Although previous experiments have shown that the growth of neuronal cells can be guided by 800 or 1064 nm light, a detailed comparison of these wavelengths for neuronal growth has only recently been performed. Researchers at the University of St. Andrews (Scotland) have demonstrated that these wavelengths are equally effective in their ability to induce neuronal guidance.
By exposing neuronal cells to a 780 nm diode laser and a 1064 nm fiber laser through a microscope (ensuring that each source produces a 1.5 μm beam waist with comparable power levels and stabilizing ambient temperature to 37ºC ±0.5ºC), the experiment confirmed neuronal growth occurred regardless of wavelength. Although the growth mechanism remains elusive, the fact that the phenomenon is not wavelength-specific suggests that the light-detection mechanism within the cell is not due to a single protein with a defined activity wavelength, as occurs, for example, with photoreceptor proteins in the mammalian eye. An additional experiment using a dual-beam optical-tweezers setup showed stronger heating at 1064 nm than at 780 nm; however, this heating was found to be insufficient to cause the neuronal growth observed. Contact David J. Stevenson at [email protected].