The optical imaging method is one of the most useful techniques to investigate dynamic neuronal activities of the brain. Available forms of the method, however, require averaging of the optical records tens of times. A new version presented here has been developed by application of the Independent Component Analysis (ICA), and it is devised to circumvent the time-consuming averaging process. As a preliminary work, parameters associated with ICA were determined on the basis of a computer simulation involving membrane potentials and noise signals. The method was then applied to the optical data obtained from hippocampal slices. The neuronal activities extracted by the present technique are in good agreement with the results produced by conventional technique that needs extensive averaging.
Target step-back consistently induced during subject's primary saccades evoked gradual change in gain, the ratio of saccade amplitude to target eccentricity. After three hundred trials, the subjects caught a target by a single saccade. Such adaptation occurred with memory-guided saccade, as well as the adaptation of visually guided saccades as has been reported in the literature. These saccades showed selectivity in adaptation. Adaptation took place even when the displaced target appearance was delayed by 400-600 ms from the end of a primary saccade. Based on these findings we propose a selective adaptation model of human saccades which bears important implication for motor learning systems.