bluuebunny/crossref_metadata_2025 huggingface dataset:
Stabilization of Dendritic mRNAs by Nitric Oxide Allows Localized, Activity‐dependent Enhancement of Hippocampal Protein Synthesis
Authors: Morris Brian J.
Published: April 2006

A small number of mRNA species are not restricted to the neuronal cell body, but are also present in neuronal dendrites. The levels of two of these dendritic mRNAs, encoding the microtubule‐associated protein MAP2 and the a subunit of calcium/calmodulin‐dependent protein kinase II (CamKllα), are increased rapidly by high‐frequency synaptic activity or by release of nitric oxide. To test the hypothesis that post‐transcriptional mechanisms might contribute to this modulation, primary cultures of rat hippocampal neurons were exposed tos‐nitroso‐N‐acetyl penicillamine (SNAP, 200 μM) or vehicle, and mRNA stability was determined. The stability of both CamKllá mRNA and MAP2 mRNA was increased by SNAP treatment, whereas the stabilities of tubulin T26 mRNA and proenkephalin mRNA were unaffected. When the intensity of staining for MAP2 immunoreactivity and CamKllα immunoreactivity was monitored in cultured hippocampal neurons, nitric oxide‐releasing agents induced increases in staining intensity that were dependent on protein synthesis but not on mRNA synthesis. These results show that nitric oxide can selectively stabilize CamKllα mRNA and MAP2 mRNA, leading to increased synthesis of the corresponding proteins. This demonstrates a mechanism whereby the presence of a particular mRNA in the vicinity of a synapse permits the levels of the protein product to be regulated by synaptic activity in a manner that is both prolonged and also highly localized to the region of stimulation. Thus, the dependence of sustained synaptic plasticity onde novoprotein synthesis need not entail a loss of anatomical specificity.
Membrane Currents Influencing Action Potential Latency in Granule Neurons of the Rat Cochlear Nucleus
Authors: Rusznák Zoltán , Forsythe Ian D. , Brew Helen M. , Stanfield Peter R.
Published: April 2006

Granule cells are the most numerous neurons in the cochlear nucleus, but, because of their small size, little information on their membrane properties and ionic currents is available. We used an in vitro slice preparation of the rat ventral cochlear nucleus to make whole‐cell recordings from these cells. Under current clamp, some granule neurons fired spontaneous action potentials and all generated a train of action potentials on depolarization (threshold current, 10–35 pA). Hyperpolarization increased the latency to the first action potential evoked during a subsequent depolarization. We examined which voltage‐gated currents might underlie this latency shift. In addition to a fast inward Na+ current, depolarization activated two outward potassium currents. A transient current was rapidly inactivated by membrane potentials positive to ‐60 mV, while a second, more slowly inactivating current was observed following the decay of the transient current. No hyperpolarization‐activated conductances were observed in these cells. Modelling of the currents suggests that removal of inactivation on hyperpolarization accounts for the increased action potential latency in granule cells. Such a mechanism could account for the ‘pauser’‐type firing patterns of the fusiform cells which receive a prominent projection from the granule cells in the dorsal cochlear nucleus.
Glutamate Metabotropic Receptor Agonists Depress Excitatory and Inhibitory Transmission on Rat Mesencephalic Principal Neurons
Authors: Bonci Antonello , Grillner Pernilla , Siniscalchi Antonio , Mercuri Nicola B. , Bernardi Giorgio
Published: April 2006

lntracellular and whole‐cell patch‐clamp recordings were used to evaluate the actions of different metabotropic glutamate receptor (mGluR) agonists on the synaptic inputs evoked on principal cells of the rat mesencephalon. Bath application of the group Ill mGluR agonists l‐2‐amino‐4‐phosphonobutyric acid (l‐AP4) and l‐serine‐O‐phosphonobutanoate (l‐SOP) did not change the holding current of the cells held at resting potential (‐60 mV) but produced a dose‐dependent inhibition of the amplitude of the excitatory and inhibitory events. l‐AP4 and l‐SOP were more effective at inhibiting the excitatory postsynaptic currents (EPSCs) than the GABAA and GABAB inhibitory postsynaptic currents (IPSCs). The suppressing effects of l‐AP4 and l‐SOP were antagonized by (S)‐2‐amino‐2‐methyl‐4‐phosphonobutanoic acid (MAP‐4) but not by ±‐α‐methyl‐4‐carboxyphenylglycine (MCPG). Moreover, the group II agonist (2S, 1′S, 2′S)‐(carboxycyclopropyl)glycine (l‐CCG1) and the group I agonist (RS)‐3,5‐dihydrophenylglycine (3,5‐DHPG) depressed in a dose‐related manner the EPSC, the GABAA IPSC and the GABAB IPSC. The suppressing effect of the two mGluRs agonists was partially antagonized by MCPG but not by MAP‐4. In addition, both l‐CCG1 and 3,5‐DHPG caused an inward shift of the holding current. To characterize the site of action of the metabotropic receptor agonists, experiments were performed to examine the amplitude and ratio of EPSC and GABAA IPSC pairs. The increase of the s2/sl ratio caused by the agonists suggests that the location of the inhibitory mGluRs was presynaptic. These results indicate that the activation of presynaptic mGluRs controls the release of excitatory and inhibitory transmitters on presumed dopaminergic cells within the ventral mesencephalon.
In Situ Hybridization and Reverse Transcription‐Polymerase Chain Reaction Studies on the Expression of the GABAc Receptor ρ1‐ and ρ2‐subunit Genes in Avian and Rat Brain
Authors: Albrecht Barbara E. , Breitenbach Ute , Stühmer Thorsten , Harvey Robert J. , Darlison Mark G.
Published: April 2006

