WHITE, T.D.*; REILLY, S.M.: Abdominal motor dynamics in mammal locomotion II: Integration of ventilation with “cross-coupled” body support and footfall patterns in trotting opossums

T.D. White and S.M. Reilly Buffalo State College and Ohio University Abdominal motor dynamics in mammal locomotion II: Integration of ventilation with “cross-couplet” body support And footfall patterns in trotting opossums. Videoflouroscopy and electromyography were used to investigate epipubic bone movement and associated abdominal muscle activation during locomotion on a motorized treadmill in two didelphid marsupials, Didelphis virginiana and Monodelphis domestica. In both species, the epipubic bones exhibited little movement during locomotion (only symmetrical gaits were observed) or ventilation. Ventilation was inferred through the visualization of diaphragmatic displacements. The observed patterns of muscle activation of abdominal muscles (external oblique, internal oblique, rectus abdominus, pyramidalis) exhibited either four bursts of activity during a stride (usually single-footed, slow walks) or two bursts per stride (faster, trotting gaits). In the former pattern, muscle activation was bilateral. At higher velocities of locomotion, both bilateral and asymmetrical, unilateral activation of muscles were observed.