VOL. 5, No. 1/2, July 2009

S. Hamid, et al. [2009] Med. Hypotheses Res. 5: 99‒103.

Development of a Circuit for Oscillating Field

Samar Hamid*, Russell E. Connally and Raymond Hayek

Faculty of Science, Macquarie University, NSW 2109, Austria

Abstract.  Weakly applied electrical fields not only promote growth of damaged axons
in the Central Nervous System but also provide them with directional cues to grow in the
desired direction rather than random sprouting. The responses of nerve processes are
polarized; with faster growth towards cathode and repulsion from the anode after a latent
period of 30 minutes. This asymmetric response is the basis of Oscillating Field Stimulation
(OFS) that requires the polarity of the field to be reversed every 15 to 30 minutes, thereby
ensuring neurite growth regardless of the perceived polarity. However these previously
designed stimulators provide limited period of stimulation due to battery life constraints and
need to be explanted afterwards. We have proposed a circuit design for an externally
powered programmable implantable extra-spinal electrical stimulator (pIEES) for application
in an animal model of spinal cord injury. This particular design allows the stimulator not
only to provide long term stimulation but can communicate with a host computer for
reprogramming if required thus eliminating the need for second surgical procedure for
explantation. This can be of value when studying the therapeutic potential of long-term
application of weak pulsed electrical field to encourage spinal reconnection in adult rats.

* Correspondence: Dr. Samar Hamid at the Faculty of Science, Macquarie University,
NSW 2109, Austria. Tel: 61 2 9850 8938. E-mail: