Controle neural da deglutição / Neural control of swallowing

ABSTRACT BACKGROUND: Swallowing is a motor process with several discordances and a very difficult neurophysiological study. Maybe that is the reason for the scarcity of papers about it. OBJECTIVE: It is to describe the chewing neural control and oral bolus qualification. A review the cranial nerves involved with swallowing and their relationship with the brainstem, cerebellum, base nuclei and cortex was made. METHODS: From the reviewed literature including personal researches and new observations, a consistent and necessary revision of concepts was made, not rarely conflicting. RESULTS AND CONCLUSION: Five different possibilities of the swallowing oral phase are described: nutritional voluntary, primary cortical, semiautomatic, subsequent gulps, and spontaneous. In relation to the neural control of the swallowing pharyngeal phase, the stimulus that triggers the pharyngeal phase is not the pharyngeal contact produced by the bolus passage, but the pharyngeal pressure distension, with or without contents. In nutritional swallowing, food and pressure are transferred, but in the primary cortical oral phase, only pressure is transferred, and the pharyngeal response is similar. The pharyngeal phase incorporates, as its functional part, the oral phase dynamics already in course. The pharyngeal phase starts by action of the pharyngeal plexus, composed of the glossopharyngeal (IX), vagus (X) and accessory (XI) nerves, with involvement of the trigeminal (V), facial (VII), glossopharyngeal (IX) and the hypoglossal (XII) nerves. The cervical plexus (C1, C2) and the hypoglossal nerve on each side form the ansa cervicalis, from where a pathway of cervical origin goes to the geniohyoid muscle, which acts in the elevation of the hyoid-laryngeal complex. We also appraise the neural control of the swallowing esophageal phase. Besides other hypotheses, we consider that it is possible that the longitudinal and circular muscular layers of the esophagus display, respectively, long-pitch and short-pitch spiral fibers. This morphology, associated with the concept of energy preservation, allows us to admit that the contraction of the longitudinal layer, by having a long-pitch spiral arrangement, would be able to widen the esophagus, diminishing the resistance to the flow, probably also by opening of the gastroesophageal transition. In this way, the circular layer, with its short-pitch spiral fibers, would propel the food downwards by sequential contraction.

RESUMO CONTEXTO: A deglutição é um processo motor com muitas discordâncias e de difícil estudo quanto a sua neurofisiologia. Talvez por essa razão sejam tão raros os artigos sobre esse tema. OBJETIVO - Descrever o controle neural da mastigação e a qualificação do bolo que se obtém durante a fase oral. Revisar os nervos cranianos envolvidos com a deglutição e suas relações com o tronco cerebral, cerebelo, núcleos de base e córtex. MÉTODOS: Revisão da literatura com inclusão de trabalhos pessoais e novas observações buscando dar consistência a necessária revisão dos conceitos, muitas vezes conflitantes. RESULTADOS E CONCLUSÃO: Em relação a fase oral da deglutição consideramos o controle neural em cinco distintas possibilidades. Fase oral nutricional voluntária, fase oral cortical voluntária primaria, fase oral semiautomática, fase oral em goles subsequentes e fase oral espontânea. Em relação ao controle neural da fase faríngea da deglutição, pode-se observar que o estímulo que dispara a fase faríngea não é o toque produzido pela passagem do bolo, mas sim a distensão pressórica, tenha ou não conteúdo em passagem. Na deglutição nutricional, alimento e pressão são transferidos, mas na fase oral da deglutição primária cortical somente pressão é transferida e temos resposta faríngea similar a nutricional. A fase faríngea incorpora como parte de sua dinâmica as atividades orais já em curso. A fase faríngea se inicia por ação do plexo faríngeo composto pelos nervos glossofaríngeo (IX), vago (X), e acessório (XI), com envolvimento do trigêmeo (V), do facial (VII), glossofaríngeo (IX) e hipoglosso (XII). O plexo cervical (C1, C2), e o nervo hipoglosso, a cada lado, formam a alça cervical de onde, com origem cervical, um ramo segue para o músculo gênio-hioide, um músculo que atua na dinâmica de elevação do complexo hiolaríngeo. Foi também considerado o controle neural da fase esofágica da deglutição. Além de outras hipóteses foi considerado que é possível que a camadas musculares consideradas como longitudinal e circular para o esôfago sejam a longitudinal composta por fibras espirais de passo longo e a circular por fibras espirais de passo curto. Essa morfologia associada ao conceito de preservação de energia, nos permite admitir que a contração da camada longitudinal por seu arranjo espiral seja capaz de alargar o esôfago diminuindo sua resistência ao fluxo e provavelmente e também abrindo a transição esofagogástrica. Desse modo a camada circular, espiral de passo curto, pode propelir o bolo por constrição sequencial de cranial para caudal.

