RESUMEN

Classical studies of the avian diencephalon hardly mention the habenulo-interpeduncular tract (a.k.a. retroflex tract), although both the habenula (HB) (its origin) and the interpeduncular nuclear complex (its target) are present. Retroflex tract fibers were described at early embryonic stages but seem absent in the adult in routine stains. However, this tract is a salient diencephalic landmark in all other vertebrate lineages. It typically emerges out of the caudal HB, courses dorsoventrally across thalamic alar and basal plates just in front of the thalamo-pretectal boundary, and then sharply bends 90° caudalwards at paramedian basal plate levels (this is the "retroflexion"), to approach longitudinally via paramedian pretectum and midbrain the rostralmost hindbrain, specifically the prepontine median interpeduncular complex across isthmus and rhombomere 1. We systematize this habenulo-interpeduncular course into four parts named subhabenular, retrothalamic, tegmental, and interpeduncular. We reexamined the chicken habenulo-interpeduncular fibers at stages HH30 and HH35 (6.5- and 9-day incubation) by mapping them specifically with immunoreaction for BEN protein, a well-known marker. We found that only a small fraction of the stained retroflex tract fibers approaches the basal plate by coursing along the standard dorsoventral pathway in front of the thalamo-pretectal boundary. Many other habenular fibers instead diverge into atypical dispersed courses across the thalamic cell mass (implying alteration of the first subhabenular part of the standard course) before reaching the basal plate; this dispersion explains their invisibility. A significant number of such transthalamic habenular fibers cross orthogonally the zona limitans (ZLI) (the rostral thalamic boundary) and invade the caudal alar prethalamus. Here, they immediately descend dorsoventrally, just rostrally to the ZLI, until reaching the prethalamic basal plate, where they bend (retroflex) caudalwards, entering the thalamic basal paramedian area. These atypical fibers gradually fasciculate with the other groups of habenular efferent fibers in their final longitudinal approach to the hindbrain interpeduncular complex. We conclude that the poor visibility of this tract in birds is due to its dispersion into a diversity of atypical alternative routes, though all components eventually reach the interpeduncular complex. This case merits further analysis of the diverse permissive versus nonpermissive guidance mechanisms called into action, which partially correlate distinctly with successive diencephalic, mesencephalic, and hindbrain neuromeric fields and their boundaries.

Asunto(s)

Habénula , Núcleo Interpeduncular , Animales , Habénula/fisiología , Embrión de Pollo , Núcleo Interpeduncular/fisiología , Vías Nerviosas/fisiología

RESUMEN

Bilinguals are widely reported to have certain kinds of cognitive advantages, including language learning advantages. One possible pathway is a language-specific transfer effect, whereby sensitivity to structural regularities in known languages can be brought to to-be-acquired languages that share particular features. Here we tested for transfer of a specific linguistic property, sensitivity to retroflexion as contrastive phonemic feature. We designed a task for bilinguals with homogeneous language exposure (i.e., bilingual in the same languages) and heterogeneous feature representation (i.e., differing levels of proficiency). Hindi and Mandarin Chinese both have retroflexion in phoneme contrasts (Hindi: stop consonants, Mandarin: sibilants). In a preregistered study, we conducted a statistical learning task for the Hindi dental-retroflex stop contrast with a group of early parallel English-Mandarin bilinguals, who varied in their Mandarin understanding levels. We based the target sample size on power analysis of a pilot study with a Bayesian stop-rule after minimum threshold. Contrary to the pilot study (N = 15), the main study (N = 50) did not find evidence for a learning effect, nor language-experience variance within the group. This finding suggests that statistical effects for the feature in question may be more fragile than commonly assumed, and may be evident in only a small subsample of the general population (as in our pilot). These stimuli have previously shown learning effects in children, so an additional possibility is that neural commitment to adults' languages prevents learning of the fine-grained stimulus contrast in question for this adult population.

Asunto(s)

Multilingüismo , Fonética , Niño , Humanos , Adulto , Teorema de Bayes , Señales (Psicología) , Proyectos Piloto , Lenguaje

RESUMEN

This study investigated cue weighting in the perception of the retroflex and non-retroflex lateral contrast in the monosyllabic words /ɭə/ and /lə/ in the Zibo dialect of Chinese. A binary forced-choice identification task was carried out among 32 natives, using computer-modified natural speech situated in a two-dimensional acoustic space. The results showed that both acoustic cues had a significant main effect on lateral identification, with F1 of the following schwa being the primary cue and the consonant-tos-vowel (C/V) duration ratio as a secondary cue. No interaction effect was found between these two acoustic cues. Moreover, the results indicated that acoustic cues were not equally weighted in production and perception of the syllables /ɭə/ and /lə/ in the Zibo dialect. Future studies are suggested involving other acoustic cues (e.g., the F1 of laterals) or adding noise in the identification task to better understand listeners' listening strategies in their perception of the two laterals in the Zibo dialect.

