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C J Wilson

Publications and source records attributed to C J Wilson.

At least 91 records · Page 5Linked to original sources
PubMed1991

Synaptic potentials evoked in spiny neurons in rat neostriatal grafts by cortical and thalamic stimulation.

1. Fetal rat striatal primordia were implanted into the neostriatum of adult rats 2 days after kainic acid lesion. Two to 6 mo after transplantation, in vivo intracellular recording and staining were performed to study the responses of spiny neurons in the grafts to the cortical and thalamic stimuli. The physiological characteristics and synaptic responses of 27 cells recorded in the grafts were compared with a sample of 23 neurons recorded from the surrounding host neostriatum in the same animals. Nineteen of the graft neurons and 19 of the host neurons were identified as spiny neurons by intracellular staining with biocytin. The responses of the remaining neurons were the same as those of identified spiny cells. 2. The spontaneous synaptically driven membrane potential shifts and long-lasting responses to afferent stimulation that are characteristic of neostriatal cells in normal animals were greatly reduced or absent in graft neurons. Presumably this reflects the reduction in synaptic input to the grafts and the lack of convergence of inputs from diverse sources. 3. Short-latency synaptic responses to cortical and thalamic stimulation were present and could consist of either excitatory postsynaptic potentials (EPSPs) or inhibitory postsynaptic potentials (IPSPs). The IPSPs were accompanied by a membrane conductance increase, and their reversal potentials could be altered by injection of chloride ions. Several minutes after impaling the cell, the IPSPs gradually disappeared, and the same stimuli could then evoke EPSPs. The disappearance of the IPSPs was independent of the presence of chloride in the electrodes. Most of the EPSP responses appeared to be monosynaptic but occurred at longer latencies than those seen in host neurons of the same type. 4. In cells not exhibiting IPSPs, or after the IPSP responses disappeared, cortical or thalamic stimulation could evoke slow depolarizing potentials and bursts of action potentials. These could not be evoked by current injection. They could be prevented or delayed by an exaggerated action potential after hyperpolarization that developed in neurons maintained in a depolarized state for several seconds, but could not be prevented by passage of hyperpolarizing current from the recording electrode. 5. The input resistance of graft spiny neurons was higher than that of the host cells, and time constants were longer. Both of these properties appeared to be due to the absence of the strong inward rectification that is usually present at resting membrane potentials in neostriatal neurons.

Animals↗
PubMed1991

Correlation of physiologically and morphologically identified neuronal types in human association cortex in vitro.

1. We examined whether the three physiologically defined neuron types described for rodent neocortex were also evident in human association cortex studied in an in vitro brain slice preparation. We also examined the relationship between physiological and morphological cell type in human neocortical neurons. In particular, we tested whether burst-firing neurons were numerous in regions of human cortex that are susceptible to seizures. 2. Although we sampled regular-spiking and fast-spiking neurons, we observed no true burst-firing neurons, as defined for rodent cortex. We did find neurons that displayed a voltage-dependent shift in firing behavior. Because this behavior was due, in large part, to a low-threshold calcium conductance, we called these cells low-threshold spike (LTS) neurons. 3. Regular-spiking neurons and LTS neurons only differed in the voltage dependence of firing behavior and the first few interspike intervals (ISIs) of repetitive firing in response to small current injections (from hyperpolarized membrane potentials). Because of the general similarities between the two types, we consider the LTS cells to be a subgroup of regular-spiking cells. 4. All biocytin-filled regular-spiking neurons were spiny and pyramidal and found in layers II-VI. The lone filled fast-spiking cell was aspiny and nonpyramidal (layer V). The LTS neurons were morphologically heterogeneous. We found 80% of LTS neurons to be spiny and pyramidal, but 20% were aspiny nonpyramidal cells. LTS neurons were located in layers II-VI. 5. In conclusion, human association cortex contains two of three physiological cell types described in rodent cortex: regular spiking and fast spiking. These physiological types corresponded to spiny, pyramidal, and aspiny, nonpyramidal cells, respectively. We sampled no intrinsic burst-firing neurons in human association cortex. LTS neurons exhibited voltage-dependent changes in firing behavior and were morphologically heterogeneous: most LTS cells were spiny and pyramidal, but two cells were found to be aspiny and nonpyramidal. It is not clear whether the absence of burst-firing neurons or the morphological heterogeneity of LTS neurons are due to species differences or differences in cortical areas.

