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Neural Pathways (neural + pathway)

Distribution by Scientific Domains

Medical Sciences	54%
Life Sciences	45%

Selected Abstracts

Mechanisms determining cholinergic neural responses in airways of young and mature rabbits,

PEDIATRIC PULMONOLOGY, Issue 2 2004
Gary L. Larsen MD
Abstract Neural pathways help control airway caliber and responsiveness. Yet little is known of how neural control changes as a function of development. In rabbits, we found electrical field stimulation (EFS) of airway nerves led to more marked contractile responses in 2- vs. 13-week-old animals. This enhanced response to EFS may be due to prejunctional, junctional, and/or postjunctional neural mechanisms. We assessed these mechanisms in airways of 2- and 13-week-old rabbits. The contractile responses to methacholine did not differ in the groups, suggesting postjunctional neural events are not primarily responsible for differing responses to EFS. To address junctional events, acetylcholinesterase (AChE) was measured (spectrophotometry). AChE was elevated in 2-week-olds. However, this should lead to less and not greater responses. Prejunctionally, EFS-induced acetylcholine (ACh) release was assessed by HPLC. Airways of 2-week-old rabbits released significantly more ACh than airways from mature rabbits. Choline acetyltransferase, a marker of cholinergic nerves, was not different between groups, suggesting that more ACh release in young rabbits was not due to increased nerve density. ACh release in the presence of polyarginine increased significantly in both groups, supporting the presence of functional muscarinic autoreceptors (M2) at both ages. Because substance P (SP) increases release of ACh, SP was measured by ELISA. This neuropeptide was significantly elevated in airways of younger rabbits. Nerve growth factor (NGF) increased SP and was also significantly increased in airways from younger rabbits. This work suggests that increases in EFS-induced responsiveness in young rabbits are likely due to prejunctional events with enhanced release of ACh. Increases in NGF and SP early in life may contribute to this increased responsiveness. Pediatr Pulmonol. 2004; 38:97,106. © 2004 Wiley-Liss, Inc. [source]

Clinical manifestation of focal cerebellar disease as related to the organization of neural pathways

ACTA NEUROLOGICA SCANDINAVICA, Issue 2008
E. Dietrichs
Neural pathways connect different parts of the cerebellum to different parts of the central nervous system. The cerebellum may be divided anatomically and functionally into three major regions. The cerebellar hemispheres and a small part of the posterior lobe vermis form the pontocerebellum, which receives inputs from the cerebral cortex via the pontine nuclei. The anterior lobe and most of the posterior lobe vermis make up the spinocerebellum, which receives afferents from the spinal cord. The nodulus and flocculus are connected with the vestibular nuclei and constitute the vestibulocerebellum. Most cases of cerebellar disease affect more than one region and different pathways. Hence, they cause generalized cerebellar symptoms dominated by impaired motor control and balance. Focal syndromes after restricted cerebellar lesions are rare. Isolated spinocerebellar affection may give gait ataxia. Vestibulocerebellar disease causes equilibrium disturbances with truncal ataxia and nystagmus. Pontocerebellar lesions typically give ipsilateral limb ataxia, but also dysartria and oculomotor dysfunction if vermal parts are involved. The clinical picture is in most cases of cerebellar disease dominated by motor disturbances, but the cerebellum also participates in the modulation of autonomic and affective responses and in cognitive functions. The cerebrocerebellar and hypothalamocerebellar circuits may be important for these tasks. [source]

The mammalian exercise pressor reflex in health and disease

EXPERIMENTAL PHYSIOLOGY, Issue 1 2006
Scott A. Smith
The exercise pressor reflex (a peripheral neural reflex originating in skeletal muscle) contributes significantly to the regulation of the cardiovascular system during exercise. Exercise-induced signals that comprise the afferent arm of the reflex are generated by activation of mechanically (muscle mechanoreflex) and chemically sensitive (muscle metaboreflex) skeletal muscle receptors. Activation of these receptors and their associated afferent fibres reflexively adjusts sympathetic and parasympathetic nerve activity during exercise. In heart failure, the cardiovascular response to exercise is augmented. Owing to the peripheral skeletal myopathy that develops in heart failure (e.g. muscle atrophy, decreased peripheral blood flow, fibre-type transformation and reduced oxidative capacity), the exercise pressor reflex has been implicated as a possible mechanism by which the cardiovascular response to physical activity is exaggerated in this disease. Accumulating evidence supports this conclusion. This review therefore focuses on the role of the exercise pressor reflex in regulating the cardiovascular system during exercise in both health and disease. Updates on our current understanding of the exercise pressor reflex neural pathway as well as experimental models used to study this reflex are presented. In addition, special emphasis is placed on the changes in exercise pressor reflex activity that develop in heart failure, including the contributions of the muscle mechanoreflex and metaboreflex to this pressor reflex dysfunction. [source]