RESUMEN

Punjabi is an Indo-Aryan language which contrasts a rich set of coronal stops at dental and retroflex places of articulation across three laryngeal configurations. Moreover, all these stops occur contrastively in various positions (word-initially, -medially, and -finally). The goal of this study is to investigate how various coronal place and laryngeal contrasts are distinguished acoustically both within and across word positions. A number of temporal and spectral correlates were examined in data from 13 speakers of Eastern Punjabi: Voice Onset Time, release and closure durations, fundamental frequency, F1-F3 formants, spectral center of gravity and standard deviation, H1*-H2*, and cepstral peak prominence. The findings indicated that higher formants and spectral measures were most important for the classification of place contrasts across word positions, whereas laryngeal contrasts were reliably distinguished by durational and voice quality measures. Word-medially and -finally, F2 and F3 of the preceding vowels played a key role in distinguishing the dental and retroflex stops, while spectral noise measures were more important word-initially. The findings of this study contribute to a better understanding of factors involved in the maintenance of typologically rare and phonetically complex sets of place and laryngeal contrasts in the coronal stops of Indo-Aryan languages.

Asunto(s)

Lenguaje , Acústica del Lenguaje , Acústica , Humanos , Fonética , Calidad de la Voz

RESUMEN

How speech sounds are represented in the brain is not fully understood. The mismatch negativity (MMN) has proven to be a powerful tool in this regard. The MMN event-related potential is elicited by a deviant stimulus embedded within a series of repeating standard stimuli. Listeners construct auditory memory representations of these standards despite acoustic variability. In most designs that test speech sounds, however, this variation is typically intra-category: All standards belong to the same phonetic category. In the current paper, inter-category variation is presented in the standards. These standards vary in manner of articulation but share a common phonetic feature. In the standard retroflex experimental block, Mandarin Chinese speaking participants are presented with a series of "standard" consonants that share the feature [retroflex], interrupted by infrequent non-retroflex deviants. In the non-retroflex standard experimental block, non-retroflex standards are interrupted by infrequent retroflex deviants. The within-block MMN was calculated, as was the identity MMN (iMMN) to account for intrinsic differences in responses to the stimuli. We only observed a within-block MMN to the non-retroflex deviant embedded in the standard retroflex block. This suggests that listeners extract [retroflex] despite significant inter-category variation. In the non-retroflex standard block, because there is little on which to base a coherent auditory memory representation, no within-block MMN was observed. The iMMN to the retroflex was observed in a late time-window at centro-parieto-occipital electrode sites instead of fronto-central electrodes, where the MMN is typically observed, potentially reflecting the increased difficulty posed by the added variation in the standards. In short, participants can construct auditory memory representations despite significant acoustic and inter-category phonological variation so long as a shared phonetic feature binds them together.

RESUMEN

Objective We investigated the results of biliary cannulation using a short-type single-balloon enteroscope in patients with a native papilla who had previously undergone Roux-en-Y gastrectomy and analyzed the factors associated with successful cannulation. Methods The study subjects consisted of patients with a native papilla who had previously undergone Roux-en-Y gastrectomy and endoscopic retrograde cholangiopancreatography using a short-type single-balloon enteroscope at our institution between September 2011 and July 2019. We carried out a retrospective investigation of the outcomes, including assessing the success rate of biliary cannulation, and analyzed the factors associated with successful cannulation. Results In total, 78 patients underwent biliary cannulation of a native papilla. The success rate of biliary cannulation was 80.8% (88.5% when including success on repeated attempts). The success rate of the standard cannulation technique was 60.3%, with the use of advanced cannulation techniques to secure the pancreatic duct providing the same additional effect as a normal anatomy. Adverse events occurred in 9.0% of cases. A multivariate analysis of the Roux-en-Y gastrectomy patients found that cannulation was more likely to be successful in patients in whom the scope could be placed in the retroflex position (odds ratio: 7.88, 95% confidence interval: 2.19-37.77, p<0.001). Conclusion Selective biliary cannulation using a short-type single-balloon enteroscope in patients with a native papilla who had undergone Roux-en-Y gastrectomy was effective and safe. The retroflex position provided a good papilla field of view and improved the success rate of biliary cannulation.