The pharmacological properties of homo‐oligomeric channels formed by the GABA type A receptor‐like ρl and ρ2 polypeptides are very reminiscent of those of the GABA type C receptors that have been extensively characterized in the retina. Similar receptors have been reported to occur in certain brain regions of a variety of vertebrate species. We have used in situ hybridization to investigate the expression patterns of the ρ1‐ and ρ ‐polypeptide genes in the brain of the 1‐day‐old chick (Gallus domesticus) and the adult rat (Rattus norvegicus). Our results show that in the chick both the ρ1‐ and ρ2‐subunit transcripts are present in the cerebellum, the optic tectum, the epithalamus and the nucleus pretectalis. However, the two messenger RNAs are often found in different populations of cells. Thus, only the ρ1‐subunit gene is expressed in the deep cerebellar nuclei, the dorsal thalamus, the ectostriatum and the tractus vestibulomesencephalicus, while only the ρ2‐subunit gene is transcribed in the nucleus habenularis lateralis and the nucleus isthmo‐opticus. In contrast, neither of the ρ‐polypeptide messenger RNAs can be detected by in situ hybridization in the rat central nervous system. Reverse transcription‐polymerase chain reaction amplification has been used to confirm the expression of the two ρ‐subunit genes in the chicken brain. Surprisingly, this highly sensitive technique also revealed transcription of these genes in the rat brain. We conclude that the ρl‐ and ρ2‐subunit genes are expressed at a much higher level in the avian brain than in the rat brain and that, at least in birds, subtypes of the GABC receptor exist.
The Recognition Memory Deficit Caused by Mediodorsal Thalamic Lesion in Non‐human Primates: A Comparison with Rhinal Cortex Lesion
Authors: Parker Amanda , Eacott M. J. , Gaffan David
Published: April 2006

Two earlier studies found that rhinal cortex ablations in the monkey (Macaca fascicularis) impaired delayed matching‐to‐sample (DMS) when the stimuli in the experiment came from a large population of possible stimuli, but not when the stimulus population was small, while uncinate fascicle section had no effect on DMS whatever the stimulus population size. The mediodorsal thalamus receives a large projection from the rhinal cortex, and has been implicated in recognition memory performance. We trained monkeys preoperatively in delayed matching‐to‐sample with large and small stimulus populations, exactly as in the earlier studies, then examined the effect of bilaterally ablating the medial portion of the mediodorsal thalamic nucleus. Mediodorsal lesion impaired postoperative delayed matching‐to‐sample performance with a large stimulus set, but had no effect on performance of DMS with a small stimulus population. In comparison with the earlier data from rhinal cortex lesions with the same methods, wherever a deficit was seen in the rhinal‐lesioned animals the mediodorsal thalamic nucleus‐lesioned animals showed a smaller deficit. We conclude that other efferents from the rhinal cortex, possibly those to the adjacent inferior temporal cortex, enable better performance in the mediodorsal thalamic nucleus‐lesioned animals than in the animals with rhinal cortex ablation.
Plasticity in the Stress‐Regulating Circuit: Decreased Input from the Bed Nucleus of the Stria Terminalis to the Hypothalamic Paraventricular Nucleus in Wistar Rats following Adrenalectomy
Authors: Mulders W. H. A. M. , Meek J. , Hafmans T. G. M. , Cools A. R.
Published: April 2006

The bed nucleus of the stria terminalis is involved in the stress‐regulating circuit by funnelling limbic information to the hypothalamic paraventricular nucleus. Since adrenalectomy influences both limbic structures (by inducing cell death in the hippocampus) and the hypothalamic paraventricular nucleus (by increased corticotrophin‐releasing hormone synthesis), we investigated whether the bed nucleus of the stria terminalis is also influenced by adrenalectomy. For this purpose, we analysed and compared the projections from the bed nucleus of the stria terminalis to the hypothalamic paraventricular nucleus in normal and adrenalectomized rats by anterograde tracer injections in the bed nucleus of the stria terminalis. Quantitative analysis of the fibre pattern in the hypothalamic paraventricular nucleus of normal rats revealed a homogeneous distribution of fibres of the bed nucleus of the stria terminalis over the different subdivisions of the hypothalamic paraventricular nucleus. In adrenalectomized rats, the absolute fibre density was significantly lower in the whole hypothalamic paraventricular nucleus (1.17 ± 0.27 10−3μm/μm3 in adrenalectomized rats versus 2.59 ± 0.24 10−3μm/μm3 in normal rats; P < 0.01) and all its subdivisions. The largest decrease of fibre density was found in the corticotrophin‐releasing hormone‐rich part of the hypothalamic paraventricular nucleus (relative fibre density; adrenalectomized rats: 0.602 ± 0.106, versus 1.095 ± 0.019 in normal rats, P < 0.01). These results show a loss of input from the bed nucleus of the stria terminalis to the hypothalamic paraventricular nucleus, and particularly to the corticotrophin‐releasing hormone neurons, following adrenalectomy. The data suggest that this pathway within the stress‐regulating circuit is functionally affected by corticosteroids in adult rats and may imply that human disorders associated with corticosteroid imbalance are allied to a changed circuitry in the brain.
GDNF is a Trophic Factor for Adult Rat Corticospinal Neurons and Promotes their Long‐term Survival after Axotomy In vivo
Authors: Giehl Klaus M. , Schacht Claudia M. , Yan Qiao , Mestres Pedro
Published: April 2006

