Faculty Bibliography

Both spatial and temporal cues determine the fate of immature neurons. A major challenge at the interface of developmental and systems neuroscience is to relate this spatiotemporal trajectory of maturation to circuit-level functional organization. This study examined the development of two extraocular motor nuclei (nIII and nIV), structures in which a motoneuron's identity, or choice of muscle partner, defines its behavioral role. We used retro-orbital dye fills, in combination with fluorescent markers for motoneuron location and birthdate, to probe spatial and temporal organization of the oculomotor (nIII) and trochlear (nIV) nuclei in the larval zebrafish. We describe a dorsoventral organization of the four nIII motoneuron pools, in which inferior and medial rectus motoneurons occupy dorsal nIII, while inferior oblique and superior rectus motoneurons occupy distinct divisions of ventral nIII. Dorsal nIII motoneurons are, moreover, born before motoneurons of ventral nIII and nIV. The order of neurogenesis can therefore account for the dorsoventral organization of nIII and may play a primary role in determining motoneuron identity. We propose that the temporal development of extraocular motoneurons plays a key role in assembling a functional oculomotor circuit. J. Comp. Neurol. 525:65-78, 2017. (c) 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

INTRODUCTION/HYPOTHESIS: Opera performance is physiological and emotional, and singing performers utilize their larynges in often strenuous ways. Historically, the training of a classical voice has been considered the paragon of healthy singing. However, the natural history of a performing larynx has not been studied systematically. There is paucity of scientific studies to guide practice patterns, particularly with regard to the course and extent of post-performance physiologic and acoustic changes. STUDY DESIGN: A prospective case series was carried out. METHODS: Principal singers in the Houston Grand Opera's 2012-2013 repertory were enlisted, for a total of seven singers. Stroboscopy was performed prior to the start of rehearsals, and at the completion of the opera's run. Data points included erythema, edema, masses or lesions, mucosal waveform, supraglottic posture; acoustic measurements were also performed. RESULTS: There were statistically significant differences (P < 0.05) in the mucosal wave on pre- and postperformance stroboscopic examinations. Acoustical measures did not achieve statistical significance, but there was a trend toward increased harmonic-to-noise ratio in postperformance measures, as well as decreased frequency range and reading F0. Measures of intra- and inter-rater reliability indicated varying levels of intra-rater reliability, and generally poor inter-rater reliability. CONCLUSIONS: This pilot study describes physiologic and acoustic changes that may occur over the course of a series of rehearsals and performances in the operatic larynx. In so doing, it highlights a need for larger studies with increased frequency of serial examinations to study in a systematized way what may be natural reactive changes that occur during performance.

OBJECTIVES/HYPOTHESIS: Inhalation injury significantly increases morbidity and mortality in burn patients. Approximately one in five burn patients have acute injury to the larynx, trachea, and/or lungs-and as many as 70% have long-term laryngeal abnormalities. Although inhalation injury to the lung has been studied extensively, no models exist to study these insults to the larynx. As such, we developed an in vivo rabbit model to create precise and reproducible laryngeal burn with resultant tissue damage as a foundation for interventional studies. METHODS: Following tubeless tracheotomy, a custom temperature-control device was employed to apply heated air (70 degrees C-80 degrees C, 150 degrees C-160 degrees C, or 310 degrees C-320 degrees C) +/- smoke derived from unbleached cotton to the larynx, endoscopically, minimizing adjacent tissue damage in six rabbits. Pain, nutrition, and level of activity were monitored. Direct laryngoscopy and histological examination were performed 24 hours following insult. RESULTS: All animals survived injury with appropriate pain control; oral intake was initiated and all were adequately ventilating via tracheostomy. Burn sequelae were noted under direct visualization 24 hours after injury, and graded levels of edema and tissue damage were observed as a function of temperature. Edema obstructed true vocal fold visualization at increased temperatures. These injury patterns correlated with graded tissue damage on histology. CONCLUSION: We created an in vivo model of laryngeal burn injury employing a custom burn device resulting in graded tissue injury. This model is critical for investigation of the mechanisms underlying burn injury, and ultimately, the development and evaluation of therapies for this challenging population. LEVEL OF EVIDENCE: N/A. Laryngoscope, 2016.

