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Objective: To describe maxillary frenum Kotlow scores in a pediatric population., Methods: A retrospective chart review was performed for children ages 0-19 years old seen at a pediatric otolaryngology clinic by one surgeon from March-December 2022. Inclusion criteria required a recorded maxillary frenum Kotlow score. Data collected included age, gender, race/ethnicity, Kotlow score, and history of maxillary frenotomy., Results: 570 children were included, comprising 267 (46.8%) females, 302 (53.0%) males, and 1 (0.2%) transgender male. Mean age was 5.0 years (95% CI 4.6-5.4). 24 patients (4.2%) had a history of maxillary frenotomy, while 546 (95.8%) did not. Among those with no maxillary frenotomy history, 21 (3.8%) had a Kotlow 1, 127 (23.3%) Kotlow 2, 261 (47.8%) Kotlow 3, and 137 (25.1%) Kotlow 4. Kotlow scores decreased with age. For children with prior maxillary frenotomy, class 1 frenum mean age was 6.9 years, and class 4 was 0.6 years (P=.008). For those without a maxillary frenotomy history, class 1 frenum mean age was 8.7 years, and class 4 was 1.3 years (P<.001). No association was found between maxillary frenotomy history and lower Kotlow scores., Conclusion: Nearly half of children have a Kotlow 3 maxillary frenum. Kotlow scores decrease as children age, reflecting elevated frenum insertion as the alveolar ridge develops. Otolaryngologists may find this data valuable when considering maxillary frenotomy in children., Competing Interests: Declaration of competing interest Alexandra F. Corbin, Lauren A. DiNardo, Deepthi S. Akella, Alison C. Ma, Douglas P. Nanu, Francesca C. Viola, and Michele M. Carr have no conflict of interests to disclose., (Copyright © 2024. Published by Elsevier B.V.)

Objective: Our study aims to assess if decreasing bottle cap size was associated with more ingestions and injuries nationally. STUDY DESIGN: Retrospective chart review., Setting: The National Electronic Injury Surveillance System (NEISS) database., Methods: The NEISS was queried for bottle cap ingestions in children 0 to 18 years old between 2002 and 2021. Demographic factors including age, race, and sex of the patient were recorded. The location where the ingestion took place and the disposition of the patient were also analyzed. Data were excluded if the narrative did not specify the ingestion of a cap of a drinking bottle., Results: A total of 415 bottle cap ingestion injuries were identified, for a national estimate of 11,683 injuries. The mean age at the time of ingestion was 10.3 ± 5.2 years and the majority of the injuries occurred in males (N = 9129, 78.4%). 46.4% (N = 5398) were Caucasian, 17.6% (N = 2046) were Black or African American, and 2.7% (N = 311) were Hispanic. 55.0% (N = 6405) of injuries occurred at an unknown location, 41.4% (N = 4781) occurred at home, and 2.8% (N = 326) occurred at school. 82.3% (N = 9584) of patients were treated in the emergency department and released, 6.9% (N = 808) were treated and admitted, 6.7% (N = 783) were treated and transferred, and 0.9% (N = 110) were held for observation. From 2002 (N = 6) to 2021 (N = 2291), there was a statistically significant increase in bottle cap ingestions (P < .001)., Conclusion: Plastic bottle cap ingestions have increased in children over the last 20 years, coincident with the change to smaller bottle caps., (© 2024 American Academy of Otolaryngology–Head and Neck Surgery Foundation.)

