Neural Response Imaging Research Articles

Idiosyncratic neural coding and neuromodulation of olfactory individuality in Drosophila

Innate behavioral biases and preferences can vary significantly among individuals of the same genotype. Though individuality is a fundamental property of behavior, it is not currently understood how individual differences in brain structure and physiology produce idiosyncratic behaviors. Here we present evidence for idiosyncrasy in olfactory behavior and neural responses in Drosophila We show that individual female Drosophila from a highly inbred laboratory strain exhibit idiosyncratic odor preferences that persist for days. We used in vivo calcium imaging of neural responses to compare projection neuron (second-order neurons that convey odor information from the sensory periphery to the central brain) responses to the same odors across animals. We found that, while odor responses appear grossly stereotyped, upon closer inspection, many individual differences are apparent across antennal lobe (AL) glomeruli (compact microcircuits corresponding to different odor channels). Moreover, we show that neuromodulation, environmental stress in the form of altered nutrition, and activity of certain AL local interneurons affect the magnitude of interfly behavioral variability. Taken together, this work demonstrates that individual Drosophila exhibit idiosyncratic olfactory preferences and idiosyncratic neural responses to odors, and that behavioral idiosyncrasies are subject to neuromodulation and regulation by neurons in the AL.

Functional Magnetic Resonance Imaging (fMRI) of Neural Responses to Visual and Auditory Food Stimuli Pre and Post Roux-en-Y Gastric Bypass (RYGB) and Sleeve Gastrectomy (SG)

Of current obesity treatments, bariatric surgery induces the most weight loss. Given the marked increase in the number of bariatric surgeries performed, elucidating the mechanisms of action is a key research goal. We compared whole brain activation in response to high-energy dense (HED) vs. low-energy dense (LED) visual and auditory food cues before and approximately 4 months after Roux-en-Y Gastric Bypass (RYGB) (n = 16) and Sleeve Gastrectomy (SG) (n = 9). We included two control groups: a low-calorie diet weight loss group (WL) (n = 14) and a non-treatment group (NT) (n = 16). Relative to the control groups, the surgery groups showed increased dorsolateral prefrontal cortex (dlPFC) and decreased parahippocampal/fusiform gyrus (PHG/fusiform) activation in response to HED vs. LED, suggesting greater cognitive dietary inhibition and decreased rewarding effects and attention related to HED foods. dlPFC activation was significantly more increased in RYGB vs. SG. We also found that postprandial increases in GLP-1 concentrations (pre to postsurgery) correlated with postsurgical decreases in RYGB brain activity in the inferior temporal gyrus and the right middle occipital gyrus in addition to increases in the right medial prefrontal gyrus/paracingulate for HED > LED stimuli, suggesting involvement of these attention and inhibitory regions in satiety signaling postsurgery.

When to replace legacy cochlear implants for technological upgrades: Indications and outcomes.

To determine indications, surgical efficacy, and audiologic outcomes of replacing Advanced Bionics Clarion C1.2 internal devices (Advanced Bionics, LLC, Valencia, CA) as a means of technology upgrade. Retrospective review, case series. Ten patients were initially implanted as a child (mean age = 3.87 years) and underwent cochlear implant reimplantation (CIR) with current Advanced Bionics internal device as a young adult (mean duration of implant use = 15.66 years). Demographic data and pre- and post-CIR speech perception scores were collected. Technology upgrade was the primary (9) or secondary (1) motivation for CIR. No surgical complications were noted, and full insertion was obtained in nine cases. Intraoperative impedance levels and neural response imaging measures were within normal limits for eight patients. At most recent post-CIR follow-up evaluation, all patients (100%) performed within or better than the 95% confidence interval of their pre-CIR word and sentence recognition scores; and 55.6%, 50.0%, and 50.0% of patients performed above the 95% confidence interval of their pre-CIR scores for the CNC words, sentences in quiet, and sentences in noise, respectively. Post-CIR audiological benefit was stable or improved compared to pre-CIR results in all categories by 3 months after reactivation. Given these results, patients who are unable to use the most current external processors due to incompatibility with a legacy internal device could consider reimplanation to optimize their overall performance with a cochlear implant. 4 Laryngoscope, 129:748-753, 2019.

