Functional Organization of the Tectum of the Tiger Salamander (Ambystoma Tigrinum)

摘要

The organization of the tectum of the tiger salamander Ambystoma tigrinum was studied using anatomical and electrophysiological methods. The tectum can be divided into two concentric areas - a gray consisting of tightly packed cells around the cerebral aqueduct and a surrounding plexiform layer. Within these structures there are two classes of cells: type W, restricted to the outer third layer of the gray, with wide dendritic arborization; type N, found throughout the gray with very narrow dendritic arborization. Recording extracellularly there is a point-to-point projection of the visual field onto the tectum. Five types of units were found similar to those in the frog, however, responsive receptive fields were larger and no functional layering was apparent. The inner half of the plexiform layer has two somesthetic projections; a point-to-point projection of the contralateral body and a deeper bilateral projection. Units respond to simple touch stimuli and receptive fields cover several square centimeters of the body. Most single units in the gray respond to both light and touch stimulation. (Author)