Valores de normalidade de um novo sistema de manometria de alta resolução por perfusão de água / Normative values for a new water-perfused high resolution manometry system

ABSTRACT BACKGROUND: Esophageal manometry is the most reliable method to evaluate esophageal motility. High resolution manometry (HRM) provides topographic contour colored plots (Clouse Plots) with simultaneous analysis from the pharynx to the stomach. Both solid state and water-perfused systems are available. OBJECTIVE: This study aims to determinate the normative data for a new water-perfused HRM. METHODS: HRM was made in 32 healthy volunteers after 8 hours fasting. HRM system used consisted of a 24-channel water-perfused catheter (Multiplex, Alacer Biomedica, São Paulo, Brazil). The reusable catheter is made of polyvinyl chloride (PVC) with 4.7 mm of diameter. Side holes connected to pressure transducers are spaced 2 cm for the analysis from the pharynx to the lower esophageal sphincter (LES). Holes are spaced 5 mm and 120° in a spiral disposition in the LES area. The sensors encompass 34 cm in total. Upper esophageal sphincter (UES) parameters studied were basal and relaxation pressures. Esophageal body parameters were distal contractile integral (DCI), distal latency (DL) and break. LES parameters studied were basal pressure, integrated residual pressure (IRP), total and abdominal length. Variables are expressed as mean ± standard deviation, median (interquartile range) and percentiles 5-95th. RESULTS: All volunteers (17 males, aged 22-62 years) completed the study and tolerated the HRM procedure well. Percentiles 5-95th range were calculated: Upper Esophageal Sphincter (UES) basal pressure 16.7-184.37 (mmHg), DL: 6.2-9.1 (s), DCI: 82.72-3836.61 (mmHg.s.cm), break: <7.19 (cm), LES basal pressure: 4.89-37.16 (mmHg), IRP: 0.55-15.45 (mmHg). CONCLUSION: The performance and normative values obtained for this low-cost water-perfused HRM seems to be adequate for clinical use.

RESUMO CONTEXTO: Manometria esofágica é o exame mais confiável para avaliar motilidade esofágica. Manometria esofágica de alta resolução (MAER) apresenta um gráfico dinâmico e colorido (Clouse plots) com análise simultânea da faringe ao estomago. Dois tipos de manometria estão disponíveis: estado sólido e por perfusão de água. OBJETIVO: Determinar os valores de normalidade de um novo sistema de manometria de alta resolução. MÉTODOS: MAER foi realizada em 32 voluntários saudáveis após jejum de oito horas. O sistema utilizado é de perfusão de água com 24 sensores (Multiplex, Alacer Biomedica, São Paulo, Brasil). O catéter permanente é feito de cloreto de polivinil (PVC) com 4,7 mm de diâmetro. Os orifícios laterais para conexão com os transdutores de pressão são espaçados de 2 cm para análise da faringe ao esfíncter esofagiano inferior (EEI) e são esparçados em 5mm em forma espiralada com 120° entre orificios. Os sensores no total englobam 34 cm. Para o esfíncter esofágico superior (EES), os parâmetros estudados foram às pressões basal e de relaxamento. Os parâmetros do corpo esofágico foram: integral de contratilidade distal (DCI), latência distal (DL) e quebra. Os parâmetros do EEI inferior foram pressões basal e de relaxamento e pressão de relaxamento integrada (IRP). As variáveis foram expressas em medias ± desvio padrão, medianas (variação de interquartis) e percentis 5-95. RESULTADOS: Todos os voluntários (17 homens, com idade variando entre 22-62 anos) terminaram e toleraram o exame. A variação dos percentis 5-95 foi calculada: pressão basal do esfíncter esofágico superior (EES) foi 16,7-184,37 (mmHg), DL: 6,2-9,1 (s), DCI: 82,72-3836,61 (mmHg.s.cm), quebra: <7,19 (cm), pressão basal do EEI: 4,89-37,16 (mmHg), IRP: 0,55-15,45 (mmHg). CONCLUSÃO: A realização dos testes e os valores de normalidade determinados por este estudo parecem ser adequadas para a prática clínica.

