Flexible choledochoscopy and removal of impacted stones of the common bile duct.

A technique of direct, piecemeal removal of impacted stones of the common bile duct is described. This routine eliminates the need for performance of an isolated Kocher maneuver or one done in conjunction with duodenotomy and sphincteroplasty. In addition, all stone fragments are removed under direct vision without damage to ductal structures.

Reciprocity of receptive field images and point images in the superior colliculus of the cat.

The largest receptive fields mapped during microelectrode penetrations through the upper strata of the cat's superior colliculus vary substantially in size and shape in different collicular regions. Previous work has shown that when these large fields are plotted in the retinotopic map of the colliculus, their profiles become elliptical and vary little in size and orientation over the central regions of the map. Such profiles are called the receptive field images (RFIs) in the visual coordinate system of the colliculus.