Conductivities and anisotropies in diffusely arranged nervous tissues; their determination and importance in neurophysiological studies.

A new method for conductivity measurements in nervous tissues is introduced. A multi-electrode device is used for successive current injections and simultaneous potential recordings, which improves statistical evidence. A procedure to investigate anisotropies in nervous tissue is theoretically developed and experimentally applied to the thoracic ganglia of the migratory locust Locusta migratoria. The region around the frontal acoustic neuropile of the metathoracic ganglion exhibits a very slight anisotropy. Its preference direction is represented by the animal's body longitudinal axis. In the mesothoracic ganglion no anisotropy at all was revealed. Inhomogenities could not be found within the nervous tissue investigated. These results are discussed with respect to neurophysiological investigations.