Abstract
The retrieval of time interval and motoric preparation during the contingent negative variation (CNV) paradigm (warning stimulus-imperative stimulus+motor response) were investigated. The participants were asked to perform the required response tasks as accurately and quickly as possible, while the inter-trial interval was varied (ITT; 3 s/10 s). The reaction time (RT), the CNV and the lateralized readiness potential (LRP), and the foreperiod-LRP (FP-LRP) were measured. Low resolution brain electromagnetic tomography (LORETA) estimated the sources of the electric current of the difference between the two conditions. The amplitude of the early CNV under the ITI-10s condition was larger than that of the ITI-3s condition over the frontal cortex, suggesting early CNV modulation as a function of the remainder of the time interval memory trace. In contrast, the amplitude of the late CNV of the ITI-3s condition was larger than that of the ITI-10s condition over the vertex of the brain. The amplitude of the FP-LRP, which seemed to increase as the memory trace was reconstructed, increased later under the ITI-10s condition compared with that under the ITI-3s condition. The LRP onset latency and the RT of the ITI-10s condition were delayed compared to those of the ITI-3s condition. In our study, the early CNV over the frontal cortex seemed to reflect the retrieval of the time interval. When the activation of the frontal cortex was larger, motoric preparation could be started relatively earlier, and reactions then seemed to be performed earlier. The estimation of the LORETA supported supplementary motor area contributes to the early CNV and precuneus and anterior cingulate to the late CNV. (Japanese Journal of Physiological Psychology and Psychophysiology, 25 (3) : 287-302, 2007.)
