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Author

Edmund M. Glaser

Other affiliations: University of Lausanne
Bio: Edmund M. Glaser is an academic researcher from University of Maryland, Baltimore. The author has contributed to research in topics: Auditory cortex & Dendrite. The author has an hindex of 19, co-authored 33 publications receiving 2150 citations. Previous affiliations of Edmund M. Glaser include University of Lausanne.

Papers
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Journal ArticleDOI
TL;DR: Exceptionally clear Golgi-Nissl sections of 300 micron thickness have been morphometrically studied by light microscopy using oil immersion objectives using a new variation of a staining procedure that combines Golgi and Nissl images in one section.

384 citations

Journal ArticleDOI
TL;DR: The degree of maturation and the differentiation of hypothalamic astrocytesin vivo are correlated with the ability of neurons to sprout branches or spines in response to steroid hormones and may underlie regionally specific differences in synaptic patterning.
Abstract: One of the more striking sexual dimorphisms in the adult brain is the synaptic patterning in some hypothalamic nuclei In the arcuate nucleus (ARC) males have twice the number of axosomatic and one-half the number of axodendritic spine synapses as females The opposite pattern is observed in the immediately adjacent ventromedial nucleus (VMN) In both cases, early exposure to testosterone dictates adult dimorphism, but the exact timing, mechanism, and site of steroid action remain unknown Astrocytes also exhibit sexual dimorphisms, and their role in mediating neuronal morphology is becoming increasingly evident Using Golgi-Cox impregnation to examine neuronal morphology and glial fibrillary acidic protein immunoreactivity (GFAP-IR) to characterize astrocytic morphology, we compared structural differences in dendrites and astrocytes from the ARC and VMN in postnatal day 2 rat pups from four hormonally different groups Consistent with previous observations, testosterone exposure induced a rapid and dramatic stellation response in ARC astrocytes Coincident with this change in astrocytic morphology was a 37% reduction in the density of dendritic spines on ARC neurons In contrast, astrocytes in the VMN were poorly differentiated and did not respond to testosterone exposure, nor were there any changes in neuronal dendrite spine density However, VMN neurons exposed to testosterone had almost double the number of branches compared with that in controls These data suggest that the degree of maturation and the differentiation of hypothalamic astrocytes in vivo are correlated with the ability of neurons to sprout branches or spines in response to steroid hormones and may underlie regionally specific differences in synaptic patterning

210 citations

Journal ArticleDOI
TL;DR: A computing light microscope has been developed that is capable of measuring accurately distances in all three coordinate axes, and analysis times are reduced from the approximately 24 hours required by camera lucida techniques and hand calculation to 30 min with this new instrument.
Abstract: Quantitative microscopic studies of individual neurons of the central nervous system, especially of their elaborate dendritic and axonal patterns, can be done only with great difficulty using conventional biological microscope instrumentation. In order to simplify and speed the gathering of such data, a computing light microscope has been developed. This instrument functions as a unit under the control of the investigator examining the histologic preparations. It is capable of measuring accurately distances in all three coordinate axes. Measurement of the length of dendrite branches is performed by means of a chord approximation. Computation is performed by means of conventional electronic analog techniques. Chord distances are computed according to the Pythagorean theorem by means of squaring, summing and square rooting. The initial coordinates of the chord are held in capacitor hold-circuits. The input to the computer section of the instrument is, by means of linear-motion transducers, fixed to the stage of the microscope along the three coordinate axes. There are two output devices, 1) a digital printer which prints on tape the distance measurements in micra (?), and 2) a plotting board on which is drawn a two-dimensional projection (in the plane of section) of the neuron. The distances measured range roughly from 3 to 100?, the accuracy of the measurement is ±l? or ±9 per cent, whichever is greater. Analysis times are reduced from the approximately 24 hours required by camera lucida techniques and hand calculation to 30 min with this new instrument.

