The mismatch negativity (MMN) in basic research of central auditory processing: a review.

In the present article, the basic research using the mismatch negativity (MMN) and analogous results obtained by using the magnetoencephalography (MEG) and other brain-imaging technologies is reviewed. This response is elicited by any discriminable change in auditory stimulation but recent studies extended the notion of the MMN even to higher-order cognitive processes such as those involving grammar and semantic meaning. Moreover, MMN data also show the presence of automatic intelligent processes such as stimulus anticipation at the level of auditory cortex. In addition, the MMN enables one to establish the brain processes underlying the initiation of attention switch to, conscious perception of, sound change in an unattended stimulus stream. 2007 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

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Invited review The mismatch negativity (MMN) in basic research of central auditory processing: A review

Adolescence has been characterized by risk-taking behaviors that can lead to fatal outcomes. This study examined the neurobiological development of neural systems implicated in reward-seeking behaviors. Thirty-seven participants (7-29 years of age) were scanned using event-related functional magnetic resonance imaging and a paradigm that parametrically manipulated reward values. The results show exaggerated accumbens activity, relative to prefrontal activity in adolescents, compared with children and adults, which appeared to be driven by different time courses of development for these regions. Accumbens activity in adolescents looked like that of adults in both extent of activity and sensitivity to reward values, although the magnitude of activity was exaggerated. In contrast, the extent of orbital frontal cortex activity in adolescents looked more like that of children than adults, with less focal patterns of activity. These findings suggest that maturing subcortical systems become disproportionately activated relative to later maturing top-down control systems, biasing the adolescent's action toward immediate over long-term gains.

https://www.jneurosci.org/content/jneuro/26/25/6885.full.pdf

Earlier development of the accumbens relative to orbitofrontal cortex might underlie risk-taking behavior in adolescents.

The mismatch negativity: a review of underlying mechanisms.

Tinnitus is an auditory phantom sensation (ringing of the ears) experienced when no external sound is present. Most but not all cases are associated with hearing loss induced by noise exposure or aging. Neuroscience research has begun to reveal how tinnitus is generated by the brain when hearing loss occurs, and to suggest new avenues for management and prevention of tinnitus following hearing injuries. Downregulation of intracortical inhibition induced by damage to the cochlea or to auditory projection pathways highlights neural processes that underlie the sensation of phantom sound.

/pdf/the-neuroscience-of-tinnitus-36nufw0byp.pdf

The Neuroscience of Tinnitus

Physiological correlates of speech acoustics are particularly important to study in humans because it is uncertain whether animals process speech the same way humans do. Studying the physiology of speech processing in humans, however, typically requires the use of noninvasive physiological measures. This is what we attempted in a recent study (Won, Tremblay, Clinard, Wright, Sagi, and Svirsky, JASA 2016) which examined the hypothesis that neural representations of formant frequencies may help predict vowel recognition. To test the hypothesis, the frequency-following response (FFR) and vowel recognition were obtained from 38 normal-hearing listeners using four different vowels. This allowed direct comparisons between behavioral and neural data in the same individuals. FFR was used because it reflects temporal encoding of formant frequencies below about 1500 Hz. Four synthetic vowels with formant frequencies below 1500 Hz were used. Duration was 70 ms for all vowels to eliminate temporal cues and to make id...

Neural encoding of vowel formant frequency in normal-hearing listeners

Electrophysiological Measures of Hearing, Speech and Language

Computerized Speech Research Environment (v. 4.2)—Userʼs Guide and Software

The ability of normal‐hearing adults to identify and discriminate novel speech sounds improves with training. Neurophysiological changes associated with this improvement include increased duration and area, as well as shortened onset latency, of the mismatch negativity (MMN) [N. Kraus et al., J. Cog. Neurosci. 7, 25–32 (1995); K. Tremblay et al., J. Acoust. Soc. Am. 102, 1–12 (1997)]. The MMN is a passively elicited, preattentive, auditory event‐related potential that reflects auditory discrimination and echoic memory [R. Naatanen et al., Acta Psychol. 42, 313–329 (1978)]. To date, little is known about the time course of neurophysiological change and the manifestation of learning. The present study examined the time course of perceptual learning and its relation to changes in the MMN with the expectation that cortically evoked potentials could provide insight into the biological processes underlying perceptual learning and serve as a clinical tool for evaluating change during efforts of (re)habilitation in the communicatively impaired. Specifically, it was found that neurophysiological change is apparent in the MMN preceding behavioral improvement. This suggests that auditory training alters the neural activity that provides the necessary coding of the speech stimuli and those changes are later integrated into functional behavior.

Kelly L. Tremblay

Papers

Neural encoding of vowel formant frequency in normal-hearing listeners

Electrophysiological Measures of Hearing, Speech and Language

Computerized Speech Research Environment (v. 4.2)—Userʼs Guide and Software

The time course of learning: Neurophysiologic changes during speech training

Auditory Rehabilitation and the Aging Brain