Association Learning↗
PubMed1991

Use of children's artwork to evaluate the effectiveness of a hospital preparation program.

Approximately 1.5 million children are hospitalized on an emergency basis per year and are not able to be fully prepared for the event due to the emergency (Azarnoff & Woody, 1981). For this reason many pre-crisis hospital preparation programs are being instituted by hospitals and pediatric nurses. This pilot study investigated the use of children's artwork to evaluate the effectiveness of a hospital preparation program. The 6 to 10 year old children attending summer school at a day care center participated in a hospital preparation program. The purpose of the program was to decrease children's anxieties and fears in the event of an emergency hospitalization.

Adaptation, Psychological↗
PubMed1991

The Periotest method for determining implant success.

The purpose of this paper is to show that the currently accepted methods for the determination of implant stability are unpredictable. It describes those techniques that are currently utilized for the assessment of implant success and discusses the problems they present. The paper will propose the Periotest method as a reliable and reproducible alternative to the methods currently available to the clinician for determining implant stability.

Dental Implants↗
PubMed1990

Parvalbumin-containing GABAergic interneurons in the rat neostriatum.

Antibodies to the intracellular calcium binding protein parvalbumin were shown to label specifically a distinct group of neostriatal GABAergic neurons. These neurons corresponded to the intensely staining subclass of neostriatal GABAergic neurons that have previously been shown to be a class of aspiny interneurons in the neostriatum. The parvalbumin neurons were aspiny neurons with varicose dendrites distributed throughout the neostriatum in a pattern identical to the intensely stained GABA neurons, and both populations of neurons showed increased numbers in the lateral part of the neostriatum. Double labeling of single neurons with both the GABA and parvalbumin antisera showed that all parvalbumin neurons were positive for GABA, but some GABA labelled neurons were not immunoreactive for parvalbumin. These parvalbumin-negative GABAergic neurons were morphologically similar to the spiny projection neurons, which are GABAergic but usually are not so heavily stained. The relationship of the GABA-containing parvalbumin neurons to the striatal mosaic organization was determined by using immunocytochemistry for another calcium binding protein, calbindin D28K, to label the matrix compartment of the striatum. The distribution of parvalbumin-positive neurons relative to the calbindin-positive matrix and calbindin-poor patches was determined by using pairs of adjacent sections stained with the calbindin and parvalbumin antisera. This analysis showed that the somata of the parvalbumin neurons were present in both patch and matrix compartments, and their axons and dendrites crossed the boundaries between compartments. A quantitative analysis of the number of neurons in each compartment revealed that the neurons showed no preferential distribution in either compartment, but instead were present according to the area occupied by that compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Interaction of cimetidine with human serum albumin.

Ultrafiltration studies have detected the existence of a weak interaction between cimetidine and human serum albumin, a finding supported by corresponding studies with this xenobiotic and bovine serum albumin. Furthermore, the binding characteristics of the interaction with human serum albumin (4 sites, K = 630 M-1) more than suffice to account for the proportion of protein-bound drug in the serum of patients subjected to cimetidine therapy. Thus, although alpha 1-acid glycoprotein is usually regarded as the specific transporter of basic drugs, the present evidence implicates albumin as the likely binding protein for cimetidine in serum.

Binding Sites↗
PubMed1990

The use of a retroviral vector to identify foetal striatal neurones transplanted into the adult striatum.

