bluuebunny/crossref_metadata_2025_split huggingface dataset:
When ‘go’ and ‘nogo’ are equally frequent: ERP components and cortical tomography
Authors: Lavric Aureliu , Pizzagalli Diego A. , Forstmeier Simon 
Published: November 2004

AbstractIn human electrophysiology, a considerable corpus of studies using event‐related potentials have investigated inhibitory processes by employing the ‘go–nogo’ paradigm, which requires responding to one type of event while withholding the response to another type of event. Two event‐related potential waveform features (N2 and P3) have been associated with larger amplitude in nogo trials than in go trials. Traditionally, these differences were thought to reflect response inhibition. Recently, the source localization of N2 to the anterior cingulate cortex, as well as the colocalization of N2 with error‐related negativity, has been interpreted in terms of conflict monitoring. In order to isolate the contribution of inhibitory processes, we matched the frequency of the go and nogo events, thus minimizing differences in response conflict between event types. A data‐driven analytical procedure contrasted go with nogo events across the entire event‐related potential segment and found that N2 reliably differentiated between the two conditions while P3 did not. Tomographical analyses of the N2 difference observed in conditions of equal go and nogo trial frequency localized N2 to the right ventral and dorsolateral prefrontal cortex. Because a growing body of evidence implicates these brain regions in inhibitory processes, we conclude that N2 does, at least in part, reflect inhibition.
Down's syndrome astrocytes have greater antioxidant capacity than euploid astrocytes
Authors: Sebastià Jordi , Cristòfol Rosa , Pertusa Maria , Vílchez David , Torán Núria , Barambio Santiago , Rodríguez‐Farré Eduard , Sanfeliu Coral 
Published: November 2004

AbstractDown's syndrome (trisomy 21) brain tissue is considered to be susceptible to oxidative injury, mainly because its increased Cu/Zn‐superoxide dismutase (SOD1) activity is not followed by an adaptive rise in hydrogen peroxide metabolizing enzymes.In vitro, trisomic neurons suffer oxidative stress and degenerate. We studied the response of trisomy 21 neuron and astrocyte cultures to hydrogen peroxide injury and found that they were, respectively, more and less vulnerable than their euploid counterparts. Differences were detected 24 h after exposures in the region of 50 µmand 500 µmhydrogen peroxide for neuron and astrocyte cultures, respectively. Cytotoxicity results were paralleled by a decrease in cellular glutathione. In addition, trisomic astrocytes showed a lower basal content of superoxide ion and a higher clearance of hydrogen peroxide from the culture medium. In the presence of hydrogen peroxide, trisomic astrocytes maintained their concentration of intracellular superoxide and hydroperoxides at a lower level than euploid astrocytes. Consistent with these results, trisomic astrocytes in neuron coculture were more neuroprotective than euploid astrocytes against hydrogen peroxide injury. We suggest that SOD1 overexpression has beneficial effects on astrocytes, as it does in other systems with similarly high disposal of hydroperoxides. In addition to a higher enzymatic activity of SOD1, cultures of trisomic astrocytes showed slightly higher glutathione reductase activity than euploid cultures. Thus, trisomy 21 astrocytes showed a greater antioxidant capacity against hydrogen peroxide than euploid astrocytes, and they partially counteracted the oxidative vulnerability of trisomic neurons in culture.
Inactivation and activation of Ras by the neurotrophin receptor p75
Authors: Blöchl Andrea , Blumenstein Lars , Ahmadian Mohammad R. 
Published: November 2004

AbstractThe neurotrophin receptor p75 induces neurotrophic and/or apoptotic signalling pathways and can also cooperate with the neurotrophic Trk receptor tyrosine kinases. Its intracellular part encloses a so‐called ‘death domain’ with a segment similar to the wasp venom mastoparan which binds small GTPases such as Rho. To study possible interactions of p75 and Ras (and Rho) we used wild‐type and mutant genes of p75 stably expressed by MDCK cells which normally have neither Trk nor p75. We found that p75 can directly bind the GTPases Ras and Rho and that the unstimulated p75 inactivates total cellular Ras through a differential influence on the dissociation of GDP and GTP from Ras and an exchange of bound Ras·GDP for free Ras·GTP. These properties of p75 could also be demonstrated in vitro and should therefore be cell type‐independent. Stimulation of p75 with nerve growth factor causes Ras activation via adapter proteins known from Trk signalling and induces rapid outgrowth of cellular processes. Both inactivation and activation of Ras by p75 are controlled by the phosphorylation state of the receptor's two intracellular tyrosines. p75 also influences Rho activation and inactivation, and the combined interactions of the receptor with the two GTPases Ras and Rho can regulate neurite formation in an efficient, synergistic way.
Long‐term effects of striatal lesions on c‐Fos immunoreactivity in the pedunculopontine nucleus
Authors: Mena‐Segovia Juan , Favila Rafael , Giordano Magda 
Published: November 2004

