Representations of Memory <ul><li>Engram </li></ul><ul><li>A physical representation of learning </li></ul><ul><li>There are 2 principles regarding the nervous system: </li></ul><ul><li>Equipotentiality – all parts of the cortex contribute equally to complex behaviors like learning </li></ul><ul><li>Any part of the cortex can substitute for any other </li></ul><ul><li>Mass Action – the cortex works as a whole </li></ul><ul><li>The more of the cortex that is involved, the better </li></ul><ul><li>The engram of memory is found in the cerebellum </li></ul><ul><li>Lateral interpositus nucleus is implicated in conditioned responses </li></ul>
  4. 4. Memory <ul><li>Short-term Memory </li></ul><ul><li>Working memory, present conscious memory </li></ul><ul><li>Memory of events that have just occurred </li></ul><ul><li>Long-term Memory </li></ul><ul><li>Memory of past events </li></ul><ul><li>Types of LTM: </li></ul><ul><li>Declarative (explicit) memory- the ability to state a memory in word; material deliberately committed to memory and data deliberately recognized as memory </li></ul><ul><li>Implicit (non-declarative) memory- material not deliberately committed to memory; recent experience on behavior not recognized as memory is being used </li></ul>LTM Explicit Memory Implicit Memory Episodic Memory Semantic Memory Procedural Memory Motor Skills Habits Simple Classically Conditioned Responses
  5. 5. Memory <ul><li>Working Memory </li></ul><ul><li>Temporary storage of memories about a task that is being attended to at the moment </li></ul><ul><li>3 components: </li></ul><ul><li>Phonologogical loop – the process which stores auditory information </li></ul><ul><li>Visuospatial sketchpad – stores visual information </li></ul><ul><li>Central executive – directs attention toward one stimulus or another & determines what information will be stored in working memory </li></ul>
  6. 6. Memory Loss <ul><li>Amnesia </li></ul><ul><li>2 types: </li></ul><ul><li>Retrograde amnesia – loss of memory for events that occurred shortly before brain damage </li></ul><ul><li>Anterograde amnesia – loss of long-term memories for events that happened after brain damage </li></ul><ul><li>Damage to the hippocampus results in elevated levels of adrenal hormones </li></ul><ul><li>It may be that memory impairment is due to increased levels of adrenal hormones </li></ul>
  7. 7. Memory Loss <ul><li>Korsakoff’s Syndrome </li></ul><ul><li>Caused by prolonged thiamine deficiency mainly due to chronic alcoholism </li></ul><ul><li>Thiamine deficiency leads to brain cell loss in the mamillary bodies of the hypothalamus projecting into the prefrontal cortex </li></ul><ul><li>Have both anterograde & retrograde amnesia </li></ul><ul><li>Have better implicit than explicit memory </li></ul><ul><li>Confabulation – making up an answer to a question & accepting it as being true is a common behavior pattern </li></ul>Normal Brain Alcoholic Brain
  8. 8. Memory Loss <ul><li>Alzheimer’s Disease </li></ul><ul><li>A dementia that becomes more prevalent with age </li></ul><ul><li>Symptoms: STM & LTM memory loss, confusion, restlessness, hallucinations, disturbances in sleeping & eating </li></ul><ul><li>Have better procedural than declarative memory; better implicit than explicit memory </li></ul><ul><li>Down’s syndrome patients get Alzheimer’s in middle age </li></ul><ul><li>Abnormal genes in several chromosomes lead to an accumulation of amyloid deposits in the brain causing neuronal degeneration & the dying axons & dendrites form plaques in many areas of the cerebral cortex & hippocampus, etc. </li></ul><ul><li>Tau protein accumulates & produces tangles from the dying cell bodies </li></ul>Normal Brain Alzheimer's Brain
  9. 9. Storing Information <ul><li>Hebbian Synapses </li></ul><ul><li>A synapse that increases in effectiveness because of simultaneous activity in the presynaptic & postsynaptic neurons </li></ul><ul><li>Habituation </li></ul><ul><li>A decrease in response to a stimulus repeatedly presented & accompanied by no change in other stimuli </li></ul><ul><li>Sensitization </li></ul><ul><li>An increase in response to a amild stimulus after an intense stimulus has been presented; a prolonged release of a neurotransmitter </li></ul>
  10. 10. Storing Information <ul><li>Long-term Potentiation </li></ul><ul><li>Increased responsiveness to axonal input as a result of repeated stimulation </li></ul><ul><li>3 properties make it the cellular basis for learning </li></ul><ul><li>Specificity – only activated synapses become strengthened </li></ul><ul><li>Cooperativity – nearly simultaneous stimulation by 2 or more axons produces LTP </li></ul><ul><li>Associativity – paring a weak input with a strong one enhances later responses to the weak input </li></ul>
  11. 11. Storing Information <ul><li>Long-term Depression </li></ul><ul><li>Prolonged decrease in responsiveness to synaptic input after repeated pairing with some previous input, generally of a low frequency </li></ul><ul><li>Occurs in the cerebellum & hippocampus </li></ul><ul><li>Almost all cases of LTP depend on NMDA & AMPA type glutamate receptors </li></ul><ul><li>Once LTP has been established, it no longer depends on NMDA synapses </li></ul><ul><li>LTP causes presynaptic changes through the release of a retrograde neurotransmitter from the postsynaptic cell </li></ul><ul><li>The relationship between LTP & learning is unknown </li></ul>

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