Importance of Crossing Midlines for Balanced Brain Function

Many of us working with children have heard it is important for development to have them cross the midlines of the body. But why is it important?

A child who has difficulty crossing the vertical midline, the invisible line creating a right and left side down the very center, and or the horizontal midline, roughly the waist line separating the top and bottom half typically has one brain hemisphere more engaged than the other. These children can present with more specialized brain function using one hemisphere more. For instance, the child may be very verbal, using language well beyond their years and reading early, but lack social engagement skills (very left hemisphere dominant). Or the child may present as being very creative, low on verbal skills and have poor emotional regulation (very right hemisphere dominant).

Both hemispheres of the brain need to be engaged for best brain function, with one dominant hemisphere gently leading the other. Our dominant hemisphere is the one opposite of our dominant hand.

The left hemisphere controls all aspects of language, logic and establishing habits. The right plays more of a discriminatory role by recognizing spatial relationships between objects, noticing patterns and faces, and perceiving danger.  The left acts more linearly, analyzing incoming information and systematically categorizing experiences, while the right acts more globally, taking everything in, and summing up the more qualitative aspects of situations.  The left-brain controls the motor functions of the right side of the body, and the right brain the left side of the body.

Children with brain-based disorder often have hemispheres out of synch with each other, or what is called poor hemispheric integration. This shows up as poor ability to synchronize arms and legs, coordinate the right and left sides of the body, cross the center of the body with arms, feet or eyes (vertical midline), bend at the waist reaching towards the feet (horizontal midline) and not having a truly dominant, skilled hand.

So what can you do to help engage both hemispheres and improve hemispheric integration?

• Play games requiring the crossing of the midlines with arms, legs and eyes, such as Simon Says. Play this game with a weighted ball for maximum benefit. Mechanical pressure to muscles helps the child regulate arousal and improves attention helping them to engage longer.
• Activities requiring synchronized and reciprocal movements of the arms and legs, such as scissoring the same arm and leg for a number of repetitions, or completion of different patterns of rhythmic movement such as walking, lifting a leg, clapping under the knee and then doing the same on the other side.
• Learning a musical instrument engaging both hands, such as piano, violin or guitar.
• Engagement in community-based activities such as swimming or martial arts.