WHY DOES THE SINGLE NEURON ACTIVITY CHANGE FROM TRIAL TO TRIAL DURINGSENSORY-MOTOR TASK

Single neuron activities from cortical areas of a monkey were recorded while performing a sensory-motor task (a choice reaction time task). Quantitative trial-by-trial analysis revealed that the timing of peak activity exhibited large variation from trial to trial, compared to th e variation in the behavioral reaction time of the task. Therefore, we developed a multi-unit dynamic neural network model to investigate th e effects of structure of neural connections on the variation of the t iming of peak activity. Computer simulation of the model showed that, even though the units are connected in a cascade fashion, a wide varia tion exists in the timing of peak activity of neurons because of paral lel organization of neural network within each unit.