Differential modulation of brain responses to face stimuli after exposure to urban versus forest environments
Presenter: Eszter Toth
Authors: Eszter Toth, Jane Raymond, Ali Mazaheri
Organization: University of Birmingham, UK
There is currently a number of epidemiological studies which suggest that an urban environment increases the risk for the development of Schizophrenia as well as mood disorders (Mortensen et a., 1999; Peen et al., 2010). In addition empirical studies have observed greater amygdala activation, a key region for emotional face processing and attention allocation as a function of an individual’s urban upbringing during stress (Lederbogen et al., 2011).
In the current 64 channel electroencephalogram (EEG) study we investigated whether transient exposure to videos of an urban versus natural environment impacted the visual evoked responses elicited by face stimuli in 24 healthy young adults. The volunteers watched 20 minute videos showing either a forest or a city walk, and subsequently performed an oddball paradigm with neutral and emotional faces as the standard and target stimuli respectively.
We focused our analysis on the early visual evoked potentials locked to the onset of the face stimuli, and found significant differences depending on the videos preceding the oddball task. Specifically, we found that the P1 over the right hemisphere was larger after the city than the forest video. Furthermore, the N170 occurred earlier over the right than the left hemisphere after the forest, but not the city video. The P1 results suggest that people attend more to faces after an urban than nature exposure video. This increased attention, which may deplete resources very fast, might account for why city living has been reported to be related to greater mental fatigue (Lee et al., 2015). The N170 latency effect may show that after nature exposure, participants process the less expressive, right side of the faces faster than the left side, perhaps to be less distracted by the task irrelevant emotional dimension of the faces. This would suggest better attentional control after nature than urban exposure.
Keywords: environment, face processing