Round window versus conventional bony cochleostomy technique in pediatric cochlear implantation; A Randomized controlled double blinded trial.

<p><strong>Background:</strong> Objective of the study was to investigate the outcomes of cochlear implantation when done via two different techniques namely, the round window or the bony cochleostomy.</p><p><strong>Methods:</strong> A single-center, double-blinded randomized controlled trial including forty prelingual, bilateral severe to profoundly deaf children less than six years from the year 2014 to 2016 in a tertiary referral center in India were randomly allocated to round window and bony cochleostomy group. Our primary outcome measures were intraoperative neural response telemetry levels, behavioral threshold (t) and comfortable (c) loudness levels. The secondary subjective outcomes were measured via the category of auditory performance (CAP) and the meaningful auditory integration scale (MAIS) score. The cases were followed up for 9 months.</p><p><strong>Results:</strong> Intra-operative, electrically evoked compound action potentials (ECAP) showed comparable mean thresholds for both the techniques except intermediate electrodes (p~0.04) showed lower values for the round window. Similarly, a lower threshold (p~0.03) and comfortable mean current levels (p~0.03) were noticed for the round window group at 6 months post-implantation. Secondary speech perception outcome scores measured via category of auditory performance (CAP) and MAIS score were comparable. </p><p><strong>Conclusions:</strong> The round window insertion technique has physiological benefit as compared to the bony cochleostomy as evidenced by better stimulation levels in the intermediate electrodes and lower mean threshold and comfortable levels in the round window with more beneficial peri-modiolar position of electrode arrays. However, comparable speech perception outcomes revealed no clinical benefit in the cochlear implant performance depending on the technique of electrode insertion. </p>

Assessment of Streamflow Simulation for a Tropical Forested Catchment Using Dynamic TOPMODEL—Dynamic fluxEs and ConnectIvity for Predictions of HydRology (DECIPHeR) Framework and Generalized Likelihood Uncertainty Estimation (GLUE)

Rainfall runoff modeling has been a subject of interest for decades due to a need to understand a catchment system for management, for example regarding extreme event occurrences such as flooding. Tropical catchments are particularly prone to the hazards of extreme precipitation and the internal drivers of change in the system, such as deforestation and land use change. A model framework of dynamic TOPMODEL, DECIPHeR v1—considering the flexibility, modularity, and portability—and Generalized Likelihood Uncertainty Estimation (GLUE) method are both used in this study. They reveal model performance for the streamflow simulation in a tropical catchment, i.e., the Kelantan River in Malaysia, that is prone to flooding and experiences high rates of land use change. Thirty-two years’ continuous simulation at a daily time scale simulation along with uncertainty analysis resulted in a Nash Sutcliffe Efficiency (NSE) score of 0.42 from the highest ranked parameter set, while 25.35% of the measurement falls within the uncertainty boundary based on a behavioral threshold NSE 0.3. The performance and behavior of the model in the continuous simulation suggests a limited ability of the model to represent the system, particularly along the low flow regime. In contrast, the simulation of eight peak flow events achieves moderate to good fit, with the four peak flow events simulation returning an NSE > 0.5. Nonetheless, the parameter scatter plot from both the continuous simulation and analyses of peak flow events indicate unidentifiability of all model parameters. This may be attributable to the catchment modeling scale. The results demand further investigation regarding the heterogeneity of parameters and calibration at multiple scales.

Assessment of Streamflow Simulation for a Tropical Forested Catchment using Dynamic TOPMODEL – Dynamic fluxEs and ConnectIvity for Predictions of HydRology (DECIPHeR) Framework and Generalized Likelihood Uncertainty Estimation (GLUE)

