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Precisely Localized LTD in the Neocortex Revealed by Infrared-Guided Laser Stimulation
H.-U. Dodt, M. Eder, A. Frick, and W. Zieglgänsberger

Supplementary Material

Supplemental figure. (A) Experimental setup used for infrared-guided laser stimulation. Neurons in the brain slice were visualized by illumination with infrared light and the gradient contrast system. At the same time, light pulses of a UV laser were fed via a quartz fiber into the microscope and directed by a dichroic mirror onto the recorded neuron. Both the slice chamber and the microscope could be positioned in x-y by remote controls. The laser spot of an optical diameter of 1 μm formed by the objective (60X, 0.9 N.A., Olympus) in the specimen plane was made visible before the experiment by a fluorescent paper, and its position was marked on the TV monitor. By positioning of the neuron to be stimulated on this point, the laser stimulation could be precisely guided by visual control.
Supplemental figure. (B) Principle of gradient contrast: A light stop, leaving open a quarter annulus, is inserted as spatial filter in the aperture plane of the condenser, reimaged by two lenses between the lamp house and the microscope. A diffuser, which can be shifted relative to the light stop, generates then an adjustable gradient of illumination across the aperture plane of the condenser. As in effect only a smoothed quarter hollow cone of light emerges from the condenser and transverses the brain slice, less stray light is generated compared with standard full cone illumination. This allows one to use an 1.4 N.A. oil immersion condenser giving superior resolution.

Supplemental Figure 1.

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