Summary: A new study finds that older adults are more likely than younger people to interpret ambiguous facial expressions as happy rather than angry. High-resolution brain imaging links this positivity bias to increased activity in the locus coeruleus — a small brainstem nucleus that helps regulate alertness and stress — and to stronger coupling between the locus coeruleus and the dorsolateral prefrontal cortex. These neural changes may support emotional resilience and help preserve well-being despite age-related cognitive decline.
The research suggests an age-related neural adaptation: as some cognitive skills decline, older adults appear to recruit the locus coeruleus and its connections with frontal control regions to favor positive interpretations of uncertain social cues. This may reduce negative bias and protect mental health in later life.
Key Facts:
- Positivity bias with age: Older adults more often judge ambiguous faces as happy, whereas younger adults tend to interpret the same expressions as threatening or negative.
- Neural adaptation: In older participants the locus coeruleus showed greater activity and stronger functional connectivity with the dorsolateral prefrontal cortex, a frontal region important for cognitive control, memory and attention.
- Protective role: Stronger locus coeruleus–prefrontal coupling was associated with better self-reported mental well-being, suggesting this pathway may help guard against emotional decline as people age.
Source: NTNU
Do you tend to see people as cheerful and approachable, or are you more likely to notice signs of displeasure or anger in their faces?
A study from the Norwegian University of Science and Technology (NTNU) shows that age influences how we resolve uncertainty in social signals. Older adults were more likely than younger adults to read ambiguous facial expressions as positive. The researchers used detailed brain imaging to understand which neural systems underlie that bias.
“We still know relatively little about how the brain resolves ambiguous social signals, even though uncertainty strongly affects mental well-being,” says Maryam Ziaei at NTNU’s Kavli Institute for Systems Neuroscience. “Being able to interpret unclear cues from others is important for social interaction and emotional health.”
Fight-or-flight center
Ziaei and colleagues focused on a tiny brainstem nucleus called the locus coeruleus (Latin for “blue spot”). Though small — only about one to one-and-a-half centimeters long — the locus coeruleus produces norepinephrine, a neurotransmitter that mediates arousal, attention and the body’s fight-or-flight responses. Its widespread connections help the brain shift between low arousal and focused attention.
“This structure helps regulate how alert and attentive we are,” Ziaei explains. “Very low activity can make us drowsy and slow, while optimal activity sharpens attention. Excessive activity, on the other hand, can cause distraction and stress.”
Adapting to cognitive decline
Reading someone’s emotions becomes harder when cues are mixed or contradictory — for example, when a person’s smile is paired with an angry gaze. In such situations the brain must resolve conflicting information to decide whether the person is friendly or hostile. Because cognitive abilities typically decline with age, the researchers asked whether the locus coeruleus adapts to help older adults interpret ambiguous social cues.
To investigate this, the team recruited 144 adults: 75 younger participants aged 21–30 and 69 older participants aged 67–75, balanced roughly by sex in each group. While undergoing high-resolution 7T MRI, participants judged faces that had been morphed across a spectrum from clearly happy to clearly angry, including intermediate and fully ambiguous expressions.
Behaviorally, everyone was slower and less confident when judging fully ambiguous faces. Crucially, older adults were more likely to select “happy” for ambiguous faces than the younger group.
Greater locus coeruleus activity in older adults
Imaging showed that older adults exhibited stronger activation in the locus coeruleus during trials with complete ambiguity. In addition, older adults displayed increased functional connectivity between the locus coeruleus and the dorsolateral prefrontal cortex (dlPFC), a frontal region central to cognitive control, working memory and attention.
The researchers collected detailed questionnaires about mood, anxiety, emotional regulation and empathy before the brain scans. They found that older participants with higher locus coeruleus–dlPFC coupling also reported better mental well-being and greater emotional resilience on these measures.
“We see a relationship between the strength of this connection and how well the person feels,” Ziaei notes. “Older adults who show stronger locus coeruleus–prefrontal engagement also tend to report higher well-being.”
Potential protection against cognitive impairment
The authors interpret these results as evidence that the locus coeruleus adapts with age to compensate for declining cognitive resources, helping older adults resolve ambiguous social information in a way that favors positive interpretations. Because weakened dlPFC function is implicated in neurodegenerative conditions such as Parkinson’s and Alzheimer’s disease, understanding this pathway could have broader clinical relevance.
Identifying how locus coeruleus signaling supports emotional processing could lead to targeted approaches — for example, behavioral interventions, stimulation or pharmacological strategies — aimed at improving social information processing and emotional health in older adults or in people with neurodegenerative illness.
The research team collaborated with Heidi Jacob from Harvard Medical School.
Key Questions Answered:
A: Older adults were more likely than younger adults to interpret uncertain facial expressions as positive.
A: The locus coeruleus, a small brainstem nucleus that regulates alertness and attention, showed increased activity and enhanced connectivity with the dorsolateral prefrontal cortex in older adults.
A: The results suggest that aging brains may adapt neural circuits to support emotional well-being, potentially helping to protect against emotional decline and cognitive disorders.
About this neuroscience, aging, and facial perception research news
Author: Nancy Bazilchuk
Source: NTNU
Contact: Nancy Bazilchuk – NTNU
Image: The image is credited to Neuroscience News
Original Research: Closed access. “Age-Related Increase in Locus Ceruleus Activity and Connectivity with the Prefrontal Cortex during Ambiguity Processing” by Maryam Ziaei et al., Journal of Neuroscience.
Abstract
Age-Related Increase in Locus Ceruleus Activity and Connectivity with the Prefrontal Cortex during Ambiguity Processing
Interpreting ambiguous environmental cues, such as facial expressions, grows more difficult with age as cognitive resources decline. Adaptive neural mechanisms are therefore essential to maintain mental well-being. The locus coeruleus (LC), the brain’s main source of norepinephrine, regulates attention, arousal and stress responses and connects broadly with cortical regions. These connections may help the aging brain meet increased cognitive demands and resolve conflicting signals.
Using ultra-high-field 7T MRI, researchers compared LC function in 75 younger adults (average ~25.8 years) and 69 older adults (average ~71.3 years) while participants completed a facial emotion recognition task with morphs that varied from unambiguous to fully ambiguous. Behaviorally, response times increased and confidence decreased for fully ambiguous faces; older adults chose “happy” for ambiguous faces more often than younger adults.
Neuroimaging revealed that older adults exhibited greater LC activity and enhanced LC–dorsolateral prefrontal cortex connectivity during absolute ambiguity. Importantly, stronger LC–dlPFC coupling in older participants correlated with better self-reported mental well-being and higher emotional resilience scores. These findings support a model in which heightened LC activity helps meet cognitively demanding tasks while enhanced LC–prefrontal connectivity promotes emotional well-being in healthy aging, highlighting a neural pathway that may contribute to resilience across the lifespan.