Showing papers by "Boston University published in 1972"
TL;DR: The morphological characteristics of Class III, Golgi Type II neurons are analyzed in Golgi impregnations of the lateral geniculate nucleus in the cat with special attention given to the complex dendritic appendages of these cells, the multilobed dendrite terminals.
Abstract: The morphological characteristics of Class III, Golgi Type II neurons are analyzed in Golgi impregnations of the lateral geniculate nucleus (LGN) in the cat with special attention given to the complex dendritic appendages of these cells, the multilobed dendritic terminals In addition, electron microscopic studies demonstrate the presence of presynaptic dendritic (ID) terminals as major components of synaptic glomeruli Electron microscopic analysis of serial thin sections confirm the dendritic origin and the complex, multilobed nature of these terminals An hypothesis is proposed identifying the ID terminal with the multilobed dendritic terminals of light microscopically identified Class III cells and the IA terminal, the “peripheral axon” of the glomerulus, with the axonal endings of all Golgi Type II cells
The Class III neuron has a short axon ramifying near the cell of origin The axon terminates in boutons en passant and boutons terminaux: single, bilobed or “claw-like” endings Optic axons terminate not in “claw-like” fashion, as previously thought, but in club-shaped endings with scalloped silhouettes The principal dendrites of Class III cells are characterized by long-stalked appendages, often multilobed and occurring at the end of preterminal stalks 5 to 100 μ in length One impregnated multilobed terminal studied in the electron microscope was found to innervate two adjacent glomeruli
The relationship of ID terminals to optic axon terminals and to other processes in synaptic glomeruli is analysed with the aid of the electron microscope The ID terminal contains vesicles of the same size as those in presynaptic dendrites and makes small, macular synaptic contacts with other pre- and postsynaptic dendrites ID terminals are the only elements in the LGN which synapse on others of their own kind, and are postsynaptic to all types of axon identified As the only postsynaptic processes containing synaptic vesicles in the dorsal layers of the LGN, they support the conclusion that there are no axo-axonic synapses in these layers The ID terminal, the optic terminal and spinous dendrites originating presumably from geniculo-cortical relay (GCR) cells, are seen to enter into a triadic relationship characteristic of the synaptic glomerulus in which the presynaptic dendrite synapses on the spinous dendrites and the optic terminal synapses on both dendrites ID terminals reconstructed from serial sections communicate as “internuncial” presynaptic dendrites between optic central axons in adjacent synaptic glomeruli IA terminals, which like ID terminals contain flattened vesicles, are presynaptic to ID terminals, as well as to postsynaptic dendrites, cell somata and axon initial segments
A model for the internuncial character of multilobed dendritic terminals and the potential for inhibition of Golgi Type II axon terminals is proposed, and theories about the function of Golgi Type II cells in lateral geniculate transmission are briefly considered
375 citations
TL;DR: In this paper, the entorhinal cortex is found to be a major contributor of afferents to the hippocampus and dentate gyrus, but knowledge of its own afferent connections has been vague.
Abstract: Although the entorhinal cortex is a major contributor of afferents to the hippocampus and dentate gyrus, knowledge of its own afferents has been vague. Regions of both the frontal and temporal lobes were found to contribute afferents to this region of the brain. These afferents form probable multisynaptic links in pathways connecting the classical sensory areas of the cortex and the limbic system.
373 citations
TL;DR: The object of this study was to determine the water content of pulpless teeth as one of the possible factors contributing toward tooth brittleness.
296 citations
TL;DR: There appears to be a critical period during which the walking response can be transformed intac from a reflexive to an instrumental action.
Abstract: Brief daily exercise of the walking and placing reflexes in the newborn leads to a high rate of responding by 8 weeks and to an earlier onset of walking alone. There appears to be a critical period during which the walking response can be transformed intac from a reflexive to an instrumental action.
268 citations
TL;DR: Four adult male rhesus monkeys were provided access individually to a group of receptive females and each male assumed dominance and engaged in frequent copulations, and plasma testosterone levels increased two- to threefold during this period.
