Abstract
While it has been accepted that midbrain or thalamic animals can exhibit the righting reflexes except the visually evoked one (Magnus, 1924), little is known about functional roles of midbrain structures on the righting reflexes. To understand their functions, partial lesions were given to the medial part of the midbrain tegmentum, and effects on air righting movements were examined. Under deep anesthesia, surgical or electrolytic lesions were made in Wistar male adult rats. Air righting movements were video recorded post operative days (p.o.d.) 2-3 and 7-8 and analyzed frame by frame. In animals with the midbrain lesioned, while air righting were sometimes abolished p.o.d.2-3, it was recovered p.o.d.7-8, but the onset time of the righting after falling was remarkably longer than intact animals. Furthermore, various defects were noted; insufficient body turns around the longitudinal axis, yawing around the falling axis, and head-up or head-down rotation around the pitching axis were often observed. The medial part of the midbrain was assumed to play important roles in control of the air righting reflex according to the initial falling condition. [J Physiol Sci. 2007;57 Suppl:S159]
