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CHAPTER 12

CHAPTER 12. Learning and Memory Learning as the Storage of Memories Brain Changes in Learning Learning deficiencies and Disorders. Start with case study: The Case of H.M. At the age of 7, HM was knocked down by a bicycle unconscious for five minutes. Three years later: minor seizures

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CHAPTER 12

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  1. CHAPTER 12 Learning and Memory Learning as the Storage of Memories Brain Changes in Learning Learning deficiencies and Disorders

  2. Start with case study:The Case of H.M. • At the age of 7, • HM was knocked down by a bicycle • unconscious for five minutes. • Three years later: minor seizures • First major seizure occurred on his 16th birthday. • As he got older: increased intensity/frequency of seizures • averaged 10 small seizures a day • one major seizure per week. • When he was 27: surgeon did bilateral removal of temporal lobes where the seizure activity was originating. • Familiar story of severe seizure disorders, except for the bilateral removal of temporal lobes- this was exceptional

  3. Why is H.M. interesting? • HM’s intelligence was not impaired by the operation. • His IQ test performance even went up, • Why? probably because post surgery was no interference from seizures. • Although H.M. could recall past events, couldn’t learn new things: • can recall personal and public events and remember songs from his earlier life, • difficulty learning and retaining new information. • Only hold new information in memory for a short while • , if distracted loses memory • Memory dissipates within few minutes • Almost COMPLETE loss of STM

  4. Types of amnesia • Anterogradeamnesia • an impairment in forming new memories • HM’s symptoms one of first documented cases • Retrograde amnesia • inability to remember events prior to impairment • Also found with HM’ • the surgery also caused considerable retrograde amnesia • Typically: etiology of amnesia unknown • H.M. unique because definitive cause of amnesia • Rare chance to look at how brain forms memories

  5. Hippocampal formation and memory • Hippocampal formation: • HM’s surgery damaged or destroyed the hippocampal formation • Structures near by along with hippocampus form this formation, nearby structures • Amygdala also important in this circuit (remember emotions!) • The hippocampus consists of several substructures • Each has different functions. • Among most important: CA1 • CA1: provides the primary output from the hippocampus to other brain areas. • Damage in that part of both hippocampi results = moderate anterograde amnesia • only minimal retrograde amnesia. • If the damage includes the rest of the hippocampus, anterograde amnesia is severe.

  6. Learning as consolidation • Consolidation • process by which brain forms a more or less permanent physical representation of a memory. • Memory is formed via consolidation • We will explain this later (LTP processes) • Retrieval = process of accessing stored memories. • Hippocampal formation plays a lead role in consolidation, • damage to that area accounts for difficulty learning new material • No consolidation, no memory!

  7. Three stages of memory • Formation of memory • Remember, “memory” is a process, not a “thing • Takes time to form permanent memory • Cognitive psychologists: 3 stages of memory • Sensory register memory: recognizing info as important • Short term memory: • Is short in duration- no more than 20 sec typically • Has limited capacity: 7+/-2 • Must engage in active effort to transfer to long term memory • Long Term memory: • Unlimited duration • Unlimited capacity • Why forgetting? Interference or tissue loss

  8. Storage of Memories in brain • STM: hippocampus stores information temporarily in the hippocampal formation. • LTM: Over time, a more permanent memory is consolidated elsewhere in the brain. • Memories are not stored in a single area • But: memory also NOT distributed throughout the brain. • different memories are located in different cortical areas • Tend to be located according to where the information they are based on was processed.

  9. Types of memory • Declarative memory • involves memories of facts, people, and events, which a person can verbalize, or declare. • variety of declarative memory subtypes: • episodic memory (events) • factual memory • autobiographical memory • spatial memory (the location of the individual and of objects in space). • Nondeclarative memory involves memories for behaviors. • Memories for procedural or skills learning: motor memory • emotional learning • stimulus-response conditioning.

  10. Declarative vs. nondeclarative memory • Why distinguish? • have different origins in the brain. • Represent very different behaviors/functions • How know which area processes which type of memory? • Animal tests: can conduct lesions • Testing rats in the radial arm maze • Determine which brain areas were involved in learning tasks corresponding to non-declarative and declarative learning • Damage particular brain areas • Test/retest rats and examine change in performance.