Objective: To compare patterns of obstruction in infants and toddlers with obstructive sleep apnea (OSA) by analyzing drug-induced sleep endoscopy (DISE) examinations., Study Design: Retrospective chart review., Setting: An academic tertiary care pediatric hospital at a single institution., Methods: Children aged ≤3 years who underwent DISE with propofol titration from 2020 to 2022 were included in the study. Data extracted included age, body mass index, comorbidities, and polysomnography parameters. The sites of anatomic obstruction during DISE were recorded using a validated 10-site scoring system., Results: A total of 86 children underwent DISE, including 15 infants (<1 year) and 71 toddlers (>1≤3 years). Sixty-two percent were male and 37% were female. The mean age of the infant group was 9.6 months (95% confidence interval [CI]: 7.92, 11.28 months), and the mean age of the toddler group was 2.3 years (95% CI: 2.06, 2.50 years). The mean total number of sites of obstruction was not significantly different between infants (N = 2.5) and toddlers (N = 3.2, P = .086). The most common subsite of significant obstruction in both infants and toddlers was the aryepiglottic folds (46.7% and 36.8%, respectively; P = .578). The sites of obstruction and frequency of their occurrence were not significantly different between the 2 groups., Conclusion: Multisite airway obstruction is common among children with OSA, especially at the epiglottis, aryepiglottic folds, and tongue base. There is no difference in sites of obstruction and their frequency between toddlers and infants., (© 2024 American Academy of Otolaryngology–Head and Neck Surgery Foundation.)

Introduction: Congenital nasal pyriform aperture stenosis (CNPAS) is a rare condition that results in neonatal respiratory difficulty. The purpose of this systematic review was to compare surgical outcomes of drilling versus dilation techniques in the treatment of CNPAS., Methods: Pubmed, Embase, and Cochrane Clinical Trials databases were searched for terms "congenital nasal pyriform aperture stenosis" or "pyriform aperture stenosis" from 2010 to 2021. Twenty-five studies were included that evaluated pediatric patients treated surgically for CNPAS with available outcomes data including complications, revisions, and length of stay., Results: A total of 51 patients with CNPAS were pooled from included studies. The median age was 29 days, 56.9% were female, and 54.9% were born full-term. The median pyriform aperture width before surgery was 5.00 mm (IQR = 4.10, 6.45). Forty (78.4%) patients underwent sublabial drilling, while 6 had a dilation procedure performed with hegar cervical dilators, 2 had a balloon dilation, and 3 were dilated with either an acrylic device, endotracheal tube, or bougie. There were no post-operative complications for 76.5% of patients, while a second surgery was required in 9 (17.6%) patients. The median length of stay was 11 days (IQR = 4, 26). No statistically significant difference was observed between sublabial drilling and surgical dilation techniques with respect to complications, need for revision surgery, or length of stay., Conclusion: Current literature is insufficient to determine if drilling or dilation is more effective in the treatment of CNPAS., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Pediatric patients and their caregivers may receive information from their primary care physician (PCP) that does not match current American Academy of Otolaryngology (AAO) guidelines. The purpose of this study is to evaluate the frequency of parents deciding to seek a second opinion based on the demographics of pediatric otolaryngologists who deliver guideline supported advice, contrary to advice from their child's PCP., Methods: A survey was distributed to parents in a pediatric otolaryngology clinic between June 2021 and July 2023. Demographics included parent age category, gender, race, and age of youngest child. The survey included a scenario depicting recurrent otitis media with clear ears and a suggestion to defer tympanostomy tube insertion per AAO guidelines after their child's PCP recommended tubes. Thirteen variations of otolaryngologist photos were used in the case, including a control case with no picture., Results: Of the 658 participants, 460 (69.9 %) were female. 551 (83.7 %) were aged 30-49 years, 70 (10.7 %) were younger, and 37 (5.6 %) were older. 545 (82.8 %) were White, 30 (4.6 %) were Black, 20 (3.0 %) were Asian, and 31 (4.7 %) were Hispanic. 