Described here are intracranial ferrules, systems, and methods for sensing and stimulating neural tissues. The ferrules are generally designed to include a holding area for retaining an implantable device. In some variations, the ferrule itself may perform the sensing and stimulating functions. In other variations, the ferrule may function to sense data from neural tissues and the implantable device may function to stimulate neural tissues. In yet other variations, the ferrule may function to stimulate, and the implantable device may function to sense data from, the neural tissues. The sensing and stimulating functions may be used to detect and/or treat various neurological conditions.