Abstract: Four adult male rhesus monkeys were provided access individually to a group of receptive females. Each male assumed dominance and engaged in frequent copulations. Plasma testosterone levels increased two- to threefold during this period. Next, each male was subjected to sudden and decisive defeat by a large all-male group, and plasma testosterone fell following this experience. Two males were later reintroduced to the females, and plasma testosterone rose rapidly to the previous elevated levels.
254 citations
TL;DR: The article follows the conceptual path forced by the synchronization problem, which leads to a reinforcement theory whose network realizations define explicit drive, reinforcement, and incentive motivational concepts.
Abstract: This article continues where section VIII of Chapter 4 leaves off. The article is filled with psychopharmacological predictions, some of which have since been confirmed. Others still need to be tested. The article follows the conceptual path forced by the synchronization problem. It leads to a reinforcement theory whose network realizations define explicit drive, reinforcement, and incentive motivational concepts.
239 citations
TL;DR: It is suggested that expressive agrammatism is only one aspect of an impairment involving all language modalities, and while normal subjects are often constrained by surface syntactic properties, agrammatic patients operate on a hierarchical scheme that excludes anything nonessential to the intrinsic meaning of a sentence.
221 citations
TL;DR: The data suggest that the ventral cochlear nucleus may be a complex of sub-nuclei each of which has its own set of output projections which arborize in periolivary cell groups of the superior olivary complex both ipsilaterally and contralaterally.
213 citations
TL;DR: In the parietal cortex of the rat, sections cut tangentially show that profiles of medium and large apical dendrites are grouped into clusters, and it is clear that the superior aspects of the cluster arrangements must intermingle with those of the neurons in adjacent clusters.
Abstract: In the parietal cortex of the rat, sections cut tangentially show that profiles of medium and large apical dendrites are grouped into clusters. The number of apical dendrites in each cluster is variable and the usual separation between individual clusters is about 50 μ. Despite these variations the pattern does not appear to be random. Reconstructions from one micron serial sections show that neurons giving rise to the ascending dendrites forming clusters are located at different levels in layer V. The cell bodies of these neurons are arranged vertically below their dendrites and show a tendency to form groups. All of the neurons have apical dendrites that ascend through the cortex with a few secondary branches occurring close to the base. The principal secondary branching begins in layer III and spreads obliquely up through layer I. Furthermore, beginning in the inferior region of layer III apical dendrites are added to the clusters at their peripheries. These are from layer III pyramids. It is clear that the superior aspects of the cluster arrangements must intermingle with those of the neurons in adjacent clusters. The neuropil surrounding the dendrites forming clusters appears to contain a few smaller dendrites. Small unmyelinated axons are the most frequent component of the surrounding neuropil and these form terminals which synapse on the spines and trunks of the clustered dendrites. There is no obvious function that can be ascribed to the clusters other than they may form a component of the columnar organization in cortex described in part by physiological techniques.
210 citations
TL;DR: An autoradiographic study of the development of 26 nuclei in the rat hypothalamus was made by injecting pregnant rats on different days of pregnancy with tritiated thymidine, finding laterally placed nuclei were found to arise on the fourteenth day of gestation while medial nuclei, in general, arose on day 16.
Abstract: An autoradiographic study of the development of 26 nuclei in the rat hypothalamus was made by injecting pregnant rats on different days of pregnancy with tritiated thymidine. The offspring were killed postnatally and the day of gestation on which peak percentages of heavily labeled neurons occurred was considered to be the birthdate of that nucleus. Postnatal animals for the first nine days were injected and were also included in the study. Laterally placed nuclei were found to arise on the fourteenth day of gestation while medial nuclei, in general, arose on day 16. Final cell divisions occurred over a period of time but the majority took place on the days indicated. Apparently a lateromedial gradient exists in the hypothalamus, and possibly a dorsoventral gradient.
209 citations
TL;DR: In this article, the impact of shelf space changes on unit sales was studied and space elasticity was hypothesized to be a function of several product-specific variables, including physical properties, merchandising c...
