Portable Functional Neuroimaging as an Environmental Epidemiology Tool: A How-To Guide for the Use of fNIRS in Field Studies

Abstract

The widespread application of functional neuroimaging within the field of environmental epidemiology has the potential to greatly enhance our understanding of how environmental toxicants affect brain function. Because many epidemiological studies take place in remote and frequently changing environments, it is necessary that the primary neuroimaging approach adopted by the epidemiology community be robust to many environments, easy to use, and, preferably, mobile. Here, we outline our use of functional near-infrared spectroscopy (fNIRS) to collect functional brain imaging data from Costa Rican farm workers enrolled in an epidemiological study on the health effects of chronic pesticide exposure. While couched in this perspective, we focus on the methodological considerations that are necessary to conduct a mobile fNIRS study in a diverse range of environments. Thus, this guide is intended to be generalizable to all research scenarios and projects in which fNIRS may be used to collect functional brain imaging data in epidemiological field surveys. https://doi.org/10.1289/EHP2049.

Figure 1.

Participant engaged in a computer-based functional near-infrared spectroscopy (fNIRS) task in Costa Rica. Here, an equipment shed is used as the scan location. Because of activity outside of the shelter (off photo right), we chose to occlude the participant’s vision in that direction with the use of poster board. In the photo, the pertinent equipment needed to conduct a mobile computer-based fNIRS study has been labeled.

Figure 2.

Photos show a greenhouse that we used as an assessment location in Costa Rica. (A) The three other stations included in the epidemiological study on health effects of pesticide exposure in farm workers. It was common for these stations to be held outside. However, it was raining on this specific day, so we conducted the functional near-infrared spectroscopy (fNIRS) assessment inside the greenhouse, which provided shelter and power. (B) Optode arrangement on a participant. (C) Because of the high levels of ambient light in the greenhouse, we used dark overcaps to cover the fNIRS optodes/detectors and to decrease the noise introduced by sunlight. The overcaps also compressed the fNIRS optodes onto the head. (D) Our equipment setup. (E) Panoramic photo taken behind the participant as he completed the fNIRS tasks while being scanned.