Changes of evoked potentials in lateral geniculate body and visual cortex during repetitive photic stimulation in the ‘Cerveau isolé’ cat

Riassunto La stimolazione fotica iterativa produce abitudine dei potenziali visivi nel gattocerveau isolé. La stimolazione olfattoria o l'attivazione elettrica della sostanza reticolare mesencefalica provocano risveglio elettroencefalografico e disabitudine.

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This research has been sponsored jointly by the Office of Scientific Research of the Air Research and Development Command, United States Air Force, through its European Office, under Contract No. AF 61(052)-107 and by the Rockefeller Foundation.

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Fellowship of the Italian Government. On leave from: Institut de Physiologie, Université de Louvain (Belgique).     

‘Identify’ and ‘lock in’: molecular integration during synaptic target recognition

Synaptic target recognition is a complex molecular event. In a differentiating presynaptic terminal, relatively ‘rare’ molecules first detect the cell identity of the synaptic target. Subsequently, many ‘common’ molecules continue the process of synaptogenesis. We present a theoretical framework for understanding synaptic target recognition and discuss the features of its molecular components and their integration, drawing on the rapid progress made in recent studies.     

‘Holding’ and ‘endorsing’ claims in the course of scientific activities

My principal aims are to show that holding, adopting and endorsing (definitions of which I provide) are distinct cognitive attitudes that may be taken towards claims at different moments of scientific activities, and that none of them are reducible to acceptance (as defined by Jonathan Cohen); to explore in detail the differences between holding and accepting, using the controversies about GMOs to provide illustrations; and to draw some implications pertinent to democratic decision-making concerning public policies about science and technology, and to the responsibilities that scientists thereby incur.     

‘Chromatoid body’ in the spermatogenesis of scorpions

Zusammenfassung Die von früheren Autoren als «Chromatoidkörper» bezeichnete Struktur der Spermatozoiden von Skorpionen,Palamnaeus bengalensis, ist kein wirklicher «Chromatoidkörper», sondern ein Hilfskörper lipoprotonischer Natur ohne jegliche RNA.     

Histochemistry of the so-called ‘golgi complex’ in the mammalian spermatid

Résumé L'examen histochimique des spermatides du bouc et du buffle montre que le «complexe de Golgi» des auteurs comprend l'idiosome constitué par des protéides et des lipidoprotéides, les bâtonnets et granules constitués par des phospholipides et peut-être des protéides et enfin les vacuoles.     

On factors involved in the mechanism of ‘Taste-blindness’

Zusammenfassung Der genetisch kontrollierte, hohe Geschmacksschwellenwert — Geschmacksblindheit — gegenüber Phenylthioharnstoff (PTC) und anderen bitteren, strukturell ähnlichen Anti-Schilddrüsensubstanzen, scheint durch die Qualität und Quantität des löslichen Speichel-Enzym-Systems Tyrosiniodinase bedingt zu sein.PTC-Geschmacksblinde sind «Alles-Esser», PTC-Schmecker hingegen weisen eine erhöhte kulinarische Selektivität auf. Diese Tatsache ist um so interessanter, als der Schwellenwert der beiden Gruppen gegenüber den klassischen Geschmacksqualitäten — süss, salzig, sauer und bitter — derselbe ist.     

Entropy measures of signal in the presence of noise: evidence for ‘byte’ versus ‘bit’ processing in the nervous system

Summary A method for detecting signal in the presence of noise in a highly specific was is described. Using action potential interval data from 12 neurons in rat cerebellum, we have demonstrated that the sequential ordering of spike intervals contains both noise and signal. We have identified and quantified the magnitude of relative entropy (uncertainty) for specified sets of interval patterns, ranging in length from 3–5 successive intervals. Some of these sets have exceptionally low entropy and thus seem to be especially meaningful as a set (word) to the brain.     

The classical ‘Golgi apparatus’ in the vertebrate nerve cells

Zusammenfassung Der Golgi-Apparat in den Neuronen des Rückenmarks der Wirbeltiere entsteht aus Ablagerungen von Osmium oder Silber an Nissl-Körperchen und an mit ihnen verbundenen Canaliculi und Spaltsystemen. Lipoidkörperchen und/oder Mitochondrien sind in bezug auf Bildung von sekundärer Bedeutung.     

Accentuate the negative: Locating possibility in Darwin’s ‘long argument’

Charles Darwin’s On the Origin of Species has an unusual format. After presenting his theory of Natural Selection in its first four chapters, there follows a series of five chapters presenting a large number of problems and objections to the theory which, he admits, appear overwhelming. Not until chapter 10 does he begin to present what he takes to be the positive evidence for his theory. In this paper I trace the evolution of this structure from its first hints in his Species Notebooks , through the 1842 Sketch and 1844 Essay to the Origin, showing that it reflects a growing awareness on Darwin’s part of what I call ’In Principle Impossible’ arguments against his theory, and of a systematic strategy for disarming them.     