Glial cell line‐derived neurotrophic factor (GDNF) is a trophic factor for several neuronal populations involved in motor control. The present study evaluates the trophic actions of GDNF on corticospinal neurons, an important central nervous system motor projection into the spinal cord. Death of spinal motoneurons and corticospinal neurons is observed in the neurodegenerative disease amyotrophic lateral sclerosis. Axotomy of adult rat corticospinal neurons at internal capsule levels induces half of them to die, and the surviving population displays severe atrophy. To examine the trophic effects of GDNF on corticospinal neurons, Fast Blue‐labelled corticospinal neurons were stereotaxically axotomized at internal capsule levels and GDNF was infused intracortically to lesioned corticospinal neurons at total doses of 2, 4, 10, 20, 40, 100 and 300 μg for 7 days. GDNF prevented axotomy‐induced death of corticospinal neurons at doses between 2 and 40 μg and abolished or attenuated their atrophy at all doses examined. In addition, treatment with 8 μg GDNF for the first 2 weeks after axotomy resulted in the long‐term survival of corticospinal neurons for 42 days. With regard to the development of treatment strategies for upper motoneuron degeneration in amyotrophic lateral sclerosis, application of GDNF via the cerebrospinal fluid may be more relevant than intracortical delivery as its diffusion within the brain parenchyma is limited. lntraventricular as well as intracisternal infusion of GDNF (300 μg over 7 days) completely prevented corticospinal neuron death. These results show that GDNF promotes the long‐term survival of corticospinal neurons and has a positive effect on their size in vivo Furthermore, the survival‐promoting effect of GDNF on corticospinal neurons after delivery via cerebrospinal fluid has important clinical implications for potential treatment of the upper motoneuron degeneration seen in amyotrophic lateral sclerosis.
Bcl‐2 Regulates the Levels of the Cysteine Proteases ICH and CPP32/Yama in Human Neuronal Precursor Cells
Authors: Korhonen Laura , Hamnér Susanne , Olsson Per‐Anders , Lindholm Dan
Published: April 2006

Members of the Bcl‐2 family are major regulators of cell death and survival. Bcl‐2 has been shown to heterodimerize with the death‐inducing protein Bax, but the mechanism of action of Bcl‐2 is not fully understood. Here we show, using the human NT‐2 neuronal cell line, that overexpression of Bcl‐2 leads to dramatic down‐regulation of the cysteine proteases ICH and CPP32/Yama, which are directly involved in cell death. In addition, the nuclear enzyme poly(ADP‐ribose) polymerase was cleaved in control cells but not in cells overexpressing Bcl‐2 following induction of apoptosis. The mRNA levels of ICH and CPP32/Yama were differentially affected by Bcl‐2 overexpression, suggesting both transcriptional and post‐transcriptional effects of the protein. These results demonstrate novel mechanisms of action of Bcl‐2 in influencing the expression of death effectors such as the cysteine proteases. The relative levels of Bcl‐2 and of various cysteine proteases ultimately determine survival and death of different cells, including neurons.
Sustained Neurotransmitter Release: New Molecular Clues
Authors: Brodin Lennart , Löw Peter , Gad Helge , Gustafsson Jenny , Pieribone Vincent A. , Shupliakov Oleg
Published: April 2006

Chemical synapses convey impulses at high frequency by exocytosis of synaptic vesicles. To avoid failure of synaptic transmission, rapid replenishment of synaptic vesicles must occur. Recent molecular perturbation studies have confirmed that the recycling of synaptic vesicles involves clathrin‐mediated endocytosis. The rate of exocytosis would thus be limited by the capacity of the synaptic clathrin machinery unless vesicles could be drawn from existing pools. The mobilization of vesicles from the pool clustered at the release sites appears to provide a mechanism by which the rate of exocytosis can intermittently exceed the rate of recycling. Perturbation of synapsins causes disruption of vesicle clusters and impairment of synaptic transmission at high but not at low frequencies. Both clathrin‐mediated recycling and mobilization of vesicles from the reserve pool are thus important in the replenishment of synaptic vesicles. The efficacy of each mechanism appears to differ between synapses which operate with different patterns of activity.
Autoinhibition of Supraoptic Nucleus Vasopressin Neurons In Vivo: A Combined Retrodialysis/Electrophysiological Study in Rats
Authors: Ludwig Mike , Leng Gareth
Published: April 2006

