Artikel i Frontiers in Neuroscience om udvikling og validering af et nyt MMN-paradigme og erfarne CI-brugeres og normalthørende kontrollers neurale og adfærdsmæssige skelnen af forskellige niveauer af afvigelse i intensitet, tonehøjde, klangfarve og rytme.
Bjørn Petersen, Anne Sofie Friis Andersen, Niels Trusbak Haumann, Andreas Højlund, Martin Dietz, Franck Michel, Søren Kamaric Riis, Elvira Brattico, Peter Vuust
Cochlear implants (CIs) allow good perception of speech while music listening is unsatisfactory, leading to reduced music enjoyment. Hence, a number of ongoing efforts aim to improve music perception with a CI. Regardless of the nature of these efforts, effect measurements must be valid and reliable. While auditory skills are typically examined by behavioral methods, recording of the mismatch negativity (MMN) response, using electroencephalography (EEG), has recently been applied successfully as a supplementary objective measure. Eleven adult CI users and 14 normally hearing (NH) controls took part in the present study. To measure their detailed discrimination of fundamental features of music we applied a new multifeature MMN-paradigm which presented four music deviants at four levels of magnitude, incorporating a novel “no-standard” approach to be tested with CI users for the first time. A supplementary test measured behavioral discrimination of the same deviants and levels. The MMN-paradigm elicited significant MMN responses to all levels of deviants in both groups. Furthermore, the CI-users’ MMN amplitudes and latencies were not significantly different from those of NH controls. Both groups showed MMN strength that was in overall alignment with the deviation magnitude. In CI users, however, discrimination of pitch levels remained undifferentiated. On average, CI users’ behavioral performance was significantly below that of the NH group, mainly due to poor pitch discrimination. Although no significant effects were found, CI users’ behavioral results tended to be in accordance with deviation magnitude, most prominently manifested in discrimination of the rhythm deviant. In summary, the study indicates that CI users may be able to discriminate subtle changes in basic musical features both in terms of automatic neural responses and of attended behavioral detection. Despite high complexity, the new CI MuMuFe paradigm and the “no-standard” approach provided reliable results, suggesting that it may serve as a relevant tool in future CI research. For clinical use, future studies should investigate the possibility of applying the paradigm with the purpose of assessing discrimination skills not only at the group level but also at the individual level.
Artikel i Hearing Research, der giver en oversigt over den forskningsmæssige brug af Mismatch Negativity Response (MMN) til objektive målinger af høretæskler i patienter med cochlear implantater.
Risto Näätänen, Bjørn Petersen, Eila Lonka, Ritva Torppa, Peter Vuust
In the present article, we review the studies on the use of the mismatch negativity (MMN) as a tool for an
objective assessment of cochlear-implant (CI) functioning after its implantation and as a function of time
of CI use. The MMN indexes discrimination of different sound stimuli with a precision matching with that
of behavioral discrimination and can therefore be used as its objective index. Importantly, these measurements
can be reliably carried out even in the absence of attention and behavioral responses and
therefore they can be extended to populations that are not capable of behaviorally reporting their
perception such as infants and different clinical patient groups. In infants and small children with CI, the
MMN provides the only means for assessing the adequacy of the CI functioning, its improvement as a
function of time of CI use, and the efficiency of different rehabilitation procedures. Therefore, the MMN
can also be used as a tool in developing and testing different novel rehabilitation procedures. Importantly,
the recently developed multi-feature MMN paradigms permit the objective assessment of
discrimination accuracy for all the different auditory dimensions (such as frequency, intensity, and
duration) in a short recording time of about 30 min. Most recently, such stimulus paradigms have been
successfully developed for an objective assessment of music perception, too.
Artikel i Frontiers in Human Neuroscience om musikalsk træning med unge døve med cochlear implantater.
