bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hunger Modulates the Responses to Gustatory Stimuli of Single Neurons in the Caudolateral Orbitofrontal Cortex of the Macaque Monkey
Authors: Rolls Edmund T. , Sienkiewicz Zenon J. , Yaxley Simon 
Published: April 2006

AbstractIn order to determine whether the responsiveness of neurons in the caudolateral orbitofrontal cortex (a secondary cortical gustatory area) is influenced by hunger, the activity evoked by prototypical taste stimuli (glucose, NaCl, HCl, and quinine hydrochloride) and fruit juice was recorded in single neurons in this cortical area before, while, and after cynomolgous macaque monkeys were fed to satiety with glucose or fruit juice.It was found that the responses of the neurons to the taste of the glucose decreased to zero while the monkey ate it to satiety during the course of which his behaviour turned from avid acceptance to active rejection.This modulation of responsiveness of the gustatory responses of the neurons to satiety was not due to peripheral adaptation in the gustatory system or to altered efficacy of gustatory stimulation after satiety was reached, because modulation of neuronal responsiveness by satiety was not seen at earlier stages of the gustatory system, including the nucleus of the solitary tract, the frontal opercular taste cortex, and the insular taste cortex.The decreases in the responsiveness of the neurons were relatively specific to the food with which the monkey had been fed to satiety. For example, in seven experiments in which the monkey was fed glucose solution, neuronal responsiveness decreased to the taste of the glucose but not to the taste of blackcurrant juice. Conversely, in two experiments in which the monkey was fed to satiety with fruit juice, the responses of the neurons decreased to fruit juice but not to glucose.These and earlier findings lead to a proposed neurophysiological mechanism for sensory‐specific satiety in which the information coded by single neurons in the gustatory system becomes more specific through the processing stages consisting of the nucleus of the solitary tract, the taste thalamus, and the frontal opercular and insular taste primary taste cortices, until neuronal responses become relatively specific for the food tasted in the caudolateral orbitofrontal cortex (secondary) taste area. Then sensory‐specific satiety occurs because in this caudolateral orbitofrontal cortex taste area (but not earlier in the taste system) it is a property of the synapses that repeated stimulation results in a decreased neuronal response.Evidence was obtained that gustatory processing involved in thirst also becomes interfaced to motivation in the caudolateral orbitofrontal cortex taste projection area, in that neuronal responses here to water were decreased to zero while water was drunk until satiety was produced.
Demonstration of a Mamillo‐Ponto‐Cerebellar Pathway
Authors: Aas Jan‐Erik , Brodal Per 
Published: April 2006

AbstractThe pathway from the mamillary complex to the cerebellum via the pontine nuclei has been studied using several anterograde and retrograde tracing techniques in the cat. We have also compared the pontine terminal regions of fibres from the mamillary complex and from the cingulate gyrus.Implantations of crystalline horseradish peroxidase wheat germ agglutinin (HRP‐WGA) in the mamillary complex and lesions of the cingulate gyrus were combined in the same animal with injections of HRP‐WGA, rhodamine‐B‐isothiocyanate (RITC), and Fluoro‐Gold in different parts of the cerebellar hemisphere.Fibres from both the mamillary complex and the cingulate gyrus terminate mainly within a transversely oriented, c‐shaped band in the ipsilateral, rostral pontine nuclei. Within this band the terminal fields of fibres from the mamillary complex and the cingulate gyrus form a mosaic‐like pattern of partly overlapping patches. Pontine regions receiving a mamillary input project mainly to the ventral paraflocculus, and to a lesser degree to the dorsal paraflocculus, but apparently not to the uvula or crus II. Judging from the literature it seems highly unlikely that other parts of the cerebellar hemispheres receive projections from these pontine regions. Fibres from the ventral paraflocculus were shown to terminate in the parvicellular part of the lateral cerebellar nucleus only.The present findings would seem to imply that inputs from the mamillary complex and a related cortical region, the cingulate gyrus, are partly integrated, partly kept separate at the precerebellar level. This would ensure that small groups of cells in the rostral pontine nuclei receive a specific set of afferents. Conceivably, the information transmitted to the cerebellum by these groups of pontine cells might be related to functions of the mamillary complex, such as learning, motivation, and spatial memory.
Noradrenaline‐ and Enkephalin‐Induced Inhibition of Voltage‐Sensitive Calcium Currents in NG108‐15 Hybrid Cells
Authors: McFadzean I. , Docherty R. J. 
Published: April 2006

