title: Concurrent silent strokes impair motor function by limiting behavioral compensation.
abstract: Silent strokes occur more frequently than classic strokes; however, symptoms may go unreported in spite of lasting tissue damage. A silent stroke may indicate elevated susceptibility to recurrent stroke, which may eventually result in apparent and lasting impairments. Here we investigated if multiple silent strokes to the motor system challenge the compensatory capacity of the brain to cumulatively result in permanent functional deficits. Adult male rats with focal ischemia received single focal ischemic mini-lesions in the sensorimotor cortex (SMC) or the dorsolateral striatum (DLS), or multiple lesions affecting both SMC and DLS. The time course and outcome of motor compensation and recovery were determined by quantitative and qualitative assessment of skilled reaching and skilled walking. Rats with SMC or DLS lesion alone did not show behavioral deficits in either task. However, the combination of focal ischemic lesions in SMC and DLS perturbed skilled reaching accuracy and disrupted forelimb placement in the ladder rung walking task. These observations suggest that multiple focal infarcts, each resembling a silent stroke, gradually compromise the plastic capacity of the motor system to cause permanent motor deficits. Moreover, these findings support the notion that cortical and subcortical motor systems cooperate when adopting beneficial compensatory movement strategies.
authors.affiliation: Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, AB, Canada T1K 3M4. jamshid.faraji@uleth.ca
authors.forename: Jamshid
authors.initials: J
authors.lastname: Faraji
authors.forename: Kristyn
authors.initials: K
authors.lastname: Kurio
authors.forename: Gerlinde A
authors.initials: GA
authors.lastname: Metz
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000223:Adaptation, Psychological / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D008297:Male; D019957:Motor Skills Disorders / Q000209:etiology / Q000503:physiopathology* / Q000523:psychology; D011897:Random Allocation; D051381:Rats; D020318:Rats, Long-Evans; D020521:Stroke / Q000150:complications / Q000503:physiopathology* / Q000523:psychology