Leo S. Demski

Bio: Leo S. Demski is an academic researcher from New College of Florida. The author has contributed to research in topics: Terminal nerve & Midbrain. The author has an hindex of 24, co-authored 49 publications receiving 1960 citations. Previous affiliations of Leo S. Demski include City University of New York & University of South Florida Sarasota–Manatee.

The terminal nerve: a new chemosensory system in vertebrates?

Abstract: Ganglion cells of the terminal nerve in goldfish are located in the olfactory nerve and bulb and send peripheral processes into the olfactory epithelium and central processes to the supracommissural nuclei of the telencephalon as well as to the retina. Correlations between terminal nerve projections and neurobehavioral studies suggest that the terminal nerve mediates responses to sex pheromones.

The Evolution of Neuroanatomical Substrates of Reproductive Behavior: Sex Steroid and LHRH-Specific Pathways Including the Terminal Nerve

Abstract: Fairly recent anatomical methods have made possible the mapping of neurobehavioral systems involving two types of reproductive hormones, gonadal steroids and the peptide luteinizing hormone releasing hormone (LHRH). Brain sites of steroid uptake are detected using autoradiography; LHRH is localized in cells and fibers using immunocytochemical procedures. Both hormone types are known to strongly influence sex behavior and it can reasonably be assumed that these effects are mediated in large part via systems identified using the anatomical procedures. Analysis of the comparative anatomy of these systems should therefore provide information useful in the construction of models concerning the evolution of neurohormonal control of reproductive behavior. The results of such a study are reported. Sex steroid and LHRH systems in cyclostomes, teleosts, amphibians, reptiles, birds and mammals are considered in detail. A synthesis of this information has led to the following ideas. Androgenic control of male reproductive systems has evolved in a number of nonhomologous motor systems controlling male reproductive behavior. Sex steroid and LHRH systems may interact at several different levels of the neuraxis but the most obvious overlap of the systems occurs in the septal and POA areas. The latter especially is a fairly constant and perhaps primitive feature. LHRH secretion into the systemic circulation was most likely the earliest means for LHRH modulation of both pituitary function and neural systems controlling reproductive behavior.Pathways for more direct delivery of LHRH to pituitary cells and brain nuclei probably developed in the early gnathostomes. The terminal nerve appears to be a rather conservative LHRH-containing pathway connecting olfactory systems with septal-preoptic nuclei. A function in pheromonal control of sex behavior is suggested. The general distribution of steroid concentrating cells and LHRH pathways in tetrapods seems to be rather constant. Absence of the systems in neocortical areas and their homologs is conspicuous.

Localization of immunoreactive tyrosine hydroxylase in the goldfish brain

Abstract: This report describes the distribution of tyrosine hydroxylase immunoreactive (TH-ir) structures in the brain of the goldfish (Carassius auratus). The localization of TH-ir cell groups revealed by immunocytochemical techniques is largely in accordance with catecholamine distribution previously reported in teleosts by using monoamine fluorescence; however, in the telencephalon and diencephalon, several new cell groups are elucidated. In the telencephalon, TH-ir cell bodies are observed in the olfactory bulb, area ventralis telencephali, and the central zone of the area dorsalis telencephali. TH-ir fibers and terminals are moderately dense throughout the telencephalon except for a sparse innervation of the area dorsalis, pars medialis. Immunostained cells are present in the suprachiasmatic nucleus and magnocellular and parvicellular components of the preoptic nucleus. Immunoreactive fibers from preoptic cells can be traced caudally in two main tracts to the infundibulum. Dense immunoreactivity around cells in the pituitary provides anatomical support for catecholamine involvement in the neuroendocrine axis probably via preopticohypophysial connections. At middiencephalic levels, immunoreactive cells are present in the ventral thalamus, nucleus pretectalis periventricularis, pars ventralis, and paraventricular organ pars anterioris. In the caudal diencephalon, TH-ir cells are seen within the posterior tuberal nuclei and dorsal to posterior recess. No immunostained cells are observed in the midbrain. In the hindbrain, tyrosine hydroxylase containing cells comprise three groups similar to that described using Falck-Hillarp histofluorescence (Parent et al., ′78), i.e., isthmal, central medullary, and medullospinal groups. Tyrosine hydroxylase immunoreactivity is interpreted as evidence for the presence of catecholamines and not only provides an anatomical basis for the functional significance of catechol amines in teleosts, but may be useful in elucidating homologous structures in tetrapod vertebrates, although certain sites of immunoreactivity may prove to be unique to teleosts.

The reproduction and development of sharks, skates, rays and ratfishes: introduction, history, overview, and future prospects

Abstract: This volume had its origin in aSymposium on the Reproduction and Development of Cartilaginous Fishes that was held at the annual meetings of the American Elasmobranch Society and the American Society of Ichthyologists and Herpetologists in Charleston, South Carolina in June 1990. The aim of this symposium was to bring together many of those scientists interested in chondrichthyan reproduction and development in order to assess the current state of knowledge in these fields.

