Wiring optimization explanation in neuroscience: What is Special about it?

This paper examines the explanatory distinctness of wiring optimization models in neuroscience. Wiring optimization models aim to represent the organizational features of neural and brain systems as optimal (or near-optimal) solutions to wiring optimization problems. My claim is that that wiring optimization models provide design explanations. In particular, they support ideal interventions on the decision variables of the relevant design problem and assess the impact of such interventions on the viability of the target system

Dynamics of Current, Charge and Mass

Electricity plays a special role in our lives and life. Equations of electron dynamics are nearly exact and apply from nuclear particles to stars. These Maxwell equations include a special term the displacement current (of vacuum). Displacement current allows electrical signals to propagate through space. Displacement current guarantees that current is exactly conserved from inside atoms to between stars, as long as current is defined as Maxwell did, as the entire source of the curl of the magnetic field. We show how the Bohm formulation of quantum mechanics allows easy definition of current. We show how conservation of current can be derived without mention of the polarization or dielectric properties of matter. Matter does not behave the way physicists of the 1800's thought it does with a single dielectric constant, a real positive number independent of everything. Charge moves in enormously complicated ways that cannot be described in that way, when studied on time scales important today for electronic technology and molecular biology. Life occurs in ionic solutions in which charge moves in response to forces not mentioned or described in the Maxwell equations, like convection and diffusion. Classical derivations of conservation of current involve classical treatments of dielectrics and polarization in nearly every textbook. Because real dielectrics do not behave in a classical way, classical derivations of conservation of current are often distrusted or even ignored. We show that current is conserved exactly in any material no matter how complex the dielectric, polarization or conduction currents are. We believe models, simulations, and computations should conserve current on all scales, as accurately as possible, because physics conserves current that way. We believe models will be much more successful if they conserve current at every level of resolution, the way physics does.Comment: Version 4 slight reformattin

The Faculty Notebook, April 2017

The Faculty Notebook is published periodically by the Office of the Provost at Gettysburg College to bring to the attention of the campus community accomplishments and activities of academic interest. Faculty are encouraged to submit materials for consideration for publication to the Associate Provost for Faculty Development. Copies of this publication are available at the Office of the Provost

Wiring optimization explanation in neuroscience: What is special about it?

Este artículo examina la distintividad explicativa de los modelos de optimización del cableado en neurociencia. Los modelos de optimización del cableado se proponen representar los rasgos organizativos de los sistemas neuronales y cerebrales como soluciones óptimas (o casi óptimas) a problemas de optimización del cableado. Afirmo que los modelos de optimización proporcionan explicaciones de diseño. En particular, estos modelos soportan intervenciones ideales sobre las variables de decisión de un problema de diseño relevante, y evalúan el impacto de esas intervenciones sobre la viabilidad del sistema en cuestión.; This paper examines the explanatory distinctness of wiring optimization models in neuroscience. Wiring optimization models aim to represent the organizational features of neural and brain systems as optimal (or near-optimal) solutions to wiring optimization problems. My claim is that that wiring optimization models provide design explanations. In particular, they support ideal interventions on the decision variables of the relevant design problem and assess the impact of such interventions on the viability of the target system.

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

Model Evaluation: An Adequacy-for-Purpose View

According to an adequacy-for-purpose view, models should be assessed with respect to their adequacy (or fitness) for particular purposes. Such a view has been advocated by scientists and philosophers alike. Important details, however, have yet to be spelled out. This paper attempts to make progress by addressing three key questions: What does it mean for a model to be adequate-for-purpose? What makes a model adequate-for-purpose? How does assessing a model’s adequacy-for-purpose differ from assessing its representational accuracy? In addition, responses are given to some objections that might be raised against an adequacy-for-purpose view

The Production of Multiform Narratives in the Heterotopic Space of Technoscience: A Critical Instance Case Study of a Western Canadian Genomics Research Facility

Broadly speaking, this thesis explores the practices used by employees of a Western Canadian genomics research facility to build four-dimensional models of the human body; models which will be used to study genetic diseases. Usiiig actor-network theory as both a theoretical and methodological foundation, I consider the ways in which both the social (human) and the technical (nonhuman) actors that comprise the genomics research facility work together to construct these models. The work is divided into two sections. First, I investigate the setting of the genomics research facility. I argue that the genomics research facility constitutes a heterotopic site of cultural production. Second, I question what the genomics research facility produces. Ultimately I argue that by using fully immersive virtual environments, and building generic and extendible virtual models of the human body, employees at the genomics research facility are able to produce complex, multiform narratives of biological processes