Claude Debru

Helmholtz and the Psychophysiology of Time

After having measured the velocity of the nervous impulse in the 1850s, Helmholtz began doing research on the temporal dimensions of visual perception. Experiments dealing with the velocity of propagation in nerves (as well as with aspects of perception) were carried out occasionally for some fifteen years until their final publication in 1871. Although the temporal dimension of perception seems to have interested Helmholtz less than problems of geometry and space, his experiments on the time of perception were technically rather subtle and seminal, especially compared with experiments performed by his contemporaries, such as Sigmund Exner, William James, Rudolf Hermann Lotze, Ernst Mach, Wilhelm Volkmann, and Wilhelm Wundt. Helmholtzs conception of the temporal aspects of perception reflects the continuity that holds between psychophysiological research and the Kantian philosophical background.

Genetics and Neuroscience

Neurogenetics is a more recent research field than neuroscience. It is characterized by the introduction of genetical techniques and techniques of molecular biology in many fields like the study of learning and memory, language, pathology etc. The field of neurogenetics merges increasingly with biological psychology. In this paper, early studies by Eric Kandel showing the dependency of long term memory on a switch of genes which enhance the learned response, as well as later studies of learning using molecular biology techniques are discussed. Sleep physiology and pathology is discussed with special emphasis on Michel Jouvet’s reprogramming theory of paradoxical sleep, which insists on the potential regulatory function of paradoxical sleep on the interaction between genetic and epigenetic features, providing a possible answer to the nature–nurture controversy

On the usefulness of the history of science for scientific education

My purpose in this, the Claude Bernard Lecture, is to convince myself as well as my audience of something that is very difficult to demonstrate, the relevance of history in a culture of innovation. This is a puzzling and challenging point. Contemporary scientific culture is based on the cult of the newer and the unexpected, which are rightly considered to be better and more promising. In what way may the knowledge of the scientific past contribute to the understanding of present science and prepare young minds to be active investigators of nature? The practice of history may appear to be a withdrawal from reality, paving the way for a very bookish and progress–preventing view of the world, just as Aristotelian physics were for centuries. Natural science took a new start when scientists realized that they should learn from nature rather than from books. There are very sound reasons why science does not need history, and many prominent scientists have, at times, expressed reluctant opinions regarding the value of the history of science for the active scientist. ‘Science is revolutionary’, said Claude Bernard. This forceful statement may be interpreted as a final condemnation of history, and there is nothing to add to it, because it is simply true. Authors of major scientific revolutions like Darwin held similar views.

Is symmetry conservation an unessential feature of allosteric theory

The role of symmetry in allosteric theory is historically and philosophically revisited. The (at least approximate) symmetry of the hemoglobin binding curves led investigators to postulate a similar symmetry or equivalence in the binding sites, which meant a symmetrical arrangement of the hemes and of the whole molecule. Later Monod introduced the concept of symmetry conservation to describe allosteric behaviour. It is shown that this postulate does not really belong to the framework of allosteric theory as it was developed in thermodynamical terms. Symmetry, however, still plays a role at levels in the underlying mathematical theory of binding and linkage in biological macromolecules.

Increase of paradoxical sleep episodes after electrical stimulation of the lateral and third ventricles in the rat

Electrical stimulation (0.3 mA in intensity, 80 Hz in frequency, 0.7 ms in signal duration) applied at 17.00 h in the lateral and third ventricles induced a significant increase of nocturnal paradoxical sleep (PS). This effect persisted for two consecutive days in both cases. Non-specific aspects involved in this effect are discussed and the results are commented on in terms of humoral processes and possible control of pineal gland activity.

Michel Jouvet: a personal and philosophical tribute

Major events in the long history of paradoxical sleep research, such as the crisis of the monoaminergic theory of sleep, as well as subsequent discoveries and theoretical functional hypotheses, are presented from an epistemological and a more general philosophical point of view.

Making Education More Inclusive and More Integrated

Improving education is a major concern for every government. Social inequalities are strengthened by inadequate educational practices. In this presentation, we will deal with two different initiatives. The first one, Hands On in the US, followed by La main a la Pâte in France, aimed at making the teaching of science at the elementary school much more practical, thus improving the results of the pupils belonging to lower social classes and their overall acceptance of the school system. This approach is now extended to the preschool and to the first years of secondary education in several European countries. Another initiative aims at creating more bridges between disciplines in sciences and humanities during the last years of secondary education, making education more integrated.

On the Relationship between Neuroscience and Philosophy: the Case of Sleep and Dreaming

In this paper, I will try to examine from both philosophical and epistemological points of view the major developments of neurophysiological research on sleep and dreaming during the last sixty years. In the nineteen fifties and sixties, neurophysiologists and psychophysiologists had great hopes regarding the contribution of sleep and dreaming studies to the understanding of consciousness mechanisms. These hopes were not entirely fulfilled. Progress in the field of sleep research was achieved thanks to developments in disciplines like neurophysiology properly said, neurochemistry, clinical medicine, etc

Postwar Science in Divided Europe: A Continuing Cooperation

This paper is devoted to an outline of certain aspects of international scientific cooperation and exchange between Eastern and Western European countries from 1950 to 1989, with an emphasis on mathematics, biochemistry and neuroscience.

Comments on Marcel Weber's "life in a physical world: the place of the life sciences

Marcel Weber’s contribution is an extremely accurate and synthetic view of the state of some discussions which are typical of what is meant today by “philosophy of biology”. Before commenting more closely his contribution, I would like to take some distance and to come closer to actual science (at least to some parts of the biological sciences). Looking at biology as a set of different sciences is more and more frequent. From mathematical biology to medical sciences and to biotechnologies, the field of biology became more and more diversified, although some common features remain at the most general level. Biology as a whole remains basically an empirical science, or a set of largely empirical researches. Philosophers dealing with biology should not underestimate biological empiricism and biological experimentalism. The extent to which this is the case, which is recognized by Marcel Weber, creates a real difficulty for philosophical thinking, because looking at biology as a largely empirical and basically experimental science, leads to the conclusion that biology is much less stabilized, at least in important parts, than it could be supposed. If you do not look at things from a purely conceptual point of view, if you avoid projecting on biology as a science in progress or rather as a set of closely related research disciplines, the idea of the structure of biological knowledge as the major problem of the philosophy “of” biology, then you get a much more realistic and richer picture of the biological sciences. Pluralism is now completely integrated in biological thinking, and experimentalism remains a most general feature. As far as I can see, Marcel Weber could agree entirely on these remarks, since he wrote a book on biological experimentalism.