Rainfall runoff modeling has been a subject of interest for decades due to a need to understand a catchment system for management, for example regarding extreme event occurrences such as flooding. Tropical catchments are particularly prone to the hazards of extreme precipitation and the internal drivers of change in the system, such as deforestation and land use change. A model framework of dynamic TOPMODEL, DECIPHeR v1 - considering the flexibility, modularity and portability - and Generalized Likelihood Uncertainty Estimation (GLUE) method are both used in this study. They reveal model performance for the streamflow simulation in a tropical catchment, i.e. the Kelantan River in Malaysia, that is prone to flooding and experiences high rates of land use change. 32 years' continuous simulation at a daily time scale simulation along with uncertainty analysis resulted in a Nash Sutcliffe Efficiency (NSE) score of 0.42 from the highest ranked parameter set, while 25.35% of the measurement falls within the uncertainty boundary based on a behavioral threshold NSE 0.3. The performance and behavior of the model in the continuous simulation suggests a limited ability of the model to represent the system, particularly along the low flow regime. In contrast, the simulation of eight peak flow events achieves moderate to good fit, with the four peak flow events simulation returning an NSE &gt; 0.5. Nonetheless, the parameter scatterplot from both the continuous simulation and analyses of peak flow events indicate unidentifiability of all model parameters. This may be attributable to the catchment modelling scale. The results demand further investigation regarding the heterogeneity of parameters and calibration at multiple scales.

The comparison of changes in hearing thresholds and insertion losses due to occlusion induced by ear impression in sound field assessment

Background and Aim: The methods of deter­mining the amount of sound attenuation by ear mold, earplug or any other foreign body that placed in or out of the ear canal, is divided in subjective and objective. Due to the contradic­tory results in the studies in this field, this study aimed to use more audiometric frequencies con­sidering the strengths and weaknesses of previ­ous studies. Methods: This study was conducted on 30 indi­viduals with normal hearing in the age range of 21-26-year-old. First the impression mold was prepared from both ears. The evaluating real ear unaided response and the real ear occluded res­ponse. In the next step, hearing thresholds were assessed by sound field with a precision of 1 dB, once in both open ear and once in both clo­sed ears. Finally, the insertion loss due to mold placement at each frequency was compared with the amount of behavioral threshold changes at the same frequency. Results: By using paired t-test at frequencies of 400, 500, 800, 1000, 1500, 1600, 2000, 2500, 3000, 4000, 5000, 6000, 6300 and 8000 Hz, the difference in behavioral hearing thresholds with and without molding was greater than the amo­unt of the insertion loss (p < 0.001). Conclusion: The insertion loss due to impre­ssion for behavioral assessment at all of the tes­ted frequencies were more than the attenuation in real ear evaluation (p < 0.001). In this regard, consequently the standard deviation of insertion loss due to impression in behavioral threshold condition was more than real ear measurement. Keywords: Sound field assessment; insertion loss; real ear occluded response; ear impression; probe microphone measurement; real ear measurement

The effects of suspended sediments on the swimming behavior of the calanoid copepod, Acartia tonsa

Copepod swimming behavior is governed by chemical and hydro-mechanical cues. The environment of copepods, however, is frequently impacted by anthropogenic activities, in particular increased levels of suspended sediment due to coastal development. To better understand the effects of sediments on copepod behavior, we used video recordings to document free-swimming in Acartia tonsa under five sediment regimes, both with and without food. Results of the video analysis indicate that as sediment concentration increased, jumping increased and swimming paths became more convoluted. In the presence of prey, swimming trajectories became circular, as opposed to without prey, where paths were more erratic and slower. There was a reverse trend at higher sediment concentrations (120 and 200 mg l−1) for net velocity, turning rate and “spread of participation” index, which could indicate a behavioral threshold. Overall, greater motility with increasing sediment concentration suggests that the copepods were trying to transport themselves out of the sediment-affected area. In the absence of food, the energy cost of this behavior may affect the fitness of Acartia tonsa and, consequently, its predators.

