A Brain-Damage Advantage for Lefties?

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A brain-damage advantage for lefties?

For an as yet unexplained reason, people who are predominantly left-handed apparently are able to withstand moderate brain damage with relatively few of the motor problems observed in righthanded victims of brain damage.

Studies of a limited number of braindamaged left-handers also indicate that they have a quicker and superior recovery of other functions, such as language and visual-spatial processing, than do their right-handed counterparts, says neuropsychologist Jordan Grafman of Walter Reed Army Medical Center in Washington, D.C.

"You can speculate that more transfer of information and shared information processing between left-handers' brain hemispheres might allow for their better recovery after brain damage,' observes Grafman. "But so far there is no evidence for this theory.'

Grafman and his colleagues chose subjects from a group of left-handed Vietnam veterans who suffered brain wounds without paralysis about 15 years ago. The study sample was composed of 13 men with right-hemisphere damage, 11 with left-hemisphere damage and 13 healthy, non-brain-damaged veterans. The researchers administered eight tests of simple motor functions, including grip strength, finger dexterity (manipulating pegs on a pegboard), coordination (finger tapping and movement tasks) and reaction tim (pressing a button as rapidly as possible after seeing a brief flash of light).

Left-handed veterans with damage to either hemisphere performed almost as well as the healthy controls and displayed no severe motor problems, report the investigators in the October PERCEPTUAL AND MOTOR SKILLS. The size of a brain would, language comprehension and preinjury intelligence scores were not related to motor performance, they note. …