Taurocholic acid-induced secretion in normal and cystic fibrosis mouse ileum

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2001
J. Hardcastle
Bile acids cause secretion throughout the intestinal tract and this process contributes to maintaining the fluidity of intestinal contents. In cystic fibrosis (CF) defective intestinal secretion can lead to excessive dehydration of the luminal contents and the development of clinical symptoms. This study was designed to investigate bile acid-induced secretion in mouse ileum and to determine whether this process was defective in CF. Taurocholic acid-induced secretion was monitored as a rise in short-circuit current (SCC) in ileal sheets from normal (Swiss MF1) and transgenic CF mice. Taurocholic acid increased the SCC in both intact and stripped ileal sheets from Swiss MF1 mice. This effect was due to a stimulation of electrogenic Cl, secretion as it was inhibited by Cl, -free conditions, serosal furosemide (frusemide), mucosal diphenylamine-2-carboxylic acid (DPC) and increased serosal K+ concentration, without being affected by reduced mucosal Na+ concentration. Taurocholic acid-induced secretion was inhibited by tetrodotoxin, indicating the involvement of a neural pathway, but this did not include capsaicin-sensitive afferent neurons or muscarinic cholinoreceptors. Mucosal mast cells also contributed to the response. Responses in tissues from transgenic wild-type mice were similar to those obtained with Swiss MF1 animals, but ilea from CF mice exhibited a lower basal SCC with significantly reduced secretory responses to acetylcholine and taurocholic acid. We concluded that taurocholic acid induces ileal secretion by a mechanism that entails activation of enteric nerves and degranulation of mucosal mast cells. Impaired bile acid-induced secretion in CF may contribute to luminal dehydration. [source]

Neurorehabilitation of Upper Extremities in Humans with Sensory-Motor Impairment

NEUROMODULATION, Issue 1 2002
Dejan B. Popovic PhD
Abstract Today most clinical investigators agree that the common denominator for successful therapy in subjects after central nervous system (CNS) lesions is to induce concentrated, repetitive practice of the more affected limb as soon as possible after the onset of impairment. This paper reviews representative methods of neurorehabilitation such as constraining the less affected arm and using a robot to facilitate movement of the affected arm, and focuses on functional electrotherapy promoting the movement recovery. The functional electrical therapy (FET) encompasses three elements: 1) control of movements that are compromised because of the impairment, 2) enhanced exercise of paralyzed extremities, and 3) augmented activity of afferent neural pathway. Liberson et al. (1) first reported an important result of the FET; they applied a peroneal stimulator to enhance functionally essential ankle dorsiflexion during the swing phase of walking. Merletti et al. (2) described a similar electrotherapeutic effect for upper extremities; they applied a two-channel electronic stimulator and surface electrodes to augment elbow extension and finger extension during different reach and grasp activities. Both electrotherapies resulted in immediate and carry-over effects caused by systematic application of FET. In studies with subjects after a spinal cord lesion at the cervical level (chronic tetraplegia) (3,5) or stroke (6), it was shown that FET improves grasping and reaching by using the following outcome measures: the Upper Extremity Function Test (UEFT), coordination between elbow and shoulder movement, and the Functional Independence Measure (FIM). Externally applied electrical stimuli provided a strong central sensory input which could be responsible for the changes in the organization of impaired sensory-motor mechanisms. FET resulted in stronger muscles that were stimulated directly, as well as exercising other muscles. The ability to move paralyzed extremities also provided awareness (proprioception and visual feedback) of enhanced functional ability as being very beneficial for the recovery. FET contributed to the increased range of movement in the affected joints, increased speed of joint rotations, reduced spasticity, and improved functioning measured by the UEFT, the FIM and the Quadriplegia Index of Function (QIF). [source]

Mindfulness-based treatments for co-occurring depression and substance use disorders: what can we learn from the brain?

