Using electroencephalography as a tool to understand auditory perception: Event-related and time-frequency analyses

Electroencephalography (EEG) largely reflects postsynaptic field potentials summed over many (hundreds of thousands of) neurons that are aligned in time and orientation. These electrical fields propagate in all directions such that determination of the sources of electrical fields measured at the surface of the head is much less accurate than localizations using fMRI. However, EEG can be measured with sub-millisecond timing resolution, offering a great advantage for studies of hearing. EEG can measure activity from various nuclei along the subcortical pathway, from primary and secondary auditory cortex and from cortical regions beyond. EEG can be particularly useful for understanding preconscious processing stages, and auditory processing in infants and others who can not make verbal responses. Traditional methods of analysis relate peaks (“components”) in the EEG time waveform to stages of processing. However, communication between brain circuits is reflected in neural oscillations, which can be measured through time-frequency analyses of EEG recordings. Such approaches reveal, for example, how frequency is encoded in the brainstem, and how predictive timing and predictive coding are accomplished in the cortex. I will illustrate these points with example applications largely from our lab and argue that EEG can greatly enhance our interpretation of psychophysical data.