SOLID-STATE LIGHTING FLICKER STUDY
Objectives: The present study investigated the effects of luminous modulation or flicker on concurrently recorded visual event-related potentials (ERPs) to performance and accuracy in a Stroop and sentence reading tasks.
Methods: Three flicker rates were presented at 0, 100, and 500 Hz in separate blocks of trials while ERPs were recorded and participants performed a Stroop and sentence reading task.
Results: Although the sentence reading and Stroop task did not support the main hypothesis that 100 Hz would adversely affect reading and reaction times, respectively, the source analysis revealed that the 500 Hz response had approximately the same mean source activation for incongruent and congruent tasks which was not the case for 100 Hz where the incongruent task resulted in significantly higher activation for the early latencies (i.e. 60-100 ms, 170-210 ms) in the left hemisphere and in the 170-210 ms range in the right hemisphere. The overall activation localized to the pulvinar nucleus of the thalamus.
Conclusions: Source analysis results suggest that 500 Hz flicker had an effect on the secondary visual pathway as evidenced by localization of the pulvinar. Furthermore, source activation for 500 Hz was not significantly different for congruent and incongruent trials whereas 100 Hz resulted in higher average brain activation between these trials in the Stroop task suggesting that more effort was required to complete this task. The amount of time under each lighting condition was, by all standards, minimal — only about 15 minutes. Yet, even with this short exposure, we found data suggestive of important influences of flicker on performance and brain outcomes, particularly in the left hemisphere.
The NICER lab also completed three studies last fall. Two of these projects involved the study of affective processing; or, how the brain processes emotional stimuli in the environment. These studies exposed participants to images with emotional content, in order to detect differences in the electrical potentials these images evoked.The third project our lab completed was a food-craving study. Previous research has indicated that food-craving correlates with evoked potentials thought to be related to the limbic system. This study involved measuring participants’ Ghrelin levels (a hormone known to stimulate the feeling of hunger), and correlated these values with evoked potentials recorded while viewing pictures of food. This is a collaborative project with Drs. Alfonso Abizaid and Kim Hellemans of Carleton University.