Showing papers by "University of California, Irvine published in 1977"

Learning and memory

Abstract: How the brain codes, stores, and retrieves memories is among the most important and baffling questions in science. The uniqueness of each human being is due largely to the memory store—the biological residue of memory from a lifetime of experience. The cellular basis of this ability to learn can be traced to simpler organisms. In the past generation, understanding of the biological basis of learning and memory has undergone a revolution. It is clear that various forms and aspects of learning and memory involve particular systems, networks, and circuits in the brain, and it now appears possible to identify these circuits, localize the sites of memory storage, and analyze the cellular and molecular mechanisms of memory.

Heterosynaptic depression: a postsynaptic correlate of long-term potentiation

Abstract: BRIEF trains of electrical stimulation delivered to any one of several hippocampal pathways often result in immediate and long-lasting enhancement of subsequent postsynaptic responses elicited by that pathway1–5. The unusual characteristics of these effects suggest that theories of long-term potentiation (specifically changes in transmitter release by the presynaptic terminal) which have evolved from work on invertebrate and neuromusclar preparations may not be appropriate to explain synaptic plasticity in hippocampus. We report here the results of experiments intended to examine the postsynaptic consequences of repetitive stimulation. We found that potentiation of one afferent tended to depress the target cell's responses to a second test input.

Development of auditory function in newborn infants revealed by auditory brainstem potentials.

Abstract: Auditory brainstem potentials were recorded from scalp electrodes in 42 infants ranging in gestational age from 25 to 44 weeks. The latencies of the various potential components decreased with maturation. Wave V, evoked by 65-dB sensation level clicks, changed in latency from 9.9 msec at 26 weeks of gestation of 6.9 msec at 40 weeks of gestation. Central conduction times in the auditory pathway also decreased with maturation from 7.2 msec at 26 weeks to 5.2 msec at 40 weeks. The effects of brainstem and cochlear disorders on auditory brainstem potentials were noted in several abnormal infants. The application of all of these techniques could permit an objective definition of both normal and abnormal sensory processes in newborn infants.

Some static and dynamical properties of a two-dimensional Wigner crystal

Abstract: The static ground-state energy of a two-dimensional Wigner crystal has been obtained for each of the five two-dimensional Bravais lattices. At constant electron number density the hexagonal lattice has the lowest energy. Phonon dispersion curves have been calculated for wave vectors along the symmetry directions in the first Brillouin zone for the hexagonal lattice. In the long-wavelength limit one of the two branches of the dispersion relation vanishes with vanishing two-dimensional wave vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}$ as $q$, the second as ${q}^{\frac{1}{2}}$. The coefficient of $q$ in the former branch is pure imaginary for certain directions of propagation in the square lattice, implying a dynamical instability of this lattice; the hexagonal lattice is stable. The vibrational zero-point energy and low-temperature thermodynamic functions have been obtained for the hexagonal lattice. The dielectric susceptibility tensor of a two-dimensional Wigner crystal ${\ensuremath{\chi}}_{\ensuremath{\alpha}\ensuremath{\beta}}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}})$ has been determined in the long-wavelength limit, in the presence of a static magnetic field perpendicular to the crystal, and the result has been used to obtain the dispersion relation for plasma oscillations in the electron crystal.

Serotonin-containing neurons: their possible role in pain and analgesia.

Abstract: Experimental evidence is reviewed showing that brain and spinal cord serotonergic neurons are involved in nociceptive responses, as well as in the analgesic effects of opiate narcotics. This evidence, based on studies employing pharmacological, surgical, electrophysiological and dietary manipulations of central nervous system serotonergic neurotransmission, suggests that increases in the activity of brain and spinal cord serotonin neurons are associated with analgesia and enhanced antinociceptive drug potency, whereas decreases in the activities of these neurons correlate with hyperalgesia and diminished analgesic drug potency.

TALE-SPIN, an interactive program that writes stories

Abstract: ANY MORE.

Histological analysis of the dynamics of growth of imaginal discs and histoblast nests during the larval development ofDrosophila melanogaster.

