Modeling concepts

We agree with the unfortunate distinction that “a biological model is often understood to be simply a diagram depicting the interrelationships of various (sub)systems in a process, whereas a physical model is expected to be a theoretical description of a process involving a number of equations of motion stemming from the first principles (if possible), testable against a range of tunable experimental conditions. It must lead to a quantitative prediction and not simply reproduce already known results” [7] cited and expressed in [8]. ”Riddled with some major misunderstandings and suffering from a lack of familiarity with the physics involved, this debate has been ongoing for some while without being picked up in mainstream neuroscientific literature.” To model something means to reduce a system with unknown behavior to another system with already well-known behavior. The two systems will never be identical, only similar in certain aspects; furthermore, their similarity is subject to the environment, so the models have their range of applicability. To model a living structure with a non-living one, ab ovo, has its dangers. One possible approach is to describe a system’s response to the environment, typically using parametrized mathematical formulas, without the aim of predicting a non-observed response. It is usually a good starting point for understanding the system’s operation, but without a deeper understanding of the details, it remains a ’looks like’ description. Neuronal modeling is a good (or bad) example of that modeling style. Hodgkin and Huxley [9] noted that their high-precision, meticulous observations could be described mathematically (the title of their paper was ”A quantitative description”). Unfortunately, with their best intention, they attempted to put a physical picture behind their formulas, although they warned that their ”equations are not anything more than an empirical description”, ”the interpretation given is unlikely to provide a correct picture of the membrane” and ”the success of the equations is no evidence in favour of the mechanism …we tentatively had in mind when formulating them”. Despite their prophetic thoughts, the hypothesized incorrect mechanism defined the development path of neuroscience for decades, and led to the present crisis leading to the need for a ”new understanding”. We discuss their ”physical model” (created by their successors) and compare it to our genuine physical model.