Asunto(s)

Anastomosis en-Y de Roux/efectos adversos , Enteroscopia de Balón/normas , Sistema Biliar , Cateterismo/normas , Colangiopancreatografia Retrógrada Endoscópica/efectos adversos , Gastrectomía/normas , Conductos Pancreáticos/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Guías de Práctica Clínica como Asunto , Estudios Retrospectivos

RESUMEN

The retroflex tract contains medial habenula efferents that target the hindbrain interpeduncular complex and surrounding areas. This tract displays a singular course. Initially, habenular axons extend ventralwards in front of the pretectum until they reach the basal plate. Next, they avoid crossing the local floor plate, sharply changing course caudalwards (the retroflexion alluded by the tract name) and navigate strictly antero-posteriorly across basal pretectum, midbrain and isthmus. Once they reach rhombomere 1, the habenular axons criss-cross the floor plate several times within the interpeduncular nuclear complex as they innervate it. Here we described the timing and details of growth phenomena as these axons navigate to their target. The first dorsoventral course apparently obeys Ntn1 attraction. We checked the role of local floor plate signaling in the decision to avoid the thalamic floor plate and bend caudalwards. Analyzing the altered floor and basal plates of Gli2 knockout mice, we found a contralateral projection of most habenular axons, plus ulterior bizarre navigation rostralwards. This crossing phenotype was due to a reduced expression of Slit repulsive cues, suggesting involvement of the floor-derived Robo-Slit system in the normal guidance of this tract. Using Slit and Robo mutant mice, open neural tube and co-culture assays, we determined that Robo1-Slit2 interaction is specifically required for impeding that medial habenular axons cross the thalamic floor plate. This pathfinding mechanism is essential to establish the functionally important habenulo-interpeduncular connection.

Asunto(s)

Movimiento Celular , Habénula/metabolismo , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Neuronas/metabolismo , Receptores Inmunológicos/metabolismo , Tálamo/metabolismo , Animales , Axones/metabolismo , Células COS , Chlorocebus aethiops , Técnicas de Cocultivo , Regulación del Desarrollo de la Expresión Génica , Genotipo , Edad Gestacional , Habénula/embriología , Péptidos y Proteínas de Señalización Intercelular/deficiencia , Péptidos y Proteínas de Señalización Intercelular/genética , Factores de Transcripción de Tipo Kruppel/deficiencia , Factores de Transcripción de Tipo Kruppel/genética , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas del Tejido Nervioso/deficiencia , Proteínas del Tejido Nervioso/genética , Fenotipo , Receptores Inmunológicos/deficiencia , Receptores Inmunológicos/genética , Transducción de Señal , Tálamo/embriología , Técnicas de Cultivo de Tejidos , Transfección , Proteína Gli2 con Dedos de Zinc , Proteínas Roundabout

RESUMEN

Objective To explore the clinical values of applying contact-mode argon plasma coagulation (APC) for retroflex colonoscopic treatment of ultra-lower rectal polyps. Methods 46 wide outsole and applanate polyps smaller than 1.0 cm located at ultra-lower rectum in 17 cases of patients were treated by contact-mode APC under U-type retroflex colonoscopy after failure in regular colonoscopic treatment. Then observe the contacting rate of APC probe with polyps, success rate of curing polyps, rate of probe being adhered and blocked by the solidification structures, incidence of submucosal emphysemas, and incidence of colonoscope ambustion. Results Under U-type retroflex colonoscopy, the probe could contact with polyps in 17 patients. The polyps in every patient were cured by APC in the first time of colonoscopic treatment, whereas all 46 polyps were cured by 97 times of APC spurt. Mild adhesions occurred between the probe and solidification structures at 5 times (5.15 %) among 97 times of APC spurt, without injuries to the coagulation surface from which when the probe separated. The solidification structures blocked the probe only twice (2.06 %). When the solidification structures were cleared, efficiency of the probe restored. No sub-mucosal emphysemas and colonoscope ambustion happened. Conclusion Applying contact-mode APC for retroflex colonoscopic treatment of ultra-lower rectal polyps is safe and effective, it can prevent the damage of colonoscope from the argon knife.