39.9 % of parents would seek a second opinion if an otolaryngologist recommended watchful waiting following evaluation of their child's otitis media. Participants given the control case were 2.23 times more likely to listen to the otolaryngologist's advice (p = .025). If a picture was provided, respondents were more likely to follow advice given if the pictured otolaryngologist was female (p = .025, OR = 1.47) or Asian (p = .042, OR = 1.53)., Conclusion: In this group, there is evidence that physician race and gender may influence decision making when considering action versus monitoring in the context of recurrent otitis media., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Introduction: Our study seeks to understand the profiles of otolaryngologists selected by Castle Connolly's Top Doctor list and how this compares to the entire field of otolaryngology., Methods: Top Doctor lists published in Castle Connolly affiliated magazines were analyzed for Otolaryngology, Otolaryngology/Facial Plastic Surgery, or Pediatric Otolaryngology physicians. Only lists published in 2021 or representing the 2021 Top Doctor lists were analyzed. Of the total 39 partnered magazines, 27 met our criteria. Information on the physician was analyzed from the Castle Connolly website and included: gender, education, faculty position, years as a Top Doctor, and certifications of each physician., Results: 879 doctors, 742 (84%) men and 137 women (16%), were included in our analysis. 509 physicians completed a fellowship, 85 (62%) women and 424 (57%) men. The fellowship type varied significantly between gender (p = .002). 122 (14%) Top Doctors completed facial and plastic reconstructive surgery and 111 (91%) were men. Of the women Top Doctors completing a fellowship, 29 (34%) completed a fellowship in pediatric otolaryngology. A logistic regression found that men have an increased odds of being on the Top Doctors list for more years than females (OR: 1.36, p < .001)., Conclusion: The percentage of women named as Top Doctors was less than the proportion of women in otolaryngology. This may be attributed to gender differences we found in fellowship type and certification. Further research into the role of otolaryngology subspecialties in selection of Top Doctors is needed to better understand gender differences., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 DiNardo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: Previous research has indicated that sleep disordered breathing (SDB) can lead to a decreased quality of life in children and their families as compared to children who do not have SDB. The purpose of this study was to examine fatigue levels in parents who had young children who were impacted by sleep symptoms as determined by the OSA-18 scale., Study Design: Survey., Setting: Three pediatric otolaryngology clinics associated with a tertiary care children's hospital in Buffalo, NY., Methods: Fatigue levels for parents of children with OSA-18 ≥ 60 were assessed using the Fatigue Severity Scale and the Chalder Fatigue Scale. Consecutive parents with at least one child between the ages of 1 and 10 were recruited. Parents scored their youngest child on the OSA-18 scale., Results: Of the 261 respondents included, 37 parents had a child with an OSA-18 score ≥60. The majority, 211 (82.1%), of participants reported 2 caregivers in the household while 30 (11.7%) had 1 caregiver in the household. Parents of children with OSA-18 ≥60 had a significantly higher mean fatigue score, 16.5 ± 5.8, compared to their counterparts, 11.9 ± 5.2, on the Chalder Fatigue Scale ( P  < .001). Similar results were reported for the total score on the Fatigue Severity Scale, 34.7 ± 10.8 compared to 28.9 ± 12.0 ( P  = .004)., Conclusion: Parents of children with OSA-18 score ≥60 are significantly more fatigued than parents of children with lower scores. Recognition of this is important for the health care community as it impacts not just the child with OSA but also their family., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: The Americans with Disabilities Act (ADA) is a federal law that forbids discrimination against individuals with certain disabilities, including hearing impairment. This study aimed to determine the nature of ADA discrimination complaints in individuals with cochlear implants., Methods: A search for court decisions containing the terms "cochlear implant" and ("Americans with Disabilities Act" or "ADA") from 1985 to 2021 was performed with the Westlaw Campus Research legal database. Cases were included and analyzed if at least one of the plaintiffs had a cochlear implant and was claiming discrimination related to their hearing impairment based on the ADA., Results: 24 cases initiated between 2003 and 2021 in 19 US states were identified based on inclusion criteria. The highest number of cases occurred in California (N = 4, 16.7 %). The alleged discrimination most frequently took place at a K-12 school (N = 9, 37.5 %), workplace (N = 7, 29.2 %), or during an encounter with police/correctional officers (N = 4, 16.7 %). Fourteen (58.3 %) cases involved complaints under Title II (Public Services) of the ADA. Seven (29.2 %) involved Title I (Employment) and 4 (16.7 %) involved Title III (Public Accommodations). Summary judgment was given in favor of the defendant or the case was dismissed entirely in 16 (66.7 %) of the cases., Conclusion: Patients with cochlear implants are still at risk of discrimination because of their disability. Cochlear implantees, school employees, workplace supervisors, and law enforcement personnel can benefit from ADA education., Competing Interests: Declaration of competing interest None., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Social media is a novel tool that many parents turn to when looking for a new healthcare provider. The purpose of this study is to assess how parents of children attending a pediatric otolaryngology practice engage with social media., Study Design: Survey., Setting: Two pediatric otolaryngology clinics associated with a tertiary care children's hospital in Buffalo, NY., Methods: Parents of children aged <18 years were surveyed. The survey consisted of 25 questions divided into 5 categories: demographics, social media accounts, social media use, use of social media to interact with pediatric otolaryngologists, and perception of pediatric otolaryngologists' social media accounts. Frequencies were calculated., Results: Three hundred five parent participants were included. 