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: _______________________________________________________