Rapid and gentle hydrogel encapsulation of living organisms enables long-term microscopy over multiple hours

Imaging living organisms at high spatial resolution requires effective and innocuous immobilization. Long-term imaging places further demands on sample mounting with minimal perturbation of the organism. Here we present a simple, inexpensive method for rapid encapsulation of small animals of any developmental stage within a photo-crosslinked polyethylene glycol (PEG) hydrogel, gently restricting movement within their confined spaces. Immobilized animals maintain their original morphology in a hydrated environment compatible with chemical treatment, optical stimulation, and light-sheet microscopy. We demonstrate prolonged three-dimensional imaging of neural responses in the nematode Caenorhabditis elegans, recovery of viable organisms after 24 h, and imaging of larger squid hatchlings. We characterize a range of hydrogel and illumination conditions for immobilization quality, and identify paralytic-free conditions suitable for high-resolution single-cell imaging. Overall, PEG hydrogel encapsulation provides fast, versatile, and gentle mounting of small living organisms, from yeast to zebrafish, for continuous observation over hours.

Investigating the Limits of Neurovascular Coupling

O'Herron etal. (2016) perform two-photon imaging of vascular and neural responses in cat and rodent primary visual cortex to investigate the limits of neurovascular coupling. Their results suggest important constraints on making inferences about neuronal responses from hemodynamic activity.

A clinical study of electrophysiological correlates of behavioural comfort levels in cochlear implantees

ObjectivesIndications for cochlear implantation have expanded today to include very young children and those with syndromes/multiple handicaps. Programming the implant based on behavioural responses may be tedious for audiologists in such cases, wherein matching an effective Measurable Auditory Percept (MAP) and appropriate MAP becomes the key issue in the habilitation program. In ‘Difficult to MAP’ scenarios, objective measures become paramount to predict optimal current levels to be set in the MAP. We aimed to (a) study the trends in multi-modal electrophysiological tests and behavioural responses sequentially over the first year of implant use; (b) generate normative data from the above; (c) correlate the multi-modal electrophysiological thresholds levels with behavioural comfort levels; and (d) create predictive formulae for deriving optimal comfort levels (if unknown), using linear and multiple regression analysis.MethodsThis prospective study included 10 profoundly hearing impaired children aged between 2 and 7 years with normal inner ear anatomy and no additional handicaps. They received the Advanced Bionics HiRes 90 K Implant with Harmony Speech processor and used HiRes-P with Fidelity 120 strategy. They underwent, impedance telemetry, neural response imaging, electrically evoked stapedial response telemetry (ESRT), and electrically evoked auditory brainstem response (EABR) tests at 1, 4, 8, and 12 months of implant use, in conjunction with behavioural mapping. Trends in electrophysiological and behavioural responses were analyzed using paired t-test. By Karl Pearson's correlation method, electrode-wise correlations were derived for neural response imaging (NRI) thresholds versus most comfortable level (M-levels) and offset based (apical, mid-array, and basal array) correlations for EABR and ESRT thresholds versus M-levels were calculated over time. These were used to derive predictive formulae by linear and multiple regression analysis. Such statistically predicted M-levels were compared with the behaviourally recorded M-levels among the cohort, using Cronbach's alpha reliability test method for confirming the efficacy of this method.ResultsNRI, ESRT, and EABR thresholds showed statistically significant positive correlations with behavioural M-levels, which improved with implant use over time. These correlations were used to derive predicted M-levels using regression analysis. On an average, predicted M-levels were found to be statistically reliable and they were a fair match to the actual behavioural M-levels. When applied in clinical practice, the predicted values were found to be useful for programming members of the study group. However, individuals showed considerable deviations in behavioural M-levels, above and below the electrophysiologically predicted values, due to various factors. While the current method appears helpful as a reference to predict initial maps in ‘difficult to Map’ subjects, it is recommended that behavioural measures are mandatory to further optimize the maps for these individuals.ConclusionThe study explores the trends, correlations and individual variabilities that occur between electrophysiological tests and behavioural responses, recorded over time among a cohort of cochlear implantees. The statistical method shown may be used as a guideline to predict optimal behavioural levels in difficult situations among future implantees, bearing in mind that optimal M-levels for individuals can vary from predicted values. In ‘Difficult to MAP’ scenarios, following a protocol of sequential behavioural programming, in conjunction with electrophysiological correlates will provide the best outcomes.