A retrovirus which encodes beta-galactosidase was used to infect embryonic rat striatal cells before grafting these cells into the lesioned adult rat striatum. Examination of the grafts after long term survival (8 months) revealed that a few small and large cells expressed large amounts of bacterial beta-galactosidase activity. The larger diameter cells were identified as neurones by their size, shape and presence of neuronal processes. The identity of the small diameter cell types was not established.

Animals↗
PubMed1990

Projection subtypes of rat neostriatal matrix cells revealed by intracellular injection of biocytin.

Individual neostriatal-matrix spiny neurons were stained intracellularly with biocytin after intracellular recording in vivo, and their axons were traced into the globus pallidus (GP), entopeduncular nucleus (EP), and/or substantia nigra (SN). The locations of the neurons within the matrix compartment of the neostriatum (NS) were established by immunocytochemical counterstaining of sections containing the cell bodies using antibodies for calbindin-D28K. This allowed nearly complete visualization of the axonal projections of single NS neurons. On the basis of their intrastriatal axonal arborizations, matrix spiny neurons could be divided into 2 types. One type, which was the more common, had local axonal arborizations restricted to the region of the dendritic field, often with axon collaterals arborizing within the dendritic field of the cells of origin. A second, less common, cell type in the matrix had local axon collaterals distributed widely in the NS. Among matrix neurons with restricted local collateral fields, 3 subtypes could be distinguished on the basis of their efferent axonal projections. Type I cells projected only to the GP. Type IIa cells projected to the GP, EP, and SN pars reticulata. Type IIb cells projected to the GP and SN but not to the EP. The shapes and densities of the GP arborizations varied in the 3 cell types, with the cells projecting only to the GP (type I) projecting more heavily and filling a larger volume there than type II cells. The dendrites and intrastriatal axon collaterals of 3 subtypes were similar in morphology. The class of matrix spiny neurons with intrastriatal axon collaterals distributed widely in the NS were observed to project to the GP. Projections beyond the GP were not identified for this cell type, but could not be ruled out. Somatodendritic morphologies of neurons did not differ according to the projection site. These results demonstrate that NS matrix spiny cells are more heterogeneous in their efferent projection patterns than previously suspected on the basis of retrograde axonal tracing and immunocytochemical studies. As predicted by those previous studies, there is a class of matrix neurons that projects only to the GP. Presumably, these cells contain enkephalin. Cells projecting to the SN and EP, and so presumably containing substance P, give off a small projection to the GP, as well, and differ in their collateralization patterns within the 3 major target nuclei.

Animals↗
PubMed1990

Firing patterns and synaptic potentials of identified giant aspiny interneurons in the rat neostriatum.

Intracellular recordings were made in vivo from 9 giant aspiny neurons in the neostriatum of urethane-anesthetized rats. The cells were identified by intracellular staining with HRP or biocytin. The neurons exhibited morphological features typical of neostriatal cholinergic interneurons. Six of the cells were obtained from intact animals, while 3 were recorded from rats with ipsilateral hemidecortications. Giant aspiny neurons were characterized by their slow irregular but tonic (3-10/sec) spontaneous activity and long-duration action potentials. Examination of the underlying membrane potential trajectories during spontaneous firing revealed that individual action potentials were triggered from spontaneous small (1-5 mV) depolarizing potentials. These spontaneous potentials exhibited the voltage sensitivity of ordinary EPSPs. They were much less frequent during the 80-200 msec pause in tonic afferent input that follows the excitation evoked by cortical or thalamic stimulation, and were decreased in frequency in decorticate animals. Their rise times and half-widths matched those expected for unitary synaptic potentials placed proximally on the surface of the neurons. Low-intensity stimulation of neostriatal afferents produced small short-latency EPSPs that appeared to be composed of responses identical to the spontaneous depolarizing potentials. The latencies of the EPSPs evoked from the cerebral cortex and thalamus were consistent with a monosynaptic input from both structures, but the maximal size of the EPSPs was much smaller than that evoked in spiny neurons, suggesting that a smaller number of afferent inputs make synapses with each of the aspiny cells. Giant aspiny neurons exhibited much larger input resistances and longer time constants than spiny neostriatal neurons. They also exhibited relatively linear steady-state current-voltage relationship compared to spiny projection cells. Input resistances ranged from 71-105 M omega, and time constants ranged from 17.8-28.5 msec. Analysis of the charging transients in response to current pulses yielded estimates of dendritic length of approximately 1 length constant. Repetitive firing of the neurons was limited by a powerful spike afterhyperpolarization and by a strong spike frequency adaptation. The sensitivity of the giant aspiny interneuron to a relatively small number of proximal afferent synaptic contacts, its tonic firing, and its widespread dendritic and axonal fields place it in an excellent position to act as a modulator of the excitability of neostriatal projection neurons in advance of the onset of movement-related neostriatal activity.

