Brain circuits mediating Pavlovian and instrumental conditioning (Video notes)

A comprehensive set of Q&A flashcards covering Pavlovian and instrumental conditioning brain circuits, PIT, and extinction from the lecture notes.

What are the four Pavlovian conditioning forms?

Appetitive excitatory; Appetitive inhibitory; Aversive excitatory; Aversive inhibitory.

What is Pavlovian conditioning?

A predictive-learning process in which a CS signals a biologically significant event, helping organisms adapt to the environment.

What is Pavlovian fear conditioning?

A Pavlovian form focused on learning CS–US pairs where the US is aversive (e.g., footshock), often studied in rodents.

What is the most common conditioned response (CR) in Pavlovian fear conditioning?

Freezing (immobility).

Which brain region is the site of CS–US convergence for fear learning?

The basolateral amygdala (BLA).

What are the roles of LA and BL (BLA) in fear conditioning?

LA processes CS/US inputs for discrete cues; BLA is critical for contextual fear conditioning via hippocampal inputs.

What is the hippocampus's role in Pavlovian fear conditioning?

Processes contextual information and contributes to context CS processing.

What does the 'dual-process theory' of context processing propose?

Context processing uses elemental features in cortex and configural representations in the hippocampus; configural representations are favored by default.

What is a configural representation in a context?

A representation that binds elemental features into a single context, enabling pattern completion from partial cues.

What is an engram?

The physical/biochemical changes in the brain that store a specific memory, represented by a neuronal ensemble.

What is the role of NMDA receptors in the BLA for fear memory acquisition?

NR2B-containing NMDA receptors in the BLA are required for acquisition; NR2B blockade (e.g., ifenprodil) impairs acquisition.

What does muscimol do in these experiments?

Muscimol is a GABA-A receptor agonist that temporarily inactivates the targeted brain region.

What is the BLA's role regarding outcome value in fear-conditioned actions?

BLA encodes changes in outcome value (incentive value) necessary for goal-directed actions.

What is Pavlovian instrumental transfer (PIT)?

A paradigm where Pavlovian CSs influence subsequent instrumental actions; has general PIT and specific PIT.

Which brain regions support General PIT?

Central amygdala (CeA) and nucleus accumbens core (NAc core).

Which brain regions support Specific PIT?

Basolateral amygdala (BLA), posterior dorsomedial striatum (pDMS), and nucleus accumbens shell (NAc shell).

What is the effect of inactivating the NAc shell versus the NAc core on PIT?

Shell inactivation abolishes specific PIT; core inactivation abolishes general PIT.

What is the 3-CS PIT design?

Pavlovian stage with S1→O1, S2→O2, S3→O3; instrumental stage with A1→O1 and A2→O2; a transfer test to assess PIT.

How does motivational state (hunger vs. satiety) affect PIT?

General PIT is abolished by satiety, while Specific PIT is preserved (sensory-specific relations remain).

Which brain circuits underlie goal-directed actions?

Prelimbic cortex (PL), posterior dorsomedial striatum (pDMS), and basolateral amygdala (BLA).

What is the PL's role in goal-directed actions?

PL is needed for acquisition; lesions before training impair acquisition, lesions after training spare retrieval/expression.

What is the role of the pDMS in goal-directed actions?

Necessary for acquisition and updating action–outcome contingencies; contributes to retrieval/expression.

How do DMS and DLS contribute to instrumental learning?

DMS supports goal-directed actions; DLS supports habitual actions.

What is the infralimbic cortex (IL) role in instrumental learning?

IL is necessary for the acquisition of habitual actions; IL inactivation before testing can restore sensitivity to devaluation.

How do PL and IL differ in their roles for goal-directed vs habitual actions?

PL is necessary for the acquisition of goal-directed actions; IL is necessary for the acquisition of habitual actions.

What is the role of the central amygdala (CeA) in habit learning?

Anterior CeA is necessary for acquisition of habitual actions; CeA interacts with DLS to promote habits.

