bluuebunny/crossref_metadata_2025_split huggingface dataset:
Altered cortical visual processing in individuals with a spreading photoparoxysmal EEG response
Authors: Siniatchkin Michael , Moeller Friederike , Shepherd Alex , Siebner Hartwig , Stephani Ulrich 
Published: July 2007

AbstractPhotosensitive individuals respond with epileptiform electroencephalography (EEG) discharges to intermittent photic stimulation. The pathogenetic mechanisms underlying this photoparoxysmal response (PPR) remain to be clarified. We investigated the involvement of magnocellular and parvocellular pathways in the processing of nonprovocative visual stimuli in healthy subjects with different phenotypic expressions of PPR (15 individuals with a local PPR, i.e. occipital discharges only, and 15 with a PPR propagating to anterior brain regions) and in 17 PPR‐negative healthy controls using pattern‐reversal visual evoked potentials (VEP). Checkerboard stimulation was performed at a low and a high spatial frequency to preferentially activate the magnocellular and parvocellular pathways. VEP habituation was also assessed over 15 blocks (each 100 trials) of recording. PPR‐positive individuals with propagating PPR showed an increase in the N75–P100 and P100–N135 VEP components for both spatial frequencies, whereas individuals with a local PPR had normal VEP amplitudes. Individuals with propagating PPR also showed a stronger VEP habituation and reported more aversive sensations during continuous visual stimulation with the high spatial frequency checkerboard. The selective increase in VEP amplitudes in individuals with propagating PPR corroborates the notion that PPR with propagation is pathophysiologically distinct from local PPR. The increase in VEP amplitudes was independent of the spatial frequency of visual stimulation, indicating an increased neuronal excitability in both the parvocellular and magnocellular pathways. The stronger habituation in these individuals may reflect a compensatory mechanism to stabilize excitability in the visual system.
Immunolabelling of the 5‐HT3B receptor subunit in the central and peripheral nervous systems in rodents
Authors: Doucet Edith , Latrémolière Alban , Darmon Michèle , Hamon Michel , Emerit Michel B. 
Published: July 2007

AbstractThe 5‐HT3 receptor is a member of the superfamily of neurotransmitter‐gated ion channels involved in fast synaptic signalling and in modulation of neurotransmitter release. As for many other channel receptors, the electrophysiological properties and the functions of the 5‐HT3 receptor are determined by subunit composition of the pentameric channel. Because in situ hybridization did not allow the detection of mRNA encoding the 5‐HT3B subunit in the rodent central nervous system, or in nearly half of the neurons expressing the 5‐HT3A subunit in peripheral ganglia, it has been suggested that subunit composition could define at least two 5‐HT3 receptor‐expressing neuronal populations. In order to challenge this hypothesis, we have developed polyclonal antibodies directed against a portion of the second intracytoplasmic loop of the mouse 5‐HT3B subunit. Immunohistochemical analysis in the mouse and the rat revealed that immunolabelling was most prominent in peripheral ganglia, particularly in trigeminal ganglia (TG). In rats, transection or ligature of the infraorbital nerve resulted in a pronounced accumulation of immunoreactive material at the proximal side of the lesioned nerve, and an up‐regulation of both subunits in 5‐HT3 receptor‐expressing TG neurons. Surprisingly, nearly 100% of neurons expressing 5‐HT3A subunits were also labelled by anti‐5‐HT3B antibodies. We also detected 5‐HT3B immunoreactivity in the rat hippocampal CA1 layer and in scattered cortical neurons, indicating that detection of 5‐HT3 subunit mRNA by in situ hybridization might not provide really complete mapping of heteromeric 5‐HT3A/B vs. homomeric 5‐HT3A receptors in the peripheral and central nervous systems in rodents.
Protein kinase C modulates the phase‐delaying effects of light in the mammalian circadian clock
Authors: Lee Boyoung , Almad Akshata , Butcher Greg Q. , Obrietan Karl 
Published: July 2007

