Cognitive impact of polluted landscape and its neural basis: Evidence based on an Event-related Potential study

Abstract

Background Abundant studies suggest that long-term exposure to air pollution such as particulate matter (PM) can impair cognitive functions. Systemic and brain inflammation induced by pollutants are recognized as the major cause. Recently, new evidence emerged that even “mild” exposure to air pollution, for instance the visual impact of air pollutants can influence mental health and cognitive performance. Such effect is hard to capture but may lead to lowered productivity in daily life. Methods We utilized the event-related potential (ERP) technique to prove the existence of cognitive impact caused by polluted landscape. Thirty-two undergraduate students from Nanjing, China participated the experiment. A dot-probe task was designed as follows. Two horizontal or two vertical dots were presented at the left or right visual field. This target was preceded by a cue (i.e., clean or polluted pictures) at either the target location (valid trials) or at the opposite location (invalid trials). Participants were asked to respond to the target (vertical or horizontal) as soon and accurate as possible. We hypothesized invalid trials and trials cued by polluted pictures would cause participants longer reaction time. Meanwhile, averaged electroencephalogram signals, i.e. the event-related potential, of four trial types (clean-valid, polluted-valid, clean-invalid, polluted-invalid) were extracted to reveal the underlying neural cognitive basis. Results There is a significant positive effect of invalidation, pollution and their interactions on response time, which means visual impact of pollution distracts attention and slows decision-making process. ERP data shows a frontal negativity for pollution trials after 1600-2000ms cue onset. This may serve as the neural basis of how human brain reacts to polluted landscapes. Conclusions To our knowledge, this is the first study adopting ERP technique to investigate the cognitive impact of visual impact caused by air pollution. The findings call for attention to this subtle phenomenon especially in developing countries.