ADDICTION, Issue 10 2010
Judson A. Brewer
ABSTRACT Both depression and substance use disorders represent major global public health concerns and are often co-occurring. Although there are ongoing discoveries regarding the pathophysiology and treatment of each condition, common mechanisms and effective treatments for co-occurring depression and substance abuse remain elusive. Mindfulness training has been shown recently to benefit both depression and substance use disorders, suggesting that this approach may target common behavioral and neurobiological processes. However, it remains unclear whether these pathways constitute specific shared neurobiological mechanisms or more extensive components universal to the broader human experience of psychological distress or suffering. We offer a theoretical, clinical and neurobiological perspective of the overlaps between these disorders, highlight common neural pathways that play a role in depression and substance use disorders and discuss how these commonalities may frame our conceptualization and treatment of co-occurring disorders. Finally, we discuss how advances in our understanding of potential mechanisms of mindfulness training may offer not only unique effects on depression and substance use, but also offer promise for treatment of co-occurring disorders. [source]

REVIEW: Stress, alcohol and drug interaction: an update of human research

ADDICTION BIOLOGY, Issue 1 2009
Magdalena Uhart
ABSTRACT A challenging question that continues unanswered in the field of addiction is why some individuals are more vulnerable to substance use disorders than others. Numerous risk factors for alcohol and other drugs of abuse, including exposure to various forms of stress, have been identified in clinical studies. However, the neurobiological mechanisms that underlie this relationship remain unclear. Critical neurotransmitters, hormones and neurobiological sites have been recognized, which may provide the substrates that convey individual differences in vulnerability to addiction. With the advent of more sophisticated measures of brain function in humans, such as functional imaging technology, the mechanisms and neural pathways involved in the interactions between drugs of abuse, the mesocorticolimbic dopamine system and stress systems are beginning to be characterized. This review provides a neuroadaptive perspective regarding the role of the hormonal and brain stress systems in drug addiction with a focus on the changes that occur during the transition from occasional drug use to drug dependence. We also review factors that contribute to different levels of hormonal/brain stress activation, which has implications for understanding individual vulnerability to drug dependence. Ultimately, these efforts may improve our chances of designing treatment strategies that target addiction at the core of the disorder. [source]

Activation of afferents to the ventral tegmental area in response to acute amphetamine: a double-labelling study

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2007
Joyce Colussi-Mas
Abstract The ventral tegmental area (VTA), primary source of the mesocorticolimbic dopaminergic system, is regarded as a critical site for initiation of behavioural sensitization to psychostimulants. The present study was undertaken to identify the neural pathways converging on the VTA that are potentially implicated in this process. Rats were sensitized by a single exposure to amphetamine (5 mg/kg, s.c.). The distribution of VTA-projecting neurons activated by amphetamine was examined by combining retrograde transport of the cholera toxin , subunit (CTb), injected into the VTA, with immunodetection of Fos. The quantitative analysis of CTb,Fos double labelling demonstrates that amphetamine induced a rapid activation of Fos in a large number of brain areas projecting to the VTA. More than half of the CTb,Fos double-labelled neurons were located in the prefrontal cortex, lateral preoptic area,lateral hypothalamus, pontomesencephalic tegmentum, dorsal raphe nucleus, ventral pallidum and nucleus accumbens. In addition, scattered CTb,Fos double-labelled cells were observed in many other VTA afferent structures, such as claustrum, lateral septum, diagonal band,magnocellular preoptic nucleus, deep mesencephalic nucleus, oral part of pontine reticular nucleus and dorsomedial tegmental area. This suggests that systemic amphetamine activates a wide population of neurons projecting to the VTA that may be important for the modulation of neurobehavioural plasticity produced by this psychostimulant. [source]

Ascending visceral regulation of cortical affective information processing

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2003
Gary G. Berntson
Abstract Over a century ago, William James proposed that strong emotions represent the perceptual consequences of somato-visceral feedback. Although the strong form of this conception is no longer viable, considerable evidence has accumulated indicating a range of visceral influences on higher neurobehavioural processes. This literature has only recently begun to consolidate, because earlier reports generally remained at the demonstration level, and pathways and mechanisms for such influences were uncertain. Recently, specific effects of visceral feedback have become apparent on cortical activity, cerebral auditory-evoked responses, anxiety, memory and behavioural aspects of immunological sickness. Moreover, considerable progress has been made recently in determining the specific neural pathways and systems underlying these actions, especially the role of noradrenergic projections from the nucleus of the tractus solitarius and the locus coeruleus to the amygdala in memory processes, and to the basal forebrain in the processing of anxiety-related information. The present paper highlights selected recent findings in this area, and outlines relevant structures and pathways involved in the ascending visceral influence on higher neurobehavioural processes. [source]