Abstract: 1. Histological analyses were made of imaginal discs and histoblasts during the larval development ofDrosophila melanogaster to determine the number of cells, the patterns of cell division and the growth dynamics in these adult primordia. Histological studies were also made of the imaginal rings which are the primordia of the adult salivary gland, fore-and hindgut, the anlage cells of the midgut and several larval and embryonic tissues. 2. In the newly-hatched larva, the immature eye-antenna, wing, haltere, leg and genital discs contain about 70, 38, 20, 36-45 and 64 cells respectively. These numbers include cells destined to form cuticular elements as well as peripodial, tracheal and nerve cells and probably the progenitors of adepithelial cells. The number of cells counted in the various imaginal disc anlagen is 1.5 to 4 times higher than the numbers deduced from genetic mosaic analyses by other investigators and reasons for these differences are given. 3. About 12 h after fertilization, mitosis ceases in all tissues of the embryo except the nervous system. After the larva hatches, mitosis resumes in most of the imaginal anlagen and in some larval tissues. The time of resumption of mitosis in the imaginal anlagen was determined after treating the larvae with colchicine for 2 h. 4. Among the imaginal discs, the eye disc is the first to begin cell division, at about 13-15 h after the hatching of the larva (first instar) followed by the wing (15-17 h), the haltere (18-20 h), the antenna, leg, and genitalia (24-26 h, early second instar), and finally the labial and dorsal prothoracic discs (52-54 h, early third instar). The cell doubling time for various discs was calculated from cell counts and the times agree closely with the doubling times deduced from clonal analyses by other workers: e.g., 7.5 h for the cells of the wing disc. 5. The imaginal ring of the hindgut first shows cell division early in the second instar. The imaginal rings of the foregut and salivary glands, the anlage cells of the midgut and the cells of the segmental lateral tracheal branches begin to divide early in the third instar. 6. The histoblasts which are the anlagen of the integument of the adult abdomen do not increase in number from the time of larval hatching until about 5 h after pupation when they begin to divide. Their behaviour contrasts with that of the histoblasts of the other dipterans such asCalliphora, Musca andDacus, which begin to divide during the second instar. 7. The histoblasts are an integral part of the larval abdominal epidermis and, unlike imaginal disc cells, secrete cuticle during larval life. Each hemisegment consists of an anterior dorsal, a posterior dorsal, and a ventral histoblast nest containing about 13, 6 and 12 cells respectively. The 62 histoblasts in each larval segment represent about 7-8% of the total number of cells that form the integument of that segment. 8. The number of cells in a particular type of histoblast nest was constant for both male and female larvae and among the different abdominal segments, except that the anterior dorsal group of the first and the seventh segments contains fewer cells than those of the other segments. Although the male and female adultDrosophila lack the first abdominal sternite and the male lacks the seventh abdominal tergite and sternite, the ventral histoblast nests of the first and the dorsal and ventral nests of the seventh abdominal segments are present in the larval stages as well as in the prepupa and have the same morphology and cell number as similar nests in the rest of the abdominal segments. 9. The cells of the imaginal discs increase in volume about six-fold and their nuclei increase in volume three-fold between the time of hatching and the initiation of mitosis. The histoblasts increase in volume about 60-fold and their nuclei increase in volume about 25-fold between larval hatching and pupariation. 10. Prior to each cell division, the nuclei of the columnar cells of the disc epithelium and of the histoblasts appear to migrate toward the apical surface of the epithelium. The cells round up and shift toward the apical region where mitosis occurs. After cytokinesis, the daughter cells move back to deeper positions in the epithelium. Because the nuclei of the non-dividing cells continue to lie deep in the epithelium, this intermitotic migration of nuclei gives these epithelia a pseudostratified appearance. 11. Analyses of the growth of larval cells and of organs confirmed the observations of earlier investigators that cell division occurs only in a few larval tissues, whereas growth in the rest of the larval tissues is by cell enlargement and polyteny. During larval life, cell division was detected only in the central nervous system, gonads, prothoracic glands, lymph glands and haemocytes. Each tissue began mitosis at a characteristic stage in larval life. The larval cells that did not divide, grew enormously, e.g., epidermal cells increased in volume 150-fold and their nuclei increased in volume 80-fold. 12. The adepithelial cells, which give rise to some of the imaginal muscles, were first identified between the thick side of the imaginal dise epithelium and the basement membrane at the beginning of the third larval instar (50-52 h). The origin of these precursors of mesodermal structures was analysed and evidence is presented that the adepithelial cells come from the disc epithelium. The question of the origin of the mesoderm of cyclorrhaphan Diptera is reviewed and it is suggested that the imaginal disc ectoderm may become segregated from the rest of the embryo before gastrulation has occurred, that is before the mesoderm has been established.

