The Endocannabinoid System: A New Player in the Neurochemical Control of. Vestibular Function? Paul F. Smith, John C. Ashton, Cynthia L. Darlington.
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The Endocannabinoid System: A New Player in the Neurochemical Control of Vestibular Function? Paul F. Smith, John C. Ashton, Cynthia L. Darlington Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago, Dunedin, New Zealand Abstract The results of recent clinical trials of medicinal cannabinoid drugs show that dizziness and vertigo are commonly reported adverse side-effects. Cannabinoid CB1 receptors were initially thought to be expressedin very low densities in the vestibular nucleus complex (VNC). Recent immunohistochemical studies have challenged this idea and suggested that CB1 receptors may exist in numbers similar to the granule cell layer of the cerebellum. This, together with evidence that brainstem CB1 receptors have a higher efficacy than those in many other parts of the brain and that application of cannabinoids can elicit potent electrophysiological effects in VNC neurons, suggests that CB1 receptors and their endogenous ligands may be important in central vestibular function. In this review, we consider the potential clinical significance of the endocannabinoid system for the development of vestibular disorders, the effects of recreational cannabis use and the therapeutic use of medicinal cannabinoids.
Envelope Following Responses to Natural Vowels Steven J. Aiken, Terence W. Picton Rotman Research Institute, Baycrest Centre for Geriatric Care and University of Toronto, Toronto, Canada Abstract Envelope following responses to natural vowels were recorded in 10 normal hearing people. Responses were recorded to individual vowels (/ /, /i/, /u/) with a relatively steady pitch, to / / with a variable and steady pitch, and to a multivowel stimulus (/ ui/) with a steady pitch. Responses were analyzed using a Fourier analyzer, so that recorded responses could follow the changes in the pitch. Significant responses were detected for all subjects to / /, /i/ and /u/ with the time required to detect a significant response ranging from 6 to 66 s (average time: 19 s). Responses to / / and / ui/ were detected in all subjects, but took longer to demonstrate (average time: 73 s). These results support the use of a Fourier analyzer to measure envelope following responses to natural speech.
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On the Relationship between Speech- and Nonspeech-Evoked Auditory Brainstem Responses J.H. Songa, b, K. Banaia, b, e, N.M. Russoa, b, e, N. Krausa-e
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Auditory Neuroscience Laboratory, Departments of Communication Sciences, c Neurobiology and Physiology, d Otolaryngology, and e Northwestern Institute for Neuroscience, Northwestern University, Evanston, Ill., USA b
Abstract Auditory brainstem response (ABR) reflects activation of the neural generators along the ascending auditory pathway when a sound is heard. In this study, we explored the relationship between brainstem encoding of click and speech signals in normal-learning children and in those with language-based learning problems. To that end, ABR was recorded from both types of stimuli. We found that the normal pattern of correlation between click- and speech-evoked ABRs was disrupted when speech-evoked ABRs were delayed. Thus, delayed responses to speech were not indicative of clinically abnormal responses to clicks. We conclude that these two responses reflect largely separate neural processes and that only processes involved in encoding complex signals such as speech are impaired in children with learning problems.