158 citations


Cited by
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Journal ArticleDOI
TL;DR: The amplitude of the P300 component is controlled multiplicatively by the subjective probability and task relevance of eliciting events, whereas its latency depends on the duration of stimulus evaluation as mentioned in this paper.
Abstract: To understand the endogenous components of the event-related brain potential (ERP), we must use data about the components' antecedent conditions to form hypotheses about the information-processing function of the underlying brain activity These hypotheses, in turn, generate testable predictions about the consequences of the component We review the application of this approach to the analysis of the P300 component The amplitude of the P300 is controlled multiplicatively by the subjective probability and the task relevance of the eliciting events, whereas its latency depends on the duration of stimulus evaluation These and other factors suggest that the P300 is a manifestation of activity occurring whenever one's model of the environment must be revised Tests of three predictions based on this “context updating” model are reviewed Verleger's critique is based on a misconstrual of the model as well as a partial and misleading reading of the relevant literature

3,451 citations

Book
12 Aug 2005
TL;DR: In An Introduction to the Event-Related Potential Technique, Steve Luck offers the first comprehensive guide to the practicalities of conducting ERP experiments in cognitive neuroscience and related fields, including affective neuroscience and experimental psychopathology.
Abstract: The event-related potential (ERP) technique in cognitive neuroscience allows scientists to observe human brain activity that reflects specific cognitive processes. In An Introduction to the Event-Related Potential Technique, Steve Luck offers the first comprehensive guide to the practicalities of conducting ERP experiments in cognitive neuroscience and related fields, including affective neuroscience and experimental psychopathology. The book can serve as a guide for the classroom or the laboratory and as a reference for researchers who do not conduct ERP studies themselves but need to understand and evaluate ERP experiments in the literature. It summarizes the accumulated body of ERP theory and practice, providing detailed, practical advice about how to design, conduct, and interpret ERP experiments, and presents the theoretical background needed to understand why an experiment is carried out in a particular way. Luck focuses on the most fundamental techniques, describing them as they are used in many of the world's leading ERP laboratories. These techniques reflect a long history of electrophysiological recordings and provide an excellent foundation for more advanced approaches. The book also provides advice on the key topic of how to design ERP experiments so that they will be useful in answering questions of broad scientific interest. This reflects the increasing proportion of ERP research that focuses on these broader questions rather than the "ERPology" of early studies, which concentrated primarily on ERP components and methods. Topics covered include the neural origins of ERPs, signal averaging, artifact rejection and correction, filtering, measurement and analysis, localization, and the practicalities of setting up the lab.

3,416 citations

Journal ArticleDOI
TL;DR: New guidelines for recording ERPs are presented and criteria for publishing the results are presented, which allow different studies to be compared readily.
Abstract: Event-related potentials ~ERPs! recorded from the human scalp can provide important information about how the human brain normally processes information and about how this processing may go awry in neurological or psychiatric disorders. Scientists using or studying ERPs must strive to overcome the many technical problems that can occur in the recording and analysis of these potentials. The methods and the results of these ERP studies must be published in a way that allows other scientists to understand exactly what was done so that they can, if necessary, replicate the experiments. The data must then be analyzed and presented in a way that allows different studies to be compared readily. This paper presents guidelines for recording ERPs and criteria for publishing the results.

2,033 citations

Journal ArticleDOI
TL;DR: Using potential distributions generated by dipole sources in spherical volume conductor models, it is demonstrated that highly significant interactions involving electrode location can be obtained between scalp distributions with identical shapes generated by the same source.

1,807 citations

Journal ArticleDOI
TL;DR: This review focuses upon key branching points during the development of ovarian follicles as well as factors involved in determining the eventual destiny of individual follicles, and discusses inconsistencies in the literature regarding the definitions of follicle recruitment and selection.
Abstract: Mammalian ovaries consist of follicles as basic functional units. The total number of ovarian follicles is determined early in life, and the depletion of this pool leads to reproductive senescence. Each follicle develops to either ovulate or, more likely, to undergo degeneration. The dynamics of ovarian follicle development have interested endocrinologists and developmental biologists for many years. With the advent of assisted reproductive techniques in humans, the possibility of regulating follicle development in vivo and in vitro has gained clinical relevance. In this review, we focus upon key branching points during the development of ovarian follicles as well as factors involved in determining the eventual destiny of individual follicles. We discuss inconsistencies in the literature regarding the definitions of follicle recruitment and selection and propose to name the two major steps of follicle development as initial and cyclic recruitment, respectively. Because some of these disparities have arisen due to differences in the animal systems studied, we also compare the development of the ovarian follicles of both humans and rats. We also review the status of knowledge of several puzzling clinical issues that may provide important clues toward unlocking the mechanisms of follicle development.

1,501 citations