Multisensory attention training for treatment of tinnitus

Spiegel, D. P. et al. Multisensory attention training for treatment of tinnitus. Sci. Rep. 5, 10802; doi: 10.1038/srep10802 (2015).Tinnitus is the conscious perception of sound with no physical sound source. Some models of tinnitus pathophysiology suggest that networks associated with attention, memory, distress and multisensory experience are involved in tinnitus perception. The aim of this study was to evaluate whether a multisensory attention training paradigm which used audio, visual, and somatosensory stimulation would reduce tinnitus. Eighteen participants with predominantly unilateral chronic tinnitus were randomized between two groups receiving 20 daily sessions of either integration (attempting to reduce salience to tinnitus by binding with multisensory stimuli) or attention diversion (multisensory stimuli opposite side to tinnitus) training. The training resulted in small but statistically significant reductions in Tinnitus Functional Index and Tinnitus Severity Numeric Scale scores and improved attentional abilities. No statistically significant improvements in tinnitus were found between the training groups. This study demonstrated that a short period of multisensory attention training reduced unilateral tinnitus, but directing attention toward or away from the tinnitus side did not differentiate this effect.This work was supported by a grant from Links Research and Grants Corporation to G.D.S

On chirp stimuli and neural synchrony in the suprathreshold auditory brainstem response

The chirp-evoked ABR has been regarded as a more synchronous response than the click-evoked ABR, referring to the belief that the chirp stimulates lower-, mid-, and higher-frequency regions of the cochlea simultaneously. In this study a variety of tools were used to analyze the synchronicity of ABRs evoked by chirp- and click-stimuli at 40 dB HL in 32 normal hearing subjects aged 18 to 55 years (mean=24.8 years, SD=7.1 years). Compared to the click-evoked ABRs, the chirp-evoked ABRs showed larger wave V amplitudes, but an absence of earlier waves in the grand averages, larger wave V latency variance, smaller FFT magnitudes at the higher component frequencies, and larger phase variance at the higher component frequencies. These results strongly suggest that the chirp-evoked ABRs exhibited less synchrony than the click-evoked ABRs in this study. It is proposed that the temporal compensation offered by chirp stimuli is sufficient to increase neural recruitment (as measured by wave V amplitude), but that destructive phase interactions still exist along the cochlea partition, particularly in the low frequency portions of the cochlea where more latency jitter is expected. The clinical implications of these findings are discussed. (C) 2010 Acoustical Society of America. [DOI: 10.1121/1.3436527

Smaller spared subcortical nuclei are associated with worse post-stroke sensorimotor outcomes in 28 cohorts worldwide

Up to two-thirds of stroke survivors experience persistent sensorimotor impairments. Recovery relies on the integrity of spared brain areas to compensate for damaged tissue. Deep grey matter structures play a critical role in the control and regulation of sensorimotor circuits. The goal of this work is to identify associations between volumes of spared subcortical nuclei and sensorimotor behaviour at different timepoints after stroke. We pooled high-resolution T1-weighted MRI brain scans and behavioural data in 828 individuals with unilateral stroke from 28 cohorts worldwide. Cross-sectional analyses using linear mixed-effects models related post-stroke sensorimotor behaviour to non-lesioned subcortical volumes (Bonferroni-corrected, P < 0.004). We tested subacute (≤90 days) and chronic (≥180 days) stroke subgroups separately, with exploratory analyses in early stroke (≤21 days) and across all time. Sub-analyses in chronic stroke were also performed based on class of sensorimotor deficits (impairment, activity limitations) and side of lesioned hemisphere. Worse sensorimotor behaviour was associated with a smaller ipsilesional thalamic volume in both early (n = 179; d = 0.68) and subacute (n = 274, d = 0.46) stroke. In chronic stroke (n = 404), worse sensorimotor behaviour was associated with smaller ipsilesional putamen (d = 0.52) and nucleus accumbens (d = 0.39) volumes, and a larger ipsilesional lateral ventricle (d = -0.42). Worse chronic sensorimotor impairment specifically (measured by the Fugl-Meyer Assessment; n = 256) was associated with smaller ipsilesional putamen (d = 0.72) and larger lateral ventricle (d = -0.41) volumes, while several measures of activity limitations (n = 116) showed no significant relationships. In the full cohort across all time (n = 828), sensorimotor behaviour was associated with the volumes of the ipsilesional nucleus accumbens (d = 0.23), putamen (d = 0.33), thalamus (d = 0.33) and lateral ventricle (d = -0.23). We demonstrate significant relationships between post-stroke sensorimotor behaviour and reduced volumes of deep grey matter structures that were spared by stroke, which differ by time and class of sensorimotor measure. These findings provide additional insight into how different cortico-thalamo-striatal circuits support post-stroke sensorimotor outcomes

Spectral and synchrony differences in auditory brainstem responses evoked by chirps of varying durations