Neurotological and Neuroanatomical Changes in the Connexin-26-Related HID/KID Syndrome I. Todta, H.C. Henniesc, W. Küsterd, J. Smollee, G. Rademacherb, S. Mutzeb, D. Bastaa, A. Eisenschenka, A. Ernsta Departments of aOtolaryngology and bRadiology at UKB, Hospital of the University of Berlin (Charité Medical School), cDepartment of Molecular Genetics and Gene Mapping, Max Delbrück Center for Molecular Medicine, Berlin, and dDepartment of Dermatology, Tomesa Clinic, Bad Salzschlirf, Germany;
Abstract The phenotype of the HID (hystrix-like ichthyosis, deafness)/KID (keratitis, ichthyosis, deafness) syndrome is primarily characterized by skin changes. However, the connexin 26 (Cx 26) autosomal dominant mutation underlying this syndrome is of special neurotological interest. In the present paper, the clinical pattern, audiovestibular and neuroimaging findings and the detailed genetic analysis of 4 patients with identical HID/KID-associated mutation D50N of Cx 26 are reported. The audiological test results demonstrated profound sensorineural hearing loss in all of the patients. Neurotological testing revealed inconsistent abnormalities in dynamic posturography (sensory organization test), but the vestibular ocular reflex upon caloric irrigation was normal in all patients. Vestibular-evoked myogenic potential testing for otolith function (saccule) showed a regular response in 1 patient and pathologic responses in 3 patients, while subjective haptic vertical (utricular function) testing was normal in all of the patients. CCT showed an extended (in length), but very thin (in diameter) bony lining between the basal portion of the internal auditory canal and the vestibule in the 3 scanned patients. Our study provides evidence for functionally intact semicircular canals and normal utricular function in subjects with the autosomal dominant D50N mutation of Cx 26, in contrast to saccular function which was generally compromised and hearing loss which was profound.
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Over-Complete Discrete Wavelet Transformation of the Normal Auditory Brainstem Response Improves Prediction of Outcome following Severe Acute Closed Head Injury
Wayne J. Wilsona, Jane A. Chapplea, Kate M. Phillipsa, Kylie T. Snella, Andrew P. Bradleyb, Ross Darnellc
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Division of Audiology, School of Health and Rehabilitation Sciences, bSchool of Information Technology and Electrical Engineering, and cSchool of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia Abstract Previous research has shown that complex statistical analysis (discriminant function analysis) of a 'normal' auditory brainstem response (ABR) result can improve this measure's ability to predict subject outcome following severe acute closed head injury (ACHI). We hypothesized that adding the ABR's timefrequency information to such an analysis would improve this predictive value even further. 'Normal' ABR results were sampled from 69 severe ACHI subjects (22 of whom died and 47 of whom lived) and their time-frequency information extracted using an over-complete discrete wavelet transformation (OCDWT). A series of logistic regression analyses then showed correct predictions of death and survival as follows: ABR measures only 72 and 89% (respectively), ABR OCDWT measures only 82 and 89% (respectively), and ABR and ABR OCDWT measures combined 86 and 93% (respectively). These results showed that the addition of time-frequency information can improve the ability of the 'normal' ABR result to predict outcome following severe ACHI.
Speech Recognition at 1-Year Follow-Up in the Childhood Development after Cochlear Implantation Study: Methods and Preliminary Findings
Laurie S. Eisenberga, Karen C. Johnsona, Amy S. Martineza, Carol G. Cokelyb, Emily A. Tobeyb, Alexandra L. Quittnerc, Nancy E. Finkd, Nae-Yuh Wangd, John K. Niparkod, and the CDaCI Investigative Team a
House Ear Institute, Los Angeles, Calif., bCallier Center for Communication Disorders, University of Texas at Dallas, Dallas, Tex., cDepartment of Psychology, University of Miami, Miami, Fla., dJohns Hopkins University, Baltimore, Md., USA Abstract The Childhood Development after Cochlear Implantation (CDaCI) study is a longitudinal multicenter investigation designed to identify factors influencing spoken language in young deaf children with cochlear implants. Normal-hearing peers serve as controls. As part of a comprehensive evaluation battery, a speech recognition hierarchy was designed to assess how well these children recognize speech stimuli across developmental stages. Data were analyzed for the earliest measures in 42 pairs of children reaching 1 year of follow-up. A number of children in the cochlear implant group who met criteria for testing approached levels of performance similar to the normal-hearing controls, and some could identify sentences in competition. These results demonstrate the responsiveness of the speech recognition hierarchy in tracking emergent skills from a sample of the CDaCI cohort. Copyright © 2006 S. Karger AG, Basel
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