Social Smiling and Laughter Are Linked to Enhanced Functional Brain Connectivity in Young Infants’ Default Mode Network
O. Allison, Caroline M. Kelsey, Tobias Grossmann
Developmental Psychobiology September 1, 2025 DOI: 10.1002/dev.70088 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study Preregistered Peer reviewed |
|---|---|
| Sample size | 35 |
| Population | 5-month-old infants |
| Topics | Default mode network |
| Key findings | Infants on average showed greater functional connectivity in the right than the left hemisphere of the Default-Mode Network. The preregistered measures of positive social engagement showed no positive associations with DMN connectivity, but a supplementary analysis found that higher smiling and laughter during daily caregiver interactions positively predicted left-hemisphere DMN connectivity. |
Abstract
Abstract The current study used functional near‐infrared spectroscopy (fNIRS) to investigate whether and how individual differences in positive social engagement among 5‐month‐old (N = 109; N = 35 final sample) infants relate to variability in functional connectivity in the human brain's Default‐Mode Network (DMN). Neuroimaging results showed that on average infants displayed greater functional connectivity in the right than in the left hemisphere of the DMN, adding to prior work indicating faster connectivity development in the right hemisphere. Results did not show any positive associations between our preregistered measures of positive social engagement and functional connectivity in the DMN. However, an additional analysis revealed that higher levels of infants’ smiling and laughter during daily social interactions with their caregivers positively predicted DMN functional connectivity in the left hemisphere. This suggests that individual differences in connectivity in a long‐range brain network implicated in a host of social and cognitive functions are associated with some aspects of infants’ positive social‐interactive behaviors.
Comparable studies
Other observational and cohort studies on default mode network, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| A default mode of brain function Normal adult human brain | 2001 | Observational study | |
| Resting-State Functional Connectivity Reflects Structural Connectivity in the Default Mode Network Healthy subjects | 2008 | Observational cohort | |
| Meditation experience is associated with increased cortical thickness Participants with extensive Insight meditation experience and matched controls | 2005 | Observational cohort | n = 20 |
| Meditation experience is associated with differences in default mode network activity and connectivity Experienced meditators and matched meditation-naive controls | 2011 | Observational cohort | |
| The precuneus/posterior cingulate cortex plays a pivotal role in the default mode network: Evidence from a partial correlation network analysis Healthy subjects | 2008 | Observational study |
Citations in the library
Cites 5
- The Brain's Default Mode Network Annual Review of Neuroscience May 4, 2015
- On the relationship between the “default mode network” and the “social brain” Frontiers in Human Neuroscience 2012
- The default mode network: where the idiosyncratic self meets the shared social world Nature Reviews Neuroscience January 22, 2021
- The default mode network and social understanding of others: what do brain connectivity studies tell us Frontiers in Human Neuroscience 2014
- Typical and disrupted brain circuitry for conscious awareness in full-term and preterm infants. Brain Communications 2022