Characteristics of the SR-evoked potentials in area 3a.

<p>(A) Percent responses evoked by DR and SR stimulations in area 3a. (B) Percent responses evoked by DR and SR stimulations in area 3b/1. (C) Amplitude of the DR- and SR-evoked potentials in area 3a. (D) Latency of the DR- and SR-evoked potentials in area 3a. Error bars in A–D indicated S.E. Asterisk in A–D indicates statistical significance at <i>P</i> < 0.05 using two-sample <i>t</i>-test.</p

Schematic drawing of experimental setting and surface map of the recording sites.

<p>(A) Stimulation of deep radial (DR) and superficial radial (SR) nerves. Three nerve cuffs were implanted: one on the radial nerve trunk (R) at the left forearm, one on the DR, representing primarily muscle afferent input, and one on the SR, representing primarily input from the skin. The DR and SR cuffs were used for electrical stimulation, and the R cuff was used for recording incoming volleys. The nerves were stimulated with biphasic constant-current pulses, 100 μs/phase, at twice the threshold (2T). The electrical stimulation-evoked field potential was recorded from the forearm region at the posterior bank of the CS of the right hemisphere. (B) Cortical surface map of the recording sites in each monkey. The electrode was inserted 8–15 mm at the anterior–posterior level. Gray lines indicate the approximate location of the CS on the cortical surface. Recording sites of the SR- or DR-evoked potentials are indicated by filled circles. Open circles indicate electrode insertions in which intracortical microstimulations were applied and no SEPs were recorded. Body parts activated at the lowest current of the microstimulation are indicated by capital letters. Values indicate the lowest microstimulation current (μA) evoking the movement. “n” indicates no effect up to 200 μA. A: anterior, P: posterior, M: medial, L: lateral.</p

Examples of DR- and SR-evoked potential distribution in area 3a.

<p>(A) Amplitude plots of the DR-evoked potentials at the anterior-posterior 10-mm level in monkey SO where the largest DR-evoked potential was observed in this animal. The circle size indicates the amplitude. A bar indicates no significant activation. (B) Latency plots of the DR-evoked potential indicated by colors. (C, D) same as (A, B), but for the SR-evoked potentials. (E–H) Same as A-D but for monkey TA. The data in A11 were from where the largest DR-evoked potential was observed in this monkey. The scale bar indicates 5 mm, separated by black and gray every 1 mm.</p

Recording sites of wrist-movement-related Purkinje cells (PCs) and dentate nucleus (DN) cells.

<p>A: Dorsal view of the right cerebellar hemisphere of monkey W. The open star indicates the center of the recording chamber. The gray dot marks the location of the electrolytic lesion indicated by the white arrowhead in B. PF: primary fissure, IV-VI: lobules IV-VI, R: rostral, L: lateral. B: Coronal section of the cerebellum of monkey W at the level of the gray line in A. The arrow indicates a recording track. The recording chamber was set at an angle to allow access to both the wrist-related cerebellar cortex and deep cerebellar nuclei (DCN). DN: dentate nucleus, AIP: anterior interpositus nucleus, PIP: posterior interpositus nucleus, h: hilum, D: dorsal, L: lateral. C: Typical examples of unit activities of simple spikes (SS, top) and complex spikes (CS, middle) for a PC and for a DN cell (DNC, bottom). D and E: Somatotopy maps of PCs for the three animals (D) and DN cells for the two animals (E). Cells with receptive fields (RFs) in distal arm (filled circles), proximal arm (open circles), face/mouth (open triangles) and hindlimb/trunk (open diamonds) are plotted. Note that all cells with RF in distal arm (filled circles) were task-related. In some cells, RF was unclear (cross marks). In D, the gray lines in the left (Monkey M) and middle (Monkey S) panels indicate locations of the PF. In the right panel (Monkey W), the open star and the PF (black line) correspond to those in A. The intersection of the two dashed lines indicates the center of the recording chamber in each animal. In E, the medial gray dashed line indicates the presumed medial edge of DN, whereas the lateral gray dashed line indicates the presumed lateral edge of DN. The medial border corresponds to the location of the axon bundle in the hilum of DN (indicated by <i>h</i> in B). The lateral border was estimated due to a lack of unit activities beyond the lines (See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108774#s2" target="_blank">Materials and Methods</a>). In both the cerebellar cortex and DN, recorded cells that had RFs in the face region were located caudal to the wrist-movement related cells, while cells that had RFs in the hindlimb/trunk were located rostrally.</p

Modulation onset of SS activity of PCs for the three animals: Earliest onset of individual PCs.