AbstractThe mammalian circadian pacemaker located in the suprachiasmatic nuclei (SCN) drives a vast array of biochemical and physiological processes with 24‐h periodicity. The phasing of SCN pacemaker activity is tightly regulated by photic input from the retina. Recent work has implicated protein kinase C (PKC) as a regulator of photic input, although stimulus‐induced PKC activity has not been examined. Here we used a combination of biochemical, immunohistochemical and behavioral techniques to examine both the regulation and role of PKC in light‐induced clock entrainment in mice. We report that photic stimulation during the subjective night, but not during the subjective day, stimulates PKC activity within the SCN. To assess the role of PKC in clock entrainment, we employed an in‐vivo infusion approach to deliver the PKC inhibitor bisindolylmaleimide I to the SCN. The disruption of PKC activity significantly enhanced the phase‐shifting effects of light, indicating that PKC functions as a negative regulator of light entrainment. Importantly, bisindolylmaleimide I infusion in the absence of light treatment did not phase shift the clock, demonstrating that transient disruption of basal PKC activity does not affect inherent pacemaker activity. The capacity of light to stimulate immediate early gene expression in the SCN was not substantively altered by PKC inhibition, suggesting that PKC does not couple light to rapid transcriptional activation. Rather, a combination of in‐vivo and cell culture assays indicates that PKC functions as an inhibitor of PERIOD1 degradation. Thus, PKC may influence clock entrainment via a post‐translational mechanism that influences clock protein stability.
Cellular correlates of spontaneous periodic events in the medial entorhinal cortex of the in vitro isolated guinea pig brain
Authors: Gnatkovsky Vadym , Wendling Fabrice , De Curtis Marco 
Published: July 2007

AbstractPeriodic potentials characterized by fast oscillations superimposed on a slow complex event are typically observed in cortical structures during sleep and anaesthesia. In the entorhinal cortex (EC) similar spontaneus periodic events (SPEs) have been described both in vivo and in vitro. Simultaneous extracellular and intracelluar recordings from superficial neurons of the entorhinal cortex of the isolated Hartley guinea pig brain preparation demonstrated that SPEs recur with a periodicity of 2–10 s and correlate to neuronal firing superimposed on a depolarizing plateau that lasts 0.7–1 s. During SPEs, putative interneurons in all layers discharged high frequency firing (> 100 Hz), whereas no activity was observed in principal neurons of deep entorhinal cortex layers. Linear correlation analysis demonstrated a tight relationship between the fast component of the extracellular SPE and subthreshold oscillatory activity/neuronal firing in both superficial neurons and putative interneurons; firing of deep principal cells was independent from SPEs occurrence. The present study demonstrates that recurrent spontaneous events analogous to periodic activity observed during sleep/anaesthesia are generated in the entorhinal cortex by the interactions between superficial neurons and interneurons.
Object‐based attention is multisensory: co‐activation of an object's representations in ignored sensory modalities
Authors: Molholm Sophie , Martinez Antigona , Shpaner Marina , Foxe John J. 
Published: July 2007

AbstractWithin the visual modality, it has been shown that attention to a single visual feature of an object such as speed of motion, results in an automatic transfer of attention to other task‐irrelevant features (e.g. colour). An extension of this logic might lead one to predict that such mechanisms also operate across sensory systems. But, connectivity patterns between feature modules across sensory systems are thought to be sparser to those within a given sensory system, where interareal connectivity is extensive. It is not clear that transfer of attention between sensory systems will operate as it does within a sensory system. Using high‐density electrical mapping of the event‐related potential (ERP) in humans, we tested whether attending to objects in one sensory modality resulted in the preferential processing of that object's features within another task‐irrelevant sensory modality. Clear evidence for cross‐sensory attention effects was seen, such that for multisensory stimuli responses to ignored task‐irrelevant information in the auditory and visual domains were selectively enhanced when they were features of the explicitly attended object presented in the attended sensory modality. We conclude that attending to an object within one sensory modality results in coactivation of that object's representations in ignored sensory modalities. The data further suggest that transfer of attention from visual‐to‐auditory features operates in a fundamentally different manner than transfer from auditory‐to‐visual features, and indicate that visual‐object representations have a greater influence on their auditory counterparts than vice‐versa. These data are discussed in terms of ‘priming’ vs. ‘spreading’ accounts of attentional transfer.
Genetic evidence for the requirement of adenylyl cyclase 1 in synaptic scaling of forebrain cortical neurons
Authors: Gong Bo , Wang Hansen , Gu Steven , Heximer Scott P. , Zhuo Min 
Published: July 2007