‘Heated’ Debates in Apoptosis

Hippocrates’ assertion that ‘what the lance does not heal, fire will’ underscores the fact that for thousands of years heat has been used to treat a variety of diseases, including cancer. Indeed, spontaneous tumor remission has been observed in patients following feverish infection [1], and expression of activated oncogenes, such as Ras, can render tumor cells sensitive to heat compared with normal cells [2, 3]. In the past, a primary drawback to the use of heat as a clinical therapy was the inability to selectively focus heat to tumors in situ. Of late, however, several approaches have been devised to deliver heat more precisely, including the use of heated nanoparticles, making hyperthermia a more clinically tractable treatment option [4, 5]. Despite these practical advances, the mechanisms responsible for heat shock-induced cell death remain controversial and ill-defined. In this Visions and Reflections we discuss recent findings surrounding the initiation of heat shock-induced apoptosis, and propose future areas of research. Received 17 March 2007; received after revision 25 April 2007; accepted 22 May 2007     

Spectrin and calpain: a ‘target’ and a ‘sniper’ in the pathology of neuronal cells

It is well documented that activation of calpain, a calcium-sensitive cysteine protease, marks the pathology of naturally and experimentally occuring neurodegenerative conditions. Calpain-mediated proteolysis of major membrane-skeletal protein, αII-spectrin, results in the appearance of two unique and highly stable breakdown products, which is an early event in neural cell pathology. This review focuses on spectrin degradation by calpain within neurons induced by diverse conditions, emphasizing a current picture of multi-pattern neuronal death and a recent success in the development of spectrin-based biomarkers. The issue is presented in the context of the major structural and functional properties of the two proteins.Received 7 March 2005; received after revision 22 April 2005; accepted 13 May 2005     

Transplantation and ‘cross-transplantation’ of free muscle grafts in the rat

Zusammenfassung Nachweis, dass ein frei transplantierter Rattenmuskel besser regeneriert, wenn er 14 Tage vor der Transplantation denerviert wurde.

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Work performed during an exchange between the Czechoslovak and US Academies of Sciences and supported in part by a grant from the MDAA.     

Nucleolus organizer region location and ‘ring’ chromosomes in the bharal

Summary Silver-staining has been used to identify the nucleolus organizer regions (NORs) in the bharal. These show homology with sheep, goat, cattle and aoudad. The association of the NORs on both telomeres of chromosome 3 results in a ring chromosome.     

‘Pitfalls’ in immune electron microscopy

Zusammenfassung Es werden die Fehlerquellen diskutiert, die bei der Untersuchung von Antigenen auftreten, wenn zu deren elektronenmikroskopischer Darstellung Antikörper, markiert mit Ferritin, verwendet werden. Durch geeignete Wahl der Fixierung können einige dieser Schwierigkeiten beseitigt werden.     

Natural selection and the ‘antiquity of man’: Intellectual impacts in the Australian colonies

Two months before the publication of Charles Darwin's On the Origin of Species (1859), Scottish geologist Charles Lyell announced a consensus on ‘the antiquity of man.’ Although stemming from separate intellectual traditions, human antiquity and natural selection had such a powerful influence on nineteenth century science that the former is often thought to be an inevitable conceptual and chronological consequence of the latter. Various scholars have argued it was in fact the acceptance of human antiquity that provided a foundation for the intelligibility and eventual acceptance of evolution by natural selection. This article investigates how these two interwoven theories affected understandings of human antiquity in Australia; itself an under-examined topic in Australian scholarship. Indeed, most historians maintain Australia's human antiquity was not ‘discovered’ or broadly understood until the advent of radiocarbon dating and professional archaeology in the 1960s. This over-simplified narrative has only recently begun to be reassessed. To contribute to this reassessment, and to the broader reclamation of human antiquity as a historical subject, this article focuses on the early decades of human antiquity's dissemination in Australia, examines its complex relationship with natural selection, and ultimately challenges narratives of its ‘recent’ discovery.     

Quantitative investigation of the P and N loss in the rat liver when using various media in the ‘freeze-substitution’ technique

Résumé Les auteurs ont examiné les possibilités de diminution du contenu en azote et phosphore et de la masse sèche au cours de la congelation-dissolution des tissus. La diminution la plus marquée a été observée après l'usage de méthanol. Tandis qu'avec l'acétone elle est insignifiante.