Cochlear implants (CIs) are primarily designed to assist deaf individuals in perception of speech, although possibilities for music fruition have also been documented. Previous studies have indicated the existence of neural correlates of residual music skills in postlingually deaf adults and children. However, little is known about the behavioral and neural correlates of music perception in the new generation of prelingually deaf adolescents who grew up with CIs. With electroencephalography (EEG), we recorded the mismatch negativity (MMN) of the auditory event-related potential (ERP) to changes in musical features in adolescent CI users and in normal-hearing age mates. EEG recordings and behavioral testing were carried out before (T1) and after (T2) a 2-week music training program for the CI users and in two sessions equally separated in time for normal-hearing (NH) controls. We found significant MMNs in adolescent CI users for deviations in timbre, intensity and rhythm, indicating residual neural prerequisites for musical feature processing. By contrast, only one of the two pitch deviants elicited an MMN in CI users. This pitch discrimination deficit was supported by behavioral measures, in which CI users scored significantly below the NH level. Overall MMN amplitudes were significantly smaller in CI users than in NH controls, suggesting poorer music discrimination ability. Despite compliance from the CI-participants, we found no effect of the music training, likely resulting from the brevity of the program. This is the first study showing significant brain responses to musical feature changes in prelingually deaf adolescent CI users and their associations with behavioral measures, implying neural predispositions for at least some aspects of music processing. Future studies should test any beneficial effects of a longer lasting music intervention in adolescent CI users.
Artikel i Neural Plasticity om CI-brugeres kortikale plasticitet i forb. rehabilitering umiddelbart efter implantation.
Cortical Plasticity after Cochlear Implantation
Bjørn Petersen, Albert Gjedde, Mikkel Wallentin and Peter Vuust
The most dramatic progress in the restoration of hearing takes place in the firstmonths after cochlear implantation. To map the brain activity underlying this process, we used positron emission tomography at three time points: within 14 days, three months, and six
months after switch-on. Fifteen recently implanted adult implant recipients listened to running speech or speech-like noise in four sequential PET sessions at each milestone. CI listeners with postlingual hearing loss showed differential activation of left superior
temporal gyrus during speech and speech-like stimuli, unlike CI listeners with prelingual hearing loss. Furthermore, Broca’s area was activated as an effect of time, but only in CI listeners with postlingual hearing loss. The study demonstrates that adaptation to
the cochlear implant is highly related to the history of hearing loss. Speech processing in patients whose hearing loss occurred after the acquisition of language involves brain areas associated with speech comprehension, which is not the case for patients whose
hearing loss occurred before the acquisition of language. Finally, the findings confirm the key role of Broca’s area in restoration of speech perception, but only in individuals in whom Broca’s area has been active prior to the loss of hearing.
Artikel i Psychomusicology om musikalsk træning med voksen CI-brugere
Singing in the Key of Life – A Study on Effects of Musical Ear Training after Cochlear Implantation
Bjørn Petersen, Malene Vejby Mortensen, Mads Hansen, Peter Vuust
Docent Bjørn ”Bønne” Petersen har fået publiceret en artikel I det amerikanske tidsskrift Psychomusicology: Music, Mind & Brain. Artiklen beskriver et studium, som undersøgte effekten af et seks måneders individuelt musikalsk høretræningsforløb på opfattelsen af musik, tale og emotionel prosodi hos døvblevne voksne med et såkaldt cochlear implantat (CI). Atten nyopererede CI-brugere medvirkede i projektet – halvdelen som deltagere i den musikalske høretræningsgruppe, den anden halvdel som deltagere i en kontrolgruppe. Høretræningen baserede sig dels på aktiv musikudfoldelse med fokus på sang og rytme, dels på computerbaserede lytteøvelser udviklet til formålet. Undersøgelsen viste en markant forbedring af musikopfattelsen i almindelighed og evnen til at skelne klangfarve, melodisk kontur og rytme i særdeleshed, efter træning. Der kunne ikke dokumenteres en effekt i forhold til taleforståelsen, men evnen til at genkende emotionel prosodi udviklede sig signifikant hurtigere hos deltagerne i musikgruppen end hos kontrolgruppen. Alle deltagerne gennemførte programmet og viste stor begejstring for træningen, navnlig sangaktiviteterne. Bjørn og hans medforfatter konkluderer, at det beskrevne musikalske høretræningsprogram kan udgøre et værdifuldt supplement til den auditive genoptræning som tilbydes nyopererede CI-brugere. Både som bidrag til et forbedret udbytte af musik og en forbedret evne til at skelne finere detaljer i tale og dermed på sigt muligvis også en forbedret generel livskvalitet.