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K S Cole

Publications and source records attributed to K S Cole.

At least 19 recordsLinked to original sources
PubMed1992

Early efferent innervation of the developing rat cochlea studied with a carbocyanine dye.

The olivocochlear pathway in the developing rat was visualized in fixed material. The fluorescent carbocyanine dye 1,1'-Dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) was applied to the cut central axons of the olivocochlear neurones at the floor of the fourth ventricle, and the termination pattern within the cochlea was examined after dye diffusion. From the day of birth (P0) to postnatal day 2 (P2), efferent innervation of the cochlea was exclusively in the region of the inner hair cells. Between P2 and P11, progressive outgrowth of neuronal processes to the outer hair cell region occurred; possible connections with the outer hair cells were occasionally seen at P4 and approached the mature pattern by P6. The efferent innervation of the organ of Corti appeared to mature progressively from the cochlear base to the apex, with outgrowth to the outer hair cells occurring earlier in the basal turn of the cochlea than in the second and third cochlear turns. Numerous blind axonal endings were observed in the spiral lamina especially at early postnatal ages. These findings may be consistent with a sequential pattern of arrival of efferent axons at the organ of Corti and ongoing death of efferent neurones in the brainstem during this period of development.

Animals↗
PubMed1990

A double-label study of efferent projections to the cochlea of the chicken, Gallus domesticus.

Intracochlear bilateral injection of the fluorescent retrograde markers fast blue and diamidino yellow was used to identify the brainstem location of the olivocochlear efferents in the domestic chicken. The overall distribution pattern of neurones was similar to that of recent studies using horseradish peroxidase as the retrograde tracer, although the number of labelled neurones was significantly greater than previously reported. The average number of labelled neurones projecting to any one cochlea was 242, with roughly equal numbers located ipsilaterally or contralaterally. After bilateral injection of the two tracers, no double-labelled neurones were detected.

Animals↗
PubMed1990

Direct visualization of death of neurones projecting to specific targets in the developing rat brain.

The fluorescent dye diamidino yellow was injected into parts of the developing visual and auditory systems in the rat. The dye was retrogradely transported by projecting neurones and was found to stain pyknotic profiles within the labelled cell populations. It is thus possible to visualize directly the death of neurones which project axons to specific and identified target regions within the nervous system.

Amidines↗
PubMed1989

Postnatal development of the efferent innervation of the rat cochlea.

The postnatal development of the efferent innervation of the rat cochlea was studied by intracochlear injection of the fluorescent retrograde neuronal traces Diamidino yellow and Fast blue. Injections were performed on adult rats and on neonatal rats ranging from 0 to 8 postnatal days. It was found that the total number of neurones labelled in the brainstem after intracochlear injection was not significantly different in the newborn rat, compared to the adult. On the basis of cell body location and laterality of projections, there was a clear separation into lateral and medial efferent systems at the earliest postnatal age studied (PO). Evidence was also found in the newborn for a tonotopicity in the lateral system projection similar to that in the adult. Differences between the newborn and adult were a slight but significantly greater number of bilaterally-projecting cells in the newborn, and the presence in the newborn of a small number of cells located in the lateral superior olivary nucleus contralateral to their target cochlea. These were extremely rare in the adult brainstem. Evidence was found for the occurrence of postnatal neuronal death in nuclei of origin of both efferent systems. It is suggested that although the overall extent and general organization of the efferent projection to the cochlea in the rat appears to be established at birth, regressive changes are occurring during the postnatal shaping and maturation of this brainstem-to-cochlea pathway.

Aging↗
PubMed1989

Descending projections from auditory brainstem nuclei to the cochlea and cochlear nucleus of the guinea pig.

