Exam 4 Study Questions Learning and Memory 13 1 13 2 What is an engram and what were Lashley s critical mistakes in looking for the engram Engram A physical representation of a memory Lashley trained rats then cut or lesioned certain areas of cortex no significant effect on performance the bigger the lesion the greater the impairment location didn t matter 2 false assumptions 1 memory is in discreet regions of cortex 2 all memories are physiologically the same What are implicit memory and explicit memory What brain regions are important for each Implicit the influences of recent experiences on behavior w o necessarily realizing that one is using memory Explicit deliberate recall of info that one remembers as a memory ie who was the main character in the last novel you read What are some differences b t short term memory working memory and long term memory What brain region is important for working memory Short term Memory Small capacity CYZUAUF Fades quickly unless rehearsed Once forgotten it is gone Working memory is alternate way of thinking of STM Lasts hours to days w o rehearsal where car is parked when where lunch date is Time needed for consolidation varies especially depending on familiarity of topic emotional content Long term Memory Infinite capacity Lasts indefinitely Could be forgotten and then later remembered w appropriate cues Phone vs names of grade school teachers Consolidated memories can be reconsolidated What were some of HM s impairments what could he still do Henry Gustav Molaison Bilateral removal of much of temporal lobe including hippocampus Anterograde amnesia Lost declarative explicit memory spatial memory Intact procedural memory a type of implicit and working memory With regard to memory what are some functions of the hippocampus Active during formation of memories during recall Consolidation of declarative explicit memory STM LTM Spatial memory Increased activity in hippocampus when doing spatial task ex imagining best route fMRI Damage impairment of spatial tasks London taxi drivers hippo active during spatial tasks larger posterior hippo positive correlation to time being a taxi driver Birds that live at high altitude and bury seeds larger hippocampus Place neurons What other brain regions are important in learning and memory and what type of learning do they subserve What is a Hebbian synapse Hebbian synapse a synapse that increases in effectiveness b c of simulataneous activity in pre and postsynaptic neurons cells that fire together wire together In other words when an axon successfully stimulates a cell it will be even more successful in the future the synapse is strengthened What is LTP What receptors are necessary Long term Potentiation LTP A burst of stimulation from axons e g 100 excitations per second for 1 4 seconds onto dendrites results in potentiated strengthened synapses for minutes days or weeks Necessitates glutamate receptors AMPA and NMDA Understand cooperativity specificity and associativity in terms of receptors LTP LTP cooperativity nearly simultaneous stimulation by two or more axons results in LTP more strongly than repeated stimulation by 1 axon LTP specificity strengthened LTP associativity input enhances later response to the weak input only active synapses become pairing a weak input with a strong How does classical conditioning probably depend on the associative nature of LTP Unimportant stimulus acquires properties of an important one through pairing Condition an eye blink in response to a tone Puff of air to cornea US subject blinks UR Present tone CS just before air subject blinks to tone alone CR Hebb rule hypothesis proposed by Donald Hebb The cellular basis of learning involves strengthening of a synapse that is repeatedly active when the postsynaptic neuron fires shows associativity What are some presynaptic changes that occur in LTP Retrograde transmitter from dendrite to axon terminal usually nitric oxide NO Decreased threshold for producing APs Increased release of neurotransmitter Expansion of axon seen in prev slide along w increase in spine number Release of NT from more sites along axon What are some postsynaptic changes that happen in LTP What is evidence that there is a functional connection between LTP and actual learning In LTP a neuron sometimes makes more NMDA Rs more than normal NMDA receptors enhances learning LTP increases GAP 43 over production of GAP 43 enhances learning and problem solving More NMDA receptors enhanced learning Alzheimer s Disease and other Dementias 13 1 What are some cognitive and non cognitive symptoms of dementia Cognitive Impairment in memory cognition accompanied by decreased ability to relate function at home work social settings Non cognitive delusions suspicions hallucinations agitation depression Up to 2 3 of AD patients develop delusions hallucinations so must distinguish b t dementia and psychosis Depression dementia are often comorbid have to distinguish b t the two What are the 4 A s of demenita Amnesia Loss of memory working memory first Agnosia Loss of ability to recognize objects Apraxia Loss of knowledge about how to do things Aphasia Loss of speech What are some symptoms of Alzheimer s Disease AD First symptoms can be mild anterograde amnesia Gradual progression to more serious memory loss and Language problems loss of vocabulary Confusion Depression Restlessness Hallucinations Delusions Sleeplessness Loss of appetite Sundowning What is the difference b t early onset and late onset AD Which one has a stronger genetic contribution EARLY ONSET STRONGER GENETIC CONTRIBUTION Early onset People 40 yr old Only about 1 or up to 10 of people w AD STRONG genetic component for early onset AD Gene for APP on chromosome 21 Also mutations in this gene account for maybe up to 10 of early onset AD Mutations in gene for presenilin can increase risk part of gamma secretase complex that chops APP into beta amyloid Late onset Over 60 yr old 5 of people b t 65 74 yr old 50 of people over 85 yr old Gene for Apolipoprotein ApoE4 which probably helps breaks down beta amyloid this version isn t very good at it increases risk by itself as well as when other risk factors are present Some other genes that increase risk but only account for small percentage of cases Half of patients have no known relative with A D so health lifestyle risk factors and age What do the neurons and the brain of an AD patient look like Brain atrophy Loss of neurons Loss of spines synapses Loss of connections
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