Electrophoresis of concanavalin A receptors along embryonic muscle cell membrane

Abstract: Fluorescent concanavalin A (con A)-labelling showed that an electric field of 4 V cm-1 grossly redistributed con A receptors alone the plasma membranes of living muscle cells within 4 h. This field produced a voltage drop of 12 mV across these 30 micronm-wide cells. The movement of receptors was independent of cell metabolism and seemed to be electrophoretic in nature.

Glutamate as transmitter of hippocampal perforant path.

Abstract: CERTAIN experimental manifestations of plasticity, such as habituation1–3 and long-term potentiation2,4–6, can be readily demonstrated at the perforant path-granule cell synapse in the fascia dentata, and these adaptations are believed to have behavioural counterparts. The perforant path–granule cell synapse may thus serve as a model for investigating the simplest components of behaviour and intellectual function. Detailed studies would, however, require knowledge of the transmitter used by the perforant path fibres. Quite apart from the problem of synaptic plasticity, identification of the perforant path transmitter would add substantially to our knowledge of excitatory transmitters in the central nervous system. Here we present pre- and postsynaptic evidence that these fibres use glutamate as their transmitter.

The effects of X-rays on the proliferation dynamics of cells in the imaginal wing disc ofDrosophila melanogaster.

Abstract: We report on the size distribution of clones marked by mitotic recombination induced by several different doses of X-rays applied to 72 h oldDrosophila larvae. The results indicate that the radiation significantly reduces the number of cells which undergo normal proliferation in the imaginal wing disc. We estimate that 1000 r reduces by 40–60% the number of cells capable of making a normal contribution to the development of the adult wing. Part of this reduction is due to severe curtailment in the proliferative ability of cells which nevertheless remain capable of adult differentiation; this effect is possibly due to radiation-induced aneuploidy. Cytological evidence suggests that immediate cell death also occurs as a result of radiation doses as low as 100 r. The surviving cells are stimulated to undergo additional proliferation in response to the X-ray damage so that the result is the differentiation of a normal wing.

Impaired monosynaptic potentiation in in vitro hippocampal slices from aged, memory-deficient rats.

Abstract: Neurophysiological experiments were conducted in vitro on 400 mu thick transverse hippocampal slices from aged and young rats. These slices exhibit neurophysiological responses similar to those of intact hippocampus. The aged rats have previously been found to exhibit impaired retention. Synaptic responses of the Schaffer collateral system were not found to be different between aged and young slices when elicited by very low frequency (0.3 Hz) electrical stimulation. However, the aged slices exhibited marked deficits in frequency and posttetanic potentiation in response to repetitive stimulation (15 Hz). This deficit was interpreted as resulting from an increased tendency to synaptic depression, rather than from impaired potentiation processes. The possibility of a relationship of these physiological deficits in hippocampal synaptic plasticity to the deficits in behavioral plasticity found in these aged animals is considered.

Cognitive Consequences of Traditional Apprenticeship Training in West Africa.

Abstract: By combining intensive ethnographic work with formal experiments, it is possible to demonstrate that a traditional form of education—apprenticeship training—does teach general problem-solving skills. An arithmetic test, anchored with problems drawn directly from tribal tailors' apprenticeship training, was administered to a sample of Vai and Gola tailors in Liberia. The tailors differ on tailoring experience and formal schooling characteristics. Both tailoring experience and schooling contribute strongly to arithmetic problem-solving success on unfamiliar problems.

Anatomical and functional aspects of the septo-hippocampal projections.