Measurement of Thresholds Using Auditory Steady-State Response and Cochlear Microphonics in Children with Auditory Neuropathy

The detection of precise hearing thresholds in infants and children with auditory neuropathy (AN) is challenging with current objective methods, especially in those younger than six months of age.The aim of this study was to compare the thresholds using auditory steady-state response (ASSR) and cochlear microphonics (CM) in children with AN and children with normal hearing.The thresholds of CM, ASSR, and visual reinforcement audiometry (VRA) tests were recorded; the ASSR and VRA frequencies used were 250, 500, 1000, 2000, and 4000 Hz.The participants in this study were 15 children with AN (27 ears) (1–7.6 years, median age 4.1 years) and ten children with normal hearing (20 ears) (1–8 years, median age four years).The thresholds of the three methods were compared, and histograms were used to represent frequency distributions of threshold differences obtained from the three methods.In children with normal hearing, the average CM thresholds (84.5 dB) were significantly higher than the VRA thresholds (10.0–10.8 dB); in children with AN, both CM and VRA responses were seen at high signal levels (88.9 dB and 70.6–103.4 dB, respectively). In normal children, the difference between mean VRA and ASSR thresholds ranged from 17.5 to 30.3 dB, which was significantly smaller than the difference seen between the mean CM and VRA thresholds (71.5–72.3 dB). The correlation between VRA and ASSR in children with normal hearing ranged from 0.38 to 0.48, whereas no such correlation was seen in children with AN at any frequency (0.03–0.19).Our results indicated that ASSR and CM were poor predictors of the conventional behavioral threshold in children with AN.

Threshold Estimation Using “Chained Stimuli” for Cortical Auditory Evoked Potentials in Individuals With Normal Hearing and Hearing Impairment

Purpose We investigated the utility of chained stimuli for threshold estimation using cortical auditory evoked potentials (CAEPs) in individuals with normal hearing sensitivity and hearing loss. The effect of the order of frequency in chained stimuli on CAEPs was also studied. Method Seventeen individuals with normal hearing and 17 individuals with mild to severe sensorineural hearing loss participated in the study. In individuals with normal hearing, CAEPs were recorded at 80 dB nHL for 4 chained stimuli with different orders of frequencies within them (Chained Stimuli 1 [CS1]: 500, 1000, 2000, 4000 Hz; Chained Stimuli 2: 4000, 2000, 1000, 500 Hz; Chained Stimuli 3: 500, 2000, 1000, 4000 Hz; Chained Stimuli 4: 4000, 1000, 2000, 500 Hz). CAEP threshold estimation was carried out using CS1 in both groups and was compared with behavioral pure-tone thresholds. Results CS1 elicited the largest amplitude responses at low and mid frequencies, whereas all 4 stimuli elicited similar amplitude responses at high frequencies. CAEP thresholds were generally within 10–20 dB above the participants' behavioral threshold in both groups. The difference between CAEP threshold and behavioral threshold was less for individuals with hearing loss compared to individuals with normal hearing. There was a significant positive correlation between CAEP threshold and behavioral threshold at all the frequencies. Conclusions CS1 could be used to elicit CAEPs for threshold estimation in adult participants with normal hearing and hearing loss of varied degrees with theoretically reduced testing time. The actual time reduction using chained stimuli and the correction factor to be applied to estimate behavioral threshold can be studied in future investigations.

Single olfactory receptors set odor detection thresholds

ABSTRACTIn many species, survival depends on olfaction, yet the mechanisms that underlie olfactory sensitivity are not well understood. Here, we examine how a conserved subset of olfactory receptors, the trace amine-associated receptors (TAARs) determine odor detection thresholds of mice to amines. We find that deleting all TAARs, or even single TAARs, results in significant odor detection deficits. This finding is not limited to TAARs, as the deletion of a canonical odorant receptor reduced behavioral sensitivity to its preferred ligand. Remarkably, behavioral threshold is set solely by the most sensitive receptor, with no contribution from other highly sensitive receptors. In addition, increasing the number of sensory neurons (and glomeruli) expressing a threshold-determining TAAR does not improve detection, indicating that sensitivity is not limited by the typical complement of sensory neurons. Our findings demonstrate that olfactory thresholds are set by the single highest affinity receptor, and suggest that TAARs are evolutionarily conserved because they determine the sensitivity to a class of biologically relevant chemicals.

