Neuroarchitecture of the lower division of the central body in the brain of the locust (Schistocerca gregaria).

We have investigated the anatomical organization of the lower division of the central body in the brain of the locust Schistocerca gregaria. Bodian preparations, Golgi impregnations, and intracellular filling with Lucifer yellow have revealed that the lower division of the central body is organized into six horizontal layers and sixteen vertical columns. Neurons of the lower division of the central body have been classified into five types of tangential neuron (TL1-TL5) and two types of columnar neuron (CL1, CL2). TL1-TL4 neurons ramify in specific layers in the lower division of the central body and in the lateral triangle (TL1, TL2 neurons), the median olive (TL3 neurons), or the dorsal shell (TL4 neurons) of the lateral accessory lobe. TL5 neurons ramify in the protocerebral bridge, in the lateral accessory lobe, and in all layers of the lower division of the central body. The two types of columnar neurons have arborizations in the protocerebral bridge and in the lower division of the central body and project to the lateral triangle of the lateral accessory lobe (CL1 neurons) or to the lower subunit of the nodulus (CL2 neurons). Possible functional implications for the processing of neuronal information in the central complex are discussed.