memory Flashcards
whats the definition of learning
-acquisition of information
whats the definition of memory
-storage of learned information
whats the definition of recall
-reacquisition of stored information
whats the definition of the engram
-physical embodiment of a memory
what are the independent memory systems
-Different forms of memory stored in different ways / regions / pathways.
e.g. playing piano vs passing exams
-Procedural vs declarative memory
=Implicit and explicit
whats procedural memory
-Skills and associations largely unavailable to conscious mind
whats declarative memory
-Available to conscious mind. Can be encoded in symbols and language
-passed from one organism to another
-not only vibe to humans
whats explicit memory
-Explicit – memory that can be consciously recalled (e.g. recalling riding a shiny new bike on the Christmas day when you were 5)
whats implicit memory
-Implicit – memory that cannot consciously recalled (e.g. learning to ride a bike). Can be different types:
=Procedural memory
=Classical conditioning
=Priming (when one stimulus influences the response to subsequent stimuli)
-like learning, associating one stimulus with another
-use 2 stimulus at once and they associate together
what are the different types of memory duration
-Immediate memory – few seconds
-Short-term memory – seconds or minutes
-Working memory
-Long-term memory – days, months, years
how does the temporal lobe have association with memory
-Electrical stimulation – hallucinations and recollection of the past experiences, correlation of activation of brain and memory storage
-Epileptic seizures – complex sensations and memories, recollect things during seizures
-Temporal lobectomy: patient HM
=8 cm of the medial temporal lobe was removed
=Intelligence, personality, etc. was intact
=Extreme anterograde amnesia
-patient had severe seizures and hence removed part of his brain therefore he could no longer make new memories
what are the important structures of the brain with memory
-Pre-frontal cortex
=working
-The hippocampus
=Essential for converting short to long term memory.
=Declarative
-Amygdala
=Multiple, processed sensory inputs (smell)
=Implicit / emotional / learnt fear
- Cerebellum
=Procedural
=Sensorimotor
what do hippocampus lesions causes
-(elective or accidental) cause memory loss
hippocampus
- Three - layered cortex
- Inputs from entorhinal cortex and beyond
- Outputs to many regions
-Enlarged in people whose work requires good spatial memory
what are the mechanisms of memory
-Long-term storage seems to be distributed
-Reverberating circuits- not believed much anymore
-The Hebbian synapse concept- 2 neurones connected to synapse fire at the same time -> increase in synapse strength
=activity modifiable, plastic synapse
whats the correlation with memory and synaptic plasticity
-Synaptic strength changes
-Facilitation / depression
-Short-term (mins / hours)
-Ca2+ availability / vesicle depletion
-Long-term facilitation / depression
-Sustained (days / weeks+)
whats long term potentiation
-LTP in hippocampal slices (and elsewhere)
-found in synapses between Ca1 (postsynaptic) and Ca3 (presynaptic)
-Post – “tetanic” LTP
-High frequency burst- stimulates neurone for brief period of time then test amplitude of epsp
-dont stimulate stim2 with high frequency
-LTP in specific pathway
-Paired LTP
-Coincident stimulus and depolarization
-Associativity
-simultaneously pre and post synaptic neurone -> amplitude of epsp
whats long term depression
-LTD in hippocampus
-leads to a decrease in amplitude of epsp
-stimulate neurones with low frequency for a prolonged time
whats Aplysia californica
-animals with similar pre organisation of nervous system
-gill withdrawal complex 10-15cm
whats short term habituation and sensitisation
-Repeated gentle stimuli to siphon causes reduced gill withdrawal
=Habituation
-Pair single tail pinch (aversive) with siphon touch
=Re-establish siphon reflex
=Short-term ~60min+
whats long term sensitisation
-Repeated pairing of siphon touch and tail pinch
-Long-term, non-habituating siphon / gill reflex
LTP, LTD AND APLYSIA
-Require receptor activation (glutamate / serotonin)
-Altered synaptic responsivity
-Mediated by second messengers (Ca2+/cAMP)
-Require protein phosphorylation changes in early stages
-Require protein synthesis for late stages
-Involve biochemical and structural pre and post-synaptic changes
How does LTP occur
-Evidence suggests often a post-synaptic event.
-Most indicates a critical role for Ca2+
-Involves trafficking of AMPA receptors to the postsynaptic membrane