To examine the role of endogenous vasopressin on the electrical activity of vasopressin neurons within the supraoptic nucleus of the rat brain in vivo, we have developed a novel technical approach for administering neuroactive drugs directly into the extracellular environment of the neuronal dendrites. A microdialysis probe was used for controlled local drug administration into the dendritic area of the nucleus during extracellular recording of single neurons in vivo. Vasopressin or selective V1 receptor antagonists were administered for between 10 and 30 min via a U‐shaped microdialysis probe placed flat on the surface of the supraoptic nucleus after transpharyngeal exposure of the nucleus in urethane‐anaesthetized rats. Microdialysis administration (retrodialysis) of vasopressin inhibited vasopressin neurons by reducing their firing rate, sometimes to total inactivity. Retrodialysis of V1‐receptor antagonists partially reversed the effect of vasopressin, and a subsequent vasopressin administration was not effective in reducing the activity of these neurons, suggesting a receptor‐mediated action of endogenous vasopressin. In addition, the duration of the periods of activity and the mean frequency during the active phase were increased in vasopressin neurons after retrodialysis of V1‐receptor antagonist, indicating a physiological role of endogenous vasopressin. Neither vasopressin nor the antagonists altered the activity of continuously firing oxytocin neurons. Thus, vasopressin released within the supraoptic nucleus may act via V1 receptors located specifically on vasopressin neurons to regulate their phasic activity by an auto‐inhibitory action. Since vasopressin release from the dendrites of vasopressin neurons is increased and prolonged after various forms of stimulation, it is proposed that this mechanism will act to limit excitation of vasopressin neurons, and hence secretion from the neurohypophysis. In addition, combined in vivo retrodialysis/ single cell recording allows controlled introduction of neuroactive substances into the extracellular fluid in the immediate vicinity of recorded neurons. This is shown to provide a novel approach to study neurotransmitter actions on supraoptic neurons in vivo.
Plateau Potentials in Cat Neocortical Association Cells In Viva Synaptic Control of Dendritic Excitability
Authors: Contreras D. , Dürmüller N. , Steriade M.
Published: April 2006

The dendrites of neocortical pyramidal cells are bombarded by myriads of synaptic inputs and express active conductances generating prominent plateau potentials. We have examined in vivo the possibility that spontaneous synaptic inputs trigger or terminate plateau potentials after blockage of K+ currents. Under barbiturate anaesthesia, pairs of cortical cells were intracellularly recorded with sharp electrodes from the cat's association cortex (areas 5–7). In one pyramidal cell, K+ channels were blocked with intracellular Cs+, while in the simultaneously impaled pyramidal cell the K+ conductances were left intact to act as a control; this second cell allowed recognition of spontaneous spindle‐related synaptic activity. Depolarizing current pulses elicited single, all‐or‐none plateau potentials (60–70 mV, 0.1–0.4 s). Plateau potentials slowly repolarized towards a break point of fast repolarization around ‐20 mV. Thalamic‐evoked inhibitory postsynaptic potentials consistently shut off the plateaus. Synchronized spontaneous activity, as occurring during thalamic‐generated spindle oscillations, either triggered or blocked the plateaus. These results suggest that spontaneously occurring synaptic activation during synchronized oscillatory states, such as those that occur during sleep spindles in vivu, may exert a strong control over the dendritic excitability in neocortical pyramidal cells.
Olivocerebellar Axon Regeneration and Target Reinnervation Following Dissociated Schwann Cell Grafts in Surgically Injured Cerebella of Adult Rats
Authors: Bravin Monica , Savio Tiziana , Strata Piergiorgio , Rossi Ferdinando
Published: April 2006

The ability of Schwann cells to induce the regeneration of severed olivocerebellar and Purkinje cell axons across an injury up to their deafferented targets was tested by transplanting freshly dissociated cells from newborn rat sciatic nerves into surgically lesioned adult cerebella. The grafted glial cells consistently filled the lesion gap and migrated into the host parenchyma. Transected olivocerebellar axons vigorously regenerated into the graft, where their growth pattern and direction followed the arrangement of Schwann cell bundles. Although some of these axons terminated within the transplant, many of them rejoined the cerebellar parenchyma beyond the lesion. Here, their fate depended on the territory encountered. No growth occurred in the white matter. Numerous fibres penetrated into the granular layer and formed terminal branches that remained confined within this layer. A few of them, however, regenerated up to the molecular layer and formed climbing fibres on Purkinje cell dendrites. By contrast, the growth of transected Purkinje cell axons into the grafts was very poor. These results underscore the different intrinsic responsiveness of Purkinje cell and olivocerebellar axons to the growth‐promoting action of Schwann cells, and show that the development and outcome of the regenerative phenomena is strongly conditioned by the spatial organization and specific features of the environmental cues encountered by the outgrowing axons along the course they follow. However, Schwann cells effectively bridge the lesion gap, induce the regeneration of olivocerebellar axons, and direct their growth up to the deafferented host cortex, where some of them succeed in reinnervating their natural targets.
NOS Expression in Nigral Cells after Excitotoxic and Non‐excitotoxic Lesion of the Pedunculopontine Tegmental Nucleus
Authors: González‐Hernández Tomás , Abdala Patricio , Rodríguez Manuel
Published: April 2006

