Questions: Prefrontal-Parietal Attention Networks and Control

Question 1

A person is deeply absorbed in a cognitively demanding task when a loud, unexpected sound occurs nearby. Compared to when they are at rest, they are slower to orient toward the sound. Which network-level mechanism best explains this?

• A. The auditory cortex is suppressed during demanding tasks, reducing perception of sounds
• B. Strong engagement of the dorsal attention network suppresses ventral attention network activity, raising the threshold for stimulus-driven attentional capture
• C. The temporoparietal junction is selectively activated during demanding tasks, blocking re-orienting
• D. Dopamine released during focused work chemically inhibits sensory processing

Answer: (B)

The dorsal attention network (DAN: DLPFC + IPS) and ventral attention network (VAN: IFG + TPJ) interact competitively. When DAN engagement is high — as during demanding voluntary attention — VAN activity is suppressed, reducing the system's responsiveness to salient but task-irrelevant stimuli. The auditory cortex is not suppressed; the bottleneck is the attentional re-orienting system, not low-level perception.

Question 2

Which brain region is most critical for automatic attentional re-orienting toward unexpected, behaviorally relevant stimuli?

• A. Dorsolateral prefrontal cortex (DLPFC)
• B. Intraparietal sulcus (IPS)
• C. Right temporoparietal junction (TPJ)
• D. Primary visual cortex (V1)

Answer: (C)

The right temporoparietal junction (TPJ) is the core node of the ventral attention network, which mediates bottom-up, stimulus-driven attentional capture. DLPFC and IPS belong to the dorsal attention network and support voluntary, top-down control. V1 is a sensory area, not an attentional control node. The right-lateralization of the VAN explains why right TPJ damage produces severe left-field spatial neglect.

Question 3

The dorsal and ventral attention networks operate in parallel and independently, each handling separate categories of attention without directly influencing each other.

• T. True
• F. False

Answer: False

The DAN and VAN interact competitively, not independently. When the DAN is strongly engaged, VAN activity is suppressed — reducing distractibility. When the VAN is activated by a salient event, it can interrupt or override DAN-mediated top-down control. Understanding this competitive balance is central to the prefrontal-parietal framework; the two networks are nodes in an ongoing negotiation over attentional allocation.

Question 4

Damage to the right temporoparietal junction is more likely than damage to the left to produce hemispatial neglect of the contralesional visual field.

• T. True
• F. False

Answer: True

The ventral attention network — responsible for re-orienting attention to unexpected, behaviorally relevant stimuli — is strongly right-lateralized, centered on the right IFG and TPJ. When the right TPJ is damaged, the re-orienting system fails: attention cannot be captured by left-field stimuli even when they are dramatically salient. Left TPJ damage produces much less severe neglect because the right hemisphere can partially compensate for bilateral attentional functions.

Question 5

According to the DAN/VAN framework, why might stimulant medications that enhance prefrontal dopamine signaling reduce distractibility in individuals with ADHD?

Model answer: Enhanced prefrontal dopamine strengthens dorsal attention network (DAN) engagement, which competitively suppresses ventral attention network (VAN) activity. Since ADHD is associated with reduced prefrontal control over the VAN — leaving individuals highly susceptible to stimulus-driven attentional capture — boosting DAN function raises the threshold at which salient but task-irrelevant stimuli can trigger VAN-mediated re-orienting, improving the signal-to-noise ratio for voluntary attention.

The key causal chain is: prefrontal dopamine → stronger DLPFC activity → stronger DAN → competitive suppression of VAN → reduced attentional capture by distractors. This maps the pharmacological mechanism directly onto the network-level framework. It also illustrates a general principle: drugs that modulate neurotransmission produce behavioral effects by shifting the balance between large-scale networks, not by acting on isolated neurons.