Abstract: In studying the impact of shelf space changes on unit sales, space elasticity was hypothesized to be a function of several product-specific variables, including physical properties, merchandising c...
TL;DR: Attention by the pediatrician to the prevention and early treatment of these “defects” is urged.
TL;DR: In this paper, the authors discuss how parameters of a cooperative advertising arrangement are currently decided upon and present decision models which demonstrate that quantitative analysis can lead to a bet on a game.
Abstract: This article discusses how parameters of a cooperative advertising arrangement are currently decided upon and presents decision models which demonstrate that quantitative analysis can lead to a bet...
TL;DR: Clinically no correlation other than duration of disease could be made with the metabolic findings, and whether these data may be explained by an abnormal genetic linkage between Huntington's chorea and carbohydrate intolerance, or by a primary imbalance of biogenic amines is not yet established.
TL;DR: A correlation is made between the extent of thecal development and the incidence of granulosa cell nexuses in follicles of normal as well as hypophysectomized rats and an intercellular junction thought to play an important role in communication is placed on.
Abstract: . Ultrastructural responses of ovarian granulosa cells to exogenous estrogen have been investigated in immature rats. Animals, 21-daysold, were hypophysectomized and a regimen of 6 daily injections was initiated 30 hr after the operation. Some rats received sesame oil only and others were given totals of 3 or 6 mg diethylstilbestrol (DES). Ovarian tissues were prepared for microscopy 24 hr after the last injection. In addition, normal rats were sacrificed at 21 days to monitor ovarian morphology at the time of hypophysectomy. Rapid simultaneous changes, occurring in cells of the pre-ovulatory rat follicle, suggest a necessity for cell communication, particularly in the multilayered avascular granulosa. Therefore, emphasis is placed on an intercellular junction (the nexus) thought to play an important role in communication. A correlation is made between the extent of thecal development and the incidence of granulosa cell nexuses in follicles of normal as well as hypophysectomized rats. If the “thec...
TL;DR: The presence of a large number of epithelio-mesenchymal contact sites during the period of rapid growth and differentiation of duodenal mucosa may reflect epithelion-meschymal cell interactions which may facilitate the maturation of the duodentum mucosa.
Abstract: In fetal rats 5–7 days before birth, the duodenal epithelium is separated from mesenchymal cells by a well-defined basal lamina. By 3–4 days before birth, when small rudimentary villi are first seen, direct contact between epithelial and mesenchymal cells occurs by means of epithelial cell cytoplasmic processes which project through gaps in the basal lamina into the lamina propria. At contact sites, the epithelial and mesenchymal cell plasma membranes were less than 100 A apart but membrane fusion was not seen. In number and size these epithelial cell processes increase strikingly during the last 2 days of gestation, and they persist in large numbers until 7–10 days after birth. Thereafter, they decrease gradually in both number and size until 3–4 wk after birth, when the morphology of the epithelio-mesenchymal interface resembles that seen in adult rats, i.e., there are only rare epithelial cell processes which penetrate deeply into the lamina propria. The presence of a large number of epithelio-mesenchymal contact sites during the period of rapid growth and differentiation of duodenal mucosa may reflect epithelio-mesenchymal cell interactions which may facilitate the maturation of the duodenal mucosa.
TL;DR: A large number of tumors form antigens thought to be "specific" — i.e., not present in nonmalignant tissues or present in lesser or inconsequential amounts, but detected in minute amounts by immunochemical methods.
Abstract: MALIGNANT tumors form antigens thought to be "specific" — i.e., not present in nonmalignant tissues or present in lesser or inconsequential amounts. Immunochemical methods detect minute amounts of ...
TL;DR: Neural networks are introduced which can be taught by classical or instrumental conditioning to fire in response to arbitrary learned classes of patterns, and some adaptation mechanisms, and arousal mechanisms for crispening the pattern weights that can fire a given cell, are noted.