  11. Declarative vs. nondeclarative memory • Research Evidence supports importance of hippocampus • Rats with damage to both hippocampi could learn the simple conditioning task of going to any lighted arm for food. • When every arm was baited with food: • Rats would skip over “new” arms • repeatedly returned to arms where the food had already been eaten. • Rats with damage to the striatum • could remember which arms they had visited • could not learn to enter lighted arms.

  12. Role of amygdala inStorage of Memories • Amygdala = significant role in nondeclarativeemotional learning. • Nonverbal learning • Procedural, spatial, visual • Particularly emotional learning • But also involved in some procedural (motor) learning • Amygdala strengthens declarative memories about emotional events: • increases activity in the hippocampus. • If electrically stimulate amygdala: activates the hippocampus, • enhances learning of a non-emotional task, such as a choice maze.

  13. STM or working memory • Remember: Working memory: temporary “register” for information while it is being used. • Working memory: • phone number you just looked up • Phone number you recall from memory while you dial the number. • holds information retrieved from long-term memory while it is integrated with other information • Or used in problem solving and decision making. • Is short in duration and capacity! • Like your working memory for files in computer • If you don’t save, it is gone

  14. Working memory = prefrontal function • Prefrontal area = working memory’s central executive. • manages behavioral strategies and decision making; • coordinates activity in brain areas involved in perceptual and response functions in a task; and • directs the neural traffic in working memory. • Damage to prefrontal area • Increased impulsivity • Lack of control for emotions • Poor short term memory

  15. TBI: Traumatic Brain injury and Memory • TBI is leading cause of death and disability in young adults • 200-300/100,000 young adults admitted to hospital with TBI each year • Most are males • Mortality peaks from 15-24 years of age • Risk peaks between 15 and 30 • 70% result of motor vehicle accident

  16. TBI: Traumatic Brain injury and Memory • Memory deficits = most marked sequels in TBI • Often persist beyond period of immediate recovery • Most frequent site of injury: temporal and basal-frontal regions of cortex • Areas highly associated with memory • Memory deficits occur in 69-80% of individuals with TBI • 36% show severe deficits • 73% of those with severe TBI show long term deficits • Predictors: degree of severity (marked by duration of loss of consciousness) and duration of amnesia

  17. TBI: Traumatic Brain injury and Memory • Memory involves 4 sequential, interrelated processes: • Paying attention • Encoding • Storage • Retrieval • Memory impairment in TBI may involve some or all of these processes • 25% of TBI patients show difficulty with encoding or storage • Often lasts for months or years • Milder cases show disruption in attention, retrieval or combo of both • Difficulty with new learning, retrieval of new information

  18. Impact on daily life • Memory deficits • Impair daily functioning • Prevent return to work/school • Impact ability to engage in daily living skills (bathing, eating, carrying out daily chores) • Depression often co-existing condition • May be biologically related • May be result of awareness of disability and loss

  19. Compensation stratgegies • Must compensate or bypass memory problems and use residual skills more effectively • Memory compensatory strategies include • Use of mnemonics and memory aids • Cognitive training and memory building • Self-awareness of limitations and feedback • Memory groups • External memory aids: • Alarms for taking medication • Electronic memory aids • Neuropage alphanumeric paging system: • Important events entered into computer • Phone system pages the individual with reminder • Issue of ecological validity: is this “normal”

  20. Compensation strategies • Memory Aiding Prompting System (MAPS) • Lifelink system for PDA • Context-aware prompting system • Can create detailed scripts that prompt individual through a sequence • Are adaptable to individual • Give info back to caregiver • Thus can be used for “training” and developing independence • But can TBI patients use technology? • Yes! If have access to technology • Some special adaptations • Need spoken messages rather than relying on reading • Needs to be adaptable • Needs to be portable- go with the patient • Cell phones more likely used in conjunction with personal computer • Given increasing number of TBI cases, it is important to understanding etiology and treatment of closed head injury

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