What is the role of the DLS in habit learning?

DLS is necessary for retrieval/expression of habitual actions; overtraining leads to habitual control.

What is the role of the BLA in habitual actions?

BLA lesions disrupt acquisition of goal-directed actions; BLA encodes incentive value necessary for goal-directed behavior.

What is extinction in Pavlovian fear conditioning?

Extinction is the formation of a new CS-noUS memory that inhibits CS–US fear; it does not erase the original memory.

Which brain networks are key to fear extinction?

BLA, medial prefrontal cortex (PL and IL), and intercalated cells (ITC) coordinating the network.

What is the PL's role in fear extinction?

PL is involved in fear expression; PL inactivation during extinction can reduce freezing, suggesting PL contributes to fear expression rather than extinction learning.

What is the IL's role in fear extinction?

IL is necessary for consolidation and retrieval/expression of fear extinction.

What are intercalated cells (ITC) in extinction?

Intercalated cells in the amygdala help regulate extinction retrieval by modulating BLA–CeA pathways; ITC lesions impair extinction retrieval.

What does optogenetic silencing of the IL show about extinction retrieval?

Silencing IL during retrieval increases freezing, indicating IL is necessary for retrieval/expression of extinction.

What are fear extinction restoration phenomena?

Renewal, spontaneous recovery, and reinstatement show extinction is new learning and can be contextually regulated.

What does extinction memory entail in context, time, and internal state?

Extinction memory expression is modulated by physical context, time (retention interval), and internal state (e.g., hunger/satiety).

What evidence supports extinction as new learning rather than erasure?

Extinction can be overridden by renewal, spontaneous recovery, reinstatement, and specific PIT persists after extinction.

What does the BLA contribute to fear extinction acquisition and consolidation?

BLA is necessary for acquisition and consolidation of fear extinction.

What is the mPFC's general role in extinction?

Involves PL and IL subregions; IL is particularly implicated in extinction consolidation and retrieval.

What is a fear extinction neuron vs a fear neuron in the BLA?

Fear neurons (red) increase after fear conditioning; extinction neurons (blue) increase during extinction; silencing extinction neurons increases fear.

What is the role of the ITC in fear extinction retrieval?

ITC cells are necessary for retrieval/expression of extinction, likely by inhibiting the BLA–CeA pathway.

How is extinction connected to memory engrams and retrieval?

Extinction creates a new memory trace (extinction memory) that competes with the original CS–US memory during retrieval.

What is the broader translational relevance of rodent fear/extinction circuitry to humans?

Human imaging shows vmPFC and anterior caudate (homologous to PL/pDMS) involvement in goal-directed actions; putamen analogous to DLS for habitual actions; cue-exposure therapies model extinction in humans.

What neural circuits are implicated in extinction recall and retrieval in humans?

vmPFC, hippocampus–mPFC interactions, and ITC-like interneuron networks are implicated in extinction recall and retrieval.

What is the overall take-home about the organization of Pavlovian and instrumental systems?

Two parallel, interacting systems—goal-directed (PL/pDMS/BLA) and habitual (IL/DLS CeA/NAc) —coexist and compete for control of behavior.

Which brain region is associated with encoding incentive value for goal-directed actions?

Basolateral amygdala (BLA).

Which brain region is associated with encoding sensory-specific properties for PIT?

BLA (in concert with pDMS and NAc shell for specific PIT).

Which brain region is essential for the general PIT effect and for general transfer of Pavlovian to instrumental performance?

CeA and NAc core.

What is the key difference between general PIT and specific PIT in terms of neural substrates?

General PIT relies on CeA and NAc core; Specific PIT relies on BLA, pDMS, and NAc shell.

What is the primary consequence of overtraining on instrumental actions?

Overtrained actions become habitual and show insensitivity to outcome devaluation.

What are the basic stages of fear memory processing in Pavlovian conditioning?

Acquisition (learning CS–US), Consolidation (stabilisation ~4–6 hours after conditioning), Retrieval/Expression (test).