Evaluación de las otoemisiones acústicas en relación a los potenciales evocados auditivos de tronco cerebral en niños / Evaluation of otoacoustic emissions in relation to brainstem evoked auditory potentials in children

RESUMEN Con el objetivo de determinar la validez del uso de la otoemisiones acústicas en comparación con los potenciales evocados auditivos de tronco cerebral (PEATC), se realizó un estudio con 96 niños entre cero a cuatro años que acudieron al Instituto Nacional de Rehabilitación en Lima, Perú. Los resultados muestran un punto de corte que corresponde a 1 en ambos oídos, con valores de likelihood ratio (LR) (+): 17,67 en OD y 16,72 en oído izquierdo, y de LR (-): 0,25 en oído derecho y 0,24 en oído izquierdo; se obtuvo Curva ROC con área bajo la curva en oído derecho de 0,830 (p<0,001) y en oído izquierdo de 0,829 (p<0,001). Según los resultados de LR (+) la sensibilidad es de 76% en el oído derecho y de 65% en el oído izquierdo que coincide con la conformación de la curva ROC. En conclusión, las otoemisiones acústicas no representarían una alternativa lo suficientemente discriminatoria como prueba de tamizaje en esta población.

ABSTRACT To determine the validity of the use of acoustic otoacoustic emissions in comparison with the evoked potentials Auditory brainstem examination (PEATC), a study was carried out with 96 children between 0 and 4 years of age that went to Instituto Nacional de Rehabilitación in Lima, Peru. The results show a cut-off point corresponding to 1 in (+): 17.67 in right ear and 16.72 in left ear, and LR (-): 0.25 in ear right and 0.24 in left ear; ROC curve with area under the right ear curve of 0.830 (p<0.001) was obtained and in left ear of 0.829 (p<0.001). According to the results of LR (+) the sensitivity is 76% in the right ear and 65% In the left ear that coincides with the conformation of the ROC curve. In conclusion, acoustic emissions would not represent an alternative sufficiently discriminatory alternative as a screening test in this population.

Sistema de medios de enseñanza sobre tronco encefálico y dirección del trabajo independiente / Brainsteam teaching aids system and direction of the independent work

El tronco encefálico, se caracteriza por sus pequeñas dimensiones y la complejidad de su estructura. Se confeccionó el sistema de medios con el objetivo de ofrecer al estudiante, los conocimientos relacionados con la configuración externa e interna del tronco encefálico, con un nivel de organización y representación que permitiera la sistematización de las características morfofisiológicas de cada una de sus porciones y su integración, contribuyendo a dirigir correctamente el trabajo independiente. El sistema incluye modelos tridimensionales y láminas, cada modelo posee una guía de señalamientos, posee además un folleto que complementa teóricamente la información que se muestra. Facilitó la integración entre configuración externa e interna del tronco encefálico, permite a su vez la vinculación básico-clínica y la inclusión del estudiante en la actividad cognoscitiva independiente. Se concluye que el sistema contribuyó a la correcta dirección del trabajo independiente, así como a la autopreparación del estudiante.

The brainstem is characterized for its small dimensions and the complexity of its structure. The system of aids were made to offer to students, the knowledge related to the external and internal configuration of the brainstem, with a level of organization and representation that permit the systematization and integration of its morphology and physiology characteristics, contributing thus to the correct direction of the independent work. The system includes models and sheets, each model possesses its guide of fixing. It possesses a pamphlet that complements the theoretical information according with its level of updating and deepening. It facilitated the integration between external and internal configuration of the brainstem, permitting the basic and clinical linking and the inclusion of the student to independent cognitive activity. It is concluded that the system of teaching aids contributed to the correct direction of the independent work of the students, as well as its himself preparation.