Action Potentials↗
PubMed1989

Capacitance compensation and bridge balance adjustment in intracellular recording from dendritic neurons.

Under most experimental conditions in intracellular recording, the proper adjustment of the amplifier is essential for the interpretation of the signals recorded from neurons. It is considered possible to accurately align the capacitance compensation and bridge balance adjustments of the amplifier simultaneously with the recording of membrane potential of an impaled cell if a number of conditions are met. In the strictest sense, these conditions are met only if: (1) the neuron is isopotential and if its electrical behavior can be adequately described using a single exponential decay constant, and if (2) that decay time constant is much longer than that of the microelectrode. These conditions cannot usually be satisfied. Because intracellular adjustment of capacitance compensation and bridge balance is necessary in many circumstances, it is desirable, to know whether any of the methods for performing these adjustments are accurate when used under less strict constraints, and to assess the nature and degree of the error that can be expected when the constraints are ignored. The results of computer simulations of a simple intracellular recording amplifier, microelectrode and a dendritic neuron model consisting of an isopotential cell and terminated finite equivalent cylinder representation of the dendrites are presented here. These studies show that the introduction of fast components of the response to intracellular current transients by the redistribution of applied charge in dendrite neurons may sometimes make it impossible to correctly apply the conventional methods of capacitance compensation and bridge balance. If the high-frequency response of the intracellular recording amplifier has sufficient fidelity, however, these adjustments can be made to a sufficient degree of accuracy using the response to sine wave calibration signals of varying frequency.

Computer Simulation↗
PubMed1989

Restoration of the corticostriatal projection in rat neostriatal grafts: electron microscopic analysis.

The corticostriatal projection in rat neostriatal grafts was studied by using the axonal transport of Phaseolus vulgaris-leucoagglutinin. The neostriatal primodia from 15-18-day embryos were used to make a cell suspension which was implanted unilaterally into the rat neostriatum 3-5 days after kainic acid lesion. Two to four months later, regions of the frontal cortex ipsilateral to the grafts were injected iontophoretically with Phaseolus vulgaris-leucoagglutinin. There were many Phaseolus vulgaris-leucoagglutinin labeled cortical fibers in the host neostriatum. Although the density of labeled fibers in the grafts was much lower than that in the surrounding host tissue, some fibers could be seen to enter the grafts and form terminal arborizations. The morphology of labeled fibers in the graft differed from that of corticostriatal fibers from the same injection but distributing in the host neostriatum. The labeled fibers in the host neostriatum arborized in an extended pattern, branching infrequently and making most of their synapses en passant at varicosities along their courses. The labeled fibers in the grafts made more dense arborizations with many short branches that formed clusters of terminals confined to small foci along their courses. The cellular composition and the structure of the neuropil in the neostriatal grafts were similar to that of the neostriatum. As those in the host, labeled corticostriatal terminals in the grafts contained densely packed round vesicles and made asymmetric synapses on dendritic spines, dendritic shafts and somata. A quantitative analysis, however, revealed that the distribution of postsynaptic elements of labeled boutons in the grafts was different from that in the hosts. More than 90% of the labeled cortical terminals in the host neostriatum contacted dendritic spines whereas only 47% of the labeled terminals in the grafts contacted spines, and 50% of them terminated on the dendritic shafts. The present study provides direct anatomic evidence to demonstrate the restoration of the corticostriatal projection in grafts. The difference in the distribution of postsynaptic elements in the grafts and the hosts may represent a response to the decreased innervation density of cortical inputs to the graft tissue, and may contribute to the recovery of corticostriatal responses by increasing the effectiveness of transmission by the fibers that do grow into the graft and form contacts there.