The substantia nigra (SN) receives afferents from cholinergic neurons of the pedunculopontine tegmental nucleus (PPTg), a neuronal population that shows high levels of nitric oxide synthase (NOS), the enzyme responsible for the synthesis of nitric oxide. We have investigated the effects of the injection in PPTg of two neurotoxins, kainic acid (an excitotoxic neurotoxin), and ethylcholine mustard azirinium ion (AF64A, a non‐excitotoxic neurotoxin), upon the SN cells of the rat, by using choline acetyltransferase (ChAT) immunohistochemistry as a marker of cholinergic neurons, and nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry and NOS immunohistochemistry as markers of nitric oxide‐producing neurons. Our results show that in normal rats, the SN contains two populations of NOS‐positive neurons: large cholinergic neurons of PPTg that invade the caudal region of the SN, and small elongated neurons lying in the SN pars compacta. After ipsilateral PPTg lesion, another population of nigral cells, constituted by medium sized neurons, became NADPHd/NOS‐positive. This was much more evident in AF64A‐injected rats, in which many medium sized neurons showed enzymatic activity and normal morphological features, at least during the 90 days after injection. Kainic acid‐injected rats, in contrast, showed nigral cell degeneration, an effect not found in AF64A material, and only a few NOS‐positive neurons. NADPHd/NOS activity was never present in degenerating neurons. These findings suggest that induction of NOS activity is not involved in nigral cell degeneration, and that nitric oxide could have a protective rather than a neurotoxic role. The possible role of nitric oxide in the pathogenesis of Parkinson's disease is discussed.
The ExDression Pattern of the Orphan Nuclear Receptor RORβ in the Developing and Adult Rat Nervous System Suggests a Role in the Processing of Sensory Information and in Circadian Rhythm
Authors: Schaeren‐Wierners Nicole , André Elisabeth , Kapfhammer Josef P. , Becker‐André Michael
Published: April 2006

RORβ is an orphan nuclear receptor related to retinoid and thyroid hormone receptors and is exclusively expressed in the central nervous system (CNS). Here we present an in situ hybridization analysis of the distribution of RORβ mRNA in the developing and adult rat CNS. The receptor localizes to areas involved in the processing of sensory information. In the cerebral cortex, RORβ mRNA was exclusively detected in non‐pyramidal neurons of layer IV and, less so, layer V. The highest expression was found in primary sensory cortices. In the thalamus highest RORβ expression was found in the sensory relay nuclei projecting to the respective cortical areas. In contrast, sensory projection neurons in the periphery, for example retinal ganglion cells and neurons of the sensory ganglia showed only little RORβ expression. RORβ is also expressed in areas involved in the generation and maintenance of circadian rhythms ‐ the suprachiasmatic nucleus, the pineal gland and the retina. In the latter two tissues, RORβ mRNA abundance oscillates with circadian rhythmicity peaking during the hours of darkness. RORβ rnRNA could not be detected in striatum, hippocampus, cerebellum, the motor nuclei of the cranial nerves or the ventral part of the spinal cord. During development, RORβ is expressed in many areas as early as embryonic day (E) 15, anticipating the distribution pattern in the adult. Our data suggest that RORβ regulates genes whose products play essential roles in the context of sensory input integration as well as in the context of circadian timing system.
Choline is a Selective Agonist of α7 Nicotinic Acetylcholine Receptors in the Rat Brain Neurons
Authors: Alkondon Manickavasagom , Pereira Edna F. R. , Cartes Wellington S. , Maelicke Alfred , Albuquerque Edson X.
Published: April 2006

In the present study, we demonstrate that choline, a precursor of acetylcholine (ACh) and a product of acetylcholine hydrolysis by acetylcholinesterase (AChE), acts as an efficient and relatively selective agonist of α7–containing nicotinic acetylcholine receptors (nAChR) in neurons cultured from the rat hippocampus, olfactory bulb and thalamus as well as in PC12 cells. Choline was able to activate postsynaptic and presynaptic α7 nAChRs, with the latter action resulting in the release of other neurotransmitters. Although choline was approximately one order of magnitude less potent than ACh (EC50 of 1.6 mM for choline and 0.13 mM for ACh), it acted as a full agonist at α7 nAChRs. In contrast, choline did not activate α4β2 agonist‐bearing nAChRs on hippocampal neurons, and acted as a partial agonist at α3β4‐containing nAChRs on PC12 cells. The ethyl alcohol moiety of choline is required for the selective action on α7 nAChR. Exposure of cultured hippocampal neurons for 10 min to choline (10–100 μM) resulted in desensitization of the native α7 nAChRs. Moreover, chronic exposure (10 days) of the cultured hippocampal neurons to a desensitizing concentration of choline (∼30 μM) decreased their responsiveness to ACh. The selective action of choline on native α7 nAChRs suggests that this naturally occurring compound may act in vivo as an endogenous ligand for these receptors. Putative physiological actions of choline include retrograde messenger activity during the development of the mammalian central nervous system and during periods of elevated synaptic activity that leads to long‐term potentiation.
Levobupivacaine caudal anesthesia in children: a randomized double‐blind comparison with bupivacaine
Authors: FRAWLEY GEOFF P. , DOWNIE SARAH , HUANG GRACE H.
Published: April 2006

Background:  Levobupivacaine is the pure S‐enantiomer of bupivacaine. Despite obvious benefits in the event of accidental intravascular injection there has been no studies demonstrating a clinically significant benefit to levobupivacaine over racemic bupivacaine for pediatric regional anesthesia. Given the similar pharmacokinetic profiles of both drugs the studies to date have been underpowered to demonstrate what is likely to be a small difference in clinical effectiveness. Our aim was to determine if there are significant differences in the clinical effectiveness of levobupivacaine compared with racemic bupivacaine for caudal anesthesia in children having lower abdominal surgery. A secondary aim was to determine if there are differences in the incidence of postoperative motor blockade between these agents.