The chirp-evoked ABR has been termed a more synchronous response, referring to the fact that rising-frequency chirp stimuli theoretically compensate for temporal dispersions down the basilar membrane. This compensation is made possible by delaying the higher frequency content of the stimulus until the lower frequency traveling waves are closer to the cochlea apex. However, it is not yet clear how sensitive this temporal compensation is to variation in the delay interval. This study analyzed chirp- and click-evoked ABRs at low intensity, using a variety of tools in the time, frequency, and phase domains, to measure synchrony in the response. Additionally, this study also examined the relationship between chirp sweep rate and response synchrony by varying the delay between high- and low-frequency portions of chirp stimuli. The results suggest that the chirp-evoked ABRs in this study exhibited more synchrony than the click-evoked ABRs and that slight gender-based differences exist in the synchrony of chirp-evoked ABRs. The study concludes that a tailoring of chirp parameters to gender may be beneficial in pathologies that severely affect neural synchrony, but that such a customization may not be necessary in routine clinical applications

Rapid neonatal hearing screening using maximum length sequence auditory brainstem response, chirps and automated signal detection

Universal Newborn Hearing Screening (UNHS) programs have been implemented in many countries throughout the world, including Australia and New Zealand. Currently the most widely accepted tests for UNHS are the Otoacoustic Emissions (OAE) and the Auditory Brainstem Response (ABR). Whilst both are popular, the ABR is often preferred because it tests a greater proportion of the auditory pathway with a higher sensitivity and specificity (Dort et al., 2000). Despite its advantages, the ABR has limitations. Of particular interest to UNHS is the time required to complete an ABR assessment. A standard ABR screening assessment can usually be completed in approximately 8 minutes for both ears (including subject preparation). This falls to approximately 3 minutes if a simple pass/fail result is all that is required, provided the infant is in natural sleep or quiet rest (Hahn et al., 1999). Part of the ABR test time is taken up by the signal averaging process. Several thousand auditory responses are required to obtain a reliable ABR at or near threshold levels. To make matters worse, each new response cannot be obtained until after the previous response has finished. Whilst these delays may seem small per neonate, they are large per UNHS program, particularly in programs where tens of thousands of neonates must be screened per year. Such delays result in significant cost to the organisations responsible for UNHS (National Center for Hearing Assessment & Management (NCHAM)), and go against the UNHS guidelines provided by the American Speech-Language and Hearing Association (ASHA) in 1997 (American Speech-Language Hearing Association Audiologic Assessment Panel 1996, 1997) which state that a screening test should be short in duration, comfortable for patients, and of minimal cost to the organization providing the screening service. This paper describes three methods that could reduce ABR acquisition time: Maximum length sequences (MLS), chirp stimuli and automated signal detection

Rapid neonatal hearing screening using modified automated auditory brainstem response maximum length sequences

Universal Newborn Hearing Screening (UNHS) is an important tool for detecting hearing impairment in newborns, but it is often hindered by unacceptably long test times. This paper will describe a preliminary data set obtained from 100 newborns using a new form of automated auditory brainstem response (AABR): a non-linear maximum length sequence (MLS) AABR with automated analysis. Initial analyses of this data suggest this new AABR test can reduce average screening times from minutes to a few seconds per newborn. The implications of this data and the possibilities for future research will be discussed

Rapid universal neonatal hearing screening using a fast automatic auditory brainstem response device

Introduction: Universal Newborn Hearing Screening (UNHS) is an important tool for detecting hearing impairment in newborns, but it is often hindered by unacceptably long test times. The successful reduction of these test times would be of significant benefit to both the institutions and the societies providing UNHS services. Methods: 78 neonates were assessed using a new automated auditory brainstem response (AABR) test that combines new maximum length sequence (MLS) techniques with automated analysis techniques. Results: Initial analyses of this data suggest this new AABR test has the potential to reduce average screening times per newborn from minutes to seconds, with some limitations. Discussion: The implications of this data and the plans for future research will be discussed

Rapid NHS using AABR with high stimulus repetition rates and automated signal detection

The automated auditory brainstem response (AABR) is an important tool for detecting hearing impairment in newborns, but it is often hindered by unacceptably long test times. On average, it takes 3 to 5 minutes per infant to acquire sufficient data to determine if an AABR waveform is present or absent. The successful reduction of this average test time would be of significant benefit to both the institutions and the societies providing UNHS services. Our aim was to determine if increased stimulus repetition rates and automated signal detection could be used to reduce AABR test time. To do this, we conveniently sampled 80 neonates (aged 0 to 3 days) from the Mater Mothers’ Hospital in Brisbane, Australia, all of whom had passed a screening test in both ears using that hospital’s hearing screening device. We reassessed these neonates in one ear (right or left) using our purpose built AABR device, obtaining AABR waveforms from each neonate using 35 dBnHL conventional click stimuli at 33 and 90 clicks per second (cps) and 35 dBnHL maximum length sequence (MLS) click stimuli at 180, 250, 500 and 833 cps with both bipolar and unipolar reconstructions. We then analysed these AABR waveforms off-line using subjective detection by a human observer, and the automatic signal detection techniques of Fsp and cross-correlation, to determine which combination of these stimulus repetition rates and automatic detection techniques provided the shortest AABR test time. We will present the results of our study, its implications for the use of the AABR in UNHS, and our plans for future research