学习与记忆宏观英文课件.ppt

1、Learning and Memory1.The basic concepts of learning&memory classification of learning&memory brain structures hosting learning&memory learning&memory in behavioral study learning&memory and neural plasticity2.The molecular basis of learning&memory studies in Aplysia studies in mouse,LTP,LTD and long

2、 term memoryBasic concepts of Learn&Mem Learning：the process of acquiring ability or knowledge that is not born learned:reading;,writing,driving etc born:sucking milk,yelling,blinking etc Memory：the retaining/maintaining of learned ability or knowledge Actually,the studies on learning and memory inc

3、lude learning,repeating,memory,and forgetting as wellSteps of memory processing Acquisition is the process of bringing knowledge into the brain and into a first-stage memory buffer via sensory organs and primary sensory cortices Consolidation is the process of rehearsing and building a robust repres

4、entation of it in the brain Storage is the creation of a relatively stable memory trace or record of knowledge in the brain Retrieval is the process of reactivating knowledge in a way that will allow it to become an image in consciousness or translated into motor outputAmnesia Retrograde amnesia:mem

5、ory loss for events before the trauma;you forget things you already knew Anterograde amnesia:an inability to form new memories following brain trauma.Classification of memories According to time course:Working memory Short term memory Long term memory According to appearance:non-declarative memory(i

6、mplicit memory)declarative memory(explicit memory)Working memory:information held“in mind.”Short-term memory:memories that last on the order of seconds to hours and are vulnerable to disruption.Long-term memory:memories that you can recall days,months,or years after they were originally stored.Impli

7、cit and explicit memory Non-declarative memory(implicit memory):Perceptual memory:acquired through the sense.Procedure learning:representation of a series of actions or perceptual processing functions that occur unconsciously and repetitions typically result in increased speed or accuracy Fear memor

8、y:Declarative memory(explicit memory):Episodic memory:a system that collects temporarily and spatially encoded events in a subjects life,such as recalls of particular experiences or episodes Semantic memory:an organization of factual information independent of specific episodes during which that inf

9、ormation was acquired.Its knowledge of the world.Declarative and non-declarativememory1.The basic concepts of learning&memory classification of learning&memory brain structures hosting learning&memory learning&memory in behavioral study learning&memory and neural plasticityBrain structures hosting l

10、earning&memory General theories about memory engram Localization of declarative memory:temporal lobe diencephalon Localization of procedure memory striatum Localization of working memory frontal cortex The search for engram-Where is the engram?Engram-the physical representation or location of memory

11、,also called memory trace Strategy/Methods:1.lesion or ablation of certain brain regions 2.recording the response of specific neuronsEffect of brain lesions on Maze learning in rats-Karl Lashleyrats given brain lesions before learning needed more trials to run the maze without going down blind alley

12、srat given brain lesions after learning made mistakes and went down blind alleys it had previously learned to avoid.a rat run through a maze to get foodThe greater the percentage of cortex destroyed,the more errors made while the rats learn to run the maze.The number of errors shown is cumulative ac

13、ross trials,suggesting that rats with larger lesions had difficulty remembering which arms of the maze were blind alleys.Karl Lashleys conclusions all cortical areas contribute equally to learning and memory it is simply a matter of getting poorer performance on the maze task as the lesion gets bigg

14、er and the ability to remember the maze worsens.It is wrong that all areas are equal,but it true that the memories are distributedBrain structures hosting learning&memory General theories about memory engram Localization of declarative memory:medial temporal lobe diencephalon brain Localization of p

15、rocedure memory striatum Localization of working memory frontal cortexLocalization of declarative memories to neocortex Studied in human Studies in monkeysThe brain lesion in patient H.M.that produced severe anterograde amnesia.(a)The medial temporal lobe was removed from both hemispheres in H.M.s b

16、rain to alleviate severe epileptic seizures.(b)A normal brain,showing the location of the hippocampus and cortex that were removed from H.M.sbrain.H.M.has partial retrograde amnesia for the years preceding the operation.Much more serious is his extreme anterograde amnesia.While he can remember a gre

17、at deal about his childhood,he is unable to remember someone he met just a few minutes earlier.Case study-H.M.Declarative memories in neocortex-studies in monkeysResponses to faces in inferotemporal cortex.(a)The location of area IT in the inferior temporal lobe of a macaque monkey.(b)Responses of a

18、 face cell.The histograms show the response of a neuron in area IT to different views of a monkeys head.The horizontal bar under each histogram indicates when the stimuluswas presented.(c)Changing responses of a cell to unfamiliar faces.Diencephalon and memoryComponents of the diencephalon involved

