Midline-crossing inhibition: an indicator of developmental delay

In normal development midline crossing integration is usually attained by eight or nine years of age. The inability to attain this developmental milestone is called midline crossing inhibition (MCI). A new method to detect MCI was used to examine the presence of MCI in a group of subjects with mental retardation. Seventeen subjects with mental retardation and an equal number of non-disabled peers participated in the study. Choice response time measurements consisting of reaction time and movement time were the dependent variables. These variables were recorded when subjects executed ipsilateral, midline and contralateral movements with each leg. Analysis of data revealed for both dependent variables significant differences between the two groups of subjects. Only the group with mental retardation exhibited contralateral times that were significantly slower than ipsilateral times. Midline crossing inhibition was evident with these developmentally delayed subjects. This new method shows promise for assessing developmental and neurological anomalies.