AGENESIS OF THE CORPUS-CALLOSUM AND VOLUNTARY WHEEL RUNNING IN MICE

Humans born without a corpus callosum (CC) are often comparatively slo w and clumsy on tasks requiring bilateral motor coordination. In this study, we attempted to identify correlates of CC agenesis in mice by e xamining an ecologically valid motor behavior: running-wheel performan ce. Mice with varying degrees of congenital CC deficits were tested on a running wheel apparatus for 7 consecutive days. The mice became mor e proficient at running with experience (i.e., rotations, time spent r unning, length of running bouts, and maximum and modal running speeds increased while variability of rotation times decreased). Multiple reg ression analysis suggested that CC deficiency may be related to 2 out of 20 measurements of running (decreased variability of rotation times and shorter maximum running bout duration), but at levels below the t raditional criteria for significance. Although these variables predict ed CC deficiency at a level significantly greater than chance (71% cor rect) in a discriminant analysis, examination of the meaning of their relationship with CC size suggested that any connection may be spuriou s.