Measures of the electrically evoked compound action potential threshold and slope in HiRes 90KTM users

ObjectivesTo investigate electrically evoked compound action potentials (eCAPs) measured with the neural response imaging (NRI) ‘SmartNRI’ algorithm. NRI thresholds and slopes were examined according to three aspects: (1) site along the cochlea, (2) development of responses over time, and (3) influence of age/duration of deafness.MethodsThirty-four individuals implanted with the Advanced Bionics HiRes 90KTM device were included. The eCAP recordings were made from four electrodes along the array at first fitting and at frequent intervals up to at least 2 years. Slope and threshold (tNRI) of the amplitude growth function were measured and a range of explanatory variables were tested for significant effects on these measures using multi-factorial analysis of variance.ResultsElectrode position emerged as a significant effect for the tNRI measure, with lowest thresholds at the apical end of the array. Mean slope was greatest for the most apical electrode, but not significantly. Slope was significantly influenced by onset of deafness, with congenital hearing loss associated with steeper slopes than acquired hearing loss. There was also a highly significant effect of duration of device use, with a gradual increase in slope over the 2 years following device activation.DiscussionThe observed effects of electrode position are consistent with a model in which eCAP threshold is governed primarily by an effect of distance between electrode and neural interface (which is shorter towards the apex of the cochlea) and in which slope is governed primarily by density of surviving neural elements.

Kliniczne zastosowanie multimodalnego zestawu testów elektrofizjologicznych w celu przewidywania optymalnych poziomów odpowiedzi behawioralnych u użytkowników implantów ślimakowych

ObjectivesIndications for cochlear implantation have expanded to include very young children and those with syndromes or multiple handicaps. In such cases programming the implant based on behavioral responses may be tedious, wherein matching effective and appropriate measurable auditory percepts (maps) and becomes the key issue in the rehabilitation program. In ‘difficult to map’ scenarios, objective measures become paramount for predicting optimal current levels to be set in the map. We aimed (a) to study the trends in multi-modal electrophysiological tests and behavioral responses sequentially over the first year of implant use, (b) to generate normative data from the above, (c) to correlate the multi-modal electrophysiological thresholds levels with behavioral comfort levels, and (d) to create predictive formulas for deriving optimal comfort levels (if unknown), using linear and multiple regression analysis.Materials and MethodsThis prospective study included 10 profoundly hearing impaired children aged 2 to 7 years with normal inner ear anatomy and no additional handicaps. They received the Advanced Bionics HiRes 90K implant with Harmony speech processor and used the HiRes-P with Fidelity 120 strategy. They underwent impedance telemetry, neural response imaging, electrically evoked stapedial response telemetry, and electrically evoked auditory brainstem response tests at 1, 4, 8, and 12 months of implant use, in conjunction with behavioral mapping. Trends in electrophysiological and behavioral responses were analysed using paired t-tests. Using Pearson’s correlation method, electrode-wise correlations were derived for NRI thresholds versus M-levels, and offset-based (apical, mid-array, and basal array) correlations for EABR and ESRT thresholds versus M-Levels were calculated over time. These were used to derive predictive formulae by linear and multiple regression analysis. Such statistically predicted M-levels were compared with the behaviorally recorded M-levels among the cohort, using Cronbach’s alpha reliability test method for confirming the efficacy of this method.ResultsNRI, ESRT, and EABR thresholds showed statistically significant positive correlations with behavioral M-levels, which improved with implant use over time. These correlations were used to derive predicted M-levels using regression analysis. Such predicted M-levels were found to be close to the actual behavioral M-levels recorded among this cohort and proved to be statistically reliable.ConclusionsThe study has explored the trends and correlations between electrophysiological tests and behavioral responses, recorded over time among a cohort of cochlear implantees. It provides a statistical method which may be used as a guideline to predict optimal behavioral levels in difficult situations among future implantees. In ‘difficult to map’ scenarios, the best outcomes will come from following a protocol of sequential behavioral programming in conjunction with electrophysiological correlates.

