Autonoesis and reconstruction in episodic memory: Is remembering systematically misleading?

Mahr and Csibra view autonoesis as being essential to episodic memories and construction as being essential to the process of episodic remembering. These views imply that episodic memory is systematically misleading, not because it often misinforms us about the past, but rather because it often misinforms us about how it informs us about the past

Episodic and semantic memory and imagination: The need for definitions

Vol. 131, No.

Experiencing Time

Experiencing Time. By Prosser Simon

Homochirality through Photon-Induced Melting of RNA/DNA: the Thermodynamic Dissipation Theory of the Origin of Life

The homochirality of the molecules of life has been a vexing problem with no generally accepted solution to date. Since a racemic mixture of chiral nucleotides frustrates the extension and replication of RNA and DNA, understanding the origin of homochirality has important implications to the investigation of the origin of life. Theories on the origin of life have generally elected to presume an abiotic mechanism giving rise to a large prebiotic enantiomer enrichment. Although a number of such mechanism have been suggested, none has enjoyed sufficient plausibility or relevance to be generally accepted. Here we suggest a novel solution to the homochirality problem based on a recently proposed thermodynamic dissipation theory for the origin of life. The ultraviolet absorption and dissipation characteristics of RNA/DNA point to their origin as photoautorophs, their replication assisted by UV light and temperature, and acting as catalysts for the global water cycle. Homochirality is suggested to have been incorporated gradually into the emerging life as a result of asymmetric right- over left-handed photon-induced denaturation of RNA/DNA occurring when Archean sea surface temperatures became close to the denaturing temperatures of RNA/DNA. This differential denaturing success would have been promoted by the somewhat right-handed circularly polarized submarine light of the late afternoon when surface water temperatures are highest, and a negative circular dichroism band extending from 220 nm up to 260 nm for small segments of RNA/DNA. A numerical model is presented demonstrating the efficacy of such a mechanism in procuring 100% homochirality of RNA or DNA from an original racemic solution in less than 500 Archean years assuming a photon absorption threshold for replication representing the hydrogen bonding energy between complementary strands. Because cholesteric D-nucleic acids have greater affinity for L-amino acids due to a positive structural complementarity, and because D-RNA/DNA+L-amino acid complexes also have a negative circular dichroism band between 200 - 300 nm, the homochirality of amino acids can also be explained by the theory

Fundamental Molecules of Life are Pigments which Arose and Evolved to Dissipate the Solar Spectrum

The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short wavelength UVC and UVB dissipation. On Earth's surface, water and organic pigments in water facilitate the near UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UVC that could have reached Earth's surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by; 1) increasing the ratio of their effective photon cross sections to their physical size, 2) decreasing their electronic excited state life times, 3) quenching non-radiative de-excitation channels (e.g. fluorescence), 4) covering ever more completely the solar spectrum, and 5) dispersing into an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earths atmosphere, we construct the most probable surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth's early atmosphere, and sheds some new light on the origin of photosynthesis.Comment: 43 pages, 3 figure

Beyond the causal theory? Fifty years after Martin and Deutscher

It is natural to think of remembering in terms of causation: I can recall a recent dinner with a friend because I experienced that dinner. Some fifty years ago, Martin and Deutscher (1966) turned this basic thought into a full-fledged theory of memory, a theory that came to dominate the landscape in the philosophy of memory. Remembering, Martin and Deutscher argue, requires the existence of a specific sort of causal connection between the rememberer's original experience of an event and his later representation of that event: a causal connection sustained by a memory trace. In recent years, it has become apparent that this reference to memory traces may be out of step with memory science. Contemporary proponents of the causal theory are thus confronted with the question: is it possible to develop an empirically adequate version of the theory, or is it time to move beyond it? This chapter traces the recent history of the causal theory, showing how increased awareness of the theory’s problems has led to the development of modified version of the causal theory and ultimately to the emergence of postcausal theories