Download - BRAIN PLASTICITY Neuroplasticity:
BRAIN PLASTICITY
Neuroplasticity: _________________________.Happens in at least 3 ways:- __________________________________________________________
- ______________________________- ________________________________________
Recently, it was found that “new” neurons and glial cells are born _____________ in specific brain regions - reorganization.
Brain plasticity occurs during:- _______________- _______________________- ______________________________
DEVELOPMENT OF NERVOUS SYSTEM:1. Neural proliferation (neurogenesis - neuronal
“birth”)2. Migration and differentiation (neural cell
precursors travel “home” and “grow up”)
3. Axon growth and synapse formation(growth cones and filopodia)
4. Neuron death and synaptic pruning: toomany neurons and synapses produced- competition for neurotrophic factors (ex.,
NGF - ___________________)
Examples of the effects of EXPERIENCE onNEURAL DEVELOPMENT and PLASTICITY
Early visual experience- studies of early __________________________
found deprived eye to ______ ability to activatevisual cortex
- only occurs if other eye is open, not if it is alsodeprived - ____________________
- these are structural effects - ________________- concept of _______________________________
Two eyes open One eye shut
Environment and the cortex- studies of rat litters separated at birth into
_______________________________________- enriched environments produces:
- ________________- ______________________- __________________- more glial cells;- larger postsynaptic zones;- larger protein content.
- some of these effects can be produced in adultanimals by giving them extensive maze training
LEARNING AND MEMORY
Learning: __________________________________________________________________________________________________________________________________________________
Memory: _________________________________________________________________________
If behavior at a later time B is different than atearlier time A, say that learning has taken placebetween time A and B
TYPES OF LEARNING:NON-ASSOCIATIVE LEARNING: _________
_______________________________________ ________________________
A. Habituation: __________________________________________________________________________
B. Sensitization: ____________________________________________________________________________
ability to recall or recognize previous experience in the form of behavioral change.
Marine snail “Aplysia Californica”
Gill-withdrawal reflex used to study habituationand sensitization (Eric Kandel’s laboratory)Habituation- touch siphon repeatedly every 30 sec leads toshort-term habituation of gill-withdrawal reflex
- can lead to ___________________ if touch is repeated over days
Sensitization- one electric shock to the tail can lead to short-
term sensitization of gill-withdrawal reflex- several electric shocks can lead to sensitization
that will be observed for weeks (long-term)
Tail
Head
long-term habituation
ASSOCIATIVE LEARNING: _______________________________________________________________________
A. Classical conditioning (also called _____________________): _____________________________________________________________________________________ (often a biologically relevant stimulus)
TerminologyUCS = ____________________ (food, water, etc.)UCR = _____________________ (salivation, etc.)
Examples: UCS - - - - - - - - - - - > UCRpinprick withdrawalfood salivationsudden loud noise startleairpuff eyeblink
CS = ________________________ (bell, light, etc.)CR = _____________________ (salivation to bell)so CR is the ____________ response
Pavlovianconditioning the process by which a neutral stimulus acquires meaning through associations with another stimulus
Development of Classical Conditioning
Example: conditioning of emotional responses -Pavlov’s dog)
UCS - - - - - - - - - - - - - > UCR(food) (salivation)
Initially CS - - - - - - - - - - > no response(bell - neutral stimulus)
Repeated pairings of CS + UCS - - - - - - > UCR(bell) + (food) (salivation)
Bell eventually comes to elicit salivation withoutthe presentation of food
CS - - - - - - - - - - - - - - - - > CR(bell) (salivation)
Note that salivation here is called conditionedresponse (CR) because it is not elicited directlyby food; classical conditioning has taken place
Also conditioning of motor responses - exampleof eye blink conditioning
CLASSICAL CONDITIONING: NEURAL BASIS
Classical conditioning of emotional responses(freezing in rats - changes in heart rate/bloodpressure or skin conductance in humans) is learned after only a few pairings
Electric shocks produce “freezing” in rats andchanges in heart rate/skin conductance in humans
Repeatedly pair auditory stimulus (CS) with shocks (UCS).- the auditory CS come to elicit freezing and changes in heart rate/skin conductances
- the ________________________ to produceclassical conditioning of emotional responses
Classical conditioning of motor responses, such aseyeblink in response to puffs of air is learned onlyafter 100s of pairings of an auditory stimulus withpuffs of air- the _______________ is necessary to produceclassical conditioning of motor responses
B. Instrumental Conditioning (also called _____________________): _________________________ __________________________________________________________________________
Terminology:Discriminative stimulus (SD): _______________ ___________________________________
Favorable outcome: _______________________________________________________________________________________________
cue that triggers the motor response (ex. sight of a lever bar).
positive reinforcers (ex. food, water, etc) or termination of negative reinforcers(termination of pain, isolation, etc).
Neural Basis of Instrumental Conditioning:- _____________________________ necessary forinstrumental motor response learning
- _______________________________________________ necessary for “detection” of reinforcer.
Example of instrumental conditioning: Catshave to learn to press a lever in order to obtainpalatable food (Thorndike’s experiment)
HUMAN MEMORY
The various stages of memory:
I. _______________ (high capacity, low duration)With Attention -
II. _________________ (low capacity & duration)With Consolidation -
III. ________________ (high capacity & duration)Retrieval - recall and recognition
Explicit memory (similar to _________________):________________________________
Two types - _______________ (time and places)- _________ (facts and knowledge)
Implicit memory (similar to _________________):_____________________________________________________________________Examples: - mirror drawing tasks
- playing video games- riding a bicycle- word associates (define fall after different stories)
Sensory registers
Short-term memory
Long-term memory
NEUROBIOLOGICAL BASES OF MEMORY
Karl Lashley (1920’s - 1950’s) and the search forthe “engram” or memory trace: ___________________________
He derived two principles from his studies:- ______________________= memories storeddiffusely all over neocortex
- _______________________= neocortex all overthe brain plays an equal role in memory storage
What was wrong with these interpretations?
Donald Hebb (early 1950’s) and ______________of short-term memories into long-term memoriesvia ________________________________
- cell assemblies: ________________________- reverberation: __________________________
___________________________________________
- task difficulty;- different “learning” systems/strategy used to
solve problems.
LESSONS FROM HUMAN AMNESIAS
Amnesia: _________________Retrograde amnesia: forget events _______ braintraumaAnterograde amnesia: forget events _____ braintrauma
Case of H.M.: __________________________________________ because of severe epilepsy (removal of enthorinal and perirhinal cortex,part of amygdala and most of hippocampus)
H.M. experienced:1. No loss of intelligence (IQ)2. Mild retrograde amnesia3. Devastating anterograde amnesia
What we learned from H.M.:1. ________________________________________2. ____________________________________3. ________________________________4. _____________________________________5. _______________________________________
Supports short- & long-term memory processesExistence of explicit vs. implicit memoryExistence of consolidation processChallenges view of diffuse memory processImplicates discrete brain regions in memory
The beginnings of Explicit Memory mechanisms
Implicit memories: various forms of implicitknowledge.
Amygdala: _______________________________
Cerebellum: _______________________________
Basal ganglia: _______________________________________________________