Investigating Mammalian Visual System with methods of informational theory

We examine a simple model of mammalian visual system. This structure is simulated by means of several hundred Hodgkin-Huxley neurons. We investigate signal processing properties of the model. Some methods taken from informational theory are applied to the analysis of Primary Visual Cortex' dynamics. Discussion of efficiency of such methods in two dimensional movement detection is presented in some detail

Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 156)

This bibliography lists 170 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1976

Steps towards operationalizing an evolutionary archaeological definition of culture

This paper will examine the definition of archaeological cultures/techno-complexes from an evolutionary perspective, in which culture is defined as a system of social information transmission. A formal methodology will be presented through which the concept of a culture can be operationalized, at least within this approach. It has already been argued that in order to study material culture evolution in a manner similar to how palaeontologists study biological change over time we need explicitly constructed ‘archaeological taxonomic units’ (ATUs). In palaeontology, the definition of such taxonomic units – most commonly species – is highly controversial, so no readily adoptable methodology exists. Here it is argued that ‘culture’, however defined, is a phenomenon that emerges through the actions of individuals. In order to identify ‘cultures’, we must therefore construct them from the bottom up, beginning with individual actions. Chaîne opèratoire research, combined with the formal and quantitative identification of variability in individual material culture behaviour allows those traits critical in the social transmission of cultural information to be identified. Once such traits are identified, quantitative, so-called phylogenetic methods can be used to track material culture change over time. Phylogenetic methods produce nested hierarchies of increasingly exclusive groupings, reflecting descent with modification within lineages of social information transmission. Once such nested hierarchies are constructed, it is possible to define an archaeological culture at any given point in this hierarchy, depending on the scale of analysis. A brief example from the Late Glacial in Southern Scandinavia is presented and it is shown that this approach can be used to operationalize an evolutionary definition of ‘culture’ and that it improves upon traditional, typologically defined technocomplexes. In closing, the benefits and limits of such an evolutionary and quantitative definition of ‘culture’ are discussed

Aerospace medicine and biology. A continuing bibliography (supplement 231)

This bibliography lists 284 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1982

Decoding the Brain: Neural Representation and the Limits of Multivariate Pattern Analysis in Cognitive Neuroscience

Since its introduction, multivariate pattern analysis (MVPA), or “neural decoding”, has transformed the field of cognitive neuroscience. Underlying its influence is a crucial inference, which we call the Decoder’s Dictum: if information can be decoded from patterns of neural activity, then this provides strong evidence about what information those patterns represent. Although the Dictum is a widely held and well-motivated principle in decoding research, it has received scant philosophical attention. We critically evaluate the Dictum, arguing that it is false: decodability is a poor guide for revealing the content of neural representations. However, we also suggest how the Dictum can be improved on, in order to better justify inferences about neural representation using MVPA

The Near-death experience: implications for neuroscience and non-local consciousness

Near-death experiences (NDE) raise important questions about the nature of human consciousness, the relationship between brain function and consciousness, the perceptual information that is available to consciousness in moments before death, the role of physical and biological mechanisms associated with altered states of consciousness, and relationships between consciousness, space-time and phenomenal reality. Challenges posed by efforts to define the NDE, claims of anomalous experiences associated with NDEs, the problem of “timing” of NDEs with respect to brain function, recent findings from neuroscience are reviewed, along with emerging evidence for quantum models of consciousness that may help elucidate the nature of NDEs. I propose that the diversity, complexity and quality of imagery retrospectively interpreted as NDEs reflect a multiplicity of potential neural pathways and the degree to which a heritable NDE predisposition is present in each unique individual. Certain NDE features are probably explainable by neuroscience and take place in 4-dimensional space-time while other NDE features such as confirmed cases of veridical perception and other so-called “anomalous” experiences may be consistent with postulated non-local characteristics of consciousness mediated by quantum-like processes or other non-classical processes (Kafatos et al., 2015) or may reflect relationships between consciousness and the environment that take place in higher order space-times. I propose an integral model that reconciles conventional neural explanations and postulated non-classical models of consciousness. The article concludes with suggestions for animal and human studies aimed at further elucidating neurophysiological mechanisms and postulated quantum-like or other non-classical mechanisms in NDEs and other kinds of transpersonal or so-called “anomalous” experiences. Well-funded cooperative research initiatives in functional brain imaging are leading to rapid advances that will make it possible in the near future to empirically test the integral model put forward in this chapter yielding more complete understandings of consciousness including NDEs and other kinds of transpersonal or anomalous experiences.

A Generative Model of Natural Texture Surrogates

Natural images can be viewed as patchworks of different textures, where the local image statistics is roughly stationary within a small neighborhood but otherwise varies from region to region. In order to model this variability, we first applied the parametric texture algorithm of Portilla and Simoncelli to image patches of 64X64 pixels in a large database of natural images such that each image patch is then described by 655 texture parameters which specify certain statistics, such as variances and covariances of wavelet coefficients or coefficient magnitudes within that patch. To model the statistics of these texture parameters, we then developed suitable nonlinear transformations of the parameters that allowed us to fit their joint statistics with a multivariate Gaussian distribution. We find that the first 200 principal components contain more than 99% of the variance and are sufficient to generate textures that are perceptually extremely close to those generated with all 655 components. We demonstrate the usefulness of the model in several ways: (1) We sample ensembles of texture patches that can be directly compared to samples of patches from the natural image database and can to a high degree reproduce their perceptual appearance. (2) We further developed an image compression algorithm which generates surprisingly accurate images at bit rates as low as 0.14 bits/pixel. Finally, (3) We demonstrate how our approach can be used for an efficient and objective evaluation of samples generated with probabilistic models of natural images.Comment: 34 pages, 9 figure

How the techniques of molecular biology are developed from natural systems

A striking characteristic of the highly successful techniques in molecular biology is that they are derived from natural occurring systems. RNA interference (RNAi), for example, utilises a mechanism that evolved in eukaryotes to destroy foreign nucleic acid. Other examples include restriction enzymes, the polymerase chain reaction, fluorescent proteins and CRISPR-Cas9. I propose that natural molecular mechanisms are exploited by biologists for their effectors’ (protein or nucleic acid) activity and biological specificity (protein or nucleic acid can cause precise reactions). I also show that the developmental trajectory of novel techniques in molecular biology, such as RNAi, is four characteristic phases. The first phase is discovery of a biological phenomenon. The second is identification of the mechanism’s trigger(s), the effector and biological specificity. The third is the application of the technique. The final phase is the maturation and refinement of the molecular biology technique. The development of new molecular biology techniques from nature is crucial for both biological and biomedical research

A Defense of Algorithmic Homuncularism

In this thesis, I defend the explanatory force of algorithmic information processing models in cognitive neuroscience. I describe the algorithmic approach to cognitive explanation, its relation to Shea’s theory of cognitive representation, and challenges stemming from neuronal population analysis and dimensionality reduction. I then consider competing interpretations of some neuroscientific data that have been central to the debate. I argue in favor of a sequenced computational explanation of the phenomenon, contra Burnston. Finally, I argue that insights from theoretical neuroscience allow us to understand why dimensionality reduction does not militate against localizing distinct contents to distinct components of functioning brain systems