AbstractHomeostatic plasticity is important to stabilize the activity level of neuronal circuits. Molecular mechanisms underlying neuronal homeostatic plasticity in response to activity deprivation are not completely understood. We found that prolonged alpha‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptor blockade by 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX) resulted in larger, faster miniature excitatory postsynaptic current (mEPSC) events with enhanced frequency in cultured forebrain cortical neurons. Furthermore, GluR1 protein level and CREB‐dependent transcription were up‐regulated. Blockade of L‐type Ca2+ channels but not kainate receptors produced similar effects to the AMPA receptor blockade. Genetic deletion of AC1 (adenylyl cyclase 1), but not AC8, a key neuronal adenylyl cyclase, significantly reduced inactivity‐induced GluR1 changes. Our results indicate the synthesis of homomeric GluR1 AMPA receptors and their possible insertion into synapses due to synaptic inactivity in the cortex. AC1 plays a subtype selective role in this process by coupling signals from L‐type Ca2+ channels to downstream signalling pathways.
Spike train signatures of retinal ganglion cell types
Authors: Zeck Günther M. , Masland Richard H. 
Published: July 2007

AbstractThe mammalian retina deconstructs the visual world using parallel neural channels, embodied in the morphological and physiological types of ganglion cells. We sought distinguishing features of each cell type in the temporal pattern of their spikes. As a first step, conventional physiological properties were used to cluster cells in eight types by a statistical analysis. We then adapted a method of P. Reinagelet al.(1999:J. Neurophysiol.,81, 2558–2569) to define epochs within the spike train of each cell. The spike trains of many cells were found to contain robust patterns that are defined by the (averaged) timing of successive interspike intervals in brief activity epochs. The patterns were robust across four different types of visual stimulus. Although the patterns are conserved in different visual environments, they do not prevent the cell from signaling the strength of its response to a particular stimulus, which is expressed in the number of spikes contained in each coding epoch. Clustering based on the spike train patterns alone showed that the spike train patterns correspond, in most but not all cases, to cell types pre‐defined by traditional criteria. That the congruence is less than perfect suggests that the typing of rabbit ganglion cells may need further refinement. Analysis of the spike train patterns may be useful in this regard and for distinguishing the many unidentified ganglion cell types that exist in other mammalian retinas.
Interactions of the basolateral amygdala with the dorsal hippocampus and dorsomedial prefrontal cortex regulate drug context‐induced reinstatement of cocaine‐seeking in rats
Authors: Fuchs Rita A. , Eaddy Jessica L. , Su Zu‐In , Bell Guinevere H. 
Published: July 2007

AbstractThe basolateral amygdala (BLA), dorsomedial prefrontal cortex (dmPFC) and dorsal hippocampus (DH) are critical elements of the neurocircuitry of drug context‐induced reinstatement of cocaine‐seeking; however, little is known about functional interactions between these brain regions. The present study tested the hypothesis that serial information processing by the BLA and dmPFC mediates drug context‐induced cocaine‐seeking, whereas the BLA and DH independently control this behaviour. Rats were trained to self‐administer cocaine in a distinct environment (cocaine‐paired context) followed by extinction training in a different environment (extinction context). On the test days, rats received unilateral microinfusions of baclofen + muscimol or of vehicle into the BLA and either the contralateral or ipsilateral dmPFC or DH. Cocaine‐seeking behaviour (i.e. nonreinforced presses on the cocaine‐associated lever) was then assessed in the cocaine‐paired and extinction contexts. Following vehicle pretreatment, exposure to the cocaine‐paired context reinstated extinguished cocaine‐seeking behaviour. BLA–dmPFC asymmetrical inactivation attenuated cocaine‐seeking behaviour relative to vehicle treatment; however, this impairment equaled that produced by ipsilateral BLA–dmPFC inactivation. Furthermore, unilateral inactivation of the BLA or dmPFC did not alter this behaviour. BLA–DH asymmetrical inactivation selectively attenuated cocaine‐seeking behaviour relative to vehicle treatment whereas ipsilateral or unilateral inactivation of the BLA and DH did not alter this behaviour. These findings indicate that the BLA and DH exhibit sequential information processing within the relapse circuitry. In contrast, interactions between the BLA and dmPFC are more complex and include parallel loops of information processing and/or necessary interhemispheric input from the dmPFC to the BLA, probably in addition to direct intrahemispheric interactions.
Deafness alters auditory nerve fibre responses to cochlear implant stimulation
Authors: Sly David J. , Heffer Leon F. , White Mark W. , Shepherd Robert K. , Birch Michael G. J. , Minter Ricki L. , Nelson Niles E. , Wise Andrew K. , O'Leary Stephen J. 
Published: July 2007

