Introduction to Neurobiology Lecture 13: Classical conditioning 1

Associative Learning Nonassociative HabituationSensitization A single type of stimulus The relationship between two stimuli or reward. 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 UR CS nothing  Training:CS+US UR CS increasing CR(=UR)  Post-training:CS CR (=UR).  Temporal relationship: 1) Simultaneous 2) Delayed (partial overlap in time) 3) Trace (separated in time. Usually 200ms-2s.

The nictitating membrane response

Circuitry for conditioning nictitating membrane response

The suppression of CF during learning of eye blink. Naive animal Trained animal

US only CS-US With PTX GABA is involved in the suppression of CF.

Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Seventh Outline Level  Eighth Outline Level  Ninth Outline LevelClick to edit Master text styles  Second level  Third level  Fourth level » Fifth level Extinction protocol with: no infusion ACSF PTX GABA is involved in the extinction of CR.

Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Seventh Outline Level  Eighth Outline Level  Ninth Outline LevelClick to edit Master text styles  Second level  Third level  Fourth level » Fifth level  The response of trained animal to tone + puff  test sessions with: ACSF NBQX (AMPA receptor antagonist) AMPA receptors are involved in the extinction of CR.

Blocking: CS “A” is tone; CS “B” is light; US is air puff. The eyeblink response to air puff is the UR The Eyeblink response to A or B is the CR B+U S CRCR B A+B+ US CRCR A/ B A+ US A+B+ US CRCR A CRCR B // CRCR A A+ US Blocking of conditioned eyelid responses

Phase I, animals received seven daily sessions of tone-airpuff conditioning; Phase II, animals underwent five sessions of tone-light-airpuff compound conditioning. Either picrotoxin (PTX) or (ACSF) was infused directly into the inferior olive. Controls experienced only the second phase of the blocking procedure. Afterward, all animals were presented with light-airpuff pairings to assess whether conditioning to the light had accrued during compound conditioning (phase II).  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 Blocking GABA is involved in blocking of conditioned eyelid responses

Circuitry for conditioning nictitating membrane response

Wild-type: Conditioned responses (%)- 80 Average peak amplitude Average peak velocity mm/s LTD-deficient mice: Conditioned responses (%)- 30 Average peak amplitude Average peak velocity mm/s

Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Seventh Outline Level  Eighth Outline Level  Ninth Outline LevelClick to edit Master text styles  Second level  Third level  Fourth level » Fifth level 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 type Red- mutants

Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Seventh Outline Level  Eighth Outline Level  Ninth Outline LevelClick to edit Master text styles  Second level  Third level  Fourth level » Fifth level 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 ’ peak amplitude and peak velocity weren ’ t changed. In contrast, those wt values were changed. Blue- wild type Red- mutants

Red - pre-lesion Blue – post-lesion Green - post-sham lesion Mutants wt (After T-4) Conditioned responses still occur after lesions of the cerebellum in both mutants and wt, but the amplitudes were significantly reduced.

Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Seventh Outline Level  Eighth Outline Level  Ninth Outline LevelClick to edit Master text styles  Second level  Third level  Fourth level » Fifth level 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

The cerebellar-olivary system LTD LTP 1.2Hz<>Rate

 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

olivepons PFCF PC’s LTD DCN CR Blocking: US inhibition USCS 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 intervals (20 to 40 ms). Response of wild-type (wt) after 2 days and after 4 days. CR- conditioned response UR- unconditioned response