I started my PhD in 2012. My main task during the first year was to perform neuropsychological assessments to children at schools using computerized tests. Specifically, we measured working memory and attention, two cognitive functions that are key for learning. The objective of this data collection was to study the effects of air pollution on the brain development of children. This was the BREATHE project. Over the course of one year, we went 4 times to 40 schools in the area of Barcelona, assessing almost 3,000 children in each of the visits. It was an exhausting but wonderful experience! All the effort was paid off by the impact that the project had on the society and, particularly, for the city of Barcelona. Different measures were implemented during the following years to reduce the impact of traffic-related exposures on the health of the population, and specifically one of the most vulnerable group of citizens, children. For instance, traffic was reduced near some of the most polluted schools.
One of the papers that was published using data from the BREATHE project was about the effects of air pollution on the functional connectivity of the brain. Functional connectivity is the synchronization of the activity in different brain areas. When two or more areas are simultaneously activated, we assume that they are connected, being part of the same network. In other words, we think that they communicate with each other and work together to generate, for instance, a thought or an action. These connections between brain areas change during maturation.
In this study, air pollution exposure was related to less mature functional brain connectivity, manifested as weaker connectivity between regions belonging to the same network (within-network connectivity) and stronger connectivity between regions from different networks (between-network connectivity)1.
At that time, I was very interested in brain imaging. I found out about this field during my bachelor’s degree in Psychology. I had the opportunity to learn about these techniques more in detail during my internship, which was on a project about the brain changes that take place during pregnancy2. I was involved in many diverse tasks, such as data collection and data analysis, my supervisors showed to me all the different aspects related to doing research using brain imaging. I was fascinated, that was a whole new world to me, so I decided that I wanted to become a researcher. For this reason, I did a master in Neuroscience and I continued my training doing my master thesis on a neuroimaging lab.
I decided that I wanted to learn more about neuroimaging when I was at the last phase of my PhD. I moved to Rotterdam (Netherlands) to work on a very novel technique of functional magnetic resonance imaging using data from the Generation R Study. This technique allows to capture different patterns of brain functional connectivity that take place during the scanning session (dynamic connectivity)3. So, instead of measuring a single average connectivity for each pair of brain areas (traditional approach), we measure multiple connectivity values for each pair of areas. This way, we can detect the changes that take place in brain connectivity across time.
This project represented an enormous challenge for me, first I had to understand the concept of dynamic connectivity, then I had to understand how the software to perform these analyses worked, then I had to generate a huge amount of scripts (in different coding languages) to analyze the data, and finally analyze the data, understand the results and communicate them. It was a fun project to work on, and I learnt a LOT, mostly programming skills, but all this learning came with a lot of frustration too. Altogether, this is one of the goals that I am particularly satisfied for having achieved. While I was working on this project I had the opportunity to collaborate on a study about air pollution and functional brain connectivity using data from Generation R4. This collaboration was the seed of my subsequent steps. My interest in going back to the field of environmental epidemiology was growing. So, I decided to apply the knowledge that I had acquired on brain imaging to continue exploring the effects of air pollution on brain function.
My recently published paper analyzed the associations between traffic-related exposures (air pollution and noise) and brain dynamic connectivity (explained above)5. We found that higher exposure levels were associated with spending more time in a connectivity configuration that is usually observed in younger children. Usually, at younger ages, children spend more time in connectivity patterns that are less organized in networks. In other words, with more connectivity between regions that belong to different networks. Older children spend more time in connectivity patterns that are more organized (brain areas that belong to the same network are connected among them). Therefore, this finding could indicate a delay in development. We also found other associations that could indicate compensatory mechanisms (i.e., higher exposure associated with more time spent in a more “mature” connectivity pattern). The potential impact of these differences on cognition and psychopathology remains to be explored by future studies.
I am currently looking for new challenges, involving working on different roles within the research environment. Those include: giving support to related scientific topics, contributing to policy making with a direct impact on society, and science communication.
References
1. Pujol J, Martínez-Vilavella G, Macià D, et al. Traffic pollution exposure is associated with altered brain connectivity in school children. Neuroimage. Apr 1 2016;129:175-184.
2. Hoekzema E, Barba-Müller E, Pozzobon C, et al. Pregnancy leads to long-lasting changes in human brain structure. Nat Neurosci. Feb 2017;20(2):287-296.
3. López-Vicente M, Agcaoglu O, Pérez-Crespo L, et al. Developmental Changes in Dynamic Functional Connectivity From Childhood Into Adolescence. Front Syst Neurosci. 2021;15:724805.
4. Pérez-Crespo L, Kusters MSW, López-Vicente M, et al. Exposure to traffic-related air pollution and noise during pregnancy and childhood, and functional brain connectivity in preadolescents. Environ Int. Jun 2022;164:107275.
5. López-Vicente M, Kusters M, Binter AC, et al. Long-Term Exposure to Traffic-Related Air Pollution and Noise and Dynamic Brain Connectivity across Adolescence. Environ Health Perspect. May 2025;133(5):57002.
