PRACTICAL SCAN SPEED IN ATOMIC-FORCE MICROSCOPY FOR LIVE NEURONS IN APHYSIOLOGICAL SOLUTION

We examined the practical scan speed for the observation of live neuro ns in a physiological solution using atomic force microscopy (AFM) wit h a desired vertical resolution of the order of 10(-8) mi which was re asonable when taking into account that a flicker of extracellular prot ein and saccharide on the neurons in the solution occurred during an o bservation period of a couple of minutes. The practical scan speed was found to be under 40 mu m/s, therefore, if we applied AFM using 100 l ines and 100 pixels per line to an observation area of 20 mu m x 20 mu m, the minimum period for acquiring one image was estimated to be abo ut 2 min. This procedure gave us good images that represented the slow three-dimensional dynamics in live neurons, such as the retrograde mo vement of surface protuberances, but suggested that another approach w as required to detect fast structural changes induced by stimulation.