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Abstract

The objective of this study was to localize the intracerebral generators for auditory steady-state responses. The stimulus was a continuous 1000-Hz tone presented to the right or left ear at 70 dBSPL. The tone was sinusoidally amplitude-modulated to a depth of 100% at 12, 39, or 88 Hz. Responses recorded from 47 electrodes on the head were transformed into the frequency domain. Brain electrical source analysis treated the real and imaginary components of the response in the frequency domain as independent samples. The latency of the source activity was estimated from the phase of the source waveform. The main source model contained a midline brainstem generator with two components (one vertical and lateral) and cortical sources in the left and right supratemporal plane, each containing tangential and radial components. At 88 Hz, the largest activity occurred in the brainstem and subsequent cortical activity was minor. At 39 Hz, the initial brainstem component remained and significant activity also occurred in the cortical sources, with the tangential activity being larger than the radial. The 12-Hz responses were small, but suggested combined activation of both brainstem and cortical sources. Estimated latencies decreased for all source waveforms as modulation frequency increased and were shorter for the brainstem compared to cortical sources. These results suggest that the whole auditory nervous system is activated by modulated tones, with the cortex being more sensitive to slower modulation frequencies.

Network Analysis of Functional Brain Connectivity Driven by Gamma-Band Auditory Steady-State Response in Auditory Hallucinations

“…The maximum ASSR response to the 40-Hz stimulus mainly occurred at the frontal–central and parietal–occipital regions, with a symmetrical distribution. These results are consistent with the findings of Herdman [20]. The connections in the normal subjects between different regions are shown.…”

Sustained Selective Attention to Competing Amplitude-Modulations in Human Auditory Cortex

“…Consistent with previous data [58], Figures 5A–C show the strongest responses in fronto-central and temporo-posterior scalp regions (see red regions/crosses in Figure 5A; channels Fz, F1, F2, F3, F4, FCz, FC3, FC4, C3, TP9, TP10, P7, P9, P10, PO9, PO10, O9, O10; see Figure S3 for single-subject data). These regions, which we considered to reflect stimulus phase-locked activity of neuronal populations in bilateral AC based on previous EEG source analyses [40], [61], [62], were then selected for channel-averaged analyses testing for attention-related effects. Averaging across 10, 20, or 50 channels yielded similar results, suggesting that the specific number of selected channels played little role as in related studies [12], [13].…”

Age-related changes in envelope-following responses at equalized peripheral or central activation

“…The primary generators of EFRs have shown to be the auditory brainstem and midbrain [Herdman et al, 2002, Kuwada et al, 2002, Picton et al, 2003, Chandrasekaran and Kraus, 2010, Parthasarathy and Bartlett, 2012]. Purcell et al .…”