AbstractHere we characterized the relationship between duration of sensorineural hearing loss and the response of the auditory nerve to electrical stimulus rate. Electrophysiological recordings were made from undeafened guinea pigs and those ototoxically deafened for either 5 weeks or 6 months. Auditory neuron survival decreased significantly with the duration of deafness. Extracellular recordings were made from auditory nerve fibres responding to biphasic, charge‐balanced current pulses delivered at rates of 20 and 200 pulses/s via a monopolar scala tympani stimulating electrode. The response to 20 pulses/s electrical stimulation of the deafened cochlea exhibited a decrease in spike latency, unaltered temporal jitter and unaltered dynamic range (of nerve firing rate against stimulus current), and a reduction in threshold after 6 months of deafness. The response to a 200‐pulse/s stimulus was similar except that the dynamic range was greater than with 20 pulses/s and was also greater in deafened animals than in undeafened animals. Deafness and pulse rate are related; in deaf animals spike recovery appears to be complete between successive stimulus pulses at a low rate (20 pulses/s), but incomplete between pulses at a moderate pulse rate (200 pulses/s). These results suggest that changes in the function of individual auditory nerve fibres after deafness may affect clinical responses during high‐rate stimulation such as that used in contemporary speech processing strategies, but not during lower rate stimulation such as that used to record evoked potentials.
Influence of host density and population structure on egg production in the coccidophagous ladybird, Chilocorus nigritus F. (Coleoptera: Coccinellidae)
Authors: Ponsonby D. J. , Copland M. J. W. 
Published: July 2007

Abstract1 Studies on aphidophagous coccinellids have indicated that patch quality, and, in particular, the age structure of the prey or the phenological age of the plant, may play an important role in stimulating oviposition behaviour. However, little is known about the egg‐laying tactics of coccidophagous species.2 When restricted to a single, large colony of overlapping generations of their diaspid host Abgrallaspis cyanophylli (Signoret), adult females of the coccidophagous ladybird Chilocorus nigritus F. varied their egg production rate in a cyclic pattern that lasted for approximately 22 days. This information was used to generate hypotheses relating to eliciting cues for oviposition.3 Two experiments were carried out in the absence of conspecific larvae to assess: (i) whether changes in host density at levels above those needed to sustain egg production in the females affected egg output and (ii) the effect of restricting beetles to various homogeneous prey population structures on daily egg production.4 Changes in host density caused a significant but transient decline in egg production whereas a heterogeneous prey population elicited significantly higher levels of oviposition than homogeneous ones with similar host densities, irrespective of the growth stage of the prey.5 Beetles were fed to satiation throughout the experiments but the data obtained suggest that cues for eliciting oviposition operated in a density‐dependent fashion. The results of the study are used to discuss the possibility that visual and chemical cues are quantitatively used by ovipositing beetles to assess patch suitability.
Surface morphology of eggs of Euproctis chrysorrhoea (Linnaeus, 1758)
Authors: Candan Selami , Suludere Zekiye , Bayrakdar Fatma 
Published: July 2007