Methods:  Three hundred and ten children ranging in age from 1 month to 10.75 years in age having lower abdominal surgery were enrolled. Patients were randomized in a double blind manner to receive a caudal block with either 0.25% bupivacaine (n = 152) or 0.25% levobupivacaine (n = 155) to a total volume of 1 ml·kg−1. Motor blockade (modified Bromage scale) and postoperative pain or distress (FLACC behavioral scale for postoperative pain) were measured at predetermined time points during the subsequent 120 min.

Results:  There were no significant adverse effects attributable to levobupivacaine. Success rates were defined as a lack of hemodynamic response to first surgical incision and low postoperative pain scores. At a mean duration of 5 min between block completion and first incision success for 1 ml·kg−1 of 0.25% bupivacaine was 91% and 94% for 0.25% levobupivacaine. Satisfactory postoperative analgesia was present in 98% of patients after bupivacaine caudal anesthesia and 97.5% for levobupivacaine. At 30 min following caudal anesthesia the incidence of postoperative motor block with racemic bupivacaine was 84% and decreased to 7% at 120 min. For levobupivacaine motor block at 30 min postcaudal was present in 85% and decreased to 11% at 120 min.

Conclusions:  Levobupivacaine is an effective agent for caudal anesthesia in children at a recommended dose of 2.5 mg·kg−1. The rapidity of onset was suitable for establishment of surgical anesthesia and postoperative analgesia was achieved in greater than 97.5% of patients. It appears to be of equivalent potency to racemic bupivacaine in children requiring lower abdominal surgery.
Brain‐derived neurotrophic factor enhances glucose utilization in peripheral tissues of diabetic mice
Authors: Yamanaka M. , Tsuchida A. , Nakagawa T. , Nonomura T. , Ono‐Kishino M. , Sugaru E. , Noguchi H. , Taiji M.
Published: April 2006

Aims: Repetitive subcutaneous or intracerebroventricular administration of brain‐derived neurotrophic factor (BDNF) ameliorates glucose metabolism and enhances energy expenditure in obese diabetic C57BL/KsJ‐db/dbmice. To explore the mechanism of action through which BDNF regulates glucose metabolism, we examined the effects of BDNF on glucose utilization and norepinephrine (NE) content in peripheral tissues of diabetic mice.

Methods: [14C]2‐deoxyglucose ([14C]2‐DG) uptake into peripheral tissues was analysed after intravenous injection of [14C]2‐DG indb/dband normal C57BL/6 mice, and [14C]2‐DG uptake and NE content in peripheral tissues were analysed after subcutaneous administration of BDNF (20 mg/kg) to maledb/dband normal mice for 8 days.

Results: [14C]2‐DG uptake in the diaphragm, heart, gastrocnemius, soleus and interscapular brown adipose tissue (BAT) ofdb/dbmice was significantly lower than in normal mice. Repetitive administration of BDNF todb/dbmice for 8 days enhanced [14C]2‐DG uptake in the diaphragm, heart, soleus, BAT and liver. The NE content in heart, skeletal muscle, interscapular BAT and liver ofdb/dbmice given BDNF was high compared withdb/dbmice given vehicle, whereas no significant change in NE content in peripheral tissues was observed in normal mice given BDNF and those given vehicle. BDNF did not affect [14C]2‐DG uptake or NE content in the white adipose tissue ofdb/dbmice.

Conclusions: These data indicate that BDNF ameliorates glucose metabolism by enhancement of glucose utilization in muscle and BAT, with this effect caused by modulation of the central and peripheral nervous systems.
A Survey of the Theoretical Economic Literature on Foreign Aid
Authors: Paul Elisabeth
Published: April 2006

This paper surveys the theoretical economic literature on foreign aid—in particular, the aid donor–recipient relationship. Economic theory, especially new institutional economics, can be very helpful in understanding foreign aid relationships—especially the incentive problems involved—and in designing institutions to improve aid effectiveness. In particular, it helps in understanding the chain of principal–agent relations inherent in the aid delivery system and the resulting potential for agency problems. The survey shows that economic theory can improve the design of cooperation modalities by aligning the incentives of donors and recipients for poverty reduction, but that, in order to address the problems, policy analysis must take into account the constraints faced by stakeholders in the aid relationship. The aid ‘contract’ should thus seek to improve the agents’ incentives to use aid effectively, given the circumstances of the developing country.
International Labour Migration in East Asia: trends, patterns and policy issues
Authors: Athukorala Prema‐chandra
Published: April 2006

This paper examines emerging patterns of labour migration in East Asia and related policy issues from the perspective of labour‐importing countries. Following a survey of the characteristics of labour flows stemming from, but more importantly occurring within, the region, it probes inter‐country differences, both in the timing of the entry of migrant workers and the degree of dependency on migrant labour in the context of rapid economic growth and labour market change. There is clear evidence that labour migration is now a structural feature of the economic landscape in these countries. The policy challenge is to design market‐based systems for making the new reliance on labour inflows consistent with changing domestic labour market conditions and the priorities of national development policy, while minimising social resentment and adverse implications for political relations with neighbouring labour‐sending countries.
Trends in Publications of Chinese Economic Studies: authors, journals and research fields, 1991–2003
Authors: Lu Ding , Chong Kwek Bin
Published: April 2006

