Evidence for bilateral control of skilled movements: ipsilateral skilled forelimb reaching deficits and functional recovery in rats follow motor cortex and lateral frontal cortex lesions.
Unilateral damage to cortical areas in the frontal cortex produces sensorimotor deficits on the side contralateral to the lesion. Although there are anecdotal reports of bilateral deficits after stroke in humans and in experimental animals, little is known of the effects of unilateral lesions on the same side of the body. The objective of the present study was to make a systematic examination of the motor skills of the ipsilateral forelimb after frontal cortex lesions to either the motor cortex by devascularization of the surface blood vessels (pial stroke), or to the lateral cortex by electrocoagulation of the distal branches of the middle cerebral artery (MCA stroke). Plastic processes in the intact hemisphere were documented using Golgi-Cox dendritic analysis and by intracortical microstimulation analysis. Although tests of reflexive responses in forelimb placing identified a contralateral motor impairment following both cortical lesions, quantitative and qualitative measures of skilled reaching identified a severe ipsilateral impairment from which recovery was substantial but incomplete. Golgi-impregnated pyramidal cells in the forelimb area showed an increase in dendritic length and branching. Electrophysiological mapping showed normal size forelimb representations in the lesioned rats relative to control animals. The finding of an enduring ipsilateral impairment in skilled movement is consistent with a large but more anecdotal literature in rats, nonhuman primates and humans, and suggests that plastic changes in the intact hemisphere are related to that hemisphere's contribution to skilled movement.
Gonzalez
Claudia L R
CL
Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Dr., Lethbridge, AB T1K 3M4, Canada. claudia.gonzalez@uleth.ca
Gharbawie
Omar A
OA
Williams
Preston T
PT
Kleim
Jeffrey A
JA
Kolb
Bryan
B
Whishaw
Ian Q
IQ
D000818:Animals; D005260:Female; D005552:Forelimb / Q000502:physiology*; D005625:Frontal Lobe / Q000293:injuries / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D009044:Motor Cortex / Q000293:injuries / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans; D020127:Recovery of Function / Q000502:physiology*