Oral contraceptive use affects manual praxis but not simple visually guided movements

A detailed analysis of both motor sequencing and visually guided movements was carried out in a group of neurologically normal women who were receiving exogenous estrogen in the form of oral contraceptives. Women were tested under both low and high estrogen conditions, in order to examine any hormone-related facilitation in the speed or accuracy of movement. Kinematic parameters examined on the visually guided motor tasks included movement onset time, duration of the reach, peak velocity, deceleration time, and endpoint accuracy (resultant error). The results showed that variations in motor performance were associated with fluctuations in estrogen level, but that this hormone sensitivity was task selective. Improved performance on a test of speeded motor sequencing, the Manual Sequence Box, was found under higher estrogen conditions, but this effect did not occur consistently in tests of rapid prehensile movements. Results are interpreted in terms of differential reliance of these tasks on left-hemisphere praxic systems.