title: Positron Emission Tomography Imaging Reveals Auditory and Frontal Cortical Regions Involved with Speech Perception and Loudness Adaptation.
abstract: Considerable progress has been made in the treatment of hearing loss with auditory implants. However, there are still many implanted patients that experience hearing deficiencies, such as limited speech understanding or vanishing perception with continuous stimulation (i.e., abnormal loudness adaptation). The present study aims to identify specific patterns of cerebral cortex activity involved with such deficiencies. We performed O-15-water positron emission tomography (PET) in patients implanted with electrodes within the cochlea, brainstem, or midbrain to investigate the pattern of cortical activation in response to speech or continuous multi-tone stimuli directly inputted into the implant processor that then delivered electrical patterns through those electrodes. Statistical parametric mapping was performed on a single subject basis. Better speech understanding was correlated with a larger extent of bilateral auditory cortex activation. In contrast to speech, the continuous multi-tone stimulus elicited mainly unilateral auditory cortical activity in which greater loudness adaptation corresponded to weaker activation and even deactivation. Interestingly, greater loudness adaptation was correlated with stronger activity within the ventral prefrontal cortex, which could be up-regulated to suppress the irrelevant or aberrant signals into the auditory cortex. The ability to detect these specific cortical patterns and differences across patients and stimuli demonstrates the potential for using PET to diagnose auditory function or dysfunction in implant patients, which in turn could guide the development of appropriate stimulation strategies for improving hearing rehabilitation. Beyond hearing restoration, our study also reveals a potential role of the frontal cortex in suppressing irrelevant or aberrant activity within the auditory cortex, and thus may be relevant for understanding and treating tinnitus.
authors.affiliation: Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany; Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Berding
authors.affiliation: Department of Medical Physics and Radiation Protection, Hannover Medical School, Hannover, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Wilke
authors.affiliation: Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany; Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany.
authors.forename: Thilo
authors.initials: T
authors.lastname: Rode
authors.affiliation: Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany.
authors.forename: Cathleen
authors.initials: C
authors.lastname: Haense
authors.affiliation: Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany.
authors.forename: Gert
authors.initials: G
authors.lastname: Joseph
authors.affiliation: Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany.
authors.forename: Geerd J
authors.initials: GJ
authors.lastname: Meyer
authors.affiliation: Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany; Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Mamach
authors.affiliation: Department of Otolaryngology, Charité, University Medicine Berlin, Berlin, Germany.
authors.forename: Minoo
authors.initials: M
authors.lastname: Lenarz
authors.affiliation: Department of Medical Physics and Radiation Protection, Hannover Medical School, Hannover, Germany.
authors.forename: Lilli
authors.initials: L
authors.lastname: Geworski
authors.affiliation: Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany.
authors.forename: Frank M
authors.initials: FM
authors.lastname: Bengel
authors.affiliation: Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany; Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lenarz
authors.affiliation: Departments of Biomedical Engineering and Otolaryngology-Head & Neck Surgery, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Hubert H
authors.initials: HH
authors.lastname: Lim
mesh_terms: D000161:Acoustic Stimulation; D000222:Adaptation, Physiological; D000328:Adult; D000368:Aged; D001303:Auditory Cortex / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D001931:Brain Mapping; D001933:Brain Stem / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D003051:Cochlea / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D019929:Cochlear Implantation; D003054:Cochlear Implants; D004566:Electrodes; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D006312:Hearing Loss, Bilateral / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D020127:Recovery of Function; D013060:Speech; D013067:Speech Perception / Q000502:physiology*