247 (81.0) were female and 57 (18.97) were male. 258 (84.6%) of the participants reported use of Facebook, which was the most popular social media platform. 238 (78.0%) of participants indicated that they would want to see medical posts and 98 (32.1%) participants indicated that they would want to see personal posts on the pediatric otolaryngologist's social media page. Younger parents were statistically more likely to check social media more often ( P  = .001) and seek a pediatric otolaryngologist's social media before seeing them ( P  = .018)., Conclusion: Use of social media by pediatric otolaryngologists may positively impact the way a small percentage of their patients' parents perceive them. Social media accounts do not appear to be a vital part of pediatric otolaryngology practice in 2022., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective(s): To describe how medical school rank may be associated with matriculation into otolaryngology residency programs., Methods: A list of medical students who matched into otolaryngology residencies in 2020, 2021, and 2022 was obtained from Otomatch (Otomatch.com). For each student, their medical school, U.S. News & World Report Best Medical School (Research) ranking, and region based on the U.S. Census divisions were recorded. The medical schools were divided into four Tiers according to rank: 1-40 (Tier 1), 41-80 (Tier 2), 81-124 (Tier 3), and 125-191 (Tier 4). Residency programs were also grouped by region, whether they were large (>3 residents/year) or small (<3 residents/year), and their Doximity reputation ranking: 1-31 (Tier 1), 32-61 (Tier 2), 62-91 (Tier 3), and 92-125 (Tier 4)., Results: Nine hundred and ninety-five medical students were included in this study. The majority of residency matriculants were MDs (N = 988, 99.3%) who came from Tier 1 (N = 410, 41.2%) or Tier 2 (N = 313, 31.5%) medical schools. Those who attended higher-tier medical schools were more likely to match into higher-tier residency programs (p < 0.001). 57.8% (N = 237) of the applicants who attended Tier 1 medical schools matriculated into a Tier 1 residency program, whereas only 24.7% (N = 42) of the applicants from Tier 4 medical schools matriculated into a Tier 1 residency program., Conclusion: Applicants who attend top-tier medical schools represent significantly more residents at top-tier otolaryngology residency programs than those from lower tier medial schools., Level of Evidence: NA Laryngoscope, 133:3353-3357, 2023., (© 2023 The American Laryngological, Rhinological and Otological Society, Inc.)

Introduction: Otolaryngology continues to be dominated by men. As of 2019, only 18.4% of practicing otolaryngologists were women. The goal of this project was to introduce female students to otolaryngology as a career., Methods: A Women in Otolaryngology event was held in September 2021. Participants included undergraduate and first- or second-year medical students from the University at Buffalo. During the event, students rotated through three skills stations working with female otolaryngology residents and attending physicians. Participants completed pre-and post-course surveys regarding their attitudes toward women in surgery and their perceptions of surgery and otolaryngology., Results: A total of 17 students that completed both the pre- and post-course surveys were included. The mean age was 22.6 years (range 18-25 yr). Specifically, 13 (76.5%) of the participants were Caucasian, three (17.6%) were Asian, and one (5.9%) was Hispanic, and 15 (88.2%) were medical students. On the pretest, 10 (55.6%) participants strongly agreed or agreed that otolaryngology as a career is open to females, while on the posttest, 16 (88.9%) participants strongly agreed or agreed (p=0.002). Nine (50.0%) participants strongly agreed or agreed that they have access to resources to help make a decision if they want to pursue a career in otolaryngology before the event, while, after the event, 16 (88.9%) participants strongly agreed or agreed (p=0.007). Five (27.8%) participants strongly agreed or agreed prior to the event that they felt confident in their knowledge of what otolaryngology includes, while afterward 15 (83.3%) strongly agreed or agreed (p=0.002)., Conclusion: The Women in Otolaryngology event increased participants' confidence in understanding otolaryngology, promoted understanding of resources available, and demonstrated the openness of the specialty to women., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, DiNardo et al.)

