The functional anatomy of manual motor behavior after unilateral frontal lobe lesions.

In normal brains different behavioral tasks lead to increased metabolism in different loci. Resting monkeys with acute hemineglect following periarcuate lesions show deficient glucose utilization (LCGU) in motor thalamus and other loci of the hemisphere with the lesion. To determine if the abnormal LCGU could be altered by a specific behavioral task, we used behavioral testing and training, and quantitative 2-deoxyglucose (2-DG) autoradiography. Animals reached criterion in a bimanual traction task (BMTT), then were tested for hand preference and responses to sensory stimuli, and received unilateral frontal or sham lesions. Operated animals showed hemineglect, and, on BMTT, intermanual coordination errors. 2-DG of frontals at rest showed deficient LCGU in 4 of 7 thalamic, and 1 of 4 cortical regions assessed. In contrast, only 2 thalamic and no cortical regions were deficient in pulling animals. Thus, in the face of structural damage and distant deficient neural activation, performance of a specific behavioral task may increase metabolism in specific brain loci, implying that plasticity of neural activation vis-a-vis behavioral demand is present even acutely after brain injury.