OBJECTIVE: Conflicting data exist regarding false vocal fold (FVF) anatomy; it is unclear if this structure is an extension of the thyroarytenoid muscle or an independent muscle system. This confusion is amplified by diverse clinical findings in the setting of unilateral recurrent laryngeal neuropathy and presbylarynges. We sought to characterize FVF behavior in these contexts. METHODS: Laryngoscopic/stroboscopic examinations from 11 patients with unilateral recurrent laryngeal nerve paresis and 12 patients with presbylarynges were reviewed by 4 laryngologists, blinded to the goal of the study but informed of diagnosis. Variables related to FVF structure and function at rest and during phonation were rated. RESULTS: In recurrent laryngeal neuropathy, no significant association between atrophic/paretic vocal fold (VF) and FVF size was observed at rest (P = .69). During phonation, FVF compression was noted bilaterally; contralateral FVF hypertrophy was more common (P = .002). In presbylarynges, neither FVF size at rest (P = .86) nor compression during phonation (P = .37) was associated with the more atrophic VF; FVF compression/hypertrophy was common. CONCLUSIONS: Consistent with clinical dogma, FVF compression was more common contralateral to VF neuropathy. This finding, however, was inconsistent and may suggest individual variability in FVF innervation and/or morphology. Intra- and interrater reliability of these clinical findings was poor.

Physical features of sensory stimuli are fixed, but sensory perception is context dependent. The precise mechanisms that govern contextual modulation remain unknown. Here, we trained mice to switch between two contexts: passively listening to pure tones and performing a recognition task for the same stimuli. Two-photon imaging showed that many excitatory neurons in auditory cortex were suppressed during behavior, while some cells became more active. Whole-cell recordings showed that excitatory inputs were affected only modestly by context, but inhibition was more sensitive, with PV+, SOM+, and VIP+ interneurons balancing inhibition and disinhibition within the network. Cholinergic modulation was involved in context switching, with cholinergic axons increasing activity during behavior and directly depolarizing inhibitory cells. Network modeling captured these findings, but only when modulation coincidently drove all three interneuron subtypes, ruling out either inhibition or disinhibition alone as sole mechanism for active engagement. Parallel processing of cholinergic modulation by cortical interneurons therefore enables context-dependent behavior.

OBJECTIVES/OBJECTIVE:Pediatric rhinoplasty has traditionally raised numerous concerns, including its impact on growth as well as the psychological sequelae of undergoing a potentially appearance-altering procedure. Our objective was to critically evaluate available individual patient data relevant to pediatric rhinoplasty, and further discuss perioperative considerations. METHODS:A systematic review was conducted using PubMed/MEDLINE databases. Data extracted and analyzed from included studies included patient demographics, surgical indications, operative approaches, outcomes, complications, revision rates, and other clinical considerations. RESULTS:Seven studies encompassing 253 patients were included, with age ranging from 7 months to 19 years. Two-thirds of patients were male. 41.7% reported antecedent trauma, and common overall surgical indications included "functional aesthetic" (24.5%) followed by cleft lip nasal deformity (15.8%). The majority (79.1%) underwent open approaches, and 71.1% of patients underwent concomitant septal intervention. The most frequently used grafting materials were septal cartilage (52.8%) and conchal cartilage (16.5%). Surgical outcomes were heterogeneous among these studies. Complication rates were only specified in 5 of the 7 studies and totaled 57 patients (39.6%). Aesthetic dissatisfaction (11.8%) and postoperative nasal obstruction (5.6%) were the most commonly reported complications. Revisions were performed in 13.5%. CONCLUSION/CONCLUSIONS:Rhinoplasty is safe in the pediatric population, although revisions rates appear greater than those reported in adults. This study of 253 represents the largest pooled sample size to date; nonetheless, non-standardized outcome measures, minimal long-term followup data, and lack of discussion regarding psychological sequelae all contribute to the need for further high-quality studies evaluating this topic.