Projections from auditory brainstem nuclei to the cochlea and cochlear nuclei in the guinea pig were studied by injection of two retrograde fluorescent neuronal tracers. For seven experiments fast blue was injected into the scala tympani of one cochlea and diamidino yellow was injected into dorsal or anteroventral cochlear nucleus of the same side. The results show that the efferent projections to the cochlea and cochlear nucleus generally form two separate neuronal systems even though they share many common nuclei of origin. The largest projections to the cochlear nucleus come bilaterally from the lateral and ventral nuclei of the trapezoid body. Other nuclei, the lateral superior olive, the ventral nucleus of the lateral lemniscus, the dorsomedial periolivary nuclei, and the medial nucleus of the trapezoid body showed an ipsilateral bias in their projections to the cochlear nucleus. An upper limit of 3.5% of the medial system olivocochlear efferent neurones projecting to the cochlea were labelled with both diamidino yellow and fast blue, suggesting that few efferent neurones projecting to the cochlea send collaterals to the cochlear nucleus in this species. However, the site of medial system olivocochlear efferent collateral terminations is the granule cell area for the cat, mouse, and gerbil. When diamidino yellow was injected in the superficial layers of the cochlear nucleus, including the superficial granule cell layer of the ventral cochlear nucleus, approximately 3.6% of medial system olivocochlear efferents projecting to the cochlea sent collaterals to the cochlear nucleus. In three animals fast blue was injected into the cochlear nucleus and diamidino yellow into the cochlea. These experiments revealed a greater proportion of the medial system olivocochlear efferents projecting to the cochlea sending collaterals to the cochlear nucleus, but this proportion was still less than 10%. These results were confirmed by the extracellular injection of horseradish peroxidase into the intraganglionic spiral bundle. Only three medial system olivocochlear efferents were observed to send collaterals to the cochlear nucleus. This number was less than 10% of all labelled medial system fibres. Although these experiments suggest that in the guinea pig the number of olivocochlear efferents sending collaterals to the cochlear nucleus is considerably smaller than is found for the cat, mouse, and gerbil, it is not possible with the current experimental procedures to conclude whether the results are due to species or methodological differences.

Animals↗
PubMed1988

Effect of spider venom on cochlear nerve activity consistent with glutamatergic transmission at hair cell-afferent dendrite synapse.

Venom from the spider Argiope trifasciata, a highly specific blocker of the ionic channels associated with invertebrate glutamatergic receptors, was perfused through scala tympani of the basal turn of the pig cochlea. Its effect on spontaneous and driven activity of single afferent neurons was studied. 0.1 U/ml spider venom altered the maximum driven activity without an effect on spontaneous activity. 1 U/ml spider venom suppressed both spontaneous and driven activity. These findings are consistent with the hypothesis that L-glutamate is the neurotransmitter of the synapse between inner hair cells and primary auditory afferent neurons. The results also suggest that the differences in spontaneous activity between neurons may originate in variations in neurotransmitter release.

Animals↗
PubMed1987

Brainstem organization of efferent projections to the guinea pig cochlea studied using the fluorescent tracers fast blue and diamidino yellow.

Intracochlear injection of the fluorescent retrograde neuronal tracers fast blue and diamidino yellow was used to investigate the distribution within the brainstem of neurones projecting to the cochlea in the guinea pig. The overall pattern of distribution of cells within the brainstem auditory nuclei was the same for both tracers and was also in broad agreement with recent studies in this species using horseradish peroxidase as the neuronal tracer. However, the total number of neurones found (mean of 1234 projecting to each cochlea) was significantly greater than that reported using horseradish peroxidase, largely as a result of more small labelled neurones being detected within the lateral superior olivary nucleus ipsilateral to the injected cochlea. The yield of labelled cells was greatest in animals in which care was taken to perfuse the whole length of the cochlear epithelium. After bilateral injections of both tracers, double-labelled cells were found in small numbers within all the large neurone medial system nuclei and the ventral nucleus of the lateral lemniscus. It was concluded that between 1-5% of the medial system neurones project to both cochleas.