Electrophysiological Correlates of Behavioral Comfort Levels in Cochlear Implantees: A Prospective Study

Indications for cochlear implantation have expanded today to include very young children and those with syndromes/multiple handicaps. Programming the implant based on behavioral responses may be tedious for audiologists in such cases, wherein matching an effective MAP and appropriate MAP becomes the key issue in the habilitation program. In 'Difficult to MAP' scenarios, objective measures become paramount to predict optimal current levels to be set in the MAP. We aimed, (a) to study the trends in multi-modal electrophysiological tests and behavioral responses sequentially over the first year of implant use, (b) to generate normative data from the above, (c) to correlate the multi-modal electrophysiological thresholds levels with behavioral comfort levels, and (d) to create predictive formulae for deriving optimal comfort levels (if unknown), using linear and multiple regression analysis. This prospective study included ten profoundly hearing impaired children aged between 2 and 7years with normal inner ear anatomy and no additional handicaps. They received the Advanced Bionics HiRes 90K Implant with Harmony Speech processor and used HiRes-P with Fidelity 120 strategy. They underwent, Impedance Telemetry, Neural Response Imaging, Electrically Evoked Stapedial Response Telemetry and Electrically Evoked Auditory Brainstem Response tests at 1, 4, 8 and 12months of implant use, in conjunction with behavioral Mapping. Trends in electrophysiological and behavioral responses were analyzed using paired t test. By Karl Pearson's correlation method, electrode-wise correlations were derived for NRI thresholds versus Most Comfortable Levels (M-Levels) and offset based (apical, mid-array and basal array) correlations for EABR and ESRT thresholds versus M-Levels were calculated over time. These were used to derive predictive formulae by linear and multiple regression analysis. Such statistically predicted M-Levels were compared with the behaviorally recorded M-Levels among the cohort, using Cronbach's Alpha Reliability test method for confirming the efficacy of this method. NRI, ESRT and EABR thresholds showed statistically significant positive correlations with behavioral M-Levels, which improved with implant use over time. These correlations were used to derive predicted M-Levels using regression analysis. Such predicted M-Levels were found to be in proximity to the actual behavioral M-Levels recorded among this cohort and proved to be statistically reliable. When clinically applied, this method was found to be successful among subjects of our study group. Although there existed disparities of a few clinical units, between the actual and predicted comfort levels among the subjects, this statistical method was able to provide a working MAP, close to the behavioral MAP used by these children. The results help to infer that behavioral measurements are mandatory to program cochlear implantees, but in cases where they are difficult to obtain, this study method may be used as reference for obtaining additional inputs, in order to set an optimal MAP. The study explores the trends and correlations between electrophysiological tests and behavioral responses, recorded over time among a cohort of cochlear implantees and provides a statistical method which may be used as a guideline to predict optimal behavioral levels in difficult situations among future implantees. In 'Difficult to MAP' scenarios, following a protocol of sequential behavioral programming, in conjunction with electrophysiological correlates will provide the best outcomes.