19、in memory.The thalamus and mammillary bodies receive afferents from structures in the medial temporal lobe.Case study of NA and Kosakoffs syndromeCase study-N.A.The only obvious damage was a lesion in his left dorsomedial thalamus.N.A.s cognitive ability was normal but his memory was impaired.He had

20、 relatively severe anterograde amnesia and retrograde amnesia for a period of about 2 years preceding the accident.While he could remember some faces and events from the years following his accident,even these memories were sketchy.He had difficulty watching television because during commercials,hed

21、 forget what was previously happening.Korsakoffs syndrome-lesions in the dorsomedial thalamus and mammillary bodies No strong correlation exists between the severity of anterograde amnesia and retrograde amnesia in Korsakoffs syndrome.The mechanisms involved in consolidation(disrupted in anterograde

22、 amnesia)are largely distinct from processes used to recall memories(disrupted in retrograde amnesia).Anterograde amnesia may be associated with diencephalic lesions results from damage to the thalamus and mammillary bodies.Retrograde amnesia,may invovles diencephalon,the cerebellum,brain stem,and n

23、eocortex.Brain structures hosting learning&memory General theories about memory engram Localization of declarative memory:Localization of procedure memory striatum Localization of working memory An eight-arm radial arm maze.If a rat learns that four of the eight arms never contain food,it will ignor

24、e these and follow a path to only thebaited arms.Hippocampus and declarative memoryTwo versions of radial arm maze task-declarative/procedure memory The first was the standard,in which the rat must move as efficiently as possible retrieving the food from each of the baited arms of the maze.In the se

25、cond version,small lights were illuminated above the arms containing food,and the unlit arms had no food.The lights could be turned on or off at any time The standard maze task was designed to require the use of declarative memory.The“light”version of the task was intended to draw on procedural memo

26、ry because of the consistent association between the presence of food and illuminated lights.If the hippocampal system was damaged,performance was degraded on the standard maze task but was relatively unaffected on the light version.Conversely,a lesion in the striatum impaired performance of the lig

27、ht task but had little effect on the standard task.This“double dissociation”of the lesion site and the behavioral deficit suggests that the striatum is part of a procedural memory system but is not crucial for the formation of declarative memories.Brain structures hosting learning&memory General the

28、ories about memory engram Localization of declarative memory:temporal lobe diencephalon brain Localization of procedure memory striatum Localization of working memory frontal cortex,area LIP Area LIP and working memory LIP:lateral intraparietal cortex(顶内沟外侧区)(a)The monkey fixates on a central point

29、while a peripheral target flashes on and off.When the fixation point disappears,and the animal knows to move its eyes to the remembered location of the target.(b)The histogram shows the response of an LIP neuron.1.The basic concepts of learning&memory classification of learning&memory brain structur

30、es hosting learning&memory learning&memory in behavioral study learning&memory and neural plasticity2.The molecular basis of learning&memory studies in Aplysia studies in mouse,LTP,LTD and long term memoryNon-associative learning Sensitization progressive amplification of a response after repeated a

31、dministrations of a stimulus Gill Withdraw Reflex in Aplysia Habituation decrease in response to a stimulus after repeated presentations Probscis extension response in Drosophila “wolf-coming”Associative learning-Classical conditioning CS:conditioned stimulus A signaling stimulus that does not elici

32、t a response by itself US:unconditioned stimulus:A stimulus is a factor that causes a response in an organism Conditioning:coupling of CS and US to elicit a responseAssociative learning-operant conditioningLearning by doing Operant conditioning differs from classical conditioning in that the animal

33、can control the presence of the unconditioned stimulus.1.The basic concepts of learning&memory classification of learning&memory brain structures hosting learning&memory learning&memory in behavioral study learning&memory and neural plasticity2.The molecular basis of learning&memory studies in Aplys

34、ia studies in mouse,LTP,LTD and long term memoryNeural basis of learning and memory:general thinking Information can be stored in the nervous system in forms of molecular,synaptic,and cellular events Neuroplasticity(or neural plasticity)is the ability of neurons and neural circuits to be remodeled b

35、y experience or environment.Memory Storage Requires Neuronal Remodeling Changes can be presynaptic(such as increased neurotransmitter),or postsynaptic(such as altered effectiveness of receptors),or both.Structural changes at the synapse may provide long-term storage.Pre-and Post-synaptic Changes That May Store MemoriesStructural Changes That May Store Memories