Dissociation of food and opiate preference by a genetic mutation in zebrafish

GENES, BRAIN AND BEHAVIOR, Issue 7 2006
B. Lau
Both natural rewards and addictive substances have the ability to reinforce behaviors. It has been unclear whether identical neural pathways mediate the actions of both. In addition, little is known about these behaviors and the underlying neural mechanisms in a genetically tractable vertebrate, the zebrafish Danio rerio. Using a conditioned place preference paradigm, we demonstrate that wildtype zebrafish exhibit a robust preference for food as well as the opiate drug morphine that can be blocked by the opioid receptor antagonist naloxone. Moreover, we show that the too few mutant, which disrupts a conserved zinc finger-containing gene and exhibits a reduction of selective groups of dopaminergic and serotonergic neurons in the basal diencephalon, displays normal food preference but shows no preference for morphine. Pretreatment with dopamine receptor antagonists abolishes morphine preference in the wildtype. These studies demonstrate that zebrafish display measurable preference behavior for reward and show that the preference for natural reward and addictive drug is dissociable by a single-gene mutation that alters subregions of brain monoamine neurotransmitter systems. Future genetic analysis in zebrafish shall uncover further molecular and cellular mechanisms underlying the formation and function of neural circuitry that regulate opiate and food preference behavior. [source]

Can the brain inhibit inflammation generated in the skin?

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 6 2002
-melanocyte-stimulating hormone, The lesson of
The neuro-immuno-cutaneous-endocrine network is not a simple construct featuring organ systems intimately involved in the bridge between body and mind. Mind-body influences are bi-directional and the skin should be considered an active neuroimmunoendocrine interface, where effector molecules of neuropeptides act as common words used in a dynamic dialogue between brain, immune system and skin. Alpha-melanocyte stimulating hormone (,-MSH), one of the principal neuroimmunomodulating peptides, seems to exercise some control on the cutaneous inflammatory process, through a central action mediated by descending anti- inflammatory neural pathways and via local direct influence on inflammatory cells infiltrating the dermis, such as monocytes, macrophages and neutrophils. ,-MSH down-regulates the production of proinflammatory cytokines, while the production of the anti-inflammatory cytokine IL-10 is stimulated by ,-MSH. Finally, ,-MSH seems to regulate the expression of surface molecules in immunocompetent cells. Thus, further studies may lead to the use of ,-MSH as an important anti-inflammatory agent in clinical dermatology. [source]

Ultrastructure of the tentacle nerve plexus and putative neural pathways in sea anemones

INVERTEBRATE BIOLOGY, Issue 3 2002
Jane A. Westfall
Abstract. Neurons of sea anemone tentacles receive stimuli via sensory cells and process and transmit information via a plexus of nerve fibers. The nerve plexus is best revealed by scanning electron microscopy of epidermal peels of the tentacles. The nerve plexus lies above the epidermal muscular layer where it appears as numerous parallel longitudinal and short interconnected nerve fibers in Calliactis parasitica. Bipolar and multipolar neurons are present and neurites form interneuronal and neuromuscular synaptic contacts. Transmission electron microscopy of cross sections of tentacles of small animals, both C. parasitica and Aiptasia pallida, reveals bundles of 50,100 nerve fibers lying above groups of longitudinal muscle fibers separated by intrusions of mesoglea. Smaller groups of 10,50 slender nerve fibers are oriented at right angles to the circular muscle formed by the bases of the digestive cells. The unmyelinated nerve fibers lack any glial wrapping, although some bundles of epidermal fibers are partially enveloped by cytoplasmic extensions of the muscle cells; small gastrodermal nerve bundles lie between digestive epithelial cells above their basal myonemes. A hypothetical model for sensory input and motor output in the epidermal and gastrodermal nerve plexuses of sea anemones is proposed. [source]

Effect of Calcitonin Gene-Related Peptide on Gonadotrophin-Releasing Hormone mRNA Expression in GT1-7 Cells

JOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2005
J. S. Kinsey-Jones
Abstract Recent evidence has shown calcitonin gene-related peptide (CGRP) to be a key mediator of stress-induced suppression of the gonadotrophin-releasing hormone (GnRH) pulse generator, although little is known about the neural pathways involved. In the present study, we investigated the potential direct action of CGRP on GnRH neurones using GT1-7 cells, an established GnRH cell line. First, we detected expression of the CGRP receptor subunits, calcitonin receptor-like receptor and receptor activity-modifying protein-1 in the GT1-7 cells by reverse transcriptase-polymerase chain reaction. Second, we have shown that CGRP inhibits GnRH mRNA expression in the GT1-7 cells, which was effectively reversed by the CGRP receptor antagonist, CGRP8-37. These results suggest that CGRP down regulates expression of GnRH mRNA, via CGRP receptors in the GT1-7 cell, thus implying that a potential direct action of CGRP may mediate a suppressive effect on the GnRH neural network. [source]

Central GABAA but not GABAB Receptors Mediate Suppressive Effects of Caudal Hindbrain Glucoprivation on the Luteinizing Hormone Surge in Steroid-Primed, Ovariectomized Female Rats

JOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2005
S. R. Singh
Abstract The neurochemical mechanisms that link caudal hindbrain glucoprivic-,sensitive' neurones with the forebrain gonadotrophin-releasing hormone (GnRH)-pituitary luteinizing hormone (LH) axis remain unclear. Available studies indicate that the amino acid neurotransmitter, ,-aminobutyric acid (GABA), inhibits reproductive neuroendocrine function, and that caudal fourth ventricular administration of the glucose antimetabolite, 5-thioglucose (5TG), enhances GABA turnover within discrete septopreoptic structures that regulate LH secretion. The current experiments utilized the selective GABAA and GABAB receptor antagonists, bicuculline and phaclofen, as pharmacological tools to investigate whether one or both receptor subtypes function within neural pathways that suppress GnRH neuronal transcriptional activation and LH release during central glucose deficiency. During the ascending phase of the afternoon LH surge, groups of steroid-primed, ovariectomized female Sprague-Dawley rats were pretreated by lateral ventricular administration of bicuculline, phaclofen, or vehicle only, before fourth ventricular injection of 5TG or vehicle. The data indicate that, 2 h after 5TG treatment, Fos immunoexpression by rostral preoptic GnRH neurones and plasma LH levels were diminished relative to the vehicle-treated controls, and that inhibitory effects of 5TG on these parameters were attenuated by pretreatment with bicuculline, but not phaclofen. These results demonstrate that central GABAA, but not GABAB receptor stimulation during hindbrain glucoprivation, is required for maximal inhibition of reproductive neuroendocrine function by this metabolic challenge. The current studies thus reinforce the view that central GABAergic neurotransmission mediates regulatory effects of central glucoprivic signalling on the GnRH-pituitary LH axis. [source]

Preference Conditioning in Healthy Individuals: Correlates With Hazardous Drinking

ALCOHOLISM, Issue 6 2010
Iris M. Balodis
Background:, Conditioned reward is a classic measure of drug-induced brain changes in animal models of addiction. The process can be examined in humans using the Conditioned Pattern Preference (CPP) task, in which participants associate nonverbal cues with reward but demonstrate low awareness of this conditioning. Previously, we reported that alcohol intoxication does not affect CPP acquisition in humans, but our data indicated that prior drug use may impact conditioning scores. Methods:, To test this possibility, the current study examined the relationship between self-reported alcohol use and preference conditioning in the CPP task. Working memory was assessed during conditioning by asking participants to count the cues that appeared at each location on a computer screen. Participants (69 female and 23 male undergraduate students) completed the Alcohol Use Disorders Identification Test (AUDIT) and the Rutgers Alcohol Problem Index (RAPI) as measures of hazardous drinking. Results:, Self-reported hazardous drinking was significantly correlated with preference conditioning in that individuals who scored higher on these scales exhibited an increased preference for the reward-paired cues. In contrast, hazardous drinking did not affect working memory errors on the CPP task. Conclusions:, These findings support evidence that repeated drug use sensitizes neural pathways mediating conditioned reward and point to a neurocognitive disposition linking substance misuse and responses to reward-paired stimuli. The relationship between hazardous drinking and conditioned reward is independent of changes in cognitive function, such as working memory. [source]

Autonomous contractile activity in the isolated rat bladder is modulated by a TRPV1 dependent mechanism,

NEUROUROLOGY AND URODYNAMICS, Issue 3 2007
Thomas Gevaert
Abstract Aims Resiniferatoxin (RTX), a vanilloid compound and agonist of the transient receptor potential channel 1 (TRPV1), is known for its beneficial effects on neurogenic detrusor overactivity. The mainstream rationale for its use is the desensitization of TRPV1 on sensory bladder afferents. However, recent findings showed that TRPV1 is present in other cell types in the bladder. To eliminate the effects of RTX on spinal and central neural circuits, we investigated autonomous contractility in normal and neurogenic rat bladders after treatment with RTX. Methods Female Wistar rats were made paraplegic at vertebral level T8,T9. Animals were intravesically pre-treated with vehicle (ethanol 5%) or RTX (100 nM) and sacrificed after 72 hr. Each bladder was excised and placed in a heated organ bath, where intravesical pressures were measured. Effects on contractile parameters of intravesical volume load, the non-selective muscarinic receptor agonist carbachol (CA) and electrical stimulation (ES) of nerves were studied in both groups. Results In RTX-treated normal bladders we found shorter contractions with higher amplitude than in control bladders (P,<,0.05). In RTX-treated neurogenic bladders the amplitude and duration of autonomous contractions were increased compared with controls (P,<,0.05). Furthermore RTX induced an increased response to CA and to ES (P,<,0.05). Conclusions RTX significantly affected the properties of autonomous bladder contractile activity. This provides evidence for local effects of RTX on bladder contractile activity, which are not mediated by afferent neural pathways and which may contribute to the beneficial effects on detrusor overactivity. TRPV1 and TRPV1+ cells seem to play an important role in (autonomous) bladder contractility. Neurourol. Urodynam. 26:424,432, 2007. © 2006 Wiley-Liss, Inc. [source]