Design and implementation of in vivo imaging of neural injury responses in the adult Drosophila wing

Live-imaging technology has markedly advanced in the field of neural injury and axon degeneration; however, studies are still predominantly performed in in vitro settings such as cultured neuronal cells or in model organisms such as Caenorhabditis elegans in which axons lack glial wrappings. We recently developed a new in vivo model for adult-stage neural injury in Drosophila melanogaster, using the highly accessible wing of the animal. Because the Drosophila wing is translucent and dispensable for survival, it allows clear and direct visualization of injury-induced progressive responses of axons and glia highlighted by fluorescent protein (FP) markers in live animals over time. Moreover, unlike previous Drosophila models of neural injury, this procedure does not require dissection of the CNS. Thus, the key preparation steps for in vivo imaging of the neural injury response described in this protocol can be completed within 30 min.

Determining Electrically Evoked Compound Action Potential Thresholds

Current cochlear implants (CIs) have telemetry capabilities for measuring the electrically evoked compound action potential (ECAP). Neural Response Telemetry (Cochlear) and Neural Response Imaging (Advanced Bionics [AB]) can measure ECAP responses across a range of stimulus levels to obtain an amplitude growth function. Software-specific algorithms automatically mark the leading negative peak, N1, and the following positive peak/plateau, P2, and apply linear regression to estimate ECAP threshold. Alternatively, clinicians may apply expert judgments to modify the peak markers placed by the software algorithms, or use visual detection to identify the lowest level yielding a measurable ECAP response. The goals of this study were to: (1) assess the variability between human and computer decisions for (a) marking N1 and P2 and (b) determining linear-regression threshold (LRT) and visual-detection threshold (VDT); and (2) compare LRT and VDT methods within and across human- and computer-decision methods. ECAP amplitude-growth functions were measured for three electrodes in each of 20 ears (10 Cochlear Nucleus® 24RE/CI512, and 10 AB CII/90K). LRT, defined as the current level yielding an ECAP with zero amplitude, was calculated for both computer- (C-LRT) and human-picked peaks (H-LRT). VDT, defined as the lowest level resulting in a measurable ECAP response, was also calculated for both computer- (C-VDT) and human-picked peaks (H-VDT). Because Neural Response Imaging assigns peak markers to all waveforms but does not include waveforms with amplitudes less than 20 μV in its regression calculation, C-VDT for AB subjects was defined as the lowest current level yielding an amplitude of 20 μV or more. Overall, there were significant correlations between human and computer decisions for peak-marker placement, LRT, and VDT for both manufacturers (r = 0.78-1.00, p < 0.001). For Cochlear devices, LRT and VDT correlated equally well for both computer- and human-picked peaks (r = 0.98-0.99, p < 0.001), which likely reflects the well-defined Neural Response Telemetry algorithm and the lower noise floor in the 24RE and CI512 devices. For AB devices, correlations between LRT and VDT for both peak-picker methods were weaker than for Cochlear devices (r = 0.69-0.85, p < 0.001), which likely reflect the higher noise floor of the system. Disagreement between computer and human decisions regarding the presence of an ECAP response occurred for 5 % of traces for Cochlear devices and 2.1 % of traces for AB devices. Results indicate that human and computer peak-picking methods can be used with similar accuracy for both Cochlear and AB devices. Either C-VDT or C-LRT can be used with equal confidence for Cochlear 24RE and CI512 recipients because both methods are strongly correlated with human decisions. However, for AB devices, greater variability exists between different threshold-determination methods. This finding should be considered in the context of using ECAP measures to assist with programming CIs.

