Questions: Executive Control Networks and the Prefrontal Cortex

Question 1

During a Stroop task, a participant sees the word 'RED' printed in blue ink and must say the ink color. Neuroimaging shows high anterior cingulate cortex activation on these incongruent trials. What does the conflict-monitoring model predict will happen on the next trial?

• A. ACC activation will decrease on the next trial as the conflict signal dissipates
• B. Dorsolateral prefrontal cortex engagement will increase on the next trial, implementing higher cognitive control in anticipation of continued demand
• C. The vmPFC will suppress the word-reading response on the next trial through emotional tagging
• D. Working memory will be automatically cleared by the ACC to prevent interference from the previous trial

Answer: (B)

The conflict-monitoring model predicts that high ACC activation on one trial signals the need for increased control on the next. The ACC detects conflict — here, between the competing responses 'say blue' and 'say red' — and recruits the dlPFC to amplify top-down control. This is a predictive, anticipatory function: the system doesn't just respond to errors, it uses conflict signals to prepare better performance. Neuroimaging confirms this: ACC activation on trial N predicts increased dlPFC engagement on trial N+1, and participants typically respond more accurately and slowly after high-conflict trials.

Question 2

A patient with damage to the ventromedial prefrontal cortex performs normally on IQ tests and logical reasoning tasks but consistently makes poor financial decisions and repeatedly chooses high-risk options on the Iowa Gambling Task despite losing money. What does Damasio's somatic marker hypothesis predict is the critical deficit?

• A. The patient cannot calculate probabilities or reason about expected value
• B. The patient lacks the physiological signals that tag risky options as emotionally aversive, so choices cannot be guided by accumulated experience of bad outcomes
• C. The patient's dorsolateral prefrontal cortex is also damaged, preventing maintenance of a strategy across trials
• D. The anterior cingulate is overactive, generating too many competing response options for the patient to resolve

Answer: (B)

Damasio's somatic marker hypothesis holds that the vmPFC integrates bodily/emotional signals with decision-relevant information. In healthy individuals, risky options generate weak physiological signals (elevated skin conductance, etc.) that mark them as dangerous before conscious deliberation completes. vmPFC patients lose this marking system — options that should feel aversive feel neutral. Intact logical reasoning (option A) makes this case especially instructive: the deficit is not in reasoning but in emotionally-guided valuation. This is why the patient keeps choosing risky decks despite being able to describe why they are risky.

Question 3

Patients with damage to the dorsolateral prefrontal cortex typically lose the ability to verbally state the rules of a task they are performing.

• T. True
• F. False

Answer: False

The characteristic deficit from dlPFC damage is perseveration, not rule amnesia. On tests like the Wisconsin Card Sorting Test, patients know when the sorting rule has changed — they can state it when asked — but they cannot hold the new rule online in a way that changes their actual behavior. They continue responding according to the old rule even while acknowledging it is wrong. This reveals that the dlPFC is specifically required to maintain task context in a form that drives action, not simply to store verbal knowledge of the rules.

Question 4

The anterior cingulate cortex functions as a conflict monitor — it detects situations where multiple competing responses are active simultaneously and signals the dorsolateral prefrontal cortex to increase cognitive control, rather than resolving the conflict itself.

• T. True
• F. False

Answer: True

This is the core of Botvinick et al.'s conflict-monitoring model. The ACC does not implement control; it detects when control is needed. High-conflict situations (incongruent Stroop trials, response uncertainty) activate the ACC, and this signal recruits the dlPFC to increase top-down control on subsequent processing. The ACC is the alarm; the dlPFC is the responder. This two-system architecture explains why the brain can adaptively modulate its level of cognitive engagement based on recent demands rather than running at maximum control at all times.

Question 5

Why do patients with vmPFC damage perform poorly on the Iowa Gambling Task even when their logical reasoning ability is fully intact? What does this tell us about the vmPFC's contribution to decision-making?

Model answer: The Iowa Gambling Task requires learning over many trials which decks are high-risk and avoiding them based on accumulated experience of losses. vmPFC patients can reason about the decks when asked directly — they can describe which are dangerous — but they don't feel them as dangerous. The vmPFC generates somatic markers: physiological signals (elevated arousal, bodily states) that tag options with emotional valence based on past experience. Without these signals, choices default to whatever seems immediately attractive or randomizes across options. Intact logic can identify the bad decks; the vmPFC is what makes them viscerally aversive in a way that actually steers decisions.

This case is a double dissociation that demonstrates the vmPFC's specific computational role. The dlPFC, by contrast, is needed for rule maintenance and working memory — patients with dlPFC damage would fail the Wisconsin Card Sorting Test but might do adequately on the gambling task. Together, the two lesion patterns confirm that executive control is not a single ability but a network of distinct functions: rule maintenance (dlPFC), value-based guidance (vmPFC), and conflict monitoring (ACC), each contributing something the others cannot supply.