Objective: To determine what prospective residency applicants look for on otolaryngology residency program websites., Study Design: Survey., Setting: The survey was distributed in a virtual format through Google Forms. A link to the survey was given at the University at Buffalo Otolaryngology Chautauqua, sent to Otolaryngology program directors with requests to forward to PGY1 residents and Otolaryngology interest groups, sent to medical school Otolaryngology interest group leaders, posted on Twitter through several accounts, and on otomatch.com., Methods: A 45 item survey was given to fourth year medical students applying to otolaryngology, re-applicants applying to otolaryngology, and first year otolaryngology residents who had recently matched. Data collected included participant's age, sex, race and ethnicity, current status in school/residency program, and their type of medical degree (MD or DO). Participants were then asked to mark the components listed that they wished to see. Components were separated into 5 categories: Application/Selection Criteria, Employment Aspects, Program Features, Social/Community, and Faculty/Contact Information. Data was analyzed using Mann-Whitney and Kruskal Wallis tests when appropriate. P value <.05 was considered statistically significant., Results: One hundred one surveys were collected. Sixty-four (63.4%) participants were fourth-year medical students, 32 (31.7%) were first-year residents, and 5 (5.0%) were re-applicants. Thirteen of the items on the survey were sought by 80% or more of respondents. Ninety-nine (98.0%) of the participants wanted to see a current resident list with photos and 97 (96.0%) wanted to see the intern year schedule online. Eighty-five percent agreed that salary and benefits information would be valuable on residency websites. Women expressed significantly more interest in salary ( P  = .034), benefits ( P  = .026), and parking information ( P  = .048)., Conclusion: Our study provides insight on key items to include on residency program websites. Websites that contain information that applicants want to use can be helpful for application decisions in the future.

Objective: Obstructive sleep apnea (OSA) is present in approximately 2% to 5% of children; however, only 15% of parents are reported to be knowledgeable about OSA in children. Sleep apnea in children can lead to cardiopulmonary disease, abnormal weight gain, failure to thrive, or learning difficulties. The purpose of our study is to assess parental knowledge of pediatric OSA to identify any knowledge gaps., Study Design: Survey., Setting: Three pediatric otolaryngology clinics associated with a tertiary care children's hospital in Buffalo, NY., Methods: In June of 2021, parents of pediatric (0-18 years) otolaryngology patients completed a survey on their knowledge of OSA. Parents were asked to rank their concern about OSA and identify symptoms of OSA. Parental demographic data collected included gender, age, race, and educational level. Respondents were asked if their child had undergone a sleep study or tonsillectomy., Results: Of the 246 parents included, 77 (31.4%) parents had a child who had a tonsillectomy, 40 (16.3%) had a child who had a sleep study done, and 25 (10.2%) had a child with both done. For recognizing the symptoms of pediatric OSA the mean was 6.3 (95% CI 5.8-6.8) out of 13 total. Symptoms least likely recognized were nocturnal enuresis and hyperactivity, 65 (27%) and 91 (37%) of parents correctly identifying these symptoms, respectively. Greater concern about OSA correlated with greater cumulative knowledge score ( P  < .001). Parents whose child had undergone a tonsillectomy were more likely to be concerned about OSA in children compared to non-tonsillectomy parents ( P  = .003), and sleep study parents were also more likely to be concerned about OSA than non-sleep study parents ( P  = .045)., Conclusion: Parents who attended a pediatric otolaryngology clinic have knowledge gaps about pediatric sleep.