AbstractThe basal ganglia are a group of subcortical nuclei classically thought to be involved in the control of movement, and they have reciprocal connections with the cortex, thalamus and structures in the brainstem. Recent findings suggest that the basal ganglia interact with structures involved in the control of the sleep–waking cycle. The pedunculopontine tegmental nucleus (PPN) maintains a close relationship with the basal ganglia and is intimately involved in the regulation of wakefulness and REM sleep. This study evaluated changes in activity of PPN neurons following striatal kainic acid‐induced lesions. Rats were injected in the anterodorsal striatum with either kainic acid or vehicle and allowed to recover for 7 or 30 days. The results showed an increase in the number of c‐Fos+ cells in the PPN 30 days but not 7 days after the striatal lesion, when motor hyperactivity was no longer detected. In addition, we found a significant correlation between the ventricular brain ratio, as an indicator of lesion size, and the number of c‐Fos+ cells in the PPN. Furthermore, the spatial distribution of cell types suggested that most c‐Fos+ cells in the PPN were not cholinergic. These results provide new insights into the functional relationship between the basal ganglia and the PPN and suggest that the striatum, through its indirect influence on the PPN, may contribute to the regulation of wakefulness and cortical activation.
Evidence for both reaching and grasping activity in the medial parieto‐occipital cortex of the macaque
Authors: Fattori Patrizia , Breveglieri Rossella , Amoroso Katia , Galletti Claudio 
Published: November 2004

AbstractIn humans, the caudal pole of the superior parietal lobule is involved in the control of both reaching and grasping movements, whereas in monkey it is reported to be involved only in the control of reaching. Using single‐unit recordings from trained macaque monkeys, we investigated whether area V6A, a visuomotor area located in the caudal part of the posterior parietal cortex, is involved in both components of prehension, the hand transport towards the visual target and the grip formation to secure the grasp. In Experiment 1, neural activity was recorded in V6A while two monkeys performed two instructed‐delay reaching tasks (reach‐to‐point and reach‐to‐grasp) under controlled conditions in darkness. Fourty‐five of 93 tested neurons (48%) were modulated during reach‐to‐point and 62% (52/84) during reach‐to‐grasp. In 63% of cells (51/81) neural activity was significantly different between reach‐to‐point and reach‐to‐grasp tasks, suggesting that grip formation could influence neural activity. In Experiment 2, two monkeys performed natural reach‐to‐grasp movements in fully lit environment; V6A neural activity and arm–hand movements were recorded by a digital camcorder and analysed frame‐by‐frame using a digital video technique. Thirty of the 58 tested neurons (52%) were modulated during natural prehension; about 30% of these neurons (8/30) were modulated only during the last phase of prehension, i.e. during finger flexion around the object to be grasped. This is the first direct demonstration that both reaching and grasping modulate neural activity in the caudal part of the posterior parietal cortex of the macaque. Our work suggests a strict functional homology between human and monkey superior parietal lobule.
Suppressor of cytokine signalling‐2 and epidermal growth factor regulate neurite outgrowth of cortical neurons
Authors: Goldshmit Yona , Greenhalgh Christopher J. , Turnley Ann M. 
Published: November 2004

