4.3 · Cues, stress, glutamate and model limitations

Learning objective

Explain reinstatement and cue learning while identifying the limits of animal models and correlational evidence.

Learning can outlast drug exposure

Environmental cues and internal states can become associated with drug effects. Later cues or stress may trigger craving or renewed seeking even when most drug has been eliminated. This connects Chapter 1’s concentration time course with Chapter 4’s longer-lasting learned and adaptive changes. Elimination is not the same event as erasing learned associations.

What a reinstatement experiment tests

In the book’s animal example, a response initially delivers drug. During extinction it no longer does, and responding declines. Later drug exposure, a previously paired cue or stress can increase responding again. This is reinstatement of a measured behavior after extinction, not proof that extinction permanently erased learning and not a complete model of a person’s recovery.

More than dopamine

The chapter discusses glutamatergic projections from prefrontal and other regions to VTA and nucleus accumbens. Learning, control and stress involve multiple signaling systems. Its BDNF discussion includes human associations and animal manipulations with different contexts; a blood BDNF association does not establish a treatment target or a single direction of effect in every brain circuit.

Evaluate the model instead of memorizing a slogan

The book presents both the brain-disease model and criticism of dopamine-only or inevitable-compulsion accounts. Ask what a model explains, which drug classes and samples support it, and what it leaves unexplained. Neural change and environmental sensitivity can coexist. Animal responding, human self-report and imaging provide different types of evidence and should not be treated as interchangeable measurements.

Check your understanding

Explain it without notes

Distinguish extinction from permanent erasure.

How can craving occur after six half-lives?

Revisit the connected course lessons and visuals

Glutamate/NMDA and GABA comparisons

Plasticity versus neurogenesis

Half-life and redistribution

Julien’s Primer of Drug Action, supplied consolidated PDF pages 49, 50, 51, 52 (Chapter 4). Locators refer to PDF captures, not printed pages. Original paraphrase and practice; source conformance reviewed, not independently clinically certified.