Introduction: Medialization thyroplasty is a procedure indicated for treatment of impaired vocal fold movement. The purpose of this study was to identify variables associated with length of hospital stay (LOS), reoperation, and readmission in patients who underwent a medialization thyroplasty procedure for unilateral vocal cord paralysis., Methods: Adults who underwent unilateral medialization thyroplasty were identified using the 2017 to 2019 NSQIP databases via Current Procedural Terminology code 31591. Data collected included patient demographics, comorbidities, preoperative labs, American Society of Anesthesiologists classification, inpatient status, operative length, and complications. Univariate and multivariate logistic regression were used to analyze effects on total LOS, reoperation, and readmission., Results: 320 patients were identified, with a mean age of 61 years (95% Cl 59.4-62.7) and a female-to-male ratio of 1.1:1. Forty-two (13.1%) patients reported dyspnea as a preoperative symptom. Seven patients (2.2%) reported postoperative complications, 2 with multiple complications: 2 surgical site infections, 2 pneumonias, 2 unplanned intubations, 2 myocardial infarctions, 1 septic shock, 1 cardiac arrest, 1 ventilator use (>48 h), and 1 acute renal failure. Fifty-one (15.9%) were inpatient procedures, with a mean LOS of 1.43 days (95% CI 0.92-1.94). Preoperative functional status and bilirubin were significantly associated with longer LOS (p < 0.001). There were 6 (1.9%) readmissions and 2 (0.6%) reoperations. In univariate analysis, dyspnea varied with reoperation which is important to note in this patient population with glottic insufficiency., Conclusion: Medialization thyroplasty is a procedure with a low risk of mortality. However, preexisting patient comorbidities are associated with an increased risk of postoperative complications and an increased length of stay., (© 2022 S. Karger AG, Basel.)

Serotonin (5-HT) is strongly implicated in the regulation of mammalian circadian rhythms. However, little is known of the functional relationship between the circadian clock located in the suprachiasmatic nucleus (SCN) and its source of serotonergic innervation, the midbrain raphe nuclei. In previous studies, we reported that electrical stimulation of the dorsal or median raphe nuclei (DRN and MRN, respectively) induced 5-HT release in the SCN. Notably, DRN- but not MRN-stimulated 5-HT release was blocked by the 5-HT(1,2,7) antagonist, metergoline, suggesting that the DRN signals to the SCN indirectly via the activation of a 5-HT-responsive multisynaptic pathway. In the present study, pretreatment with the 5-HT(2,7) antagonist, ritanserin, also significantly inhibited DRN-electrically stimulated SCN 5-HT release. However, pretreatment with the 5-HT(1A) antagonist, NAN-190, or the 5-HT(2) antagonists ketanserin and cinanserin had little suppressive effect on this DRN-stimulated 5-HT release. In complementary behavioral trials, electrical stimulation of the DRN during subjective midday caused a 1.3-h advance in the free-running circadian activity rhythm under constant darkness, which was inhibited by metergoline. Collectively, these results are evidence that: (1) DRN-stimulated 5-HT release in the SCN requires the activation of an intermediate target with receptors having 5-HT(7) pharmacological characteristics; (2) electrical stimulation of the DRN induces phase-resetting of the circadian activity rhythm; and (3) activation of 5-HT receptors is necessary for this DRN-stimulated circadian phase-resetting. In view of the dynamic changes in DRN neuronal activity incumbent with the daily sleep-activity cycle, and its functional linkages to the SCN and intergeniculate leaflet, the DRN could serve to provide behavioral/arousal state information to various sites comprising the brain circadian system.

The consummatory components of ingestion and rejection, organized in the caudal brainstem, include licking, swallowing, and the oral phase of rejection (gaping). Studies employing electrical-stimulation induced motor activity have localized interneurons controlling these complex motor patterns to the medullary reticular formation (RF), but the characteristics of these neurons during more naturally induced behavior are unknown. The purpose of the present study was to record the activity profiles of RF neurons during licking, swallowing, and oral rejection in response to gustatory stimulation. Two-hundred and two neurons recorded from awake, freely moving rats were broadly classified as orally related (67%) or non-orally related (33%). Orally related neurons included a large number that were rhythmically active during licking (n = 76; 38%). These "lick-rhythmic" neurons were widely distributed in the RF, but were concentrated in the caudal medullary reticular formation adjacent to the hypoglossal nucleus (Probst's region) and further rostral in the intermediate zone (IRt) of the RF. An analysis of autocorrelations determined that lick-rhythmic neurons in these regions were more closely coupled to licking than to lick-rhythmic neurons more lateral in the parvocellular RF (PCRt). In addition to neurons with weak lick-rhythmic activity, the PCRt also contained a disproportionate number of neurons with orosensory or mixed oro-sensorimotor properties. These data provide evidence for functional specialization within different regions of the medullary RF. A high proportion of lick-rhythmic neurons also showed differential activity associated with swallowing (41%) and/or gaping (75%), further suggesting that the different components of ingestion and rejection share brainstem substrates instead of being produced by unique subsets of interneurons.