Abstract: The origins, distribution, and cellular targets of the septo-hippocampal projections are reviewed. It appears that the distribution of acetylcholinesterase-positive neurons in the medial septum and diagonal bands and those cells labelled after injections of horseradish peroxidase into the hippocampus coincide; however, the possibility of a non-acetylcholinesterase septal projection remains. Good agreement is found between the distribution of hippocampal acetylcholinesterase and the patterning of silver grains after injection of [3H]leucine into the medial septum. A major target of septal efferents to the hippocampus is the interneuron population; the possibility of septal mediation of intrahippocampal circuitry via this anatomical arrangement is discussed.

Budding in Hydra attenuata: Bud stages and fate map

Abstract: Ten bud stages are defined and their profiles illustrated. A fate map of the developing bud of Hydra attenuata was made using vital intracellular marking. Marks made at increasing distances from the young bud tip end up in increasingly more proximal regions of the bud. There is no major difference between the recruitment patterns of cells from above, below and lateral to the bud tip. The angular positions of cells on the parent is directly correlated with their final angular positions on the bud axis. Therefore, tissue is recruited in concentric rings around the young bud tip and is distorted directly outward into the bud column. At the youngest bud stages, the fate map of the bud extends about 180° around the parent. Tissue recruitment from the parent ends at the time that tentacle rudiments appear on the bud. Thus, tissue recruitment and hydranth morphogenesis are separate processes.

Histochemical evidence of altered development of cholinergic fibers in the rat dentate gyrus following lesions: I. Time course after complete unilateral entorhinal lesion at various ages

Abstract: The entorhinal cortex of rats was removed at various times during development, and the reaction of the cholinergic septohippocampal input to the dentate gyrus was examined by use of acetylcholinesterase histochemistry. When the ipsilateral entorhinal cortex is completely removed, the outer 70-75% of the molecular layer of the dentate gyrus is almost completely denervated. After such a lesion at 5 to 33 days of age, the acetylcholinesterase staining initially intensified throughout the denervated area, indicating that the septohippocampal fibers branched or elongated. This reaction could be detected within one day after a lesion at 11 days of age and within three or five days after lesions at earlier or later times. Whereas the initial response of the septohippocampal fibers was independent of the age at which the lesion was made, their final localization depended on the developmental state of the animal. After lesions at the age of 5 or 11 days, the reactive septohippocampal fibers became restricted to the outer one-sixth to one-third of the molecular layer within two days after appearance of their initial reaction. A similar concentration of reactive fibers was demonstrable after lesions at 16, 18 or 21 days of age, but some reaction persisted in the middle third of the molecular layer. Finally, after lesions at 26 or 33 days of age the proliferating cholinergic fibers ultimately were uniformly distributed throughout the outer 60% of the molecular layer. These results suggest that septohippocampal fibers initially extend or sprout throughout the denervated area to replace the lost perforant path fibers. However, the reactive fiber population becomes restricted to the outer edge of the molecular layer if the entorhinal lesion is made before the period of cholinergic synaptogenesis and concentrates in this same zone if it is made while cholinergic synapses are forming. We suggest that either the proliferative reaction continues in the outer part of the molecular layer and subsides in other parts of the denervated area or septohippocampal fibers move outward through the molecular layer to assume a more superficial location. After entorhinal lesions at 16 days of age or later the pale-staining zone (containing fibers that originate in hippocampus regio inferior) immediately deep to the denervated area widened. If the lesion was made earlier, this zone never developed at most septotemporal levels of the dentate gyrus. These results are probably related to the extension of regio inferior fibers into the denervated area.

Female-Female Pairing in Western Gulls (Larus occidentalis) in Southern California.

Abstract: Pairs of females that remain together from one year to the next are associated with the presence of supernormal clutches in western gull nests. Intervals between laying of eggs in supernormal clutches are less than those found in normal clutches, a result indicating both females in a pair contribute to the clutch. Most eggs in supernormal clutches are infertile. The pairs of females occupy territories that are not shared with a resident male. In three homosexual pairs one of the females exhibited behaviors normally ascribed only to males.

