Central control of cardiorespiratory interactions in fish

Fish control the relative flow rates of water and blood over the gills in order to optimise respiratory gas exchange. As both flows are markedly pulsatile, close beat-to-beat relationships can be predicted. Cardiorespiratory interactions in fish are controlled primarily by activity in the parasympathetic nervous system that has its origin in cardiac vagal. preganglionic neurons. Recordings of efferent activity in the cardiac vagus include units firing in respiration-related bursts. Bursts of electrical stimuli delivered peripherally to the cardiac vagus or centrally to respiratory branches of cranial, nerves can recruit the heart over a range of frequencies. So, phasic, efferent activity in cardiac vagi, that in the intact fish are respiration-related, can cause heart rate to be modulated by the respiratory rhythm. In elasmobranch fishes this phasic activity seems to arise primarily from central feed-forward interactions with respiratory motor neurones that have overlapping distributions with cardiac neurons in the brainstem. In teleost fish, they arise from increased levels of efferent vagal activity arising from reflex stimulation of chemoreceptors and mechanoreceptors in the orobranchial, cavity. However, these differences are largely a matter of emphasis as both groups show elements of feed-forward and feed-back control of cardiorespiratory interactions. (C) 2008 Elsevier GmbH. All rights reserved.

The anatomical connections of the macaque monkey orbitofrontal cortex. A review

The orbitofrontal cortex (OfC) is a heterogeneous prefrontal sector selectively connected with a wide constellation of other prefrontal, limbic, sensory and premotor areas. Among the limbic cortical connections, the ones with the bippocampus and parabippocampal cortex are particularly salient. Sensory cortices connected with the OfC include areas involved in olfactory, gustatory, somatosensory, auditory and visual processing. Subcortical structures with prominent OfC connections include the amygdala, numerous thalamic nuclei, the striatum, hypothalamus, periaqueductal gray matter, and biochemically specific cell groups in the basal forebrain and brainstem. Architectonic and connectional evidence supports parcellation of the OfC. The rostrally placed isocortical sector is mainly connected with isocortical areas, including sensory areas of the auditory, somatic and visual modalities, whereas the caudal non-isocortical sector is principally connected with non-isocortical areas, and, in the sensory domain, with olfactory and gustatory areas. The connections of the isocortical and non- isocortical orbital sectors with the amygdala, thalamus, striatum, hypotbalamus and periaqueductal gray matter are also specific. The medial sector of the OfC is selectively connected with the bippocampus, posterior parabippocampal cortex, posterior cingulate and retrosplenial areas, and area prostriata, while the lateral orbitofrontal sector is the most heavily connected with sensory areas of the gustatory, somatic and visual modalities, with premotor regions, and with the amygdala.

Multimodal evoked potentials and the ovarian cycle in young ovulating women

There is controversy over how hormonal conditions influence cerebral physiology. We studied pattern-shift visual evoked potentials (PS-VEP), brain stem auditory evoked potentials (BAEP) and short-latency somatosensory evoked potentials (SSEV) in 20 female volunteers at different phases of the menstrual cycle (estrogen phase, ovulatory day and progesterone phase). Statistical analysis showed decreased latencies for P 100 (PS-VEP), N 19and P 22 (SSEV) waves in the progesterone phase compared with the estrogen phase. There was no significant difference between the estrogen and the ovulation day values. Comparing the three above stages, there were no significant differences in the brainstem auditory evoked potentials. The reduction of the latencies of the potentials generated in multisynaptic circuits provides the first consistent neurophysiological basis for a tentative comprehension of human pre-menstrual syndrome.

Sudden bilateral deafness from hyperleukocytosis in chronic myeloid leukemia

Sudden-onset bilateral deafness as a clinical manifestation of hyperleukocytosis in chronic myeloid leukemia (CML) is a rare occurrence. We found only 27 clinical descriptions in 16 published papers. In this work, the authors present a review on deafness in CML and describe a new case with prominent hyperleukocytosis, where the neurological findings suggest slowing of the circulation through small blood vessels in the brainstem as the cause of deafness. The evolution was good after treatment. To our knowledge, this is the second case documented with electrical auditory brainstem-evoked potentials and the first with magnetic resonance imaging. Copyright (C) 2000 S. Karger AG, Basel.