2318 Augmenting perception through direct electrical stimulation of adult somatosensory cortex

OBJECTIVES/SPECIFIC AIMS: Our main objectives are to study sensory encoding in the adult cortex and quantify rodents’ ability to use intracortical microstimulation to guide behavior. METHODS/STUDY POPULATION: Three rats were implanted with unilateral bipolar stimulating electrodes. The electrodes were connected to a wireless neural stimulator housed in the rat’s backpack. The rat’s swim path was tracked by a video camera above the circular pool, and stimulation parameters were updated in real-time based on distance from the platform. Stimulation was delivered as the distance from the platform increased. Stimulation amplitude was determined through behavioral threshold testing, and parameters ranged from 15–75 μA with 100-Hz pulse trains and 0.2-ms pulses. Rats were first challenged with the 4-platform task in which the submerged platform was randomized across 4 possible locations. This dissociated visual cues from the platform location, as rats had knowledge of the 4 possible locations, but had to use stimulation to guide them efficiently. Next, rats were tasked with the more challenging random-platform task. Visual cues were completely dissociated from the platform location by randomizing the platform location across the entire pool. Performance using the neuroprosthetic device was assessed by comparing trials when the device was on (stimulation trial) Versus off (no-stim trial) for the 2 tasks. RESULTS/ANTICIPATED RESULTS: 4-platform task: Rats visited less potential platform locations when the neuroprosthetic was on Versus off. Rats were also more likely to visit the correct platform location on their first swim trajectory when brain stimulation was delivered. When artificial cues were not available, rats had a greater chance of visiting the platform location from the previous trial. This indicated that rats relied on visuospatial memory without the neuroprosthetic. Random platform task: Performance was measured by taking the ratio of the rat’s actual path length to the optimal path length. When the neuroprosthetic was on, rats demonstrated superior performance through a smaller path to length ratio compared with when the device was off. The platform locations of catch trials were matched to a random subset of stimulation trials, permitting a paired sample t-test. Both rats had significantly shorter path lengths when the device was on. DISCUSSION/SIGNIFICANCE OF IMPACT: Rodents have excellent navigation skills that have been well studied. They have been shown to rely on multimodal sensory information from visual, olfactory, auditory, and idiothetic cues to navigate through their environment. The importance of these cues depends on both their environmental presence and task relevance. In the original Morris water maze experiment, rats use vision to form a visuospatial map of the platform location for allocentric navigation. Here, we have shown that sensory augmented rats can pick up on novel sensory information delivered through ICMS to efficiently find a hidden platform when visual cues are made irrelevant.Our results have implications for the design of the bi-directional sensorimotor neuroprosthetic. We have demonstrated that mammals can interpret artificial sensory information to guide behavior. Future directions include investigating sensory encoding in other primary sensory areas and downstream targets along the somatosensory neuraxis.

Ca2+-activated Cl current predominates in threshold response of mouse olfactory receptor neurons

In mammalian olfactory transduction, odorants activate a cAMP-mediated signaling pathway that leads to the opening of cyclic nucleotide-gated (CNG), nonselective cation channels and depolarization. The Ca2+ influx through open CNG channels triggers an inward current through Ca2+-activated Cl channels (ANO2), which is expected to produce signal amplification. However, a study on an Ano2−/− mouse line reported no elevation in the behavioral threshold of odorant detection compared with wild type (WT). Subsequent studies by others on the same Ano2−/− line, nonetheless, found subtle defects in olfactory behavior and some abnormal axonal projections from the olfactory receptor neurons (ORNs) to the olfactory bulb. As such, the question regarding signal amplification by the Cl current in WT mouse remains unsettled. Recently, with suction-pipette recording, we have successfully separated in frog ORNs the CNG and Cl currents during olfactory transduction and found the Cl current to predominate in the response down to the threshold of action-potential signaling to the brain. For better comparison with the mouse data by others, we have now carried out similar current-separation experiments on mouse ORNs. We found that the Cl current clearly also predominated in the mouse olfactory response at signaling threshold, accounting for ∼80% of the response. In the absence of the Cl current, we expect the threshold stimulus to increase by approximately sevenfold.