Trains of Epidural DC Stimulation of the Cerebellum Tune Corticomotor Excitability
Figure 4
Motor maps corresponding to responses recorded in left gastrocnemius muscle (upper panels) and left tibialis anterior muscle (bottom panels), ipsilaterally to the site of cerebellar direct current stimulation for one rat. Data are represented using contour plots with coordinates. -axis and -axis refer to sagittal and coronal coordinates, respectively (coordinates of Bregma: 0/0 mm). Intensities of corticomotor responses are illustrated in -axis using a linear scale. The so-called “hot spots” (shown in red) are identified. Stimuli are applied every mm in the sagittal axis and every 0.5 mm in the coronal axis (matrix of = 54 sites of stimulation). Coordinates of stimulation are established using the stereotactic frame. Left panels: recordings in basal condition; middle panels: recordings after application of anodal direct current stimulation (post-ADCS); right panels: recordings after application of cathodal direct current stimulation (post-CDCS). Maximal responses obtained at baseline are set at 100%, for both the gastrocnemius muscle and tibialis anterior muscle. ADCS induces a reorganization of the corticomotor map, restricting the representation of the most intense motor responses around the hot spot (“focusing effect”) and reducing the intensity of the hot spot. By contrast, application of CDCS redistributes the representation of the most intense motor responses and increases the magnitude of the hot spot. The number of peaks in the axis with values above 50% of maximal corticomotor responses (NP50) is indicated in the upper right corner of each panel. Note the clear drop after ADCS and the slight increase after CDCS, as compared to baseline.