Motor evoked potentials from the pelvic floor

NEUROUROLOGY AND URODYNAMICS, Issue 7 2003
Søren Brostrøm
Proper function of the lower urinary tract depends on the integrity of the central and peripheral nervous pathways on multiple levels, and the complexity of this system leaves it susceptible to even minor lesions. While dysfunction of the lower urinary tract is prevalent amongst patients with nervous system disease, e.g., multiple sclerosis (MS), most women with lower urinary tract dysfunction (LUTD) have no overt neurological cause. Refined neuro-diagnostic approaches are needed to reveal neurogenicity in these patients. A potential method is transcranial magnetic stimulation (TMS), which is used routinely to test the motor innervation of limb muscles, but also can be applied to test pelvic floor efferents. To resolve the lack of methodological clarity and the need for normative values for the use of pelvic floor motor evoked potentials (MEPs), 30 healthy women and 16 women with MS were studied. Methods The healthy women underwent MEP studies with various stimulus and recording modalities, and, to test reproducibility, 18 of them were retested at a separate session. The women with MS underwent MEP testing as well as urodynamic studies. Results From the methodological studies of healthy women, the use of invasive concentric needle electrodes was found to be superior to surface electrodes. When applying magnetic stimuli over the sacral region, various methodological problems were encountered. In the healthy women, a large variability of responses was noted, the long-term reproducibility of pelvic floor MEP latencies was poor, and in some cases responses could not be obtained. In the study of women with MS, prolonged central conduction times were found, along with many cases of unevokable responses, and a poor correlation of MEPs to urodynamic findings. The problems of obtaining selective recordings from the inaccessible pelvic floor musculature are discussed, and possible sources of variability in MEPs from the pelvic floor are considered. By relating the findings in the present studies to those of others using different modalities, some reflections are presented on the nature of the neural pathways to the pelvic floor activated by magnetic stimulation. As unevokable responses from the pelvic floor were an occasional finding among the healthy women, it is argued that a pelvic floor non-response in a patient with suspected corticospinal lesion should be interpreted with care, and should not carry the same clinical significance as an absent limb response. Conclusions The inherent limitations of pelvic floor MEPs are discussed, and it is concluded that while there seems to be only limited clinical value of pelvic floor MEP testing, there might be some interesting scientific perspectives in studies that aim to control and explain the variability of responses. Neurourol. Urodynam. 22:620,637, 2003. © 2003 Wiley-Liss, Inc. [source]

Conserved neurochemical pathways involved in hypothalamic control of energy homeostasis

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2007
Paul M. Forlano
Abstract The melanocortin system, which includes ,-melanocyte-stimulating hormone (,-MSH) and its endogenous antagonist, agouti-related protein (AgRP), is fundamental for the central control of energy homeostasis in mammals. Recent studies have demonstrated that many neuropeptides involved in the control of ingestive behavior and energy expenditure, including melanocortins, are also expressed and functional in teleost fishes. To test the hypothesis that the underlying neural pathways involved in energy homeostasis are conserved throughout vertebrate evolution, the neuroanatomical distribution of ,-MSH in relation to AgRP was mapped in a teleost (zebrafish, Danio rerio) by double-label immunocytochemistry. Zebrafish ,-MSH- and AgRP-immunoreactive (ir) cells are found in discrete populations in the ventral periventricular hypothalamus, the proposed arcuate homologue in teleosts. Major ascending projections are similar for both peptides, and dense ir-fibers innervate preoptic and ventral telencephalic nuclei homologous to paraventricular, lateral septal, and amygdala nuclei in mammals. Furthermore, ,-MSH and AgRP-ir somata and fibers are pronounced at 5 days post fertilization when yolk reserves are depleted and larvae begin to feed actively, which supports the functional significance of these peptides for feeding behavior. The conservation of melanocortin peptide function and projection pathways further support zebrafish as an excellent genetic model system to investigate basic mechanisms involved in the central regulation of energy homeostasis. J. Comp. Neurol. 505:235,248, 2007. © 2007 Wiley-Liss, Inc. [source]