AbstractFactors that regulate neurite outgrowth are important in determining the wiring of the central nervous system. Here we describe that the intracellular regulator of cytokine signalling, suppressor of cytokine signalling‐2 (SOCS2) and epidermal growth factor (EGF), both of which are expressed in the cortical plate during neural development, promote neurite outgrowth of cortical neurons. Cortical neurons derived from transgenic mice that over‐express SOCS2 had an increased rate of neurite outgrowth and an increased length and number of primary neurites compared with wild‐type neurons. EGF produced a similar effect in wild‐type cortical neurons and further enhanced the SOCS2‐induced neurite outgrowth. The mechanism of neurite outgrowth induction by SOCS2 and EGF at least partially overlapped as phosphorylation of the EGF receptor in SOCS2 over‐expressing or EGF‐stimulated neurons was increased on Tyrosine845, the Src binding site and neurite outgrowth in both protocols was blocked by inhibitors of the EGF receptor kinase and Src kinase.
Increased extracellular dopamine concentrations and FosB/ΔFosB expression in striatal brain areas of heterozygous GDNF knockout mice
Authors: Airavaara Mikko , Planken Anu , Gäddnäs Helena , Piepponen Timo Petteri , Saarma Mart , Ahtee Liisa 
Published: November 2004

AbstractGlial cell line‐derived neurotrophic factor (GDNF) has been shown to be involved in the maintenance of striatal dopaminergic neurons. To study whether reduced levels of endogenous GDNF affect the striatal dopaminergic transmission we estimated the basal extracellular levels of dopamine in vivo, the basal expression of FosB‐related proteins in striatal brain areas as well as the effects of acute and repeated cocaine on locomotor activity and dopamine output in mice lacking one GDNF allele (heterozygous GDNF+/– mice). As expected the striatal GDNF protein content was found to be smaller in the GDNF+/– mice than in their wild‐type littermates. Unexpectedly the extracellular dopamine concentration in the GDNF+/– mice in the dorsal striatum (CPu) was 2.0‐fold, and in the nucleus accumbens (NAc) 1.6‐fold the concentration found in the wild‐type littermates. Also FosB/ΔFosB–like immunoreactivity was found to be elevated in the CPu as well as in the core and in the shell of NAc of the GDNF+/– mice as compared with the wild‐type mice. This suggests chronic postsynaptic activation of these brain areas and is in line with elevated extracellular dopamine concentrations. Cocaine's effects acutely and after repeated treatment on locomotor activity were similar in the GDNF+/– and the wild‐type mice. Neither did cocaine's acute effects on dopamine output differ between the mice of the two strains. Our findings demonstrate that reduced levels of endogenous GDNF induce alterations in dorsal striatal and accumbal dopaminergic transmission, and stress the importance of endogenous GDNF in the regulation of the dopaminergic neurons.
Brief exposure to predator odor and resultant anxiety enhances mesocorticolimbic activity and enkephalin expression in CD‐1 mice
Authors: Hebb Andrea L. O. , Zacharko Robert M. , Gauthier Michelle , Trudel France , Laforest Sylvie , Drolet Guy 
Published: November 2004

AbstractThe present study assessed alterations in mesolimbic enkephalin (ENK) mRNA levels after predator [2,5‐dihydro‐2,4,5‐trimethylethiazoline (TMT)] and non‐predator (butyric acid) odor encounter and/or light–dark (LD) testing in CD‐1 mice immediately, 24, 48 and 168 h after the initial odor encounter and/or LD testing. The nucleus accumbens, ventral tegmental area, basolateral (BLA), central (CEA) and medial amygdaloid nuclei, prelimbic and infralimbic cortex were assessed for fos‐related antigen (FRA) and/or ENK mRNA as well as neuronal activation of ENK neurons (FRA/ENK). Mice exposed to TMT displayed enhanced freezing and spent less time in the light of the immediate LD test relative to saline‐ or butyric acid‐treated mice. Among mice exposed to TMT, LD anxiety‐like behavior was associated with increased FRA in the prelimbic cortex and accumbal shell and decreased ENK‐positive neurons in the accumbal core. Mice displaying high TMT‐induced LD anxiety exhibited increased ENK‐positive neurons in the BLA, CEA and medial amygdaloid nuclei relative to mice that displayed low anxiety‐like behavior in the LD test after TMT exposure. In the BLA and CEA, ‘high‐anxiety’ mice also displayed increased FRA/ENK after TMT exposure and LD testing. In contrast to neural cell counts, the level of ENK transcript was decreased in the BLA and CEA of ‘high‐anxiety’ mice after TMT exposure and LD testing. These data suggest that increased FRA may regulate stressor‐responsive genes and mediate long‐term behavioral changes. Indeed, increased ENK availability in mesolimbic sites may promote behavioral responses that detract from the aversiveness of the stressor experience.
Nitric oxide synthase inhibition prevents neuronal death in the developing visual cortex
Authors: Zhang Yueting , Zhang Jie , Zhao Baolu 
Published: November 2004