Abstract: Neural networks are introduced which can be taught by classical or instrumental conditioning to fire in response to arbitrary learned classes of patterns. The filters of output cells are biased by presetting cells whose activation prepares the output cell to “expect” prescribed patterns. For example, an animal that learns to expect food in response to a lever press becomes frustrated if food does not follow the lever press. It's expectations are thereby modified, since frustration is negatively reinforcing. A neural analog with aspects of cerebellar circuitry is noted, including diffuse mossy fiber inputs feeding parallel fibers that end in Purkinje cell dendrites, climbing fiber inputs ending in Purkinje cell dendrites and giving off collaterals to nuclear cells, and inhibitory Purkinje cell outputs to nuclear cells. The networks are motivated by studying mechanisms of pattern discrimination that require no learning. The latter often use two successive layers of inhibition, analogous to horizontal and amacrine cell layers in vertebrate retinas. Cells exhibiting hue (in)constancy, brightness (in)constancy, or movement detection properties are included. These results are relevant to Land's retinex theory and to the existence of opponent- and nonopponent-type cell responses in retinal cells. Some adaptation mechanisms, and arousal mechanisms for crispening the pattern weights that can fire a given cell, are noted.
01 Apr 1972
TL;DR: In this article, the authors present a survey of teaching styles and approaches based on adult learning for the 1970s and 1980s in the context of education for social work (ESW).
Abstract: (1972). Innovations in Teaching Styles and Approaches Based upon Adult Learning. Journal of Education for Social Work: Vol. 8, No. 2, pp. 32-39.
TL;DR: With these bounds it becomes possible to study the effect of element geometry, the order of interpolation functions and other intrinsic and discretization parameters on Cn(K) and to isolate the factors that may lead to ill-conditioning.
Abstract: N a previous Note1 it has been shown (see also Refs. 2 and 3) that the spectral condition number Cn(K) of the global (stiffness) matrix K arising from a uniform mesh of finite elements (or of finite differences) discretization can be expressed by Cn(K) = cNes2m where 2m is the order of the differential equation and c a coefficient independent of Nes, the number of elements per side, but dependent on the order of the interpolation polynomials inside the element. This condition is "natural", since it is inherently associated with the approximation of the continuous problem by the discrete (algebraic) one. Nonuniform meshes of finite elements introduce many additional factors which may adversely affect the condition of the system. It is the purpose of this Note to describe a technique for establishing bounds on the condition number for irregular meshes of finite elements. With these bounds it becomes possible to study the effect of element geometry, the order of interpolation functions and other intrinsic and discretization parameters on Cn(K) and to isolate the factors that may lead to ill-conditioning. The matrix K is termed ill-conditioned when \Q~sCn(K) = 1, where s denotes the number of decimals in the computer. The bounds on Cn(K) are expressed in terms of the extremal eigenvalues of the element matrices. Since the element matrices are of restricted size, derivation of the bounds on Cn(K) as a function of the discretization parameters become straightforward for any problem and any element. Particular attention is focused on the possibility of improving the condition of the matrix by scaling. Bounds on the Extremal Eigenvalues
TL;DR: MUELLER et al. as mentioned in this paper found that 4-year-olds almost always displayed social interest and usually received replies to the things they said in free play and that the maintenance of verbal interaction was multidetermined.
Abstract: MUELLER, EDWARD. The Maintenance of Verbal Exchanges between Young Children. CmLD DEVELOPMENT, 1972, 43, 930-938. Although spontaneous verbal interaction among preschool children is reputed to be limited as the result of their egocentrism, a direct examination revealed that 4-year-olds almost always displayed social interest and usually received replies to the things they said in free play. The maintenance of verbal interaction was found to be multidetermined; however, when many causative factors operated in 1 direction, the outcome was perfectly predictable. The 2 most powerful predictors of whether a given message would receive a reply were its technical quality and the visual attention of the listener at its beginning.
TL;DR: It is concluded that the patient with Broca’s aphasia and agrammatism does not have a consistent simplified grammar, nor does his performance represent an economy of effort, but rather it is an effort to approximate his residual knowledge of standard English.
TL;DR: Differentiating mitral cells were followed in serial section analysis of mouse embryos from day 12 of gestation (E12) to E14 and the first identified young neurons (postmitotic neuroblasts) were seen at E12.
