Abstract
Optical measurement of cortical activity in the brain using laser beam has the following advantages compared to white light: (1) laser beam is easy to be focused on the cell stained with voltage-sensitive dye (the beam waist is nearly equal to the wavelength): (2) the light is monochromatic, then, the overlap between the excitation and the emission from the dye stained in the cell is negligible: (3) the optical measurement system of the cortical activity is a small size and a simple design. We propose the system of the laser image mapping applied to the intact brain with the voltage-sensitive dye. An optical fiber with a short length can be used for transmitting the laser light. The beam spot emerged out of the fiber can be controlled by using SELFOC micro-lens. The optical image mapping of cortical activity from a few cells or aggregated cells is produced from the small or large laser beam spot size.
