Free Will and Jerry Coyne (Introduction)

by David Turell , Sunday, August 16, 2015, 14:25 (3387 days ago) @ David Turell

David: the so called intention spike whish precedes the event is also not identified in any exact way. It is not clear exactly what it represents, thought, intention, gearing up, for the simple reason that we are not observing a hard-wired computer. It takes micro-seconds for the biochemical reactions to produce ions which send messages. These problems are discussed in detail by neuroscientists who work I have published here. We are unfortunately once or twice removed from exactly what is going on.-Here is an article to extend my point about neuron spikes, an area in which Coyne is not an expert:-http://inference-review.com/article/big-neuroscience-"What, in fact, is the complex, multivariate neural code that the brain uses to generate complex cognitive, perceptual, and motor behavior in the first place? This code is related, somehow, to the behavior of neuron spiking, but we do not yet know how.-"Neuron spikes are explained, Markram suggests, primarily by membrane behavior from ion charge differences; temporal sequencing is thus of greater relevance than higher-order patterns like oscillations. Once data have been generated, they are used to scale up a multivariate simulation. To simulate biologically realistic neurons and their connections, a model of neuron behavior is needed. Markram's theories are based on the Hodgkin and Huxley equations, a set of non-linear differential equations describing the initiation and propagation of action potentials.28 Alan Lloyd Hodgkin and Andrew Huxley presented their model in the 1950s, using the common electrical circuit as a framework. The NEURON software developed during the 1990s at Yale, and used today in a range of neuroscience projects (including the HBP), is based on the H-H model.-"The H-H model is not a complete explanation of neuron spike behavior, or even of ion channel behavior. Still, some advances have been made. Hodgkin and Huxley could not determine the temporal activation sequence of ion conduction. They could only approximate it. Research in the 1960s and 1970s was able partially to solve the problem by using the pore theory of membrane-spanning proteins. Aside from such relatively minor tweaks, however, it is the basic H-H model that remains dominant in neuroscience today. -"In their initial research, Hodgkin and Huxley introduced first-order rate equations describing the probability that an ion gate is in an open state. Their equations depended on a number of parametric fudges. How they came to their specific fudges remained unexplained, and Hodgkin and Huxley acknowledged as much. -"A typical HBP protocol thus has the following form:
a.A research paper is scanned for its numerical parameters: applied stimulus protocols, reverse potentials of ion channels, and inactivation kinetics.
b.Since the equations required to model H-H from empirically discovered parameters are often missing from the literature, curve digitization is used to recreate them. This is a technology that converts graphical images into numerical formulas. Given a standard activation curve plotted in a Cartesian coordinate system, curve digitization extracts a function that re-creates the curve in the coordinate system. An open source package, Engauge Digitizer, is currently used for this purpose.
c.After digitization and curve fitting, another software package, GenericFit, is used to simulate the H-H model.
d.Since the initial simulation generated is usually wrong, parameter readjustments are required. The computer model is made to fit the experimental results by tweaking the numbers extracted from the parameter identification, a process known as double fudging. -"This is not a scheme calculated to inspire confidence, if only because errors introduced at the level of individual neurons are propagated to groups and circuits of neurons in the downstream simulation."