Seqüência de moebius: Manifestações clínicas e avaliação auditiva

Introduction: Children with Moebius syndrome may present paralysis of cranial nerves III, IV, V, VI, VII, VIII, IX, X and XII, compromising motor and sensorial functions. Hands and feet defects (syndactyly, equinovarus and arthrogryposis) are frequently associated. These manifestations can be attributed to the use of misoprostol during pregnancy to induce abortion. Study design: Clinical prospective. Aim: To evaluate the main clinical manifestations, hearing acuity and possible etiologic factors in children with Moebius syndrome. Material and method: The children were submitted to clinical, otolaryngological and hearing acuity assessment. Hearing acuity was evaluated through behavioral tests, pure tone audiometry, tympanometry and auditory brainstem response (ABR). We investigated possible etiologic factors. Results: Three boys and two girls were evaluated. The main manifestations were: facial paralysis, paralysis of masseter muscle, defects in dental occlusion, retraction of tympanic membrane, equinovarus, oblique palpebral fissure and tongue atrophy. Conductive hearing loss was detected in three children and sensorineural hearing loss in one child. The use of misoprostol during pregnancy was reported by four mothers. Conclusions: The children with Moebius syndrome evaluated in the present study manifested palsies of various cranial nerves, especially V, VII and XII nerves, responsible for motor and sensorial alterations. Inadequate eustachian tube function associated to conductive hearing loss was frequent. The use of misoprostol during pregnancy was reported by the mothers and it was considered a possible etiologic factor.

Sidestream cigarette smoke and cardiac autonomic regulation

Background: The literature has already demonstrated that cigarette influences the cardiovascular system. In this study, we performed a literature review in order to investigate the relationship between sidestream cigarette smoke (SSCS) and cardiac autonomic regulation. Methods. Searches were performed on Medline, SciELO, Lilacs and Cochrane databases using the crossing between the key-words: cigarette smoking, autonomic nervous system, air pollution and heart rate variability. Results: The selected studies indicated that SSCS exposure affects the sympathetic and parasympathetic responses to changes in arterial blood pressure. Moreover, heart rate responses to environmental tobacco smoke are increased in smokers compared to non-smokers. The mechanism involved on this process suggest increased oxidative stress in brainstem areas that regulate the cardiovascular system. Conclusion: Further studies are necessary to add new elements in the literature to improve new therapies to treat cardiovascular disorders in subjects exposed to sidestream cigarette smoke. © 2013 Valenti et al; licensee BioMed Central Ltd.

Mechanisms in the bed nucleus of the stria terminalis involved in control of autonomic and neuroendocrine functions: A review

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The Edinger-Westphal nucleus II: Hypothalamic afferents in the rat

Numerous functions have been attributed to the Edinger-Westphal nucleus (EW), including those related to feeding behavior, pain control, alcohol consumption and the stress response. The EW is thought to consist of two parts: one controls accommodation, choroidal blood flow and pupillary constriction, primarily comprising cholinergic cells and projecting to the ciliary ganglion; and the other would be involved in the non-ocular functions mentioned above, comprising peptide-producing neurons and projecting to the brainstem, spinal cord and prosencephalic regions. Despite the fact that the EW is well known, its connections have yet to be described in detail. The aim of this work was to produce a map of the hypothalamic sources of afferents to the EW in the rat. We injected the retrograde tracer Fluoro-Gold into the EW, and using biotinylated dextran amine, injected into afferent sources as the anterograde control. We found retrogradely labeled cells in the following regions: subfornical organ, paraventricular hypothalamic nucleus, arcuate nucleus, lateral hypothalamic area, zona incerta, posterior hypothalamic nucleus, medial vestibular nucleus and cerebellar interpositus nucleus. After injecting BDA into the paraventricular hypothalamic nucleus, lateral hypothalamic area and posterior hypothalamic nucleus, we found anterogradely labeled fibers in close apposition to and potential synaptic contact with urocortin 1-immunoreactive cells in the EW. On the basis of our findings, we can suggest that the connections between the EW and the hypothalamic nuclei are involved in controlling stress responses and feeding behavior. © 2013 The Authors.