AbstractCandan, S., Suludere, Z. and Bayrakdar, F. 2007. Surface morphology of eggs of Euproctis chrysorrhoea (Linnaeus, 1758). —Acta Zoologica (Stockholm) 88: 000–000.Filaments covering the egg batches and chorion structure were studied both by light and scanning electron microscopy in the brown‐tailed moth Euproctis chrysorrhoea (Linnaeus, 1758). Females lay eggs in masses on the underside of apple leaves. The egg batches are covered with brown hairs derived from the bodies of the female. Each female lays about 200–400 eggs. The spherical eggs are about 0.84 mm long and 0.47 mm wide. Newly deposited eggs are golden‐yellow and darken after the onset of embryonic development. The micropylar area appears somewhat depressed and has a circular outline. The region is surrounded by a rosette of 10–12 petal‐shaped primary cells, which are completely surrounded by a series of secondary and tertiary cells. The remainder of the egg is largely smooth, but shows aeropyles. These are located in the corners of ill‐defined polygons.
Uncommon mechanism of egg incubation in the endemic Southern hermit crab Loxopagurus loxochelis: how is this phenomenon related to egg production?
Authors: Torati Lucas S. , Mantelatto Fernando L. 
Published: July 2007

AbstractThe aim of the present work was to characterize the egg production of Loxopagurus loxochelis. A total of 71 ovigerous females were obtained, 28% of which were simultaneously incubating eggs at different developmental stages. This phenomenon can be the result of incomplete fertilization, or may represent a rapid gonadal cycle by this species in this area, which is, to our understanding, the best explanation of this phenomenon. Egg volume decreased 25.6% during the incubation period. The reproductive output based on dry and wet weight was 6.8 and 19.3%, respectively. Water was the prevailing component of the eggs, representing 86.0% of the total weight at initial stage, increasing to 95.1% at the final stage. Ash content increased at the same time as a decrease in the organic content occurred, indicating the consumption of yolk and absorption of salts from the water medium. In conclusion, we hypothesized that this population has the capacity to copulate and deposit another brood even before the release of the larvae from the previous one, intensifying the reproductive effort of these hermit crabs as a strategy of adaptation in a region considered the northern limit of the geographical distribution of this species.
Gene transfer of the KATP channel restores age‐related erectile dysfunction in rats
Authors: So Insuk , Chae Mee Ree , Lee Sung Won 
Published: July 2007

OBJECTIVETo determine if gene transfer of the ATP‐sensitive potassium (KATP) channel can reverse age‐related erectile dysfunction in the rat, as the KATP channel is an important subtype of potassium channels regulating smooth muscle tone.MATERIALS AND METHODSIn an in vitro study, gene were transferred using cDNA of the KATP channel in cultured human corporal smooth muscle (CSM) cells and human embryonic kidney (HEK) cells. After gene transfer, the activities of transferred channels were assessed by the patch‐clamp technique. In an in vivo study, 15 old rats were used for groups of gene therapy and nine young adult rats were used as normal controls. The old rats were divided into three groups, i.e. controls and two gene‐transfer groups (Kir6.1 + SUR2B and Kir6.2 + SUR2B). The intracavernosal pressure (ICP) response to cavernosal nerve stimulation was assessed after intracorporal injection with naked cDNA of the KATP channel. The transgene expression of the KATP channel was examined by reverse transcription‐polymerase chain reaction (RT‐PCR) in rats transfected with cDNA of Kir 6.1 and 6.2.RESULTSThe transferred gene of the KATP channel was functionally active and appropriate for gene transfer. The mean (sem) ratio of ICP to systemic blood pressure in the gene‐transfer groups, at 79.4 (1)% and 76.5 (2.6)% (both eight rats) was significantly higher than that in age‐matched control rats, at 59.4 (3.3)% (eight), and similar to that in the young control rats, at 77.1 (2.7)% (nine). The RT‐PCR showed expression of Kir6.1 and 6.2 genes in the transfected groups.CONCLUSION In vivo gene transfer of the KATP channel can physiologically restore erectile function in aged rats, and might be applicable to the development of new forms of therapy for treating human erectile dysfunction.