The adaptive pattern of the auditory N1 peak revealed by standardized low-resolution brain electromagnetic tomography

Abstract

The N1 peak in the late auditory evoked potential (LAEP) decreases in amplitude following stimulus repetition, displaying an adaptive pattern. The present study explored the functional neural substrates that may underlie the N1 adaptive pattern using standardized Low Resolution Electromagnetic Tomography (sLORETA). Fourteen young normal hearing (NH) listeners participated in the study. Tone bursts (80 dB SPL) were binaurally presented via insert earphones in trains of ten; the inter-stimulus interval was 0.7 s and the inter-train interval was 15 s. Current source density analysis was performed for the N1 evoked by the 1st, 2nd and 10th stimuli (S1, S2 and S10) at three different timeframes that corresponded to the latency ranges of the N1 waveform subcomponents (70–100, 100–130 and 130–160 ms). The data showed that S1 activated broad regions in different cortical lobes and the activation was much smaller for S2 and S10. Response differences in the LAEP waveform and sLORETA were observed between S1 and S2, but not between the S2 and S10. The sLORETA comparison map between S1 and S2 response showed the activation was located in the parietal lobe for the 70–100 ms timeframe, the frontal and limbic lobes for the 100–130 ms timeframe, and the frontal lobe for the 130–160 ms timeframe. These sLORETA comparison results suggest a parieto-frontal network that might help to sensitize the brain to novel stimuli by filtering out repetitive and irrelevant stimuli. This study demonstrates that sLORETA may be useful for identifying generators of scalp-recorded event related potentials and for examining the physiological features of these generators. This technique could be especially useful for cortical source localization in individuals who cannot be examined with functional magnetic resonance imaging or magnetoencephalography (e.g., cochlear implant users).

Age Differences in the Neuroelectric Adaptation to Meaningful Sounds

“…Therefore, in the present study, the N1 wave appears to reflect the general encoding of acoustic energy elicited by sound onset irrespective of the early spectro-temporal details and/or location of the stimulus. The lack of domain-specificity in N1 suppression is consistent with the notion that the N1 wave reflects the registration of sound stimuli and/or signal detection as opposed to signal discrimination [8]. Another possibility is that the complex meaningful sounds used in the present study did not contain sufficient category-specific acoustic details and/or the complex sounds stimulated semantic processing in higher cortical centers that goes beyond early N1 responses [60,61].…”

“…Among them, the N1a is most prominent at temporal electrodes; the N1b at midline central electrodes and the N1c extends to fronto-polar and right temporal electrodes [6,8]. Despite this distinction, Perrault and Picton [58] were unable to dissociate the N1a from the N1b subcomponent in a variety of experimental manipulations on healthy young adults.…”

“…However, this model cannot be used to explain the results of our study as we found no effect on the latencies of the N1 and P2 waves across the stimulus train. In a prior study using pure tones, Zhang et al [8] found a significant stimulus order effect on the N1 latency, i.e., reducing N1 latencies with progressing stimulus positions along the stimulus train. Their results were indeed consistent with the facilitation model [2].…”

“…From a physiological perspective, neural adaptation reflects a process by which the brain encodes stimulus invariance and likely occurs because of neural refractoriness in which a neuron can only respond to a stimulus after a sufficient period of recovery following a response to a preceding stimulus [4,5]. Studies using event-related potentials (ERPs) have consistently reported a reduction in the amplitude of a negative wave peaking at about 100 ms after sound onset (N1) with stimulus repetition [6,7,8]. Other studies have shown reduced P2 amplitudes (positive wave peaking at about 180 ms post-stimulus) for sounds coming from identical spatial locations [9].…”

Caracterização dos potenciais evocados auditivos corticais em indivíduos com longo tempo de uso do implante coclear

“…Desde que Davis (1939) descreveu que a percepção do som pode alterar o eletroencefalograma do humano ouvinte, e que estas modificações podem ser extraídas deste registro, inúmeros pesquisadores têm utilizado os potenciais evocados auditivos (PEA) para descrever a resposta do sistema auditivo frente à estimulação (SHALLOP, 1993;GROENEN et al, 1996;EGGERMONT et al, 1997;KILENY et al, 1997;OKUSA et al, 1999;SHARMA et al, 2002;PANTEV et al, 2002;BEYNON et al, 2002;SHARMA et al, 2004;SINGH et al, 2004;GILLEY et al, 2005;SHARMA et al, 2005;KELLY et al, 2005;ROMAN et al, 2005;GORDON et al, 2005;BAUER et al, 2006;DORMAN et al, 2007;GIRAUD et al, 2007;MCNEILL et al, 2007;KRAL & EGGERMONT, 2007;GILLEY et al, 2008;BROWN et al, 2008;KURNAZ et al, 2009;MCNEILL et al, 2009;MARIAM et al, 2009;JOHNSON, 2009;FRIESEN et al, 2009;HANCOCK et al, 2010;KRAL & SHARMA, 2011;ZHANG et al, 2011;CASTAÑEDA-VILLA et al, 2012).…”