Loss of movement selectivity following a cortical infarct.
(a) Scheme of the average map showing major changes in forelimb (FL), hindlimb (HL) and tail (TL) representation after stroke. Colors shows the preferential activation of different regions, showing the specificity of each zone (single vs multiple movements). Dotted circle indicates the average position of our ischemic lesion and white dots represent the grid of stimulation used in ICMS experiments. (b) Surface area eliciting movement of forelimb (FL) alone, forelimb + hindlimb (HL) or tail (TL), or the three body parts together at a stimulation current of 30 μA in sham (black, n = 9) and ischemic animals (red, n = 6). The quantitative analysis was performed in regions rostral and caudal to the infarct (see Fig. 1). Following stroke, very few sites retain their selectivity for forelimb movements, while most cortical locations elicit simultaneous movement of forelimb, hindlimb and tail (t-test, p < 0.05). Data are mean ± SE. (c) Map of the Transition Index (TI; see Methods) showing for each pixel the tendency to gain (blue) or lose (red) forelimb movement after stroke in our experimental sample. The colorimetric index is defined within a range of (see Methods).