AbstractVoltage‐sensitive calcium currents were recorded from chemically differentiated neuroblastoma × glioma hybrid (NG108‐15) cells using the whole‐cell clamp technique. Both noradrenaline and [D‐Ala2, D‐Leu5] enkephalin (DADLE) reversibly depressed the amplitude of the calcium current by up to 30%. The response to noradrenaline occluded that to DADLE suggesting that both agonists depress the same fraction of current. The response to DADLE but not that to noradrenaline desensitized rapidly. Cells responded normally to noradrenaline when desensitized to the opioid. Responses to either agonist were absent in cells pre‐incubated with pertussis toxin. In addition the response to noradrenaline became irreversible in cells dialysed internally with a non‐hydrolysable analogue of GTP. The response to noradrenaline was not affected by treatment of the cells with either membrane‐permeable analogues of cAMP or a combination of forskolin and isobutylmethylxanthine. It is concluded that both noradrenaline and DADLE depress the same fraction of voltage‐dependent calcium current in NG108‐15 cells; that the responses are mediated by a pertussis‐sensitive GTP‐binding protein but are not secondary to a reduction in the intracellular concentration of cAMP; and that desensitization of the opioid response occurs at a site linked intimately to the opioid receptor rather than at a common site in the transduction pathway between receptor activation and reduction in the calcium channel current.
Oxytocin Neurotransmission in the A1‐area of the Brainstem Induces Hormonal Vasopressin Release in Rats
Authors: Hermes Michael L. H. J. , Buijs Ruud M. , van Heerikhuize Joop J. , van den Born Jaap , van der Woude Tjitske P. 
Published: April 2006

AbstractTo investigate the role of the oxytocin innervation of the caudal ventrolateral medulla, immunocytochemical techniques were used to demonstrate the presence of oxytocin fibres and terminals in close apposition to noradrenergic neurons of the A1‐area.Subsequently, in freely moving animals fitted with an indwelling jugular venous catheter and a bilaterally implanted chronic cannula in the A1‐area, it was examined whether infusions of oxytocin in this area were able to influence hormonal vasopressin release. It appeared that nanomolar (50–500 nM) concentrations of oxytocin induce a fourfold rise in plasma vasopressin values. The specificity of this effect was established with control infusions of Ringer, vasopressin, and the addition of an antagonist to oxytocin. It was not possible to demonstrate a major role for oxytocin in the A1‐area in the release of hormonal vasopressin occurring during haemorrhage.These data permit us to conclude that oxytocin acts on presumably noradrenergic neurons of the A1‐area leading to the release of vasopressin into the peripheral circulation. The circumstances under which oxytocin is released in this area remain to be established.
Hippocampal Noradrenaline and Serotonin Release over 24 Hours as Measured by the Dialysis Technique in Freely Moving Rats: Correlation to Behavioural Activity State, Effect of Handling and Tail‐Pinch
Authors: Kalén Peter , Rosegren Evald , Lindvall Olle , Björklund Anders 
Published: April 2006

AbstractHippocampal extracellular levels of noradrenaline (NA), 5‐hydroxytryptamine (5‐HT), and 5‐hydroxyindole‐acetic acid (5‐HIAA) were monitored with the microdialysis technique in freely moving rats. In one experiment 30 min samples were collected during 24 h of continuous perfusion, and the monoamine output was compared to the behavioural activity state, as arbitrarily classified in three categories: sleep/rest, drowsiness and full alertness associated with complex behaviours. In the individual animal the hippocampal NA and 5‐HT output showed pronounced fluctuations during the 24 h period, but the 30 min sampling times did not allow for a clear‐cut correlation to behavioural activity state. However, the mean NA and 5‐HT output for all animals during the dark period of the day was 43 and 38% higher, respectively, than during the light period, and the average NA and 5‐HT levels in samples collected during periods of high behavioural activity was 34 and 45% higher, respectively, than during periods of rest or sleep. In contrast, there were no detectable changes in extracellular 5‐HIAA. The selective serotonin uptake blocker indalpine, added to the perfusion fluid at 1 μM, increased the extracellular 5‐HT levels 6‐fold, with a similar correlation to behavioural activity state as without indalpine.In a second experiment the effect of handling and tail‐pinch was studied in 15 min sample fractions. Gentle handling of the animals during the sampling period increased the hippocampal NA and 5‐HT output by 32 and 72%, respectively, and a similar increase (63 and 48%) was obtained by application of tail‐pinch. Maximum NA output was reached during the handling or tail‐pinch period, whereas maximal 5‐HT levels were detected in the subsequent 15 min sample fraction. No changes in extracellular 5‐HIAA was observed.It is concluded (1) that intracerebral microdialysis provides a useful method for the study of extracellular NA and 5‐HT in the hippocampal formation of conscious rats during active behaviour; (2) that there are substantial fluctuations in hippocampal NA and 5‐HT output in freely moving rats which correlate with the light‐dark cycle as well as with the activity state of the animals; (3) that the spontaneous variations in 5‐HT output are maintained during reuptake blockade; and (4) that behavioural activation through gentle handling or tail‐pinch elicits NA and 5‐HT release. The present data support a role of the forebrain NA and 5‐HT systems in behavioural state control and highlights the necessity of experimental designs in which the spontaneous fluctuations in transmitter release are controlled for in studies of, for example, drug effects on NA and 5‐HT release in conscious animals.
Dependence of Retinogeniculate Transmission on Membrane Voltage in the Cat
Authors: Lo Fu‐Sun , Sherman S. Murray 
Published: April 2006