Animals↗
PubMed1989

Intracellular recording of identified neostriatal patch and matrix spiny cells in a slice preparation preserving cortical inputs.

1. The morphology, electrical membrane properties, and corticostriatal excitatory postsynaptic potentials (EPSPs) of two groups of neostriatal projection cells, patch cells, and matrix spiny cells were compared in the rat by the use of an in vitro slice preparation that preserves inputs from medial agranular cortex. Spiny cells were stained intracellularly with biocytin and identified as belonging to the patch (striosomal) compartment or to the matrix by immunohistochemistry for the 28 kD calcium-binding protein calbindin on the same sections. 2. Patch and matrix neurons had very similar axonal and dendritic morphology. Both patch and matrix cells extended their dendrites and local axon collaterals almost exclusively in their respective compartments. Patch cells and most matrix cells had local axon collaterals within or near the parent dendritic domain. However there was a class of matrix cells that extended axon collaterals over a much wider portion of the neostriatum but still restricted to the matrix compartment. 3. Input resistance and membrane time constant were estimated from the membrane response to intracellularly applied current pulses. The average values of matrix cells were and 8.41 ms. The values of patch cells were 31.8 M omega and 8.19 ms and were within the range of those of matrix cells. Both types of cells showed the same kinds of membrane nonlinearities when tested with the use of current pulses. Input resistance and time constant were both strongly affected by a fast anomalous rectification and were thus voltage-dependent, decreasing with membrane polarization. Slow ramplike depolarizing responses were observed in response to depolarizing current steps. 4. Repetitive firing was examined with the use of depolarizing current pulses. In both types of spiny cells, trains of action potentials showed little adaptation of spike frequency and linearly increased with current intensities less than 1 nA. The slopes frequency, calculated from the first and second intervals, were 115.0 and 107.2 Hz/nA, respectively, for matrix cells and 86.0 and 82.8 Hz/nA for patch cells. 5. Stimulation of the medial agranular cortex induced EPSPs in some striatal cells in both compartments. EPSP in matrix cells often showed both short-latency and long-latency components, corresponding to two early components of the response observed in vivo. Some matrix cells, and all patch cells, showed only the longer latency EPSP component. The average latency was 6.3 ms in matrix cells and 9.1 ms in patch cells. The relationship between EPSP amplitude and membrane potential was nonlinear, with EPSP amplitude and duration increasing with decreasing membrane polarization.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1988

Relationship of the axonal and dendritic geometry of spiny projection neurons to the compartmental organization of the neostriatum.

Intracellular injection of HRP combined with immunocytochemistry for [Leu]enkephalin was used to demonstrate striatal spiny neuron dendritic and local axonal arborizations in the same section as enkephalin-rich patches (striosomes). Cobalt intensification of the first DAB reaction prior to the immunoperoxidase steps resulted in good contrast between the black reaction product in the intracellularly labeled cells and the brown staining for [Leu]enkephalin. Serial reconstructions of the labeled cells and nearby boundaries between the enkephalin-rich striosomes and enkephalin-poor matrix allowed the relationship between the arborizations of the labeled cells and these boundaries to be established. It was also possible to examine the relationship to compartmental boundaries of a second neuronal class consisting of large, pallidallike neurons whose somatodendritic morphology was outlined by immunoperoxidase-labeled terminals. We found that spiny projection neurons in both compartments have dendritic arbors and local axonal collaterals that are confined by compartmental boundaries. The termination or recurvature of dendrites at such boundaries suggests that the cellular basis of striatal compartmental organization is provided by this class of striatal neuron. On the other hand, large pallidumlike striatal neurons were found to have dendrites that extend across compartmental boundaries. These results support previous reports that striatal spiny projection neurons preserve the compartmental segregation of parallel striatal input-output systems, whereas other classes of striatal neurons may serve to provide limited integration between compartments.

