Cortical undercuts in the rat produce asymmetrical behavioral response without altering catecholamine concentrations

Baseline spontaneous activity of male Sprague-Dawley rats was established in home running wheel cages 3 weeks prior to cortical undercutting. Rats received unilateral 2-mm-diameter circular lesions undercutting layer VI of either the left or right frontal cortex. The right hemisphere lesion group showed a 63% increase in spontaneous activity and rats with left hemisphere lesions were no more active than sham-operated controls. No significant intergroup differences in norepinephrine concentrations were noted in the frontal or posterior cortex or locus ceruleus either ipsilateral or contralateral to the lesion site. In addition, there were no significant group differences in dopamine content of the caudate nucleus. Results suggest that the lateralized neural substrates controlling locomotor asymmetry are probably postsynaptic to cortical norepinephrine fibers and may involve glutamatergic corticostriatal projections.