Amidines↗
PubMed1987

Release of chemicals by prostaglandin-treated female fathead minnows, Pimephales promelas, that stimulate male courtship.

Intramuscular injection of PGF2 alpha tromethamine salt (Sigma) did not induce sexual behavior in female fathead minnows, Pimephales promelas, when in the presence of male conspecific. However, coresident males exhibited an increased frequency of courtship behavior, consisting of approach and leading, to females following PGF2 alpha treatment. When presented with both saline-injected and PGF2 alpha-injected females, males showed increased courtship only to PGF2 alpha-treated females. Isolated males also showed increased leading behavior following the introduction of water exposed to PGF2 alpha-treated females, but not with water exposed to PGF2 alpha-treated males, untreated females or males, or PGF2 alpha alone. Hence, PGF2 alpha appears to induce the release of a female-specific chemical in P. promelas that triggers courting behavior in conspecific males.

Animals↗
PubMed1987

Quantitative estimate of bilaterally projecting medial olivocochlear neurones in the guinea pig brainstem.

Bilateral intracochlear injections of the fluorescent retrograde neuronal tracers fast blue and diamidino yellow were used to identify efferent neurones in the guinea pig brainstem which project to the inner ear on both sides. Bilaterally projecting neurones, detected by their double-labelled appearance in fluorescence microscopy, were found in all the nuclei of origin of the large neurone extra-LSO system of olivocochlear neurones. No double-labelled neurones were found in the small neurone LSO system. When precautions were taken to maximize their capture, these bilaterally projecting neurones comprised 5.4% of the total extra-LSO system neurones projecting to any one cochlea. On the basis of these quantitative data, it was suggested that the bilaterally projecting neurones may correspond to the small group of binaurally activated cochlear efferents identified in physiological studies.

Amidines↗
PubMed1987

Segregation of efferent projections to different turns of the guinea pig cochlea.

Localized intracochlear injections of the fluorescent retrograde label diamidino yellow were used to investigate the organization of efferent projections from the brainstem to different turns of the cochlea, in the guinea pig. It was found that the location of small neurones within the lateral superior olive ipsilateral to the injection varied in a systematic manner when injections proceeded from base to apex of the cochlea. In addition, a cruder form of cochleotopic organization was present in that most of the large medial system efferent neurones were labelled only after injection into the 3 most basal turns of the cochlea. The decline of medial system efferent innervation proceeding from base to apex was most striking for the contralateral efferent neurones. The details of base to apex innervation density were different for the different nuclei of origin of the medial system, implying the existence of complex subsystems within the medial neurone population.

Animals↗
PubMed1984

Prostaglandin induction of spawning behavior in Cichlasoma bimaculatum (Pisces cichlidae).

Prostaglandin (PG) stimulates female spawning behavior in goldfish and in some other teleosts in which female reproductive behaviors consist of postovulatory oviposition acts. This study examined the effects of PG on female sexual behavior in a teleost fish, Cichlasoma bimaculatum, in which female reproductive behaviors involve both preovulatory courtship and substrate cleaning behaviors, and post-ovulatory oviposition behavior. In females of established pairs, PGF2 alpha injection (5 micrograms, im) at any stage of the spawning cycle, or in the parental phase, rapidly induced substrate cleaning which soon merged into oviposition behavior (without egg release). These results support a role for PG in oviposition behavior of Cichlasoma. However, indomethacin (1 mg, ip), a PG synthesis inhibitor, did not block oviposition in ovulated females which had begun to spawn. Indomethacin may not have lowered PG levels sufficiently. Alternatively, as shown by J.J. Polder (1971, Neth. J. Zool. 21, 265), oviposition behavior may be induced or maintained by other factors associated with the spawning situation.

Animals↗
PubMed1976

Electrical properties of the squid axon sheath.