AbstractDuring postnatal development of the visual cortex of golden hamster, there is a transient increase in both the expression and the activity of nitric oxide synthase (NOS), which coincides temporally with the formation of ipsilateral retino‐collicular and retino‐geniculate projections and the functional differentiation of primary visual cortex, suggesting the involvement of NO in the maturation of the visual cortex. In the present study, an inhibitor of NOS, N‐nitro‐l‐arginine (L‐NNA) was used to block the NOS activity of newborn golden hamster, and effects on development were examined. L‐NNA treatment caused an increase in mortality, and suppression of both body weight gain and nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐d) activity in the early phase of treatment (before postnatal day 14, PD14). The growth of NADPH‐d‐positive neurons in the visual cortex was also suppressed by the treatment. In control animals, significant numbers of apoptotic neurons were detected by terminal deoxynucleotidyl transferase‐mediated dUTP nick end labelling assay on PD14, and this apoptosis mainly affected cells in cortical layers II and III. NOS inhibition largely rescued neurons from undergoing apoptosis, indicating that NO may serve as a signal triggering apoptosis and play a role in the maturation of the visual cortex.
Evidence that exogenous and endogenous fractalkine can induce spinal nociceptive facilitation in rats
Authors: Milligan E. D. , Zapata V. , Chacur M. , Schoeniger D. , Biedenkapp J. , O'Connor K. A. , Verge G. M. , Chapman G. , Green P. , Foster A. C. , Naeve G. S. , Maier S. F. , Watkins L. R. 
Published: November 2004

AbstractRecent evidence suggests that spinal cord glia can contribute to enhanced nociceptive responses. However, the signals that cause glial activation are unknown. Fractalkine (CX3C ligand‐1; CX3CL1) is a unique chemokine expressed on the extracellular surface of spinal neurons and spinal sensory afferents. In the dorsal spinal cord, fractalkine receptors are primarily expressed by microglia. As fractalkine can be released from neurons upon strong activation, it has previously been suggested to be a neuron‐to‐glial signal that induces glial activation. The present series of experiments provide an initial investigation of the spinal pain modulatory effects of fractalkine. Intrathecal fractalkine produced dose‐dependent mechanical allodynia and thermal hyperalgesia. In addition, a single injection of fractalkine receptor antagonist (neutralizing antibody against rat CX3C receptor‐1; CX3CR1) delayed the development of mechanical allodynia and/or thermal hyperalgesia in two neuropathic pain models: chronic constriction injury (CCI) and sciatic inflammatory neuropathy. Intriguingly, anti‐CX3CR1 reduced nociceptive responses when administered 5–7 days after CCI, suggesting that prolonged release of fractalkine may contribute to the maintenance of neuropathic pain. Taken together, these initial investigations of spinal fractalkine effects suggest that exogenous and endogenous fractalkine are involved in spinal sensitization, including that induced by peripheral neuropathy.
Identification of three new alternatively spliced variants of the rat mu opioid receptor gene: dissociation of affinity and efficacy
Authors: Pasternak David A. , Pan Ling , Xu Jin , Yu Rui , Xu Ming‐Ming , Pasternak Gavril W. , Pan Ying‐Xian 
Published: November 2004

AbstractMu opioid receptors mediate the pharmacological actions of morphine and morphine‐like drugs, such as heroin. The mouse and human Oprm genes undergo splicing. In these present studies, we have identified and characterized three new MOR‐1 splice variants from the rat Oprm gene. Using an RT‐PCR approach, we isolated the new exons 7, 8 and 9 downstream of exon 3. The rat exons 7 and 9 were homologous to the mouse exons 7 and 9 while the rat exon 8 was not. Northern blot analysis with the new exon probes showed distinctive and abundant transcripts of the variants in the rat brain. Full‐length cDNA clones containing the new exons, rMOR‐1C1, rMOR‐1C2 and rMOR‐1D were obtained using an RT‐PCR approach. Each contained the same exons 1, 2 and 3 as the original rMOR‐1, followed by different combinations of the new exons in place of exon 4. In addition, we also isolated another new variant, rMOR‐1A, which contains only exons 1, 2 and 3, and is homologous to the human variant MOR‐1A previously identified. All the variants were highly mu‐selective in binding studies with little difference in affinities for the mu ligands among the variants. However, functional evaluation of assessments of the variants using agonist stimulated [35S]GTPγS binding assays revealed marked differences among the variants, both in terms of potency and efficacy of the drugs. The relative efficacy of a series of mu opioids to each other varied depending upon the variant studied. Efficacy in the [35S]GTPγS assay did not correlate with either receptor binding affinity or with potency. Thus, selectivity of opioid action might be achieved by designing compounds with varying efficacies at different MOR‐1 variants.
Variants of TRP ion channel mRNA present in horseshoe crab ventral eye and brain
Authors: Bandyopadhyay Bidhan C. , Payne Richard 
Published: November 2004