Abstract: Differentiating mitral cells were followed in serial section analysis of mouse embryos from day 12 of gestation (E12) to E14. Animals at E11 and E15 were also examined. Olfactory nerve axons reach the presumptive olfactory bulb at E12 and many penetrate deeply into the intermediate (mantle) layer at this time. The first identified young neurons (postmitotic neuroblasts) were also seen at E12. Many had a tangential orientation, and they occurred only in the region where olfactory nerve axons were present. Olfactory nerve axons (and also mitral cell axons formed later) are characterized by numerous longitudinallyoriented microtubules and an extensive system of transversely and longitudinallyorinted cisternae of smooth endoplasmic reticulum (SER). Near the growing tips of olfactory nerve axons, the microtubules disappear and the SER becomes more extensive and irregular.
The four stages of early mitral cell differentiation determined in the companion paper (Hinds, '72) were confirmed by electron microscopic analysis. In the earliest cells of the primitive radial stage few organelles occur in the perikaryon, but in later cells of this stage and in cells of the pre-axonic tangential stage a Golgi complex and a pair of centrioles occurs on one side of the nucleus at the base of the largest tangential process, thus determining a cell polarity within the tangential plane. This initial polarity at E12 seems to be random and unrelated to the polarity attained when axon outgrowth occurs at E13 and E14, suggesting a re-orientation prior to axon outgrowth. The growing tips of primitive tangential processes were studied and compared with those of growing primitive radial processes and growing axons.
TL;DR: Results suggest that both increased sensitivity to interference and a failure to verbally encode new information are involved in the Korsakoff patient's memory deficits.
TL;DR: The method is extremely sensitive: tritium-labeled digest derived from less than 1 μg of polynucleotide is required to evaluate the base composition, including most of the so-called minor or modified bases which are natural constituents of RNA.
TL;DR: Patients with left-frontal, right-parietal, and right or left temporal-lobe damage were tested on two spatial tasks that involved either personal or extrapersonal spatial rotations, and results indicated a lesion-space dichotomy.
Abstract: Patients with left-frontal, right-parietal, and right or left temporal-lobe damage were tested on two spatial tasks that involved either personal or extrapersonal spatial rotations. The results indicated a lesion-space dichotomy: the left-frontal patients were the most impaired group on the personal spatial task while the right-parietals were the most impaired on the extrapersonal spatial test. The temporal-lobe patients had little, if any, difficulty with either task. These data support the hypothesis that the frontal and parietal regions mediate qualitatively different spatial capacities.
TL;DR: Olfactory bulb development in mouse embryos from day 10 of gestation (E10 to E15) was studied with 1 μ plastic sections and Golgi impregnations.
Abstract: Olfactory bulb development in mouse embryos from day 10 of gestation (E10) to E15 was studied with 1 μ plastic sections and Golgi impregnations. Olfactory nerve axons reach the presumptive olfactory bulb region of the cerebral vesicle at E12, the same time that the first young neurons (postmitotic neuroblasts) are seen in the newly-formed intermediate (mantle) layer. By E14 many of the presumptive mitral cells are oriented tangential to the surface and have grown a long axon that enters the lateral olfactory tract on the surface of the presumptive piriform cortex.
The following probable sequence of differentiation of mitral cells was determined from Golgi impregnations of E14 and E15 animals: (1) After regrowth of an internal and external process following rounding up at mitosis, the nucleus and perikaryon of certain ventricular cells migrate into the deepest portion of the intermediate layer and start to re-orient into a tangential orientation. This stage is called the primitive radial stage.(2) The growth of tangential processes combined with withdrawal or atrophy of external and internal primitive radial processes follows to produce cells in the pre-axonic tangential stage. (3) The tangential cells then acquire a long, thin, unbranched process (axon) oriented towards the lateral olfactory tract and a larger, branching process (dendrite) running in the opposite direction. This stage is called the tangential mitral cell stage. (4) Radial re-orientation of the perikaryon and dendrites of these cells and external migration of the perikaryon results in cells in the radial mitral cell stage.