The Nervous System

Abstract: Experimental Neurology By Prof Paul Glees Pp xii + 532 (Oxford: Clarendon Press; London: Oxford University Press, 1961) 75s net

Diversity of life

Abstract: It is clear that the above can lead to confusion when scientists of different countries are trying to communicate with each other. Another example is the burrowing rodent called a gopher found throughout the western United States. In the southeastern United States the term gopher refers to a burrowing turtle very similar to the desert tortoise found in the American southwest. One final example; two North American mammals known as the elk and the caribou are known in Europe as the reindeer and the elk. We never sing “Rudolph the Red-nosed elk”! Confused? This was the reason for creating an internationally recognized system of naming organisms. To avoid confusion, living organisms are assigned a scientific name based on Latin or Latinized words. The English sparrow is Passer domesticus or Passer domesticus (italics or underlining these two names is the official written representation of a scientific name). Using a uniform naming system allows scientists from all over the world to recognize exactly which life form a scientist is referring to. The naming process is called the binomial system of nomenclature. Passer is comparable to a surname and is called the genus, while domesticus is the specific or species name (like your given name) of the English sparrow. Now scientists can give all sparrow-like birds the genus Passer but the species name will vary. All similar genera (plural for genus) can be grouped into another, “higher” category (see below). Study the following for a more through understanding of taxonomy. Taxonomy Analogy Kingdom: Animalia Country

The Vertebrate Eye and Its Adaptive Radiation.

Abstract: The new Conductivity Bridge derives its bridge source. voltage from a self-contained vacuum tube oscilltor adjusted to approximately 1,000 cycles. Voltage for the amplifier and null indicator tubes is provided by a.builtin D.C. power supply which operates directly from the A.C. power source. 9-324 Conductivity Bridge, without Conductivity Cell, for use with 110 volts 5060 cycle A.C. 9-351.Cosi~uCvity Cell, for use with Conductivity Bridge, constant 0.8, $20.00

µ-MAR

Abstract: A novel method, µ-MAR, able to both coarse and fine register 3D point sets.The method overcomes noisy data problem using model based planes registration.µ-MAR iteratively registers a 3D markers around the object to be reconstructed.It uses a variant of the multi-view registration with subsets of data.Transformations to register the markers allow to reconstruct the object accurately. Many applications including object reconstruction, robot guidance, and. scene mapping require the registration of multiple views from a scene to generate a complete geometric and appearance model of it. In real situations, transformations between views are unknown and it is necessary to apply expert inference to estimate them. In the last few years, the emergence of low-cost depth-sensing cameras has strengthened the research on this topic, motivating a plethora of new applications. Although they have enough resolution and accuracy for many applications, some situations may not be solved with general state-of-the-art registration methods due to the signal-to-noise ratio (SNR) and the resolution of the data provided. The problem of working with low SNR data, in general terms, may appear in any 3D system, then it is necessary to propose novel solutions in this aspect. In this paper, we propose a method, µ-MAR, able to both coarse and fine register sets of 3D points provided by low-cost depth-sensing cameras, despite it is not restricted to these sensors, into a common coordinate system. The method is able to overcome the noisy data problem by means of using a model-based solution of multiplane registration. Specifically, it iteratively registers 3D markers composed by multiple planes extracted from points of multiple views of the scene. As the markers and the object of interest are static in the scenario, the transformations obtained for the markers are applied to the object in order to reconstruct it. Experiments have been performed using synthetic and real data. The synthetic data allows a qualitative and quantitative evaluation by means of visual inspection and Hausdorff distance respectively. The real data experiments show the performance of the proposal using data acquired by a Primesense Carmine RGB-D sensor. The method has been compared to several state-of-the-art methods. The results show the good performance of the µ-MAR to register objects with high accuracy in presence of noisy data outperforming the existing methods.

A Standardized Terminology for Describing Reproductive Development in Fishes

Abstract: As the number of fish reproduction studies has proliferated, so has the number of gonadal classification schemes and terms. This has made it difficult for both scientists and resource managers to communicate and for comparisons to be made among studies. We propose the adoption of a simple, universal terminology for the phases in the reproductive cycle, which can be applied to all male and female elasmobranch and teleost fishes. These phases were chosen because they define key milestones in the reproductive cycle; the phases include immature, developing, spawning capable, regressing, and regenerating. Although the temporal sequence of events during gamete development in each phase may vary among species, each phase has specific histological and physiological markers and is conceptually universal. The immature phase can occur only once. The developing phase signals entry into the gonadotropin-dependent stage of oogenesis and spermatogenesis and ultimately results in gonadal growth. The spawning cap...