The purpose of the present experiment is to identify, in detail, results of the preceding experiment of authors that the amplitude of N₁ potential was dominant over motor cortex area contralateral to moving limb, with bipolar lead and is to investigate negative potential appearing the scalp preceding voluntary movement depends on a precaution stimulus or on readiness of movement execution only.
In addition to, discussing' the difference of CNV (Contingent Negative Variation) and N₁ potential is, also, the purpose of the present experiment.
The present experiment gave the following results.
1. The results obtained with monopolar lead were that the amplitude of N₁ potential was maximal at lead placement Cz in all movement.
2. The results obtained with bipolar lead were that the amplitude of N₁ potential showed, relatively, lower tendency in the combination within central area and showed, relatively, higher tendency in the combination of other lead placement to central area.
3. Judging from all the scalp, the amplitude of N₁ potential showed high tendency at central area.
4. In particular, clear difference was identified between the latency of CNV and that of N₁ potential.
5. As showing much the same amplitude except for lead placement Cz, CNV extended from central area over the scalp.