Reductions in N-acetylaspartylglutamate and the 67 kDa form of glutamic acid decarboxylase immunoreactivities in the visual system of albino and pigmented rats after optic nerve transections

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2003
John R. Moffett
Abstract This study compares the immunohistochemical distributions of N-acetylaspartylglutamate (NAAG) and the large isoform of the ,-aminobutyric acid (GABA)-synthesizing enzyme glutamic acid decarboxylase (GAD67) in the visual system of albino and pigmented rats. Most retinal ganglion cells and their axons were strongly immunoreactive for NAAG, whereas GAD67 immunoreactivity was very sparse in these cells and projections. In retinorecipient zones, NAAG and GAD67 immunoreactivities occurred in distinct populations of neurons and in dense networks of strongly immunoreactive fibers and synapses. Dual-labeling immunohistochemistry indicated that principal neurons were stained for NAAG, whereas local interneurons were stained for GAD67. In contrast to the distribution observed in retinorecipient zones, most or all neurons were doubly stained for NAAG and GAD67 in the thalamic reticular nucleus. Ten days after unilateral optic nerve transection, NAAG-immunoreactive fibers and synapses were substantially reduced in all contralateral retinal terminal zones. The posttransection pattern of NAAG-immunoreactive synaptic loss demarcated the contralateral and ipsilateral divisions of the retinal projections. In addition, an apparent transynaptic reduction in GAD67 immunoreactivity was observed in some deafferented areas, such as the lateral geniculate. These findings suggest a complicated picture in which NAAG and GABA are segregated in distinct neuronal populations in primary visual targets, yet they are colocalized in neurons of the thalamic reticular nucleus. This is consistent with NAAG acting as a neurotransmitter release modulator that is coreleased with a variety of classical transmitters in specific neural pathways. J. Comp. Neurol. 458:221,239, 2003. © 2003 Wiley-Liss, Inc. [source]

Age-specific functions of Stone Handling, a solitary-object play behavior, in Japanese Macaques (Macaca fuscata)

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2007
Charmalie A.D. Nahallage
Abstract Stone handling (SH) in Japanese macaques, a form of solitary-object play, is newly acquired only by young individuals, and is the first example of a directly nonadaptive behavior that is maintained as a behavioral tradition within free-ranging provisioned social troops. We report here the first systematic investigation of this behavior in a stable captive social troop, the Takahama troop, which is housed in an outdoor enclosure of the Primate Research Institute (PRI), Kyoto University, Japan. This study was conducted to evaluate relevant competing hypotheses regarding the function of object play (e.g., misdirected foraging behavior and motor training) to explain the proximal causes and ultimate function(s) of SH. The "misdirected foraging behavior" hypothesis can be ruled out because of the lack of a clear temporal relationship between feeding and the occurrence of SH in any age class. Age-related differences in SH performance and behavioral patterns were observed, suggesting possible differences in the immediate cause and ultimate function between young and adults. Young individuals engaged in frequent bouts of short duration, involving locomotion and vigorous body actions throughout the day, which is typical for play by young in general. This pattern of behavior is consistent with the motor training hypothesis, which states that play occurs during the development of motor and perceptual skills and is thus potentially critical for neural and cognitive development. This practice is continued by those who acquire it at an early age, with adults engaging in significantly fewer but longer bouts that involve more stationary, complex manipulative patterns, almost exclusively in the late afternoon. We propose that for adults, at the proximate level SH is psychologically relaxing, but ultimately functions to maintain and regenerate neural pathways, and potentially helps to slow down the deterioration of cognitive function associated with advanced age in long-lived provisioned and captive macaques. Am. J. Primatol. 69:1,15, 2007.© 2006 Wiley-Liss, Inc. [source]

Segmentation induced by intraluminal fatty acid in isolated guinea-pig duodenum and jejunum