<p>Means, SDs and Ranges are in milliseconds. PC all: all PCs. PC inc: PCs showing increased SS activity as the earliest modulation regardless of movement direction. PC dec: PCs showing decreased SS activity as the earliest modulation. <i>n</i>: numbers of PCs in individual categories. Note: sum of PC inc and PC dec equals PC all. There was no significant difference between PC inc and PC dec in all three animals (<i>p</i>>0.21, 0.80, 0.60 in monkey M, S, W, Mann-Whitney U-test).</p><p>Modulation onset of SS activity of PCs for the three animals: Earliest onset of individual PCs.</p

Movement kinematics of the wrist joint.

<p>A: Movement trajectories to 8 peripheral targets (10 trials for each target [square]) in the pronated forearm posture in monkey M. The target locations required 20° changes in the angle of the wrist joint. Each trace represents a single trial of movement. B: An example temporal profile of wrist angle (displacement) in a single trial. C: An example temporal profile of wrist speed in a single trial. Filled inverted triangle indicates the time of target acquisition (i.e., when the cursor moved into the target). Black circles with error bars indicate the mean ± SD of the time of target acquisition in eight movement directions (twenty trials each). Vertical dashed line labeled ‘Move’ indicates movement onset.</p

Modulation onset of activity of DN cells for the two animals: Onset of all modulations of all DN cells.

<p>Most DN cells showed modulation for two to eight movement directions. Mod all: all modulations. Mod inc: increases in modulation. Mod dec: decreases in modulation. See also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108774#pone-0108774-g012" target="_blank">Fig. 12C and D</a>. Mod inc occurred earlier than Mod dec in monkey M and S (<i>p</i><5.3×10⁻²⁰ and 0.09, respectively, Mann-Whitney U-test).</p><p>Modulation onset of activity of DN cells for the two animals: Onset of all modulations of all DN cells.</p

Modulation onset of SS activity of PCs for the three animals: Onset of all modulations of all PCs.

<p>Most PCs showed modulation for two to eight movement directions. Mod all: all modulations. Mod inc: increases in modulation. Mod dec: decreases in modulation. <i>n</i>: numbers of modulations in individual categories. See also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108774#pone-0108774-g006" target="_blank">Fig. 6C and D</a>. There was significant difference between Mod inc and Mod dec in monkey M and S (<i>p</i><0.0003 and 0.002, respectively, Mann-Whitney U-test), but not in monkey W (<i>p</i><0.13, Mann-Whitney U-test).</p><p>Modulation onset of SS activity of PCs for the three animals: Onset of all modulations of all PCs.</p

Three types of activity in wrist-movement-related DN cells.

<p>Raster plots and histograms of typical examples of three types of activity in DN cells with RFs in the distal part of the arm. Neuron activity recorded in the pronated posture is illustrated. DN cells were classified into three types based on movement-related modulations between −200 to +200 ms relative to movement onset. This figure uses the same conventions as <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0108774#pone-0108774-g004" target="_blank">Figure 4</a>. A: Activity of type 1 DN cells showed suppression before movement onset. B: Activity of type 2 DN cells showed suppression before movement onset for some directions and facilitation for other directions. C: Activity of type 3 DN cells showed facilitation before movement onset. Note that the scale bars for discharge rate shown in the top row of panels differ for the three cells.</p

Temporal patterns of recruitment of all PCs and DN cells with facilitation or suppression of activity for eight different directions.

<p>A: PCs. B: DN cells. In each time bin (20 ms), blue dots represent the number of PCs or DN cells with decreased activity, and red diamonds represent the number of PCs or DN cells with increased activity for eight different directions of movement in the pronated posture in each animal. Blue and red lines indicate mean numbers of blue dots and red diamonds in individual bins, respectively.</p