Meeting Abstract
25.2 Saturday, Jan. 4 13:45 Templates and anchors revisited: Distinguishing the ‘phenomenon’ of locomotion from the ‘mechanisms’ that produce it BERTRAM, JEA*; HASANEINI, SJ; Univ. of Calgary, Calgary; Univ. of Calgary, Calgary jbertram@ucalgary.ca
Studies of animal locomotion involve interpreting both the complexities of the observable motions and their functional consequences. With the multi-dimensional dynamics, and the highly redundant activation systems responsible, it has been difficult to organize the hierarchy of neuro-muscular and mechanical influences so that the challenges faced, and strategies utilized, can be found. It has been suggested that low dimension models of ‘targeted behavior’ (templates) represent broad categories of locomotion behavior emulated by a wide range of organisms. These template behaviors are achieved by the organism (and validated in research) through specific mechanisms that allow testable verification and are referred to as ‘anchors’. This approach has two serious problems; the first is identifying a non-arbitrary method of linking the measurable mechanism (anchor) to the model. The second, and more fundamental problem, is justifying and identifying a legitimate ‘targeted’ behavior (template) – why should organisms target a low dimension conceptual model of their behaviour (where reduced dimensionality is advantageous only for mathematical analysis)? As an alternative, we recommend adjusting this approach to replace ‘templates’ with the recognition that, at its essence, terrestrial locomotion is a dynamic interaction between the mass of the organism and the substrate – the irreducibly basic ‘phenomenon’ of locomotion is the time varying center of mass trajectory. This vector defines the movement strategy implemented by the organism to accomplish its translation across the substrate (and the alternative strategies that are avoided). The trajectory is mediated and guided by the limbs directly interacting with the substrate, action that links the discrete mechanisms of locomotion with the realistic representation of what is accomplished.