Idosos residentes em uma instituição de longa permanência: adaptação à luz de Callista Roy / Elderly residents in homes for the aged: adjustment in the light of Callista Roy / Residentes mayores en un hogares para ancianos: adaptación a la luz de Callista Roy

Objetivou-se avaliar o processo de adaptação de idosos que buscam, voluntariamente, residir em Instituição de Longa Permanência para Idosos (ILPI), na cidade de Fortaleza-CE, com base no modelo teórico de Roy. Pesquisa descritiva, realizada em uma IPLI com treze idosos residentes. A coleta de dados foi por meio de entrevista, nos meses de outubro e dezembro de 2011. Os dados foram tratados pela análise de conteúdo temática. Emergiram as seguintes temáticas: Eu Físico, subdividido em sensação corporal e imagem corporal; e Eu Pessoal, subdividido em auto coerência, auto ideal e ser moral-ético-espiritual. Assim, a opção de morar em ILPI não mudou efetivamente a vida dos idosos. Estes conseguiram adaptação ao local e convivem bem com os estímulos internos e externos.

This study aimed to evaluate the adaptation of elderly individuals voluntarily reside in Institution for the Aged (LTCF) in the city of Fortaleza-CE, based on the theoretical model of Roy. Descriptive study, in a IPLI involving thirteen elderly residents. Data collect was through interviews in the months of October and December 2011 and organized by thematic content analysis. The following themes has emerged: I Physical subdivided into body sensation and body image; Staff and I, subdivided into self-consistency and auto ideal be moral-ethical-spiritual. Thus, the option to live in ILPI not effectively changed the lives of elderly people. They managed to adapt to the local and coexist well with internal and external stimuli.

Este estudio tuvo como objetivo evaluar la adaptación de las personas mayores que residen voluntariamente en la Institución para la tercera edad (LTCF) en la ciudad de Fortaleza-CE, basado en el modelo teórico de Roy. Estudio descriptivo, en un IPLI con trece ancianos residentes. Los datos fueran recogidos a través de entrevistas en los meses de octubre y diciembre de 2011 y organizados mediante análisis de contenido temático. Emergieron los siguientes temas: subdivide I Física en la imagen corporal y sensación de cuerpo; El personal y yo, subdividen en auto-consistencia y auto ideal ser moral-ético-espiritual. Por lo tanto, la opción de vivir en ILPI no cambió de manera efectiva la vida de los ancianos. Se las arreglaron para adaptarse a lo local y convivir bien con los estímulos internos y externos.

Central chemoreceptors and neural mechanisms of cardiorespiratory control

The arterial partial pressure (P CO2) of carbon dioxide is virtually constant because of the close match between the metabolic production of this gas and its excretion via breathing. Blood gas homeostasis does not rely solely on changes in lung ventilation, but also to a considerable extent on circulatory adjustments that regulate the transport of CO2 from its sites of production to the lungs. The neural mechanisms that coordinate circulatory and ventilatory changes to achieve blood gas homeostasis are the subject of this review. Emphasis will be placed on the control of sympathetic outflow by central chemoreceptors. High levels of CO2 exert an excitatory effect on sympathetic outflow that is mediated by specialized chemoreceptors such as the neurons located in the retrotrapezoid region. In addition, high CO2 causes an aversive awareness in conscious animals, activating wake-promoting pathways such as the noradrenergic neurons. These neuronal groups, which may also be directly activated by brain acidification, have projections that contribute to the CO2-induced rise in breathing and sympathetic outflow. However, since the level of activity of the retrotrapezoid nucleus is regulated by converging inputs from wake-promoting systems, behavior-specific inputs from higher centers and by chemical drive, the main focus of the present manuscript is to review the contribution of central chemoreceptors to the control of autonomic and respiratory mechanisms.