A fast cholinergic modulation of the primary acoustic startle circuit in rats

Cochlear root neurons (CRNs) are the first brainstem neurons which initiate and participate in the full expression of the acoustic startle reflex. Although it has been suggested that a cholinergic pathway from the ventral nucleus of the trapezoid body (VNTB) conveys auditory prepulses to the CRNs, the neuronal origin of the VNTB-CRNs projection and the role it may play in the cochlear root nucleus remain uncertain. To determine the VNTB neuronal type which projects to CRNs, we performed tract-tracing experiments combined with mechanical lesions, and morphometric analyses. Our results indicate that a subpopulation of non-olivocochlear neurons projects directly and bilaterally to CRNs via the trapezoid body. We also performed a gene expression analysis of muscarinic and nicotinic receptors which indicates that CRNs contain a cholinergic receptor profile sufficient to mediate the modulation of CRN responses. Consequently, we investigated the effects of auditory prepulses on the neuronal activity of CRNs using extracellular recordings in vivo. Our results show that CRN responses are strongly inhibited by auditory prepulses. Unlike other neurons of the cochlear nucleus, the CRNs exhibited inhibition that depended on parameters of the auditory prepulse such as intensity and interstimulus interval, showing their strongest inhibition at short interstimulus intervals. In sum, our study supports the idea that CRNs are involved in the auditory prepulse inhibition of the acoustic startle reflex, and confirms the existence of multiple cholinergic pathways that modulate the primary acoustic startle circuit. © 2013 Springer-Verlag Berlin Heidelberg.

Commissural nucleus of the solitary tract regulates the antihypertensive effects elicited by moxonidine

The rostral ventrolateral medulla (RVLM) contains the presympathetic neurons involved in cardiovascular regulation that has been implicated as one of the most important central sites for the antihypertensive action of moxonidine (an α2-adrenergic and imidazoline agonist). Here, we sought to evaluate the cardiovascular effects produced by moxonidine injected into another important brainstem site, the commissural nucleus of the solitary tract (commNTS). Mean arterial pressure (MAP), heart rate (HR), splanchnic sympathetic nerve activity (sSNA) and activity of putative sympathoexcitatory vasomotor neurons of the RVLM were recorded in conscious or urethane-anesthetized, and artificial ventilated male Wistar rats. In conscious or anesthetized rats, moxonidine (2.5 and 5. nmol/50. nl) injected into the commNTS reduced MAP, HR and sSNA. The injection of moxonidine into the commNTS also elicited a reduction of 28% in the activity of sympathoexcitatory vasomotor neurons of the RVLM. To further assess the notion that moxonidine could act in another brainstem area to elicit the antihypertensive effects, a group with electrolytic lesions of the commNTS or sham and with stainless steel guide-cannulas implanted into the 4th V were used. In the sham group, moxonidine (20. nmol/1. μl) injected into 4th V decreased MAP and HR. The hypotension but not the bradycardia produced by moxonidine into the 4th V was reduced in acute (1. day) commNTS-lesioned rats. These data suggest that moxonidine can certainly act in other brainstem regions, such as commNTS to produce its beneficial therapeutic effects, such as hypotension and reduction in sympathetic nerve activity. © 2013 IBRO.

Avaliação auditiva por meio de potencial evocado auditivo em lactentes com indicadores de risco para deficiência auditiva. Qual a importância no diagnóstico e prognóstico?

Pós-graduação em Bases Gerais da Cirurgia - FMB

Potenciais evocados auditivos de tronco encefálico e emissões otoacústicas evocadas transientes: achados em pacientes com doença renal crônica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Potencial evocado auditivo de tronco encefálico em cães

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise histopatológica e imunoistoquímica de encéfalo de cães com cinomose tratados com ribavirina

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relação entre os sinais clínicos neurológicos e os achados tomográficos de 20 cães com suspeita de neoplasia intracraniana

Pós-graduação em Medicina Veterinária - FMVZ