Results of a Multicenter Clinical Study Evaluating a New Smart Algorithm to Measure Neural Response Imaging

To evaluate the smart algorithm in speed and reliability of threshold estimation compared with the algorithm available in the standard fitting software and to evaluate the possibility of using programs based on the smart algorithm instead of programs derived from behavioral measures. Twenty subjects unilaterally implanted with a CII Bionic Ear or HiRes90K device. Neural response imaging thresholds (tNRI) were measured using both the smart approach within the Research Studies Platform for Objective Measures and the SoundWave fitting software. Measurements were performed intraoperatively, at first fitting, and after 3 months of implant use. Each subject received a standard behavioral program and a SmartNRI program. Speech perception tests were conducted at 3 months, and subjective preferences were documented. Smart tNRI and SoundWave tNRI at each session; speech test results and subject preferences at the 3-month session. High correlations were found between smart tNRI and SoundWave tNRI. The time required to obtain NRI thresholds with the smart algorithm was a quarter of the time needed with SoundWave. Although most tested subjects preferred their behavioral programs, there were no significant differences in performance between SmartNRI and behavioral programs. Neural response imaging thresholds were obtained more rapidly with the smart algorithm than with SoundWave. Because no differences were observed between SmartNRI and behavioral programs, SmartNRI programs may be a useful alternative to behavioral programs in difficult to fit cases, where user feedback is sometimes difficult to obtain.

Multicentre investigation on electrically evoked compound action potential and stapedius reflex: how do these objective measures relate to implant programming parameters?

ObjectivesThe aims of this study were to collect data on electrically evoked compound action potential (eCAP) and electrically evoked stapedius reflex thresholds (eSRT) in HiResolutionTM cochlear implant (CI) users, and to explore the relationships between these objective measures and behavioural measures of comfort levels (M-levels).MethodsA prospective study on newly implanted subjects was designed. The eCAP was measured intra-operatively and at first fitting through neural response imaging (NRI), using the SoundWaveTM fitting software. The eSRT was measured intra-operatively by visual monitoring of the stapes, using both single-electrode stimulation and speech bursts (four electrodes stimulated at the same time). Measures of M-levels were performed according to standard clinical practice and collected at first fitting, 3 and 6 months of CI use.ResultsOne hundred seventeen subjects from 14 centres, all implanted unilaterally with a HiResolution CII Bionic Ear® or HiRes 90K®, were included in the study. Speech burst stimulation elicited a significantly higher eSRT success rate than single-electrode stimulation, 84 vs. 64% respectively. The NRI success rate was 81% intra-operatively, significantly increasing to 96% after 6 months. Fitting guidelines were defined on the basis of a single NRI measurement. Correlations, analysis of variance, and multiple regression analysis were applied to generate a predictive model for the M-levels.DiscussionUseful insights were produced into the behaviour of objective measures according to time, electrode location, and fitting parameters. They may usefully assist in programming the CI when no reliable feedback is obtained through standard behavioural procedures.

Helix electrode pull back: electrophysiology and surgical results

electrodes. Recent reports showed the effect of an increased focusing of the intracochlear electrical field by a surgical modification of the commonly performed insertion (Todt et al., 2005; 2008) called ‘pull-back’. Focusing the intracochlear field is assumed to further increase the number of virtual channels. It has been shown that this further increase of the perimodiolar position led to a better frequency discrimination with the Nucleus Advance array (Basta et al., 2010). The aim of the present study was to investigate the effect of the modified insertion technique in the temporal bone (TB) to be able to perform the technique with the helix electrode. In a second step, we looked at the intraoperative electrophysiological changes due to the electrode pull-back. Method Ten TB with a view on the scala tympani were investigated. The intracochlear movements of the helix electrode positioning were recorded. After assessing the video-based recordings, the absolute change of three different distances (tip change, modiolus approximation distance, and pull back distance) was calculated. To define the pixel-based frame distances, the known contact-to-contact distances of the electrode provided by the manufacturer were used. Video analysis was performed with Metra software. Additionally, we investigated the electrophysiological effect of the electrode pull-back by pre- and post-pull-back measurements of the spread of excitation (SOE) and the neural response imaging (NRI) threshold in 10 implanted patients. A modified round window approach was performed. The pullback distance from the surgeons perspective was subjectively limited to 1.5 mm. Therefore, the first and the second cochleostomy markers were used (distance 3 mm). Measurements of the SOE were performed with the RSPOM software (Advanced Bionics software platform, Valencia, CA, USA) using the variable recording algorithm. Measurement contacts were electrodes 4, 8, and 12. Pre- and post-pullback current levels were intraindividually equally chosen, but varied interindividually. For the calculation of the pull-back effect, the electrode width of the SOE at 60% was used. RSPOM and equally current level were used for the measurements of the NRI thresholds.

