classical conditioning. associative learning nonassociative habituationsensitization a single type...
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Associative
Learning
Nonassociative
Habituation Sensitization
A single type of stimulus The relationship between two stimuli
Classical
conditioning Operant
conditioning
Extinction
Blocking
Definitions
• An Unconditioned stimulus (US) is a stimulus which “naturally” elicits an (unconditioned) response (UR). For example:An airpuff to the eye is an unconditioned stimulus which elicits an eyeblink (nictitating membrane response).
• A conditioned stimulus (CS) is a “neutral” stimulus (e.g. a tone), which, by being associated with the US, leads after learning to a conditioned response (CR).
Basic paradigm
• Before learning, US -> URCS -> nothing
• Training: CS+US -> URCS -> increasing
CR(=UR)• Post-training: CS-> CR (=UR).• Temporal relationship of CS,US: Simultaneous,
delayed (partial overlap in time) or trace (separated in time). Usually strongest conditioning effects for ISI of 200ms-2s.
Single unit recording of complex spike responses of cerebellar Purkinje cells over the course of the behavioral training.
The inferior olive’s ability to convey US to the cerebellum becomes functionally suppressed, as eyeblink conditioning occurs.
Blocking neuronal activity in cerebellar output
• Superior cerebellar peduncle blocked using perfusion of TTX
• Expression of eyeblink conditioning blocked, but not acquisition
Krupa and Thompson, PNAS 1995
Cerebellar LTD and Learning-Dependent Timing of Conditioned Eyelid Responses
S.K.E.Koekkoek,H.C.Hulscher,B.R.Dortland,R.A.Hensbroek,Y.Elgersma,T.J.H.Ruigrok,C.I.De Zeeuw*
Science 2003
Inhibition of climbing fibers is a signal for the extinction of conditioned eyelid responses
Medina, Nores and MaukNature 2002
Inhibitory Cerebello-olivary projections and blocking effect in classical conditioning.
Kim, Krupa and ThompsonScience 1998
• phase 1 : seven daily sessions of tone-airpuff conditioning.
• phase 2 : five sessions of tone-light-airpuff compound conditioning while either PTX or ACSF was infused.
• phase 3 : all animals were presented with light-airpuff pairing tests.
•controls experienced only the second phase of the blocking procedure.
Blocking of conditioned eyelid responses
• Both control and PTX animals exhibited significant learning to the light CS compared with the ACSF animals - blocking did not occur in the PTX group.
• PTX had no effect on the performance of CRs and URs during the compound conditioning, indicating that PTX selectively affected blocking.
ACSF
PTX
CONTROL
Phase 1 phase 2 phase 3
Infusion of picrotoxin into the inferior olive prevented extinction of conditioned responses
• Training: five daily sessions
• Extinction protocol with: no infusion ACSF
PTX
Infusion of NBQX into the inferior olive caused extinction of conditioned
responses• Retraining: five daily
sessions• Tone plus unconditioned
stimulus test sessions with: ACSF NBQX (AMPA receptor
antagonist)
• Trial or time dependent influence?
olivepons
PF CF
PC’s
LTD
DCN
CR
Blocking: US inhibition
US CS
PTX: blocks inhibition prevents blocking prevents extinction
Extinction: without US or with NBQX
The daily training consisted of 10 blocks of 10 trials.
The trials were separated by a random The trials were separated by a random intervalsintervals (20(20 to 40 ms)to 40 ms)..
Response of wild-type (wt) after 2 days and after 4 days.CR- conditioned response
UR- unconditioned response
Wild-typeWild-type::
Conditioned responses (%)- 80
Average peak amplitude- 0.68
Average peak velocity- 32.6 mm/s
LTD-deficient LTD-deficient micemice::
Conditioned responses (%)- 30
Average peak amplitude- 0.44
Average peak velocity- 19.6 mm/s
Average CS-alone responses of a wild-type animal and a L7-PKCi mutant
• At T-4 (but not at T-2) the wt shows well-timed responses around the US onset time.
• The response peak of the mutant doesn’t change.
At T-4 (but not at T-2) there are changes between wt and the mutant.
Blue- wild typeRed- mutants
Average CS-alone responses when the ISI is extended to 500 ms
• If the timing is LTD-dependent, the amplitude and velocity in the L7-PKCi mutant should not be influenced by the length of the ISI.
indeed, the mutants’indeed, the mutants’ peak amplitude and peak amplitude and peak velocity weren’t peak velocity weren’t changedchanged..In contrast, those wt In contrast, those wt values were changedvalues were changed..
Blue- wild typeRed- mutants
Red - pre-lesion
Blue – post-lesion
Green - post-sham lesion
Mutants wt
)After T-4(
Conditioned responses still occur after Conditioned responses still occur after lesions of the cerebellum in both mutants lesions of the cerebellum in both mutants and wt, but the amplitudes were and wt, but the amplitudes were significantly reducedsignificantly reduced..