Synaptic vesicle pool size, release probability and synaptic depression are sensitive to Ca2+ buffering capacity in the developing rat calyx of Held

The calyx of Held, a specialized synaptic terminal in the medial nucleus of the trapezoid body, undergoes a series of changes during postnatal development that prepares this synapse for reliable high frequency firing. These changes reduce short-term synaptic depression during tetanic stimulation and thereby prevent action potential failures during a stimulus train. We measured presynaptic membrane capacitance changes in calyces from young postnatal day 5-7 (p5-7) or older (p10-12) rat pups to examine the effect of calcium buffer capacity on vesicle pool size and the efficiency of exocytosis. Vesicle pool size was sensitive to the choice and concentration of exogenous Ca2+ buffer, and this sensitivity was much stronger in younger animals. Pool size and exocytosis efficiency in p5-7 calyces were depressed by 0.2 mM EGTA to a greater extent than with 0.05 mM BAPTA, even though BAPTA is a 100-fold faster Ca2+ buffer. However, this was not the case for p10-12 calyces. With 5 mM EGTA, exocytosis efficiency was reduced to a much larger extent in young calyces compared to older calyces. Depression of exocytosis using pairs of 10-ms depolarizations was reduced by 0.2 mM EGTA compared to 0.05 mM BAPTA to a similar extent in both age groups. These results indicate a developmentally regulated heterogeneity in the sensitivity of different vesicle pools to Ca2+ buffer capacity. We propose that, during development, a population of vesicles that are tightly coupled to Ca2+ channels expands at the expense of vesicles more distant from Ca2+ channels.

Ultrastructural study of the effects of cyclosporine in the brainstem of Wistar rats submitted to the ethidium bromide demyelinating model / Estudo ultra-estrutural dos efeitos da ciclosporina no tronco encefálico de ratos Wistar submetidos ao modelo desmielinizante do brometo de etídio

The ethidium bromide-demyelinating model (EB) was used to study remyelination in the brainstem under the use of cyclosporine (CsA). Wistar rats were submitted to intracisternal injection of 0.1 percent EB or 0.9 percent saline solution, and others were taken as histologic controls (group I). Within those injected with EB, some have not received immunosuppressive treatment (II); some were treated by intraperitonial route with CsA (III.E - 10 mg/kg/day). Rats from group III.C were injected with saline solution and treated with CsA. The animals were perfused from 15 to 31 days post-injection collecting brainstem sections for light and transmission electron microscopy studies. After EB injection it was noted the presence of macrophages and non-degraded myelin debris, demyelinated axons, oligodendrocyte or Schwann cell remyelinated axons, groups of infiltrating pial cells, hypertrophic astrocytes and few lymphocytes. Tissue repair of EB-induced lesions in group III.E was similar to that of group II, but with the presence of a higher density of oligodendrocytes near remyelinating areas.

Empregou-se o modelo desmielinizante do brometo de etídio (BE) com o objetivo de estudar a remielinização no tronco encefálico frente ao uso de ciclosporina (CsA). Foram utilizados ratos Wistar, submetidos à injeção de BE a 0,1 por cento ou de solução salina na cisterna pontina, assim como controles histológicos (grupo I). Dos animais injetados com BE, alguns não receberam tratamento imunossupressor (II); outros foram tratados por via intraperitoneal com CsA (III.E - 10 mg/kg/dia). O grupo III.C incluiu animais injetados com salina e tratados com CsA. Os animais foram perfundidos dos 15 aos 31 dias pós-injeção, com colheita de material do tronco encefálico para estudos de microscopia de luz e eletrônica de transmissão. Após injeção de BE, foram observados macrófagos e restos de mielina não-degradada, axônios desmielinizados ou remielinizados por oligodendrócitos e por células de Schwann, grupos de células piais infiltrantes, astrócitos hipertróficos e poucos linfócitos. O processo de reparo das lesões no grupo III.E apresentou-se similar ao do grupo II, porém com maior densidade de oligodendrócitos próximos às áreas de remielinização.

Long-term outcome in coma.

