Figure 2.

Detection of signal in noise and M1 modulations. Example traces of horizontal movement of the virtual hand for three trials with different noise levels: low (A), optimal (B), and high (C). The colored horizontal bars represent the position of the targets (green, RAT; brown, NAT). In the trials shown in A and C, the monkey incorrectly selected the NAT, whereas in B it correctly picked the RAT and received a reward (indicated by a black arrow). The pulses delivered through both stimulating channels are shown. The RAT is subthreshold. The corresponding neuronal ensemble activity (monkey M, 120 units from M1) is shown in the bottom plots. Note that neuronal modulations reflect the speed and direction of arm movements. The color scale shows normalized firing rate (in Hz).