neuropsychology of memory

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Neuropsychology of Memory. Types of memory problems a pure amnesia is relatively rare memory problems commonly occur after a traumatic brain injury (TBI) TBI results in brain damage of two sorts: lesions - PowerPoint PPT Presentation

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  • Neuropsychology of MemoryTypes of memory problemsa pure amnesia is relatively rarememory problems commonly occur after a traumatic brain injury (TBI)TBI results in brain damage of two sorts: lesionstwisting and shearing of brain structures and damage from bony protuberances of brain, particularly of the temporal lobes

  • Neuropsychology of MemoryMemory problems following TBIpost-traumatic amnesiaretrograde amnesiaanterograde amnesia

  • Neuropsychology of MemoryMemory problems following TBIpost-traumatic amnesiaafter severe TBI, individuals typically lose consciousnessafter they begin to regain consciousness, there is often a gradual recovery during which patients have difficulty keeping tracking of and remembering ongoing events, though there may be islands of lucidity and memory

  • Neuropsychology of MemoryMemory problems following TBIretrograde amnesiarefers to difficulty remembering events that occurred prior to injurythe duration of amnesia varies but can extend back for several yearsduration of retrograde amnesia typically shrinks as time passes

  • Neuropsychology of Memoryretrograde amnesiaduration of retrograde amnesia typically shrinks as time passese.g., Russell (1959) described case of TBI as a result of a motorcycle accident1 week post accident patient had lost 11 years of memory extending back from injury2 weeks post accident patient had last 2 years of memoryabout 10 weeks post injury memories of the last two years gradually returned

  • Neuropsychology of MemoryMemory problems following TBIretrograde amnesiathis pattern of results suggests that retrograde amnesia is a retrieval problemthe pattern of damage/recovery -- from most distant to most recent -- has been argued by some to reflect a failure of consolidation (Ribots Law)

  • Neuropsychology of MemoryMemory problems following TBIretrograde amnesiaformal testing of amnesics using famous faces/famous events has shown that there appears to be recall and recognition for old faces/events

  • Neuropsychology of Memoryretrograde amnesiaButters & Cermak (1986) reported a case study of an eminent scientist (born 1914) who had written his autobiography only two years prior to becoming amnesictested him by asking him questions all drawn from his autobiography

  • Neuropsychology of Memory

  • Neuropsychology of Memoryretrograde amnesiathe pattern of results in some individuals appear to depend upon the nature of the retrieval cue presentedWarrington and McCarthy (1988) showed that an amnesic patient was impaired when shown faces of famous people and asked to recall themhowever, performance was normal when tested using recognition procedures

  • Neuropsychology of Memoryretrograde amnesia (RA)pattern of memory gradient varies across patients (See Moscovitch et al. 2006)If lesion restricted to hippocampus, RA extends back a few years onlyWhen lesion includes entire hippocampal formation or extends to adjacent regions, severe ungraded RA (ungraded means that memory loss is equivalent at all time periods since acquisition); some labs have reported graded retroactive amnesia (recent memories are poorer than more remote memories)

  • Neuropsychology of MemoryMemory problems following TBIanterograde amnesiarefers to problems of learning new factsalthough sometimes amnesia is specific to learning of verbal material (following LHD) or visuo-spatial material (following RHD) amnesia usually affects learning of many types of new information

  • Neuropsychology of MemoryAmnesic syndromedense form of memory deficit (as assessed by standardized testing)relatively spared performance in other domains

  • Neuropsychology of MemoryCauses of amnesiaKorsakoffs syndrome: drinking too much, eating too little, resulting in a thiamine deficiency and brain damagedamage to brain following viral infection (e.g., viral encephalitis)lesion to critical brain regions -- e.g., HManoxia following heart attack, suicide attempt, etc.