AbstractThe mammalian lateral geniculate nucleus seems organized to gate or control the gain of retino‐geniculate transmission, the result of which is then relayed to the visual cortex. We have performed in vivo intracellular studies of retinogeniculate transmission along these retino‐geniculo‐cortical pathways in cats by recording the retinally evoked excitatory postsynaptic potential (EPSP) in geniculate neurons. In cats, these pathways are organized into two parallel and functionally distinct channels, the X and Y pathways. We found that nearly all geniculate X cells display a fairly conventional voltage dependency for their retinally evoked EPSPs, because the amplitudes of these EPSPs decrease fairly linearly with membrane depolarization as the EPSP reversal potential is approached. Rare X cells and all Y cells, however, show an unconventional response: over a wide range of membrane potentials, their EPSP amplitudes increase with membrane depolarization. This increase does not result from alterations in neuronal input resistance and instead seems due to changes in synaptic conductance. The underlying cause of this voltage dependency remains to be determined. None the less, it does afford an interesting means by which retinogeniculate transmission can be gated, since non‐retinal inputs (e.g. corticogeniculate axons) that can control a relay Y cell's membrane potential can also modulate the cell's EPSP amplitude.
Differential Calcium Binding Protein Immunoreactivity Distinguishes Classes of Relay Neurons in Monkey Thalamic Nuclei
Authors: Jones E. G. , Hendry S. H. C. 
Published: April 2006

AbstractThe distributions of neurons displaying immunoreactivity for two calcium binding proteins, parvalbumin and 28Kd calbindin, were studied in the thalamus of M. fascicularis. Colocalization experiments were carried out to determine the extent to which parvalbumin‐ and calbindin‐like immunoreactivity was found in the same cells and the extent to which either was localized in GABAergic interneurons. Anterograde and retrograde tracing experiments involving the fluorescent tracer, fast blue, were also used to determine that cells expressing the calcium binding proteins projected upon the cerebral cortex.In the dorsal thalamus, nuclei are distinguished by different patterns of parvalbumin‐like and calbindin‐like immunoreactivity. In certain nuclei, for example the lateral dorsal and anterior pulvinar, neurons express immunoreactivity for only one of the calcium binding proteins. In others, neurons in different layers, for example the dorsal lateral geniculate nucleus, or in different compartments, for example the intralaminar nuclei, express immunoreactivity for either parvalbumin or calbindin; in other nuclei, for example the ventral group, neurons are mixed and immunoreactivity for parvalbumin and calbindin is commonly colocalized. In the ventral thalamus and epithalamus, similar patterns are observed.Colocalization of parvalbumin‐ and GABA‐immunoreactivity is found in all cells of the reticular nucleus but only in certain cells in selected nuclei of the dorsal thalamus, namely the dorsal lateral geniculate and magnocellular medial geniculate. No calbindin‐positive cells are also GABA‐positive.Most parvalbumin and/or calbindin positive cells in the dorsal thalamus project to the cerebral cortex, as indicated by the retrograde tracing studies, and many parvalbumin positive fibres entering the cerebral cortex could also be shown to contain fast blue anterogradely transported from a thalamic injection.Most of the major sensory and motor pathways entering the dorsal thalamus express parvalbumin immunoreactivity. The optic tract also expresses calbindin immunoreactivity but most other calbindin positive fibres entering the thalamus ascend in the midbrain tegmentum.The differential distributions of parvalbumin and calbindin implied by these results suggest that thalamic cells belonging to different functional systems and projecting differentially upon the cerebral cortex can be distinguished by differential expression of these or closely related calcium binding proteins. This may yield clues to their differential responsivity to afferent driving.
The Organization of Connections between Areas V5 and V1 in Macaque Monkey Visual Cortex
Authors: Shipp S. , Zeki S. 
Published: April 2006

