A dual electrode arrangement, is provided, wherein two, preferably unidirectional, electrode configurations flank a nerve junction from which a preselected nerve branch issues, proximally and distally to the junction, with respect to the brain. The arrangement is conducive to the following: generating efferent action-potential propagations, substantially restricted to the preselected nerve branch, inhibiting afferent action-potential propagations, from the preselected nerve branch, selectively generating action-potential propagations, in a subset of nerve fibers of a predetermined diameter range, substantially restricted to the preselected nerve branch, and selectively inhibiting action-potential propagations, in a subset of nerve fibers of a predetermined diameter range, substantially restricted to the preselected nerve branch. The dual electrode arrangement is further conducive to monitoring naturally-occurring, efferent action-potential propagations, heading towards the preselected nerve branch, and monitoring naturally-occurring, afferent action-potential propagations, from the preselected nerve branch. The unidirectional electrode configurations may be monopolar, bipolar, tripolar, or multipolar. Communication with extracorporeal stations, and closed loop operations are also provided.