Animals↗
PubMed1988

Cellular mechanisms controlling the strength of synapses.

The mechanisms suspected as contributors to the regulation of synaptic strength act at a variety of sites along the causal chain that links activity in a presynaptic neuron to activity in a postsynaptic one. At several places in this chain, morphological factors are expected to have a powerful influence, and at several others, key insights into the mechanisms controlling synaptic action have been achieved using morphological techniques. A variety of presynaptic mechanisms controlling the release of neurotransmitter have been most directly shown to regulate the potency of synaptic connections. Traditional interpretations of the effect of postsynaptic geometry on synaptic strength need to be reevaluated in light of new views of the functional properties of dendritic membrane, and the new neurophysiological data must be incorporated into a more comprehensive view of the behavior of spatially distributed excitable membrane with specific patterns of distributed synaptic inputs.

Animals↗
PubMed1988

Induced Changes in Chloroplast Protein Accumulation during Heat Bleaching in Euglena gracilis.

When growing cultures of light-grown Euglena gracilis Z are exposed to slightly elevated temperatures (33 degrees C) there is a time-dependent decrease in chlorophyll (bleaching) and a gradual transformation of chloroplasts into rudimentary plastids. A study was undertaken whose primary objective was to document major changes in polypeptide composition in the stroma and in thylakoids of cells that have been exposed to the bleaching temperature for up to 57 hours. A novel polypeptide of about 60,000 to 63,000 M(r) whose function is presently unknown, accumulates in the stroma and in thylakoids in response to growth at the bleaching temperature. The levels of the large and small subunit of ribuolosebisphosphate carboxylase, on the other hand, decrease to very low levels at about 33 hours and remain very low for the duration of the temperature treatment. Of two polypeptides associated with the light-harvesting chlorophyll-protein complex of photosystem II (28,000 and 24,500 M(r)) only the level of the smaller polypeptide decreases at the elevated temperature. The levels of 28,000 M(r) species remain virtually unchanged throughout the temperature treatment period. Changes in chloroplast polypeptide composition were also studied in cells that were allowed to recover at room temperature from an initial treatment at 33 degrees C. Bleaching Euglena could provide a useful tool for studying the interaction between the nucleus and chloroplast genetic system that govern the development and maintenance of this vital organelle to plants.

Journal Article↗
PubMed1988

An examination of the mechanism of ligament contracture.

It has been proposed that the mechanism of ligament contraction involves conversion of fibroblasts to a contractile form similar to the phenomenon recently documented in wound contraction. In this study rat knees were surgically immobilized in flexion and a sham operation was performed on the contralateral knees. Mechanical studies revealed that the flexion contracture increased rapidly for two weeks. The anterior cruciate ligaments (ACL) were contracted and contributed to the flexion contractures. Histologic studies of the ACL showed no increase in the cellularity of the contracted ligaments. In the contracted ligaments, staining for the contractile protein actin was heavy. Previous transmission electron microscopy studies have demonstrated fibroblast cytoplasm in processes far from the visible cell body and it is hypothesized that this cytoplasm was responsible for increased actin staining away from the visible cell body. This study supports the concept that ligament fibroblasts, modulated to a form containing increased quantities of the contractile protein actin, play an active role in the contraction of ligamentous tissue.

Actins↗