AbstractTransient receptor potential (TRP) channels mediate light‐induced Ca2+ entry and the electrical response in Drosophila photoreceptors. The role of TRP channels in other invertebrate photoreceptors is unknown, particularly those, exemplified by Limulus ventral eye photoreceptors, in which calcium release from intracellular stores is prominent. We have amplified cDNA encoding three variants of a Limulus TRP channel. LptrpA and LptrpBencode proteins of 896 and 923 amino acids, differing by a 27 amino acid insert within the C‐terminus. LptrpC encodes an alternative 63 amino acid sequence in the pore domain compared with LptrpB. LptrpB and LptrpC are present in ventral eye mRNA, while LptrpA is only present in brain mRNA. In situ hybridization indicates the presence of Lptrp in photoreceptors of the Limulus ventral eye. Some canonical TRP channels can be activated by diacylglycerol analogs. Injection of a diacylglycerol analog, 1‐oleoyl‐2‐acetyl‐sn‐glycerol (OAG), into Limulus photoreceptors can activate an inward current with electrical characteristics similar to the light‐activated current. However, simultaneous elevation of cytosolic calcium concentration appears to be necessary. Illumination attenuates the response to OAG injections and vice versa. These results provide molecular and pharmacological evidence for a TRP channel in Limulus ventral eye that may contribute to the light‐sensitive conductance.
Some Males are Choosier Than Others: Species Recognition in Blue Waxbills
Authors: Brooks  , Luddem  , Collins  , Winter  
Published: November 2004

AbstractWe investigated whether species specific mating preferences differed between the sexes in three species of blue waxbill (genus Uraeginthus). We compared male preference for conspecific females versus heterospecific blue waxbill females using two-way choice trials. The results were compared with predictions of the strength of species specific mating preferences made on the basis of several different hypotheses. These predictions were made according to the specific behavioural and morphological traits of the three species, their phylogenetic relatedness and relative geographical location. Males did not prefer conspecific females whenever they were given a choice of a larger heterospecific female. Furthermore, males tended to discriminate between females more strongly when there was a large difference in size between the two species of females that they had been presented with. Relating the strength of males preference for conspecific females to the predictions made according to the different hypotheses it appeared that males were discriminating between females on the basis of their size. We compared male mate preferences for conspecifics versus heterospecifics with female mate preferences for conspecifics versus heterospecifics that had been ascertained in a previous study. There were marked differences between preference for conspecifics between the sexes for all three species, suggesting that males and females used different criteria to choose mates when discriminating between related species. Males appeared to use female size whereas females appeared to use the degree of male ornamentation, suggesting that mate preference is under a different selective pressure between the sexes. The results of this study have identified that there is a potential for hybridisation between blue breast females and both red cheek and blue cap males. In the event of a geographical change leading to sympatry between these species the degree of hybridisation will depend on the preference criteria within each species and the differences in morphology between those species. This will ultimately determine how discrimination between heterospecifics will interact with conspecific mate choice.
Phoresy of Rhabditophanes schneideri (Bütschli) (Rhabditida: Alloionematidae) on pseudoscorpions (Arachnida: Pseudoscorpiones)
Authors: Ćurčić Srećko , Sudhaus Walter , Dimitrijević Rajko , Tomić Vladimir , Ćurčić Božidar 
Published: November 2004

Abstract
A total of 227 phoretic J3 dauer juveniles of the nematode Rhabditophanes
schneideri (Bütschli) were observed attached to 63 out of 4845 specimens of
three species of pseudoscorpion from Belgrade, Serbia and Montenegro.
Analysis of the numbers of phoretic dauer larvae on different body regions
revealed that the majority were attached to different pedipalpal and pedal
segments. Only a few nematodes were carried on the prosoma and opisthosoma
and none were observed on the chelicerae.