The importance of intra-operative imaging during cochlear implant surgery

Two unusual cases of cochlear implant (CI) surgery complication are reported: introduction of the electrode array into the superior semicircular canal with normal morphology and a growing amplitude of neural potential (neural response imaging, NRI) during intra-operative monitoring control. In the first case, a two-year-old patient affected by congenital sensorineural profound deafness was bilaterally implanted with two Clarion 90 k devices and intra-operative electrophysiological and radiological controls were performed. After introduction of the array in the right side NRI was performed and a neural potential was found only on two apical electrodes. Radiological intra-operative control with antero-posterior trans-orbital plain films was performed to assess the position of the electrodes inside the cochlea. Radiography showed the electrode array in the superior semicircular canal in the right ear. The electrode array was removed and reinserted correctly. In the second case, a 72-year-old man underwent left cochlear implantation for sensorineural profound deafness of unknown origin. Intra-operative electrophysiological testing (NRI) showed the presence of neural potential on three tested channels. In this case, as routinely employed since 2006, an intra-operative static fluoroscopy control was performed, this showed the electrode array in the superior semicircular canal. The electrode array was removed and reinserted correctly. In conclusion, intra-operative monitoring tests during CI surgery play different roles: measurement of impedances and NRI can evaluate the integrity of implant electrodes and the status of the electrode cochlea interface, but they cannot be the only way to confirm correct positioning of the array. In our opinion the intra-operative radiological check is helpful during CI surgery, especially when there is any doubt about correct electrode insertion. Copyright © 2009 John Wiley & Sons, Ltd.

The importance of intra-operative imaging during cochlear implant surgery

Two unusual cases of cochlear implant (CI) surgery complication are reported: introduction of the electrode array into the superior semicircular canal with normal morphology and a growing amplitude of neural potential (neural response imaging, NRI) during intra-operative monitoring control. In the first case, a two-year-old patient affected by congenital sensorineural profound deafness was bilaterally implanted with two Clarion 90 k devices and intra-operative electrophysiological and radiological controls were performed. After introduction of the array in the right side NRI was performed and a neural potential was found only on two apical electrodes. Radiological intra-operative control with antero-posterior trans-orbital plain films was performed to assess the position of the electrodes inside the cochlea. Radiography showed the electrode array in the superior semicircular canal in the right ear. The electrode array was removed and reinserted correctly. In the second case, a 72-year-old man underwent left cochlear implantation for sensorineural profound deafness of unknown origin. Intra-operative electrophysiological testing (NRI) showed the presence of neural potential on three tested channels. In this case, as routinely employed since 2006, an intra-operative static fluoroscopy control was performed, this showed the electrode array in the superior semicircular canal. The electrode array was removed and reinserted correctly. In conclusion, intra-operative monitoring tests during CI surgery play different roles: measurement of impedances and NRI can evaluate the integrity of implant electrodes and the status of the electrode cochlea interface, but they cannot be the only way to confirm correct positioning of the array. In our opinion the intra-operative radiological check is helpful during CI surgery, especially when there is any doubt about correct electrode insertion.

