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Summary: A new study reveals that older adults are more likely than younger people to interpret ambiguous facial expressions as happy rather than angry. Using brain imaging, the researchers found that this positivity bias is related to increased activity in the locus coeruleus (the small “blue dot” in the brain that regulates alertness and stress) and its connection to the dorsolateral prefrontal cortex.
This neural adaptation may help older adults maintain emotional well-being even when their cognitive abilities decline. The findings suggest that age-related brain changes protect against negative prejudice and support resilience to stress and cognitive decline.
Key facts:
Positivity bias with age: Older adults tend to view ambiguous faces as happy, while younger adults interpret them as threatening. Brain adaptation: The locus coeruleus becomes more active in older adults, improving connectivity with the frontal lobe for emotional control. Protective role: This neural adaptation can safeguard mental health and cognitive function during aging.
Source: NTNU
Do you find it easy to perceive the people you know as happy and positive? Or are you attentive and look for signs of dissatisfaction and anger in their facial expressions?
Your perceptions may be related to how old you are. A new study from the Norwegian University of Science and Technology (NTNU) shows that older people tend to interpret ambiguous facial expressions as positive to a greater extent than younger people.
“We know little about how the brain interprets ambiguous signals. At the same time, we know that uncertainty affects people’s mental well-being. Being able to interpret the ambiguous signals we receive from our environment is crucial for our well-being,” says researcher Maryam Ziaei from the Kavli Institute for Systems Neuroscience at NTNU.
Fight or flight center
Zianei studies how a small organ at the bottom of our brain, called the locus coeruleus, works when we try to understand other people’s emotions.
The name Locus coeruleus is Latin and can be translated as “the blue spot” or “the blue zone.” The body plays an important role when we concentrate on solving tasks. It helps capture our attention when we are distracted, such as when we are walking down the street absorbed in our own thoughts and suddenly a car approaches behind us.
The “blue spot” is no more than a centimeter and a half high and only a few millimeters wide, but it plays an important role in our response to stress and panic, as it produces norepinephrine, the body’s “fight or flight” hormone.
“This structure regulates how alert and attentive we are. With too little activity, we will be sleepy and lethargic, while more activity makes us awake and focused. But we can also have too much activity in the locus coeruleus, then we become distracted and experience stress,” Ziaei said.
Adapt to cognitive decline
Perceiving another person’s emotional signals can be challenging if these signals are contradictory. If you are talking to a person who is smiling and looking angry at the same time, you should be alert and pay attention to understand whether the person is friendly or not. This means that the small blue organ in the brain must function optimally.
At the same time, our cognitive abilities tend to deteriorate with age. It now appears that the Locus coeruleus is able to adapt and compensate for this weakening.
To learn more about this, researchers at the Kavli Institute had people of different ages study images of faces with different expressions, while measuring brain activity.
A total of 75 people aged 21 to 30 and 69 people aged 67 to 75 participated in the study, half divided between women and men of both age groups.
The images they had to interpret showed faces that went from being clearly happy, more or less ambiguous, to clearly angry.
“We saw that participants took longer to interpret ambiguous expressions, while older participants interpreted them as happy to a greater extent,” Ziaei said.
More active among the elderly
“It may be that the younger we are, the more we tend to interpret these ambiguous signals negatively, as if they represent a threat. In people with good mental health, this will change with age,” he said.
The researchers measured brain activity and took photographs of the brain while the participants evaluated the images. They found that older participants showed more activity than younger participants in the Locus coeruleus when the images were completely ambiguous.
The researchers also saw that older participants had greater activity in the connection between the locus coeruleus and the frontal lobe, more specifically the dorsolateral prefrontal cortex. This part of the frontal lobe is particularly related to cognitive control, memory and attention.
Before the study, the study participants were thoroughly surveyed using questionnaires. They were asked a series of questions related to mental health, such as the occurrence of anxiety or depression, emotion regulation and empathy. This allowed the researchers to create a profile of each participant’s state of mental well-being.
“We also see a correlation between how much this connection between the LC and the dorsolateral prefrontal cortex is activated and how well the person feels. We found that older participants who had greater activity in the connection between the locus coeruleus and the dorsolateral prefrontal cortex also had better well-being,” Ziaei says.
Protects against cognitive decline
Researchers believe this shows that the locus coeruleus adapts as we age, compensating for reduced cognitive abilities.
Dorsolateral prefrontal cortex function, or weaknesses in its functioning, is also associated with diseases such as Parkinson’s disease and Alzheimer’s. This makes the findings even more interesting, according to the researchers.
The identification of this signaling pathway may bring researchers closer to the specific treatment of emotional difficulties in depression in old age or in neurodegenerative diseases.
The fact that the locus coeruleus responds more actively to sensory impressions that arouse attention has a protective effect against cognitive decline as people age.
An example is when you suddenly hear the sound of a car behind you, even though you are totally absorbed in your own thoughts, a phenomenon that has been demonstrated by other research.
“If we can make changes here, whether with stimulation, with medication or with exercise, we may be able to affect the function of this part of the brain. Not just in people with diseases, but in all people. What we want to understand here is the connection between our ability to process social information and how it relates to feeling well mentally,” Ziaei says.
The researchers worked closely with Heidi Jacob from Harvard Medical School, Boston, USA.
Key questions answered:
A: Older adults were more likely to perceive uncertain facial expressions as positive compared to younger participants.
A: The locus coeruleus, a small region that regulates alertness and attention, showed increased activity and connectivity with the prefrontal cortex in older adults.
A: It suggests that aging brains adapt to promote well-being, potentially protecting against emotional decline and cognitive diseases such as Alzheimer’s.
About this research news in neuroscience, aging and facial perception
Author: Nancy Bazilchuk
Source: NTNU
Contact: Nancy Bazilchuk – NTNU
Image: 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. Neuroscience Magazine
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, becomes increasingly difficult with age, especially as cognitive resources decline. Managing these challenges requires adaptive neural mechanisms that are essential for maintaining mental well-being.
The locus ceruleus (LC), the brain’s main source of norepinephrine, regulates attention, arousal, and stress response. With extensive cortical connections, the LC supports adaptation to cognitive demands and resolution of conflicting signals from the environment, particularly in old age.
Previous research suggests that LC interacts with the prefrontal cortex (PFC) during high-conflict tasks. However, it is still unclear whether LC activity and its connectivity with the PFC supports the processing of emotional ambiguity and contributes to emotional well-being in healthy aging.
To address this gap, we used 7T-MRI to examine LC function in 75 younger adults (25.8 ± 4.02 years, 35 women) and 69 older adults (71.3 ± 4.1 years, 35 women) during the transformed facial emotion recognition task with variable ambiguity: unambiguous, intermediate, and absolute ambiguity.
Behaviorally, participants had longer response times and lower confidence during the absolute ambiguity condition, while older adults perceived ambiguous faces as happy more often than younger adults.
Neuroimaging results revealed that older adults exhibited greater LC activity and better connectivity with the dorsolateral PFC (dlPFC) during absolute ambiguity compared to younger adults.
This greater connectivity in older adults was linked to better self-reported task-independent mental well-being questionnaires and higher emotional resilience scores derived from principal components analysis.
Overall, these findings suggest that greater LC activity supports the management of cognitively demanding tasks, while greater LC-dlPFC connectivity promotes emotional well-being, highlighting the role of this neural pathway in healthy aging.