Serotonin (5-HT) plays important regulatory roles in mammalian circadian timekeeping; however, little is known concerning the regulation of serotonergic activity in the circadian clock located in the suprachiasmatic nuclei (SCN). By using in vivo microdialysis to measure 5-HT release we demonstrated that electrical or pharmacological stimulations of the dorsal or median raphe nuclei (DRN and MRN, respectively) can alter basal release of 5-HT in the hamster SCN. There were similar increases in SCN 5-HT release after electrical stimulation of either the MRN or DRN, indicating that both could contribute to the serotonergic activity in the SCN. Systemic pretreatment with the 5-HT antagonist metergoline abolished DRN-induced SCN 5-HT release but had little effect on MRN-induced SCN 5-HT release, suggesting different pathways for these nuclei in regulating 5-HT output in the SCN. Microinjections of the 5-HT1A autoreceptor agonist 8-OH-DPAT or antagonist WAY 100635 into the MRN caused significant inhibition and stimulation of SCN 5-HT release, respectively. Both drugs had substantially less effect in the DRN. These differential drug actions indicate that somatodendritic 5-HT1A autoreceptors on MRN neurons provide the prominent raphe autoregulation of 5-HT output in the SCN. Collectively the current results are evidence that DRN as well as MRN neurons can contribute to the regulation of 5-HT release in the hamster SCN. On the basis of the current observations and those from recent anatomic tracing studies of serotonergic projections to SCN it is hypothesized that DRN input to the SCN could be mediated by a DRN --> MRN --> SCN pathway involving a 5-HT-sensitive multisynaptic interaction between the DRN and MRN neurons.

Serotonin (5-HT) has been strongly implicated in the regulation of the mammalian circadian clock located in the suprachiasmatic nuclei (SCN). However, little is known of the pattern of neuronal 5-HT release in the SCN or of the factors involved in regulating its release. Using in vivo microdialysis, we demonstrated the existence of a daily rhythm in the output of 5-HT in the SCN of freely behaving hamsters. This rhythm was characterized by a sharp increase in release from a nadir during late midday to peak levels at the light/dark transition. Output declined to basal levels throughout the remainder of the night. A similar pattern also was evident under constant darkness, with increased 5-HT output occurring at the onset of subjective night. Locomotor activity induced by exposure to a novel running wheel had a pronounced phase-dependent effect on 5-HT release in the SCN, with stimulation during the light phase and suppression during the late dark phase. Systemic application of the somatodendritic 5-HT1A agonist BMY 7378 had a significantly greater suppressive effect on 5-HT release in the SCN during the late dark phase compared with mid light phase, indicating that a variation in raphe autoreceptor response may underlie the time-dependent effects of wheel running on 5-HT release. Collectively, these results show that the daily rhythm in output of 5-HT in the SCN is generated endogenously, and that behavioral state can strongly influence serotonergic activity in the circadian clock in a phase-dependent manner.

The location, organization and anatomical connections of a central pattern generator (CPG) for licking are discussed. Anatomical and physiological studies suggest a brainstem location distributed within several subdivisions of the medullary reticular formation (RF). The involvement of widespread RF regions is evident from brainstem recording experiments in awake freely moving preparations and studies employing electrical stimulation of the frontal cortex to produce ororhythmic activity. The complex multifunctional properties of RF neurons producing licking are indicated by their activity during licking, swallowing and the rejection of an aversive gustatory stimulus. Anatomical studies place descending inputs to a brainstem CPG for licking to widely distributed areas of both the medial and lateral RF. In contrast, most projections originating from brainstem orosensory nuclei terminate primarily within the lateral RF. Because many pre-oromotor neurons appear concentrated largely in the intermediate zone of the RF (IRt), it is hypothesized that neurons from both lateral and medial sites converge within the IRt to control oromotor function.