The first impedance data on the squid giant axon gave a lossy membrane capacity of 1 muF/cm2 from 1-200 kHz. The remaining observations of one experiment up to 5 MHz were not included in the simple conclusions and have now been ascribed to the mostly Schwann cell sheath. The results of these fragmentary data, 1.6 omega-cm2 and 12.5 membrane layers, are within the range of recent current clamp and electron microscope conclusions to give them independent confirmation and support.

Animals↗
PubMed1976

Analogue solution for electrical capacity of membrane-covered cubes in cubic array at high concentration.

Earlier measurements have shown that the equations derived for the resistance of suspension of spheres apply up to a volume concentration of 100% for close-packing forms. They have also shown, by a resistance-capacitance analogue, that they apply for the capacity of a close-packing of membrane-covered square cylinders in square array, approximating muscle and nerve. The present work is an extension of the two-dimensional to a three-dimensional array of membrane-covered cubes in a cubic array. It is found by measurements of a three-dimensional electrolytic analogue that the capacitance is indeed expressed by an extension of the analytic solution at low concentrations up to 100% volume concentration of the membrane-covered form, such as epithelial tissues. There is thus at least one example each of two-and three-dimensional forms which conform to the low concentration analysis up to 100% volume and so give a basis for the extensions to other and more complicated forms to complete a survey to work begun by Fricke in 1923.

Cell Physiological Phenomena↗
PubMed1975

Analogue solution for electrical capacity of membrane covered square cylinders in square array at high concentration.

Analytical solutions of Laplace equations have given the electrical characteristics of membranes and interiors of spherical, ellipsoidal, and cylindrical cells in suspensions and tissues from impedance measurements, but the underlying assumptions may be invalid above 50% volume concentrations. However, resistance measurements on several nonconducting, close-packing forms in two and three dimensions closely predicted volume concentrations up to 100% by equations derived from Maxwell and Rayleigh. Calculations of membrane capacities of cells in suspensions and tissues from extensions of theory, as developed by Fricke and by Cole, have been useful but of unknown validity at high concentrations. A resistor analogue has been used to solve the finite difference approximation to the Laplace equation for the resistance and capacity of a square array of square cylindrical cells with surface capacity. An 11 x 11 array of resistors, simulating a quarter of the unit structure, was separated into intra- and extra-cellular regions by rows of capacitors corresponding to surface membrane areas from 3 x 3 to 11 x 11 or 7.5% to 100%. The extended Rayleigh equation predicted the cell concentrations and membrane capacities to within a few percent from boundary resistance and capacity measurements at low frequencies. This single example suggests that analytical solutions for other, similar two- and three-dimensional problems may be approximated up to near 100% concentrations and that there may be analytical justifications for such analogue solutions of Laplace equations.

Biological Transport↗
PubMed1975

Resistivity of axoplasm. I. Resistivity of extruded squid axoplasm.

Six methods have given squid axoplasm resistivities of from 1.0 to 6.9 times seawater (X SW), so another was tried. A 100-mum platinized electrode was to be inserted from each end of an axion in iso-osmotic sucrose and impedance between them measured vs. separation. But observations that the resistance of axons in sucrose increased steadily ruled this out. Axoplasm from two or three axons was transferred to a glass capillary, 0.6 mm ID, and the 1-kHz series resistance and reactance were measured at electrode separations from 16 to 2 mm. The resistance was linear vs. distance, giving the resistivity, while the reactance was nearly constant, implying constant electrode contributions. Frequency runs from 10 Hz to 30 kHz at 10 mm gave electrode impedances of the form (jomega)-alpha, allowing 1-2% effects on the axoplasm resistivities. In nine experiments, one was discarded for cause, the range and average resistivities were, respectively, 1.2-1.6 and 1.4 times those of artificial seawater (19.7 omegacm at 24.4 degrees C). No single cause for the variability was apparent. These experiments essentially confirm the means and variations of two early experiments with intact axons and recent results with a single internal electrode to give overall resistivities of 1.4 +/- 0.2 X SW.

Animals↗