OBJECTIVE: To assess the relationship between Modified Glasgow Coma Scale, its components, brain stem reflexes and long term functional outcome in children with acute non-traumatic coma. METHOD: MGCS and brainstem reflexes were assessed at 6 hourly intervals for 72 hours from the time of admission. The children were followed up regularly and functional outcome was assessed at the end of 9 months. The lowest score of the MGCS and worst brain stem reflexes were used for the analysis. RESULTS: Higher total MGCS score and verbal response score had a significant positive correlation with better functional outcome as measured by GOS and intelligence quotient. There was no association between the language function and the initial MGCS, its components and brain stem reflexes. Lower verbal response (P = 0.005) was the only factor that was found to be individually associated with poorer long term GOS score and intelligence quotient by multivariate linear regression analysis. CONCLUSION: In the long term prediction of outcome in acute non-traumatic coma, MGCS is not useful. However, verbal response, a component of MGCS, correlates well with long term functional outcome and intelligence quotient.

Central actions of somatostatin in the generation and control of breathing

The neuropeptide somatostatin is involved in many functions in the central nervous system as well as in the periphery. When it is centrally injected, an irreversible apnea is often developed. In the present review, we discuss the effects of somatostatin as the result of its actions at three levels of the respiratory neural network: a) by modulating the output of cranial or spinal motoneurons; b) by altering the genesis of the respiratory rhythm in the brainstem; and c) by regulating the chemosensory drive input into the respiratory pattern generator.

Brainstem auditory evoked responses in young urban and rural boys--a comparison.

Brainstem auditory evoked responses (BAER) were studied in a total of 194 boys in the age group between 10-15 yrs taken from a busy metropolitan city and also from a relatively quiet town in order to compare their values and to look into the probable cause of the difference between them, if any. BAER were tested with the help of Compact-4 (Nicolet, USA) instrument using the standard technique. In general, the BAER values of the two sample populations were found to be almost similar with no gross differences in terms of peak latency and inter peak latencies. The values were found to be comparable to adult male values as reported earlier.

Neural regulation of glucose homeostasis.

The regulation of blood glucose is generally stated to be under the control of the endocrine system. But the endocrine secretion is itself regulated by the central nervous system, especially the hypothalamus. The brain can sense the energy status of the body by using neural afferent signals and metabolic cues such as glucose. A variety of experimental evidences have been put forth to support the postulate that there are "glucoreceptors", sensitive to blood glucose and glucose utilization, in the hypothalamus. Gastrointestinal afferents, which carry information about the energy intake, reach the hypothalamic regions and interact with the glucose sensitive mechanisms. Available evidence suggests that obesity and decreased body weight, resulting from lesions of the hypothalamic 'satiety' and 'feeding' centres respectively, are not only due to altered food intake, but also to derangement in glucose homeostasis. The medial preoptic area does the fine tuning of energy balance (regulation of food intake) in response to alterations in the temperature, locomotor activity and sleep wakefulness. Thus the hypothalamus regulates energy balance through its control of energy intake on the one hand, and its expenditure and storage on the other. Neuroendocrine system and autonomic nervous system deal with storage and expenditure of energy.

Brainstem auditory evoked potentials among rubber factory workers.

The study was conducted on 27 rubber factory workers for the functional assessment of brainstem auditory pathway. Neurobehavioural questionnaire was administered to the workers and the personal sampler was used to evaluate the respirable particulate load inhaled per day of each worker along with qualitative analysis for PAH compounds. Evoked potential recording was carried out for brainstem auditory responses. Chest X-rays of workers exhibited varied abnormal features. Multiple regression analysis of data showed definite prolongation of latencies with increasing concentration of respirable particulate load though it was not statistically significant. Comparison with normative data indicated prolongation of latencies of rubber factory workers.

Endogenous vasopressin and the central control of heart rate during dynamic exercise

The present article contains a brief review on the role of vasopressinergic projections to the nucleus tractus solitarii in the genesis of reflex bradycardia and in the modulation of heart rate control during exercise. The effects of vasopressin on exercise tachycardia are discussed on the basis of both the endogenous peptide content changes and the heart rate response changes observed during running in sedentary and trained rats. Dynamic exercise caused a specific vasopressin content increase in dorsal and ventral brainstem areas. In accordance, rats pretreated with the peptide or the V1 blocker into the nucleus tractus solitarii showed a significant potentiation or a marked blunting of the exercise tachycardia, respectively, without any change in the pressure response to exercise. It is proposed that the long-descending vasopressinergic pathway to the nucleus tractus solitarii serves as one link between the two main neural controllers of circulation, i.e., the central command and feedback control mechanisms driven by the peripheral receptors. Therefore, vasopressinergic input could contribute to the adjustment of heart rate response (and cardiac output) to the circulatory demand during exercise.