Gambling Near-Misses Enhance Motivation to Gamble and Recruit Win-Related Brain Circuitry

Summary“Near-miss” events, where unsuccessful outcomes are proximal to the jackpot, increase gambling propensity and may be associated with the addictiveness of gambling, but little is known about the neurocognitive mechanisms that underlie their potency. Using a simplified slot machine task, we measured behavioral and neural responses to gambling outcomes. Compared to “full-misses,” near-misses were experienced as less pleasant, but increased desire to play. This effect was restricted to trials where the subject had personal control over arranging their gamble. Near-miss outcomes recruited striatal and insula circuitry that also responded to monetary wins; in addition, near-miss-related activity in the rostral anterior cingulate cortex varied as a function of personal control. Insula activity to near-misses correlated with self-report ratings as well as a questionnaire measure of gambling propensity. These data indicate that near-misses invigorate gambling through the anomalous recruitment of reward circuitry, despite the objective lack of monetary reinforcement on these trials.

One-Year Results of the Banded Neural Response Imaging Study

To investigate the relationship between single-channel and banded neural response imaging (NRI) responses and to evaluate whether banded NRI measurements are better correlated to fitting parameters than single-channel NRI measurements. Nineteen profoundly deaf subjects implanted with a HiRes 90K cochlear implant from Advanced Bionics Corporation (Valencia, CA). Neural response imaging thresholds (tNRIs; single-channel and banded tNRIs) were measured intraoperatively; at first fitting; and after 3, 6, and 12 months of implant use. Relationships between those measurements and correlations between those measurements and implant program parameters were investigated. Single-channel and banded tNRI collected at each measurement session. Banded NRI could be recorded reliably and was not more time-consuming than the routine single-channel NRI. Significant correlations (Pearson R; p < 0.05) were observed between first-fitting banded tNRI and most comfortable levels at 12 months, with a higher level of significance than the correlations observed with single-channel tNRI. Banded NRI may be a more appropriate fitting tool than single-channel NRI. However, the sample size was small, and more data are necessary to confirm these findings.

Relationships among objective measures and speech perception in adult users of the HiResolution Bionic Ear

The purpose of this study was to describe speech recognition performance for subjects using electrically evoked stapedial reflex thresholds (eSRT) based on programs with the HiResolution Bionic Ear system. A secondary goal was to evaluate the relationship of the electrically evoked compound action potentials (eCAP) as measured with neural response imaging (NRI) relative to the subjects' most comfortable stimulation levels (M levels). M levels, eSRT and eCAP thresholds were measured in 19 postlinguistically deafened adults using either a CII or HiRes 90K cochlear implant. The results showed that eSRTs could be measured easily in a majority of subjects, whereas eCAPS were measured in all subjects. There were close agreements between eSRTs and M levels in the subjects' behaviorally based programs. In contrast, the correspondence between M levels and eCAP thresholds was not as strong. New programs were created with M levels based on the eSRTs for 11 subjects. Programs created using eSRTs as a guide for setting levels yielded better speech recognition than programs using conventional behavioural measures of M levels. These data indicate that individuals can obtain strong benefits from cochlear implants using programs with stimulation levels based on objective measures. Copyright © 2008 John Wiley & Sons, Ltd.

Relationships among objective measures and speech perception in adult users of the HiResolution Bionic Ear

The purpose of this study was to describe speech recognition performance for subjects using electrically evoked stapedial reflex thresholds (eSRT) based on programs with the HiResolution Bionic Ear system. A secondary goal was to evaluate the relationship of the electrically evoked compound action potentials (eCAP) as measured with neural response imaging (NRI) relative to the subjects' most comfortable stimulation levels (M levels). M levels, eSRT and eCAP thresholds were measured in 19 postlinguistically deafened adults using either a CII or HiRes 90K cochlear implant. The results showed that eSRTs could be measured easily in a majority of subjects, whereas eCAPS were measured in all subjects. There were close agreements between eSRTs and M levels in the subjects' behaviorally based programs. In contrast, the correspondence between M levels and eCAP thresholds was not as strong. New programs were created with M levels based on the eSRTs for 11 subjects. Programs created using eSRTs as a guide for setting levels yielded better speech recognition than programs using conventional behavioural measures of M levels. These data indicate that individuals can obtain strong benefits from cochlear implants using programs with stimulation levels based on objective measures. Copyright © 2008 John Wiley & Sons, Ltd.