THE JOURNAL OF PHYSIOLOGY, Issue 2 2004
Rachel M. Gwynne
Small intestinal movements depend on the composition of the chyme with mixing predominating at high nutrient levels and propulsion being prevalent at low nutrient levels. The mechanisms coupling nutrients to motility are unknown. We used computer analysis of video recordings of isolated guinea-pig duodenum, jejunum and ileum to examine movements induced by a fatty acid, decanoic acid. Increasing intraluminal pressure past a threshold using control saline consistently evoked propulsive reflexes: lumen-occluding constrictions appeared at the oral end propagating at 20.4 ± 2.4 mm s,1 (mean ±s.d., jejunum) to the anal end before being repeated until the intraluminal pressure was returned to control. Subthreshold pressure increases sometimes evoked a transient series of constrictions appearing at the oral end and propagating anally at 18.4 ± 4.7 mm s,1 (jejunum). At basal pressures, decanoic acid dose-dependently induced motor activity consisting of 40,60 s episodes of constrictions separated by 40,200 s periods of quiescence and lasting up to 2 h. Five contraction patterns were identified within episodes including localized stationary constrictions; constrictions that propagated slowly (5,8 mm s,1) for short distances orally or anally; and constrictions that propagated orally or anally for the length of the preparation at 14,20 mm s,1. Decanoic acid induced motor activity was reversibly abolished by tetrodotoxin (3 ,m), hyoscine (1 ,m) and hexamethonium (100 ,m), but was insensitive to blockade of P2 purinoceptors by PPADS (60 ,m). Thus, decanoic acid induces motor activity equivalent to segmentation in guinea-pig small intestine in vitro and this depends on intrinsic neural pathways. [source]

Clinical manifestation of focal cerebellar disease as related to the organization of neural pathways

Do psychotherapies produce neurobiological effects?

ACTA NEUROPSYCHIATRICA, Issue 2 2006
Veena Kumari
Background:, An area of recent interest in psychiatric research is the application of neuroimaging techniques to investigate neural events associated with the development and the treatment of symptoms in a number of psychiatric disorders. Objective:, To examine whether psychological therapies modulate brain activity and, if so, to examine whether these changes similar to those found with relevant pharmacotherapy in various mental disorders. Methods:, Relevant data were identified from Pubmed and PsycInfo searches up to July 2005 using combinations of keywords including ,psychological therapy', ,behaviour therapy', ,depression', ,panic disorder', ,phobia', ,obsessive compulsive disorder', ,schizophrenia', ,psychosis', ,brain activity', ,brain metabolism', ,PET', ,SPECT' and ,fMRI'. Results:, There was ample evidence to demonstrate that psychological therapies produce changes at the neural level. The data, for example in depression, panic disorder, phobia and obsessive compulsive disorder (OCD), clearly suggested that a change in patients' symptoms and maladaptive behaviour at the mind level with psychological techniques is accompanied with functional brain changes in relevant brain circuits. In many studies, cognitive therapies and drug therapies achieved therapeutic gains through the same neural pathways although the two forms of treatment may still have different mechanisms of action. Conclusions:, Empirical research indicates a close association between the ,mind' and the ,brain' in showing that changes made at the mind level in a psychotherapeutic context produce changes at the brain level. The investigation of changes in neural activity with psychological therapies is a novel area which is likely to enhance our understanding of the mechanisms for therapeutic changes across a range of disorders. [source]

Anatomical basis for a successful upper limb sympathectomy in the thoracoscopic era

CLINICAL ANATOMY, Issue 4 2004
L. Ramsaroop
Abstract In this clinico-anatomical study, factors potentially responsible for unsuccessful upper limb sympathectomy (ULS) by the thoracoscopic route were evaluated. This study comprised two subsets: 1) in the clinical subset, 25 patients (n = 50 sides) underwent bilateral second thoracic ganglionectomy for palmar hyperhidrosis, and factors predisposing to unsuccessful ULS were identified; and 2) in the anatomical subset, the neural connections of the first and second intercostal spaces were bilaterally dissected in 22 adult cadavers (22 right, 21 left; n = 43 sides). Alternate neural pathways (ANP) were noted in 9 of 50 sides in the 25 clinical cases (18%). In three asthenic patients (5 sides), fascia overlying the longus colli muscle mimicked the sympathetic chain. The right superior intercostal vein (SIV) was located anterior to the second thoracic ganglion in 6 of 50 sides (12%) and predisposed to troublesome bleeding in 2 of 50 cases; the SIV was posterior to the ganglion in 19 of 50 sides (38%), posing no technical problem. On the left, the SIV was noted outside the field of dissection in all but one case. A successful outcome to sympathectomy was noted in all 25 patients. A spectrum of sympathetic contributions to the first thoracic ventral ramus for the first intercostal space was noted in 37 of 43 anatomical cases (86%). These were categorized according to the arrangements of the intrathoracic ramus between the second intercostal nerve and the first thoracic ventral ramus. The cervicothoracic ganglion (37/43 cases; 86%) and an independent inferior cervical ganglion (6/43 cases; 14%) were always located above the second rib. The second thoracic ganglion was consistently located in the second intercostal space. This study demonstrates that ANPs have little clinical significance when a second thoracic ganglionectomy is undertaken. Technical failures may be avoided if the surgeon is mindful of anatomical variations at surgery. Clin. Anat. 17:294,299, 2004. © 2004 Wiley-Liss, Inc. [source]