Proliferation of differentiated glial cells in the brain stem

Classical studies of macroglial proliferation in muride rodents have provided conflicting evidence concerning the proliferating capabilities of oligodendrocytes and microglia. Furthermore, little information has been obtained in other mammalian orders and very little is known about glial cell proliferation and differentiation in the subclass Metatheria although valuable knowledge may be obtained from the protracted period of central nervous system maturation in these forms. Thus, we have studied the proliferative capacity of phenotypically identified brain stem oligodendrocytes by tritiated thymidine radioautography and have compared it with known features of oligodentroglial differentation as well as with proliferation of microglia in the opossum Didelphis marsupialis. We have detected a previously undescribed ephemeral, regionally heterogenous proliferation of oligodendrocytes expressing the actin-binding, ensheathment-related protein 2' 3'- cyclic nucleotide 3' -phosphodiesterase (CNPase), that is not necessarily related to the known regional and temporal heterogeneity of expression of CNPase in cell bodies. On the other hand, proliferation of microglia tagged by the binding of Griffonia simplicifolia B4 isolectin, which recognizes an alpha-D-galactosyl-bearing glycoprotein of the plasma membrane of macrophages/microglia, is known to be long lasting, showing no regional heterogeneity and being found amongst both ameboid and differentiated ramified cells, although at different rates. The functional significance of the proliferative behavior of these differentiated cells is unknown but may provide a lowgrade cell renewal in the normal brain and may be augmented under pathological conditions.

Probable función de las vías serotoninérgicas del tallo cerebral en el trabajo de parto en la rata / Probable function of serotonergic pathways of the brainstem in parturition labor in the ratas

La aplicación de serotonina (5-HT) en el núcleo del tracto solitario (NTS) de la rata grávida a término produjo distocia, la que consistió en la supresión del parto o bien, en el retraso del mismo (7-30 horas). En relación a la salud de los productos, en el primer caso, todos los productos murieron en el útero, mientras que en el segundo, una parte de ellos murió durante el trabajo de parto (30-70 por ciento). En contraste, en las ratas del grupo control el parto ocurrió en la fecha esperada o bien, con un ligero retraso (2-4 horas), pero en ambos casos, los productos nacieron normales. Finalmente, dicha distocia probablemente se debe a la disfunción de los sistemas eferentes ocitocinérgico, tanto el humoral magnocelular, como el neural parvocelular, ya sea por la inhibición que ocurre en el NTS, lo que interrumpe la información proveniente principalmente del cérvix uterino o bien por la activación de la vías serotoninérgicas centrales. Esto probablemente disminuye la actividad eléctrica del núcleo supraquiasmático (NSQ), lo que a su vez, produciría una disfunción del núcleo paraventricular (NPV)

Extraretinal modulation of accessory optic units in the pigeon

Electrophysiolgical methods were used to investigate the pretectal and telencephalic control of units within the nucleus of the basal optic root (nBOR) of the accessory optic system of pigeons. Electrical stimulation of the pretectal lentiform nucleus mainly produced excitatory effects on nBOR units with temporal-to-nasal directional preference (among 109 cells, 51% were excited, 23% were inhibited and 23% were not affected) and inhibitory effects on units with nasal-to-temporal preferences (among 88 cells, 43% were inhibited, 38% were not affected and 19% were excited). Electrical stimulation of the visual cortex) produced mainly inhibitory effects on units with downward preferences (among 123 units, 47% were inhibited, 24% were excited and 29% were not affected), and mixed effects on units with upward preferences (among 79 cells, 30% were excited, 36% were inhibited and 34% were not affected). Excitatory effects of LM stimulation had first-spike latente latencies ranging from 2-20 ms (mean ñ SEM, 5.5 ñ 0.7 ms), whereas latencies of W stimulation ranged from 6 to 30 ms (13.0 ñ 0.9 ms). These results provide additional information about the neural substrates of the optokinetic nystagmus