Abstract: The invention includes several embodiments of a device for recording electrical activity, particularly the electrical field, from nerve, particularly brain, tissue slices. The device is preferably used for the testing or screening of the effect of physiologically active compounds on the electrical activity of brain tissue slices, which is either electrically evoked or spontaneously occurring. Thus, the invention also includes methods for testing or screening using the device in this manner, for example, to identify compounds that can enhance long term potentiation.