Empirical projects

The goal of this project is to study whether the neurons in your brain need to be spiking for you to be conscious. Answering this question has major public health consequences for administering anesthesia, treating people with brain injuries, and understanding what happens in the brain during near-death experiences.

In this study, we measure participants’ neurophysiological (EEG), subjective, and behavioral responses in states of normal wakefulness to visual and auditory stimuli that vary in granularity of subjective characteristics, such as meaningfulness. This study advances our understanding of consciousness by clarifying the relationship between stimulus complexity and measures of brain complexity and phenomenology.

In this proof-of-concept study, we analyzed three existing EEG datasets where 40 participants performed an active face perception task, an active visual oddball task, and a passive auditory oddball task. We computed the perturbational complexity index (PCIst) and Lempel-ziv complexity (LZc) for every trial and analyzed the results using Bayesian mixed-effects models. We found that i) PCIst was higher for meaningful visual stimuli but that LZc could be higher or lower; i) PCIst was higher for rare visual stimuli but LZc was lower; and ili) PCIst was higher for rare auditory stimuli but LZc did not discriminate rare vs. frequent auditory stimuli.

The purpose of this study was to investigate whether the selection of two common EEG reference methods (average-reference and mastoids-reference) had any measurable effects on event-related potentials (ERPs) evoked during a canonical visual oddball experiment. Although it was predicted based on prior studies that a P3 ERP effect would be observed in the target condition for both reference-selection methods, a trending P3 effect was only observed using the mastoids-reference method.