  • Neuropsychology of MemoryKorsakoffs syndromeHistory1881, a neurologist Carl Wernicke described a syndrome involving ataxia, oculomotor problems (gaze palsies and nystagmus), peripheral neuropathy, and confusion. This condition came to be known as Wernicke's encephalopathy Korsakoff identified several patients with confusion, confabulation, sensory loss (especially of the feet), and anterograde amnesia

  • Neuropsychology of MemoryKorsakoffs syndromeTerminologyAtaxia problems of muscular coordination; e.g., people duck walk, feet apart, stiff-legged oculomotor problems (gaze palsies and nystagmus); abnormal eye movementspalsy = paralysis; nystagmus = involuntary rapid eye movements peripheral neuropathy = functional disturbance of peripheral nervous system

  • Neuropsychology of MemoryKorsakoffs syndromeHistory1901 Bonhoffer realized Korsakoffs patients had passed through the Wernicke's encephalopathy stagetoday syndrome is called alcoholic Korsakoff syndrome. There are seven primary defining features of this disease:

  • Neuropsychology of MemoryDefining features of alcoholic Korsakoff syndromea.a retrograde amnesia with a temporal gradient (i.e., better preserved memories from the remote than from the more recent past)b.anterograde amnesia, meaning a nearly complete inability to learn new information from the time of the disease onset onward.

  • Neuropsychology of Memoryc.confabulation, which is a tendency to "fill in the gaps" of one's memories with plausible made-up stories. confabulations are rare among chronic Korsakoff patients who've had the disease for more than 5 years. Patients in the chronic stage are more likely to say "I don't know" or remain silent when faced with memory failures rather than to invent stories.

  • Neuropsychology of Memoryd.generally preserved IQ, including a normal digit span.e.personality changes, the most common of which is apathy, passivity and indifferenceinability to formulate and follow through a series of plansf. lack of insight into their condition. How can someone with a shattered memory remember that he has become unable to remember?

  • Neuropsychology of MemoryKorsakoffs syndromeworst impairments are on episodic memory tests, including list learning of words, figures, or faces, paragraph recall.relatively preserved semantic memory, including normal verbal fluency, vocabulary, rules of syntax, and basic arithmetic operationsintact sensori-motor memory (mirror tracing, mirror reading, pursuit rotor)intact performance on implicit memory tests

  • Neuropsychology of MemoryNeuropathology of Korsakoffs syndrome most sources attribute the amnesia to combined lesions in two diencephalic structures: regions of the thalamus and the mammillary bodies of the hypothalamus

  • Neuropsychology of MemoryHM, Hippocampal manprototype of amnesia attributable to hippocampal damagebilateral mesial temporal lobe resection extending 8 cm. back from the temporal tips, including the uncus and amygdala, and destroying the anterior two-thirds of the hippocampus and hippocampal gyrus, for the treatment of intractable epilepsy in 1954. surgery led to a permanent, severe anterograde amnesia, limited retrograde amnesia, and normal intelligence.

  • Neuropsychology of MemoryHM, Hippocampal manPerceptual, motor, and cognitive functioningIQ above average; language function intact, speech fluency slightly impaired; spelling poorAppreciation of puns and linguistic ambiguitiesDifficulty with some spatial tasks (e.g., could not use spatial floor plan to navigate through a novel building, but could reproduce a floor plan of family home)

  • Neuropsychology of MemoryHM, Hippocampal manMemoryAlmost no capacity for new learning regardless of materials (short stories, word lists, pictures, etc.)But there are certain tasks requiring memory that are intact in H.M.Mirror drawing (covered?)

  • Neuropsychology of MemoryMultiple memory systems perspectiveHM also has a retrograde amnesia; that is, he forgets events that occurred prior to surgeryHis retrograde amnesia is temporally graded: The closer the event to surgery the less likely he is able to recall itThis finding suggests that the medial temporal lobes are not always required to retrieve memories (One possibility is that some process occurs that makes it possible to retrieve information that does not rely on medial temporal lobes)

    Long-term memory consists of all the different types of memory shown in the previous slideExplicit (declarative) memory refers to memory that can be declared or described to other peopleIt includes episodic memory, memory for events in our personal past. Episodic memories are temporally dated, spatially located, and personally experience semantic memory, our general knowledge about things in the world

  • Neuropsychology of MemoryMultiple memory systems perspectiveIn 1962 Milner and colleagues showed that HM improved on tasks requiring skilled movementsHMs improvement was comparable to controlsSkill was called mirror tracing because it requires participants to draw the outline of a star while looking at the reflection of his hand and the star on the mirrorHM from had no conscious recollection of having done this task in the pastThis is now viewed as a form of non-declarative or implicit memory tasks

  • H.M.s skilled learning performance

  • Encoding and Retrieval from long-term memory (LTM)Multiple memory systems perspectiveOther forms of implicit memory include priming effects that were reported by Warrington & Weiskrantz (1968)In this study amnesics shown list of words (e.g., absent); at test participants were given word stem completion task (e.g., abs_____), and instructed to complete with first word that comes to mindRes

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