Complex Movement Patterns: Modifiability and Constraints

Abstract

Most behaviours involve complex morphological systems and vice versa morphological systems are used by the organism in many different ways. During evolution and ontogeny changes in kinematics and function of skeletal and muscular systems must be coordinated with changes in their neural control. Neuromotor patterns are sometimes believed to be conserved in evolution, leading to diversification at the level of musculoskeletal design. Vertebrate motor patterns used in feeding are reviewed to examine this hypothesis. Stereotyped behaviour is not necessarily the result of phylogenetic constraints but may also result from the functional demands imposed by the mechanics of the jaw apparatus and the nature of the task performed. Sensory feedback and descending control not only contribute to ‘online’ control of movement but also shape the development of motor patterns and learning behaviour and indicate a potentially large flexibility. The neural and sensory apparatus that produces this flexibility will be subject to evolutionary modification. In the absence of a demand for flexibility motor patterns may become stereotyped in some species, while they are very flexible in others. To the extent that morphological systems perform independent movements during different behaviours, separate basic motor patterns may be required, which may be coordinated in different ways.

The Neural Substrate for ‘Learned’ and ‘Nonlearned’ Activities in Birds: A Discussion of the Organization of Bulbar Reticular Premotor Systems with Side-Lights on the Mammalian Situation

“…However, the sequence of pecking and mandibular transport requires a series of rather similar jaw and tongue movements [for more details, see accompanying paper by Bout, 1998]. Moreover, some feeding types such as, for example, straining in ducks consist of repetitions of fast uniform jaw movements.…”

“…Comparative studies can help to recognize generalized patterns of motor activity during the various activities reflecting the fixed action patterns, whereas functional diversification may depend upon evolutionary changes of mechanical systems rather than upon changes of neural systems [discussions in Lauder, 1991;Nishikawa et al, 1992;Dicke and Roth, 1998]. In a companion paper Bout [1998] discusses the existence, or rather the absence of stereotypies in feeding mechanisms of several groups of vertebrates. His survey leads to the conclusion that the concept of the fixed action pattern should be replaced by the concept of modal action pattern.…”

Stereotypy, flexibility and coordination: key concepts in behavioral functional morphology

“…There are at least two other possible causes of inflexibility (Bout, 1998). First, it could be that the optimal or adaptive response is the same for all treatments being considered (Wainwright, 2002).…”

Preface

“…The papers of Bout [1998] and Dubbeldam [1998] discuss the flexibility of jaw and tongue mechanisms and the organization of the reticular premotor systems in control of these mechanisms, respectively. The focus of the first paper Preface is on mechanisms in reptiles and birds, with some comments on the situation in fishes and mammals.…”

“…What kinds of modulations can be expected, what are the consequences for the concept of the central pattern generator? Quite a lot of work has been done on jaw and tongue mechanisms in reptiles [see Bout, 1998], but little is known about the organization of reticular premotor systems for oral functions in these animals [for a recent overview on the organization and connections of the reptilian reticular formation, see ten Donkelaar, 1998]. Therefore, emphasis in the discussion on premotor systems [Dubbeldam, 1998] is on the avian situation and the comparison with mammals.…”