Parallel to the rise of the Chinese economy has been the worldwide growth in economic scholarship on China. This paper examines the trends in the literature on the Chinese economy across journals, authors and research fields and, where possible, identifies events contributing to these trends. It is hoped that identification of these trends will provide useful references for researchers, not only in sourcing information but also in considering channels for publication in the field of Chinese economic studies.
Interdisciplinarity and Political Science
Authors: Moran Michael
Published: April 2006

‘Interdisciplinarity’ is an ancient notion in the social sciences, but has acquired both pedagogic and policy popularity in recent decades. Paradoxically, it only makes sense in a disciplinary world. The disciplines have been greatly strengthened in recent decades, and interdisciplinarity can partly be understood as a response by interests threatened by disciplinarity. It is also a strategy used by disciplines in crisis, and by dissidents from disciplinary hierarchies.
A Critique of the Lees-Marshment Market-Oriented Party Model
Authors: Ormrod Robert P.
Published: April 2006

This article presents conceptual and empirical criticisms of the Lees-Marshment market-oriented party model. Conceptual criticisms are the short-term approach, the narrow focus on voters, the nature of the relationship to competitors, a tendency towards centralisation and the lack of a distinction between the related concepts of ‘market orientation’ and ‘marketing orientation’. Empirical studies demonstrate problems with the model when applied to certain party types and electoral systems, the limitations on implementation of the model due to ideology and scarce resources, the partial application of the model in practice, and the constraints on the market-oriented party when in government.
Political Marketing Theory and Practice: A Reply to Ormrod's Critique of the Lees-Marshment Market-Oriented Party Model
Authors: Lees-Marshment Jennifer
Published: April 2006

In this article I discuss the ‘Lees-Marshment model’ of a market-oriented party in response to the criticisms from Robert Ormrod. In doing this I note recent modifications I have made, comment on its comparative potential and put forward my own evaluation of the areas that need development such as communication of delivery, implementation and empirical verification.
A Tale of Two Parties? The Failure of the Catch-All Parties in the 2005 German Elections
Authors: Sloam James
Published: April 2006

The German elections of 2005 proved a critical turning point for a number of reasons. The result led to the fall of Gerhard Schröder's Red-Green government, to the first ‘grand coalition’ between the two Volksparteien (catch-all parties) since the 1960s, and to the election of Germany's first woman and first easterner to the job of chancellor. The election campaign saw the Christian Democrats throw away a strong lead and lose the opportunity to govern with their preferred coalition partner, the liberal Free Democratic party. The results raised key questions about the German party system. Why did the Social Democrats and Christian Democrats achieve their lowest combined score since 1949? How should we explain the success of the smaller parties? To what extent can this be considered a lasting development? This article argues that shrinking support for the two main parties is likely to lead to greater instability in the party system without a clear improvement in the German economy.
Facts, Fantasies and the Future of Child Care in the United States
Authors: Scarr Sandra , Phillips Deborah , McCartney Kathleen
Published: April 2006

Psychologists in both family practice and developmental research may be puzzled about the scientific status of research on child care as it affects children, parents, and caregivers. What conclusions can be reached about mothers in the labor force, about the advisability of various child care arrangements, about their short and long-term consequences, and what advice do we as psychologists have to offer in the public interest to parents of infants and young children? In this article, we review research on child care, and discuss its implications for the nation and for psychology as a research enterprise and a helping profession.
Perception of Synthesized Audible and Visible Speech
Authors: Massaro Dominic W. , Cohen Michael M.
Published: April 2006

The research reported in this paper uses novel stimuli to study how speech perception is influenced by information presented to ear and eye. Auditory and visual sources of information (syllables) were synthesized and presented in isolation or in factorial combination. A five-step continuum between the syllables ibal and idal was synthesized along both auditory and visual dimensions, by varying properties of the syllable at its onset. The onsets of the second and third formants were manipulated in the audible speech. For the visible speech, the shape of the lips and the jaw position at the onset of the syllable were manipulated. Subjects’ identification judgments of the test syllables presented on videotape were influenced by both auditory and visual information. The results were used to test between a fuzzy logical model of speech perception (FLMP) and a categorical model of perception (CMP). These tests indicate that evaluation and integration of the two sources of information makes available continuous as opposed to just categorical information. In addition, the integration of the two sources appears to be nonadditive in that the least ambiguous source has the largest impact on the judgment. The two sources of information appear to be evaluated, integrated, and identified as described by the FLMP-an optimal algorithm for combining information from multiple sources. The research provides a theoretical framework for understanding the improvement in speech perception by hearing-impaired listeners when auditory speech is supplemented with other sources of information.
Similarity Involving Attributes and Relations: Judgments of Similarity and Difference Are Not Inverses
Authors: Medin Douglas L. , Goldstone Robert L. , Gentner Dedre
Published: April 2006

Conventional wisdom and previous research suggest that similarity judgments and difference judgments are inverses of one another. An exception to this rule arises when both relational similarity and attributional similarity are considered. When presented with choices that are relationally or attributionally similar to a standard, human subjects tend to pick the relationally similar choice as more similar to the standard and as more different from the standard. These results not only reinforce the general distinction between attributes and relations but also show that attributes and relations are dynamically distinct in the processes that give rise to similarity and difference judgments.
Answering Reading Comprehension Items without Passages on the SAT
Authors: Katz Stuart , Lautenschlager Gary J. , Blackburn A. Boyd , Harris Felicia H.
Published: April 2006