AbstractArea V5 or MT of primate extrastriate visual cortex is specialized for involvement in the analysis of motion and receives input from two layers, 4B and 6, of the striate cortex or V1. Injections of horseradish peroxidase ‐ wheatgerm agglutinin into V5 reveal a patchy distribution of labelled cells and axonal terminals in layer 4B, suggesting the presence of a segregated and functionally specialized subsystem within the layer. The patches are similar in size and frequency to the cytochrome oxidase blobs of layers 2 and 3, but bear little systematic relationship to them. V5‐efferent cells in layer 6, however, tend to avoid the cores of the blobs.The back projection from V5 is continuously distributed in layers 6 and 1, though it is absent inside representations of the central 10° in the latter; it is also diffusely distributed between the patches in layer 4B and over a territory wider than that occupied by labelled cells. It is thus inferred that the back projection probably influences (a) V5‐efferent cells other than those projecting to the injected site in V5, and (b) cells projecting to locations other than V5.There are no major changes in the cortical frequency of V5‐efferent cells with eccentricity in the visual field representation. The V5‐efferent cells of layer 6 are tenfold less frequent than those of layer 4B and as a population may therefore be involved with only a limited sector of directions of movement. Furthermore, their topographic distribution does not always coincide exactly with that of the layer 4B population, as if a site in V5 receives information about slightly non‐corresponding regions of the visual field from the two layers.
The Organization of Connections between Areas V5 and V2 in Macaque Monkey Visual Cortex
Authors: Shipp S. , Zeki S. 
Published: April 2006

AbstractArea V2 of the cerebral cortex of higher primates has a complex cytochrome oxidase architecture whose most characteristic element is a set of stripes running orthogonal to its long axis. These stripes can be related to the segregation between the various pathways in which V2 participates. In the macaque monkey the more metabolically active stripes are alternately thick and thin and only one set, the thick stripes, is found to possess clusters of labelled cells following injections of horseradish peroxidase — wheatgerm agglutinin into area V5. Some of these clusters, but not all, coincide with substructures inside the thick stripes. V2 of the owl monkey has a similar organization except that the diversification into thick and thin stripes is less prominent, both in terms of their appearance and in that more than every alternate stripe is connected to area MT, the likely homologue of V5.The return projection from V5 to V2 is more widespread than the origin of the forward projection. It extends not only between the clusters of V5‐efferent cells within the thick stripes but also across the intervening thin stripes and less active interstripes. Because the latter subserve functions different from those of the thick stripes it would seem that their receipt of a back projection from an area to which they do not project, V5, may be relevant to the process of intergration of signals relating to different attributes of vision.
Onset Characteristics of Long‐Term Potentiation in the Guinea‐Pig Hippocampal CA1 Region in Vitro
Authors: Gustafsson B. , Asztely F. , Hanse E. , Wigström H. 
Published: April 2006

AbstractThe temporal development of long‐term potentiation (LTP) was examined in the CA1 region of the hippocampal slice preparation (bath temperature 30°C). LTP was evoked by a single brief afferent tetanus (3–40 impulses at 50 Hz) given in the presence of picrotoxin (to facilitate LTP induction). Short‐lasting potentiation processes unrelated to LTP were excluded by comparing the potentiation obtained in picrotoxin solution with that obtained in normal solution or in the presence of the N‐methyl‐D‐aspartate receptor antagonist 2‐amino‐5‐phosphonovalerate. LTP was also evoked by pairing single test volleys with brief (2–3 impulses) heterosynaptic tetani in picrotoxin solution. Both methods showed no significant rise of LTP until about 3 s after the induction event. LTP thereafter developed almost linearly towards a peak within 20–25 s after the tetanus, the time course being practially independent of the induction method and of the relative amount of LTP evoked. The latency and rise time of LTP depended on bath temperature, being about twice as long at 25°C as at 30°C. Following the peak, LTP rapidly decayed to less than half its peak value in 8 min, the decay tending to be less with longer trains. The LTP component reaching its peak 20–25 s after a tetanus was practically occluded after a saturating homosynaptic tetanization, and was only partially recovered 1 h afterwards. The latency to the onset of LTP suggests an indirect coupling between the calcium influx, presumed to trigger the potentiation, and the expression of LTP. The independence of the early time course with respect to the induction strength indicates that the intervening system(s) operates in a linear manner.
Effects of Nucleus Basalis Magnocellularis Lesions in Rats on Delayed Matching and Non‐Matching to Position Tasks
Authors: Dunnett Stephen B. , Rogers Derek C. , Jones Graham H. 
Published: April 2006

AbstractThe effects of quisqualic acid lesions of the nucleus basalis magnocellularis on short‐term memory capacities of the rat have been investigated using the delayed matching and non‐matching to position tasks. The lesions do not disrupt performance of either task by pretrained animals, but do disrupt the ability to acquire the non‐matching contingency, and to reverse to the non‐matching task when trained on the matching task. The unidirectional nature of the reversal deficit has been replicated. The generalized disruption of performance of either task by the muscarinic antagonist scopolamine was comparable in lesioned and control rats. The lesions were associated with extensive loss of acetylcholinesterase staining in the basal forebrain and in the neocortex, and 55% depletions of choline acetyltransferase activity in the neocortex but not in the hippocampus. These observations demonstrate that the cholinergic projection from nucleus basalis to the neocortex is not critical for normal short‐term memory, but that lesions involving this system do disrupt specific types of conditional discrimination learning.