Ultrastructural evidence for bouton proliferation in the partially deafferented dentate gyrus of the adult rat

Abstract: A quantitative morphological study of the changes in the dentate gyrus molecular layer in response to the removal of perforant path afferents was made utilizing electron microscopic techniques. Alterations in 1. the population of remaining afferents, 2. glial cells, and 3. granule cell dendrites are reported. The major observation was an increase in intact bouton density in the region of denervation which began at 5 days post-lesion and continued through 11 days post-lesion, the longest post-lesion survival time studied.

Performance and mood during and after gradual sleep reduction.

Abstract: Long-term gradual sleep reduction effects were investigated on 4 young adult collegiate couples. The battery of assessment tools included a sleep log, Stanford Sleepiness Scale, Profile of Mood States, Feeling Tone Checklist, a measure of circadian oral temperature, Williams Word Memory test, Digit Span test, Wilkinson Auditory Vigilance task, Wilkinson Addition task, Minnesota Multiphasic Personality Inventory, Rapid Alternation task, psychiatric and medical examinations, and a subjective effects questionnnaire. It was concluded that 6–8 months of gradual sleep restriction, down to 4.5–5.5 hrs per night, does not result in behavioral effects measurable by the instruments used. Subjective fatigue appears to be the limiting factor in determining tolerability of gradual sleep restriction. At the end of an additional 12-month follow-up period, total sleep time was still 1–2.5 hrs below baseline, but measures of well-being had returned to baseline levels.

Modulation of Learning and Memory: Effects of Drugs Influencing Neurotransmitters

Abstract: Drugs have been utilized for many years as experimental tools in the analysis of the biological mechanisms underlying behavior. An assumption implicit in this approach is that an assessment of the actions of various drugs on behavior, coupled with knowledge of mechanisms of drug action, will provide important information concerning the neurobiological bases of behavior.

A stress inoculation approach to anger management in the training of law enforcement officers

Abstract: Consultation with law enforcement personnel in the area of conflict-management has typically been concerned with interpersonal rather than intrapersonal conflict. An approach to anger management that is based on cognitive self-control techniques is described as it has been used in the training of police officers. The approach follows a procedure called "stress inoculation" that has been applied to anxiety and pain (Meichenbaum, 1975). Data are presented on the anger experiences of policemen, and suggestions are offered for the selection of police candidates regarding their proneness for provocation.

Characterization of putative amino acid transmitter release from slices of rat dentate gyrus.

Abstract: — Superfused slices of the rat dentate gyrus were employed to study the release of GABA, glutamate and aspartate, which are considered strong neurotransmitter candidates in this region. The introduction of Ca2+ to a Ca2+-free superfusion medium containing a depolarizing agent augmented the efflux of all three amino acids. The response to application of Ca2+ nearly always occurred within 30 s, the shortest interval tested in these studies. The efflux rate reached a peak within 90 s and then declined to a level slightly greater than the prestimulation baseline. The failure to maintain the maximal rate with continued exposure to Ca2+ and depolarizing influences appeared not to result from a reduction in Ca2+ permeability caused by continuous depolarization. Ca2+ also stimulated the efflux of exogenously loaded radiolabeled GABA, glutamate and aspartate, but not proline. Exogenously loaded GABA was more readily released than endogenous GABA. Otherwise the effects of various treatments on their efflux rates were qualitatively similar. Mg2+ inhibited Ca2+-dependent efflux. Ba2+, but not Mg2+, stimulated amino acid efflux in the absence of Ca2+. Extracellular Na+ was not required to support Ca2+-dependent efflux. Addition of Ca2+ to a Ca2+-free medium in the absence of a depolarizing agent released GABA from the slices, but not glutamate or aspartate. K+-enriched medium and the depolarizing alkaloid, veratridine, stimulated both Ca2+-dependent and Ca2+-independent release processes. Na+-free medium enhanced the Ca2+-independent releasing action of elevated K+. Ca2+-independent release was inhibited by raising the Mg2+ concentration by 15 or 30 mM and appeared to be inhibited by Ca2+ as well. Amino acid output in the absence of Ca2+ is probably not directly related to transmission and is considered to result partially from a general increase in membrane permeability induced by depolarization in a Ca2+-free medium and partially from stimulation of carrier-mediated amino acid efflux. These results support previously suggested transmitter roles for GABA, glutamate and aspartate in the rat dentate gyrus.