Performance of college undergraduates on the Reading Comprehension task of the SAT was well above chance when the passages were deleted. Moreover, examinees and test items performed similarly with or without the passages: individual performance correlated with verbal SAT score, and the difficulty of items belonging to a passage correlated with a normative measure based on equated delta. The findings demonstrate that the Reading Comprehension task substantially measures factors unrelated to reading comprehension.
Representational Transfer in Problem Solving
Authors: Novick Laura R.
Published: April 2006

Previous research on transfer in problem-solving has primarily been concerned with the transfer of a specific solution procedure from a source problem to an analogous target problem. This paper considers whether transfer may also occur at a more general level of description, namely that responsible for specifying a common representation (e.g., a matrix) for two problems. The results of an experiment showed convincingly that representational transfer can occur in the absence of a common solution procedure for the problems. This result opens up a new area of research on transfer in problem solving.
Cultural Adjustment of International Students
Authors: Kagan Henya , Cohen Jo
Published: April 2006

Cultural adjustment involves both acculturation and assimilation. In the present study cultural adjustment is conceptualized similarly to Mendoza and Martinez's Model of Acculturation (1981). It is suggested that cultural adjustment is a process of multiple interacting factors distinguished by different behavioral, cognitive, affective and demographic attributes and by different levels, varying from cultural assimilation to cultural transmutation. A total of 159 students, 92 international and 67 U.S. students, responded to mailed questionnaires. The main findings suggest that cultural adjustment is simultaneously affected by employment level, language spoken at home, having both American and native friends, internal decision making, and work value. The study supports a native-extinction, host-association model of cultural adjustment.
William James on Sensation and Perception
Authors: Dember William N.
Published: April 2006

Beginning with an analysis of a famous quotation from James’ Principles, this essay details some of the highlights of James’ treatment of sensation and perception. The primary source is a chapter on discrimination and comparison, in which emphasis is placed on the way people react to difference and sameness, reactions that may be fundamental to the psychophysical methods developed by Fechner and to later techniques, such as stimulus scaling and signal detection procedures, as well as to recent methods (preferential looking and habituation-dishabituation) for investigating perception in human infants. One can see considerable continuity between many of the issues raised in the Principles and those that have been addressed by perceptionists over the ensuing century, but James seems not to have had the direct impact in this domain that he has had, for example, on current conceptions of emotional processes. His associationist and functionalist positions may find contemporary expression in the seemingly disparate approaches known as connectionism and ecological psychology.
William James on Reasoning
Authors: Nickerson Raymond S.
Published: April 2006

James looked for general principles in terms of which reasoning could be understood, and, in doing so, he sought to understand what it was about human beings that made them human.
The Neurobiology of Learning and Memory: William James in Retrospect
Authors: Thompson Richard F.
Published: April 2006

William James did much to set the stage for psychobiology. Beyond insisting that brain structures and processes must be the basis of explanations of mental phenomena, he expressed ideas about brain localization and plasticity in neural networks that foreshadowed many aspects of current neurobiology of learning and even connectionist theory.
William James and the Construction of Emotion
Authors: Mandler George
Published: April 2006

The theory of emotion was a centerpiece of William James’ Principles of Psychology. It introduced the notion that complex phenomena, such as the experience of emotion, could be derived (constructed) from a combination of more basic processes or behaviors. Despite their shortcomings, James’ views on emotion shaped research on emotion for the succeeding century, and laid the groundwork for constructivist approaches in psychological theory.
On Splitting the Universe
Authors: Markus Hazel
Published: April 2006

Although many aspects of James’ theorizing about the self have been enormously influential, his notion of the self as the central object in mental life has been largely ignored. He believed that the fundamental psychological processes-attention, perception, emotion, conception, reasoning, will, consciousness-could not be understood without an appreciation of the nature and functioning of the self. The value of reclaiming this idea is discussed.
The Last shall be First: How Memory Strength Affects Children's Retrieval
Authors: Brainerd C.J. , Reyna V.F. , Howe M.L. , Kevershan J.
Published: April 2006

When items are read out of storage during unconstrained recall, how should their memory strengths affect recall order? Commonsense argues that items will present themselves to consciousness in the order of their relative memory strength and that, hence, the read out sequence will be stronger to weaker. In experiments with 6- to 13-year-olds, however, this sequence was never obtained. Dichotomous measures of memory strength (strong vs. weak) showed that weak items were always recalled before strong items. Continuous measures of memory strength showed that the sequence was weaker to stronger to weaker. This pattern, which we term the cognitive triage effect, occurred at all age levels, for a variety of material, with different definitions of memory strength, and became more pronounced with age. Three results suggested that the pattern was not due to a deliberate strength-based ordering strategy: The pattern was observed in children as young as age 6; it was present at the earliest stages of recall; and adults (who also exhibited the pattern) were unaware of what they were doing.
When does Human Object Recognition use a Viewer-Centered Reference Frame?
Authors: Tarr Michael J. , Pinker Steven
Published: April 2006

How do people recognize an object in different orientations? One theory is that the visual system describes the object relative to a reference frame centered on the object, resulting in a representation that is invariant across orientations. Chronometric data show that this is true only when an object can be identified uniquely by the arrangement of its parts along a single dimension. When an object can only be distinguished by an arrangement of its parts along more than one dimension, people mentally rotate it to a familiar orientation. This finding suggests that the human visual reference frame is tied to egocentric coordinates.