Fig. 1.

a Reconstruction on a lateral view of the left hemisphere in each monkey of the location and extent of the lesion aimed at the M1 hand representation (red territory) and BDA injection sites (territory in dark green for the core of the injection site and light green for the halo), as seen in transparency of the cortical surface. The actual volume of the lesions and BDA injections sites are given in Fig. 6b and Table 1. Mk-LA is not shown as it was excluded from the neuroanatomical analysis (see Table 1). b Photomicrograph of a typical BDA injection site in PMd and resulting BDA retrogradely labelled callosal cells in the opposite hemisphere. c View of the “Brinkman box” used for behavioural assessment of manual dexterity, representing a variation in our modified Brinkman board task (see text). The left picture shows the open facet of the “box” allowing access to the 20 wells, in which the pellets are placed. The right picture shows that “box” from above with the monkey’s hand aimed to a well filled with a pellet to be grasped using the precision grip between the index finger and the thumb. At the beginning of the test, the 20 wells are each filled with a pellet. As the top facet of the “box” is transparent, the hand movements are executed under visual control. The behavioural test was taped with a video camera placed below the “box”. d Raw ICMS map established post-lesion in Mk-BI, as it represented the basis to identify positions where to perform penetrations with the syringe to infuse muscimol in PMd or PMv and then injections of BDA. Along the axes, “R” is for rostral and “M” is for medial. The circles represent the positions of electrodes penetrations for ICMS on the cortical surface, with colour code to represent the body territory activated at the lowest threshold along the corresponding electrode penetration. The threshold value is given by the size of the circle in microAmps (see on the right of the ICMS map). Circles comprising 2 colours are for ICMS electrode penetrations along which 2 body territories were activated at comparable threshold values. The purple arrows are for the sites of infusion of muscimol in PMd or in PMv, which were then used also as sites for BDA injections. Six sites of BDA injections were selected in PMd and 5 sites in PMv. BDA was injected in PMd and in PMv at sites where digits were activated by ICMS (yellow circles), or at sites where ICMS elicited at lowest threshold a wrist movement (red circles). In the latter case (wrist representation), there was also some ICMS effect on the digits, but at higher threshold. Note in M1 the presence of a few ICMS sites where digits movements were elicited at low intensity, but much fewer than on the pre-lesion ICMS map (not shown). Note also the presence of numerous non-micro-excitable sites, typical of the post-lesion ICMS map