Unique naturalistic brain mapping study provides valuable insights

Sleep patterns, physical activity, mood, and heart rate can influence brain connectivity in the short and long term, findings from a unique high-precision brain mapping study suggest.

Researchers have found that even small changes in heart rate or mood, or even a single sleepless night, can affect brain networks involved in attention, memory and cognition up to two weeks later.

This study is unusual in that a single participant is the principal investigator. The study results include data collected over approximately five months from cognitive and psychological tests and 30 functional MRI (fMRI) scans, and show that daily activities and physical factors vary from a few days to a few days. It provides valuable insight into how brain networks are affected over the course of a week.

The results highlight the importance of monitoring patients over time in their natural environment, rather than simply relying on patient visits, said lead researcher Ana Maria Triana, Ph.D., Department of Computer Science, Faculty of Science, Aalto University. , Department of Neuroscience, Department of Biomedical Engineering, Ph.D.) said. Finland spoke Medscape Medical News.

Such monitoring could leverage emerging technologies such as smartphones, which can track a person's sleep, physical activity and other patterns over time, she said.

“Our behavior and mental states are constantly shaped by our environment and experiences. However, the brain's functional connectivity in response to environmental, physiological, and behavioral changes over time scales ranging from days to months. Little is known about the response,” Triana added in the release.

The findings were published online on October 8, 2024. PLOS Biology.

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Mental state is influenced by various external factors. Triana's team is keen to study how behavior and brain activity in people with mental disorders “covary” over time.

The relationship between behavior and brain activity has traditionally been studied in cross-sectional designs that sample large numbers of individuals at specific points in time. However, such studies do not necessarily lead to similar results within a single individual.

A growing field of research known as precision functional mapping uses brain activity data collected from fMRI. This approach showed that individual-specific functional connectivity differs from group-average connectivity.

Triana said there is a clear need for longer-term studies with frequent measurement points outside the lab to study the relationship between brain and behavior.

“The brain is not an isolated organ. It responds to stimuli and it also responds to the environment,” she said.

Collecting “good data”

The current study only included Triana, an active 33-year-old with no history of severe mental, neurological, or chronic illness, as a participant.

Triana completed a series of questionnaires at baseline to assess personality traits (Big 5 Inventory) and stress (Perceived Stress Scale). [PSS]), mood (Patient Health Questionnaire-9) [PHQ-9]), anxiety (Generalized Anxiety Disorder 7-Item Scale), and sleep (Pittsburgh Sleep Quality Index).

Researchers collected responses to the PHQ-9 and PSS periodically throughout the study.

Triana also underwent 30 fMRI scans over 15 weeks to measure functional brain connectivity.

While in the scanner, Triana performed four tasks. The psychomotor alertness test is a cognitive test, and the dual N-back test measures attention and working memory. Write down your thoughts freely. And watching a movie (Part 2 of “The Grand Budapest Hotel''). The researchers also measured eye tracking, heart rate, and breathing rate.

Throughout the 133-day study, they used sensors, smartphones, and smart “rings” to collect daily information about sleep, physical activity, autonomic nervous system activity, and mood. She also completed occasional surveys asking about her stress, pain levels and mood.

Although she initially found the constant monitoring to be a nuisance, Triana quickly adapted and testing became part of her daily routine. She emphasized her determination to collect “good data”.

Effects of sleepless sleep

This study focused on variations in task performance that are reflected in the brain's functional connectivity. The researchers looked at the correlation between average blood oxygen level-dependent signals across the region of interest, along with other connectivity measures.

The researchers used two models for their analysis. The first accounted for factors from the previous day, and the second included a longer lag, examining how external factors influenced functional connectivity for up to 15 days.

This study revealed a significant relationship between the previous night's restless sleep and the brain's default mode network, fronto-parietal network (FPN), and somatomotor network. Sleep disruption was associated with decreased connectivity in most network connections.

“However, the effects of sleep duration on working memory are not immediately apparent and are observed with a two-week lag,” the researchers noted. Additionally, time spent awake in bed emerged as an important predictor of brain connectivity.

“In other words, spending more time in bed without sleeping increased the connectivity of selected links,” the researchers noted.

The results suggest that “multiple factors related to sleep quality, not just sleep duration, are important for the efficiency of node communication within and between networks,” the researchers added.

Triana pointed out that these findings are extremely important because sleep has a significant impact on almost all mental illnesses.

Regular physical activity is 'important'

Other analyzes showed that the previous day's inactivity time was a key factor influencing changes in the integration between networks in the FPN.

“Our results suggest that physical activity plays an important role in influencing changes in functional connectivity associated with working memory over time,” the authors write . “In particular, lower physical activity the previous day is associated with lower FPN integration.”

The researchers also found a link between recent physical activity, as well as activity over the past few days, and brain connectivity.

“These findings suggest that physical activity levels have both immediate and delayed effects on brain networks, suggesting that regular physical activity maintains optimal integration and communication of brain networks over time. “This supports the idea that it may be important for

Additional results support the notion that the association between brain connectivity and external factors extends beyond the previous day, suggesting a more long-term and persistent relationship between external influences and neural processes. suggests.

This study also showed that prior heart rate variability (HRV) is related to resting-state functional connectivity.

“Our results suggest that recent HRV (less than 5 days) is correlated with resting regional functional connectivity. Specifically, FPN is significantly influenced by the previous day's resting HRV. Although expected, this association had not previously been reported in a group-based study,” the authors said.

Additionally, past mood was associated with brain connectivity at rest and while watching movies.

“A once in a lifetime opportunity”

These data “offer a unique opportunity” to develop new methods for analyzing multivariate brain and sensor data, such as longitudinal studies that combine data from fMRI, smartphones, and wearables.

Triana's own research team aims to repeat the experiment, this time with patients diagnosed with mental disorders.

“The next step is to really understand how these variations occur in people diagnosed with the disorder and see if these changes correlate with symptoms,” she said. .

This could lead to a better understanding of the disorder and ultimately better treatments, she added.

This study included data from a single individual, limiting the generalizability of the results. Additionally, variables and time lags were analyzed separately in the second model, so there was no assessment of interactions between variables.

It is unclear whether the influence of external factors on functional connectivity extends beyond the 2-week period studied. Another possible limitation is that researchers have not investigated whether current connections may shape responses to future events.

comment on the research Medscape Medical NewsDr. Monica Rosenberg, associate professor of psychology at the University of Chicago, said the “shocking” paper was an “important illustration” that many aspects of daily life influence functional brain organization. Ta.

“We often use a single snapshot of brain data to infer a person's unique patterns, such as brain connectivity patterns and behavior, but changes within an individual over different time scales are important to us. “We need to consider how this will affect our measurements,” she said.

The study will enable future research in this area “by sharing a unique and densely sampled dataset,” Rosenberg added.

The study authors received support from the Ella and Georg Ernroot Foundation. Aalto University Aalto Brain Center; and the Finnish Research Council. The authors report no relevant disclosures of conflicts of interest.