A growing number of laboratories are using research interfaces to conduct experiments with cochlear-implant (CI) users. Because these interfaces bypass a subject's clinical sound processor, several concerns exist regarding safety and stimulation levels. Here we suggest best-practice approaches for how to safely and ethically perform this type of research and highlight areas of limited knowledge where further research is needed to help clarify safety limits. The article is designed to provide an introductory level of technical detail about the devices and the effects of electrical stimulation on perception and neurophysiology. From this, we summarize what should be the best practices in the field, based on the literature and our experience. Findings from the review of the literature suggest that there are three main safety concerns: (a) to prevent biological or neural damage, (b) to avoid presentation of uncomfortably loud sounds, and (c) to ensure that subjects have control over stimulus presentation. Researchers must pay close attention to the software-hardware interface to ensure that the three main safety concerns are closely monitored. An important area for future research will be the determination of the amount of biological damage that can occur from electrical stimulation from a CI placed in the cochlea, not in direct contact with neural tissue. As technology used in research with CIs evolve, some of these approaches may change. However, the three main safety principles outlined here are not anticipated to undergo change with technological advances.

Objective Perioperative lumbar drain (LD) use in the setting of endoscopic cerebrospinal fluid (CSF) leak repair is a well-established practice. However, recent data suggest that LDs may not provide significant benefit and may thus confer unnecessary risk. To examine this, we conducted a meta-analysis to investigate the effect of LDs on postoperative CSF leak recurrence following endoscopic repair of CSF rhinorrhea. Data Sources A comprehensive search was performed with the following databases: Ovid MEDLINE (1947 to November 2015), EMBASE (1974 to November 2015), Cochrane Review, and PubMed (1990 to November 2015). Review Method A meta-analysis was performed according to PRISMA guidelines. Results A total of 1314 nonduplicate studies were identified in our search. Twelve articles comprising 508 cases met inclusion criteria. Overall, use of LDs was not associated with significantly lower postoperative CSF leak recurrence rates following endoscopic repair of CSF rhinorrhea (odds ratio: 0.89, 95% confidence interval: 0.40-1.95) as compared with cases performed without LDs. Subgroup analysis of only CSF leaks associated with anterior skull base resections (6 studies, 153 cases) also demonstrated that lumbar drainage did not significantly affect rates of successful repair (odds ratio: 2.67, 95% confidence interval: 0.64-11.10). Conclusions There is insufficient evidence to support that adjunctive lumbar drainage significantly reduces postoperative CSF leak recurrence in patients undergoing endoscopic CSF leak repair. Subgroup analysis examining only those patients whose CSF leaks were associated with anterior skull base resections demonstrated similar results. More level 1 and 2 studies are needed to further investigate the efficacy of LDs, particularly in the setting of patients at high risk for CSF leak recurrence.

One way to provide pitch information to cochlear implant users is through amplitude-modulation rate. It is currently unknown whether amplitude-modulation rate can provide cochlear implant users with pitch information adequate for perceiving melodic information. In the present study, the notes of a song were encoded via amplitude-modulation rate of pulse trains on single electrodes at the apex or middle of long electrode arrays. The melody of the song was either physically correct or modified by compression or expansion. Nine cochlear implant users rated the extent to which the song was out of tune in the different conditions. Cochlear implant users on average did not show sensitivity to melody compression or expansion regardless of place of stimulation. These results were found despite the fact that three of the cochlear implant users showed the expected sensitivity to melody compression and expansion with the same task using acoustic pure tones in a contralateral acoustic ear. Normal-hearing listeners showed an inconsistent and weak effect of melody compression and expansion when the notes of the song were encoded with acoustic pulse rate. The results suggest that amplitude-modulation rate provides insufficient access to melodic information for cochlear-implant and normal-hearing listeners.

Ninety-four unilateral CI patients with bimodal listening experience (CI plus HA in contralateral ear) completed a questionnaire that focused on attitudes toward hearing aid use postimplantation, patterns of usage, and perceived bimodal benefits in daily life. Eighty participants continued HA use and 14 discontinued HA use at the time of the questionnaire. Participant responses provided useful information for counseling patients both before and after implantation. The majority of continuing bimodal (CI plus HA) participants reported adapting to using both devices within 3 months and also reported that they heard better bimodally in quiet, noisy, and reverberant conditions. They also perceived benefits including improved sound quality, better music enjoyment, and sometimes a perceived sense of acoustic balance. Those who discontinued HA use found either that using the HA did not provide additional benefit over the CI alone or that using the HA degraded the signal from the CI. Because there was considerable overlap in the audiograms and in speech recognition performance in the unimplanted ear between the two groups, we recommend that unilateral CI recipients are counseled to continue to use the HA in the contralateral ear postimplantation in order to determine whether or not they receive functional or perceived benefit from using both devices together.