The distribution of neurons in the medullary reticular formation (RF) activated by the ingestion of sucrose or rejection of quinine was examined using standard immunohistochemical techniques to detect the expression of the Fos protein product of the immediate-early gene c-fos. Double-labeling techniques were used to gain further insight into the possible functional significance of RF neurons exhibiting Fos-like immunoreactivity (FLI). Compared with sucrose and unstimulated controls, quinine elicited significantly more FLI neurons in three specific RF subdivisions: parvocellular reticular nucleus (PCRt), intermediate reticular nucleus (IRt), and dorsal medullary reticular nucleus (MdD). Moreover, the number of FLI neurons in the RF of quinine-stimulated animals was significantly correlated with the degree of oromotor activity. Thus, the distinct distribution of FLI neurons throughout the RF after quinine may reflect the activation of a specific oral rejection circuit. The double-labeling results indicated a high degree of segregation between FLI neurons and premotor projection neurons to the hypoglossal nucleus (mXII) retrogradely labeled with Fluorogold. Thus, although there were a significant number of double-labeled neurons in the RF, the major concentration of premotor projection neurons to mXII in IRt were medial to the preponderance of FLI neurons in the PCRt. In contrast, there was substantial overlap between FLI neurons in the RF and labeled fibers after injections of the anterograde tracer, biotinylated dextran into the rostral (gustatory) portion of the nucleus of the solitary tract. These results support a medial (premotor)/lateral (sensory) functional topography of the medullary RF.

1. The activity of 34 hypoglossal (mXII) neurons was characterized during the ingestion and rejection of gustatory stimuli in the awake rat. Intraoral infusions of water, sucrose, sodium chloride, or hydrochloric acid initiated ingestion responses; infusions of quinine monohydrochloride initiated rejection responses. Electromyographic (EMG) activity from three oropharyngeal muscles monitored the occurrence of lick cycles and swallows (ingestion) and gape cycles (rejection). In addition, the orofacial region was videotaped to provide an independent assessment of lingual and jaw movements in relation to neural activity. 2. EMG activity during lick and gape cycles was quantified by calculating the duration, magnitude, and peak time of muscle contractions. Lick and gape cycles produced highly differentiated patterns of activity from jaw-opener (anterior digastric, AD), lingual protrudor (geniohyoid, GEN), and lingual retractor (styloglossus, STY) muscles. Lick cycles were characterized by an alternating two-phase sequence of protrusion-retraction; gape cycles by an initial coactivation of both lingual muscles (phase I), followed by a sequence of protrusion (phase II) and retraction (phase III). Contraction durations were significantly longer during gape cycles compared with lick cycles for the AD (Xlick +/- 59 ms; Xgape +/- 134 ms, means +/- SD), GEN (Xlick +/- 77 ms; Xgape +/- 200 ms), and STY (Xlick +/- 93 ms; Xgape +/- 220 ms) muscles. 3. Thirty-one out of 34 mXII neurons were functionally classified as protrudor- or retractor-related by cross-correlating anterior digastric EMG activity with neural activity during licking. Fourteen out of 34 neurons were protrudor-related, 17/34 were retractor-related. These classifications were largely consistent with the results from an analysis of a subset of cells (n = 14) that directly compared neural activity with videotaped records of visible tongue movements. 4. The magnitude of mXII activity during ingestion and rejection was compared by determining the mean number of spikes per lick, gape, and swallow for each neuron. Five out of 14 (36%) protrudor-related and 10/17 (59%) retractor-related cells had significant increases in activity during gape responses compared with the number of spikes per lick cycle. This increased activity of mXII neurons was consistent with the more robust lingual motor activity during the gape response. Two protrudor-related and three retractor-related neurons showed significant decreases in activity during gape responses. Although a similar proportion of mXII neurons exhibited decreases in activity during swallows compared with licks (3 protrudor- and 1 retractor-related), fewer mXII neurons (1 protrudor- and 1 retractor-related) showed increased activity during swallows.(ABSTRACT TRUNCATED AT 400 WORDS)