Does Cognitive Load Affect Measures of Consciousness?
André Sevenius Nilsen, Johan Frederik Storm, Bjørn Erik Juel
Brain sciences September 13, 2024 DOI: 10.3390/brainsci14090919
Summary
A significant finding reveals that the P300b event-related potential, which indicates conscious awareness of unexpected auditory patterns, was notably influenced by cognitive load during a demanding working memory task. In a study involving 12 participants, while P300b responses changed under cognitive strain, measures based on signal diversity from electroencephalography (EEG) remained stable. This suggests that signal diversity metrics could be reliable for assessing consciousness in clinical settings where attention and sensory processing are compromised, providing a promising tool for better understanding consciousness.
Abstract
Developing and testing methods for reliably measuring the state of consciousness of individuals is important for both basic research and clinical purposes. In recent years, several promising measures of consciousness, grounded in theoretical developments, have been proposed. However, the degrees to which these measures are affected by changes in brain activity that are not related to changes in the degree of consciousness has not been well tested. In this study, we examined whether several of these measures are modulated by the loading of cognitive resources. We recorded electroencephalography (EEG) from 12 participants in two conditions: (1) while passively attending to sensory stimuli related to the measures and (2) during increased cognitive load consisting of a demanding working memory task. We investigated whether a set of proposed objective EEG-based measures of consciousness differed between the passive and the cognitively demanding conditions. The P300b event-related potential (sensitive to conscious awareness of deviance from an expected pattern in auditory stimuli) was significantly affected by concurrent performance on a working memory task, whereas various measures based on signal diversity of spontaneous and perturbed EEG were not. Because signal diversity-based measures of spontaneous or perturbed EEG are not sensitive to the degree of cognitive load, we suggest that these measures may be used in clinical situations where attention, sensory processing, or command following might be impaired.