Mismatch Negativity Brain Response Research Articles

Preperceptual Human Number Sense for Sequential Sounds, as Revealed by Mismatch Negativity Brain Response?

Humans and some other species can nonlinguistically operate on the quantities of things or events, including sounds. Whether this ability is restricted to conscious percepts of sounds developing in approximately 200 ms is, however, unclear. To this end, we recorded the mismatch negativity (MMN) brain response, an index of preperceptual auditory change detection, of adult humans who passively listened to rare sequences of four 50-ms tones ("deviants") interspersed among frequently repeated tones ("standards"). Each tone was either 1000 or 1500 Hz in frequency. Deviants differed from standards in a ratio of the tones of the 2 frequencies. MMN was found for deviants by 160 ms from the onset of their largest ratio difference from standards (2:2 vs. 4:0), suggesting some ability of the human brain to operate on the number of sequential sounds of specific frequencies at a preperceptual time scale.

Long‐term exposure to noise impairs cortical sound processing and attention control

Long-term exposure to noise impairs human health, causing pathological changes in the inner ear as well as other anatomical and physiological deficits. Numerous individuals are daily exposed to excessive noise. However, there is a lack of systematic research on the effects of noise on cortical function. Here we report data showing that long-term exposure to noise has a persistent effect on central auditory processing and leads to concurrent behavioral deficits. We found that speech-sound discrimination was impaired in noise-exposed individuals, as indicated by behavioral responses and the mismatch negativity brain response. Furthermore, irrelevant sounds increased the distractibility of the noise-exposed subjects, which was shown by increased interference in task performance and aberrant brain responses. These results demonstrate that long-term exposure to noise has long-lasting detrimental effects on central auditory processing and attention control.

Pre-attentive categorization of vowel formant structure in complex tones

It has been demonstrated that vowel information can be extracted from speech sounds without attention focused on them, despite widely varying non-speech acoustic information in the input. The present study tested whether even complex tones that were constructed based on F0, F1 and F2 vowel frequencies to resemble the defining features of speech sounds, but were not speech, are categorized pre-attentively according to vowel space information. The Mismatch Negativity brain response was elicited by infrequent tokens of the complex tones, showing that the auditory system can pre-attentively categorize speech information on the basis of the minimal, defining auditory features. The human mind extracts the language-relevant information from complex tones despite the non-relevant variation in the sound input.

Pre-attentive categorization of vowel formant structure in complex tones

It has been demonstrated that vowel information can be extracted from speech sounds without attention focused on them, despite widely varying non-speech acoustic information in the input. The present study tested whether even complex tones that were constructed based on F0, F1 and F2 vowel frequencies to resemble the defining features of speech sounds, but were not speech, are categorized pre-attentively according to vowel space information. The Mismatch Negativity brain response was elicited by infrequent tokens of the complex tones, showing that the auditory system can pre-attentively categorize speech information on the basis of the minimal, defining auditory features. The human mind extracts the language-relevant information from complex tones despite the non-relevant variation in the sound input.

Mismatch Negativity Brain Response as an Index of Speech Perception Recovery in Cochlear-Implant Recipients

Speech-discrimination performance and the mismatch negativity (MMN) response elicited by vowel changes were used to track vowel-perception improvement of 5 adult cochlear-implant (CI) recipients. The MMN was recorded several times during the first 3 years after CI activation. Artefacts, presumably caused by CI, contaminated most of the brain responses until 1 year after CI activation. We found that speech discrimination improved over time and the MMN, observed in all patients after 2.5 years of CI use, was first seen for the larger vowel difference and later for the smaller one.

The perception of speech sounds by the human brain as reflected by the mismatch negativity brain response

This article outlines the contribution of the mismatch negativity (MMN) to our understanding of the perception of speech sounds by the human brain. MMN data indicate that each sound, both speech and non-speech, develops its neural representation (corresponding to the percept of this sound) in the neurophysiological substrate of auditory sensory memory. The accuracy of this representation, determining how accurately this sound is discriminated from the other sounds, can be probed with the MMN separately for any auditory feature (such as frequency or duration). Furthermore, the accuracy of discriminating different speech sounds can also be evaluated by using the MMN. In addition, the MMN data show that the perception of the phonemes, and probably also of larger linguistic units (syllables and words), is based on permanent language-specific phonetic traces that can be located with magnetoencephalographic (MEG) recordings in the posterior part of the left-hemisphere auditory cortex. These traces appear to serve as recognition models for the corresponding speech sounds in speech perception. MMN studies further suggest that these language-specific traces for the mother tongue develop during the first few months of life. Moreover, the MMN can also be used as an index of the development of such traces for a foreign language learned later in life.