Mismatch Negativity Elicited by Verbal and Nonverbal Stimuli: Comparison with Potential N1

THIEME 160 Original Research Mismatch Negativity Elicited by Verbal and Nonverbal Stimuli: Comparison with Potential N1 Mirtes Brückmann1 Michele Vargas Garcia2 1 Graduate Program in Disorders of Human Communication, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil 2 Department of Speech-Language Pathology, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil Address for correspondence Mirtes Brückmann, Master, Av Roraima, 1000, prédio 26, Bairro Camobi, Santa Maria, SC, CEP: 97105-900, Brazil (e-mail: ). Int Arch Otorhinolaryngol 2020;24(2):e160–e165. Abstract Keywords ► evoked potentials ► auditory ► adult ► hearing ► auditory cortex Introduction Mismatch negativity (MMN) is a long latency auditory evoked potential, represented by a negative wave, generated after the potential N1 and visualized in a resulting wave. Objective To identify the time of occurrence of MMN after N1, elicited with verbal and nonverbal stimuli. Methods Ninety individuals aged between 18 and 56 years old participated in the study, 39 of whom were male and 51 female, with normal auditory thresholds, at least 8 years of schooling, and who did not present auditory processing complaints. All of them underwent audiologic anamnesis, visual inspection of external auditory meatus, pure tone audiometry, speech audiometry, acoustic immittance measures and the dichotic sentence identification test as a screening for alterations in auditory processing, a requirement to participate in the sample. The MMN was applied with two different stimuli, with these being da/ta (verbal) and 750 Hz and 1,000 Hz (nonverbal). Results There was a statistically significant difference between the latency values of the N1 potential and the MMN with the two stimuli, as well as between the MMN with verbal and nonverbal stimuli, and the latency of the MMN elicited with da/ta being greater than that elicited with 750 Hz and 1,000 Hz, which facilitated its visualization. Conclusion The time of occurrence of MMN after the N1 elicited with verbal stimuli was 100.4 ms and with nonverbal stimuli 85.5 ms. Thus, the marking of the MMN with verbal stimuli proved to be more distant from N1 compared with the nonverbal stimuli. Introduction Among the auditory evoked potentials, there are long latency potentials, also called cortical and/or cognitive potentials, that evaluate the neuroelectric activity in the cerebral cortex, in response to an acoustic or electrical stimulus.1,2 These potentials are most commonly used to evaluate auditory abilities objectively.3–5 The long latency auditory evoked potential (LLAEP) record shows a sequence of negative (N) and positive (P) peaks, among which are the potential P1-N1-P2-N2-P300 and mismatch negativity (MMN). The P1-N1-P2 complex represent the corti- received August 11, 2018 accepted July 3, 2019 published online November 4, 2019 DOI https://doi.org/ 10.1055/s-0039-1696701. ISSN 1809-9777. cal potentials and provide information on the arrival on the auditory stimuli to the cortex.6 The potential N2 is considered a mixed potential, and the P300, a cognitive potential that depends on the attention of the subject to be elicited.7 The MMN is a LLAEP represented by a negative wave generated after the potential N1 and visualized in a resulting wave.8 This potential is elicited passively, and it is not necessary for the individual to pay attention to the sound stimuli;9,10 it arises when the cortex automatically discriminates between two different sound stimuli, based on their already acquired sound memory.11–13 Copyright © 2020 by Thieme Revinter Publicações Ltda, Rio de Janeiro, Brazil Mismatch Negativity Elicited by Verbal and Nonverbal Stimuli This potential has its main origin in the auditory cortex, but depending on the characteristics of the stimuli used, it can be generated in different places of the cortex,12,14,15 or in the frontal cortex, thalamus, and hippocampus.16 Mismatch negativity elicited by stimuli that differ in frequency can be generated in the temporal and frontal lobes, especially in the right hemisphere.14 The MMN elicited by verbal stimuli originates in the left hemisphere of the temporal cortex.17 Mismatch negativity is a good tool to perform an objective evaluation in patients with difficulty or impairment in communication, or those whose auditory discrimination is under investigation.18 When using verbal stimuli in an evaluation, for example, this potential may complement the behavioral evaluation that may not be sufficient in some cases for cognitive or linguistic reasons, as they provide additional information about the biological processes involved in speech processing. In addition, this information may direct the rehabilitation and therapeutic follow-up of the individual.19,20 However, Brazilian researchers rarely use this potential, further reducing their chances of participating in clinical evaluation, which may be due to the fact that it is a potential with a certain “difficulty” to be analyzed, considering the parameters of registration, equipment and age of the evaluated individuals, this may cause a variation in the identification of the valley. Therefore, there is a need for better details of both the recording parameters and stimuli, as well as the potential marking technique, which is little explored in the studies already performed. Therefore, the objective of this study is to identify the time of occurrence of MMN after N1, elicited with verbal and nonverbal stimuli. Method This is an observational and descriptive study, with a convenience sample, which was approved by the Human Research Ethics Committee, under the number CAAE 54827416.5.0000.5346. The study followed the principles of beneficence established through resolutions 466/1221 and 510/16.22 All individuals invited to participate in the study were informed about the procedures and, after acceptance, all of them signed the informed consent form. Adult subjects aged between 18 and 59 years old of both genders were invited to participate in this research. This population was chosen because there are not many studies on the parameters of MMN in this age group in the SmartEP equipment (Intelligent Hearing Systems, Miami, FL, USA) yet. Also, we chose not to divide the sample into different age groups, since, according to one study,23 which compared adult individuals aged between 18 and 24 years with elderly individuals between 60 and 80 years, there was no difference in the latency and amplitude of MMN for these age groups. Another study,24 that evaluated individuals aged between 18 and 80 years, only observed a decrease in amplitude with increasing age. However, the authors evaluated a group of more advanced age than that of the group in the current study, which could justify this result. These facts allow the justification of non-segregation of the sample in the current study in different age groups. Brückmann, Garcia To participate in the survey, volunteers (...truncated)