Dear Ulises,

I've never used pin metal electrodes in my studies. They polarize and don't allow to record in DC mode. For EAG I use Ag/AgCl electrodes connected to antennal surface with saline bridges. For single sensilla - glass microelectrodes (also with Ag/AgCl inside).

Thank you Marianna Zhukovskaya, I appreciate your feedback. I am really enjoying your work on novelty, stress and grooming behavior of the cockroach.  Appreciate your reply.  

http://nelson.beckman.illinois.edu/courses/physl416/ventralNerve.html 

Introduction

The cockroach ventral nerve cord is a complex neuronal system. However, one example of neuronal integration can easily be explored with this preparation; the conversion of mechanosensory input from primary sensory fibers into responses of giant interneurons. The mechanosensory input is derived from the stimulation of the pair of appendages at the tip of the abdomen called the cerci. Each cercus bears a large number of long tactile hairs which are so sensitive they may be stimulated by not only direct touch, but also by vibrations of the substrate upon which the insect rests, or by air movements, including low frequency sound waves. Through neuronal processing thought to be at the terminal ganglia, the cerci work in concert to determine the velocity and direction of the stimulus disturbing the hair cells (usually air displacement caused by an oncoming predator). The cerci have on their surface hundreds of tiny hairs, each connected to individual mechanoreceptors. The axons of the mechanoreceptors project to the sixth (or terminal) abdominal ganglion where they make synaptic connections with two sets of giant nerve fibers (Figure 1). The giant fibers then project to the thoracic ganglia and the head and are involved in the coordinated evasive response elicited by cercal stimulation. The focus of this laboratory experiment is to correlate the escape response elicited by stimulation of the cerci to the electrophysiological activities of the ventral nerve cord and cercal nerves during cercal stimulation. We will also measure the conduction velocity of the ventral nerve to estimate the minimum time needed by the animal to escape. The stimulation of the cerci will be accomplished by using air displacements.

There is a great thesis available "Electrophysiological measurements of

spontaneous action potentials in crayfish nerve in relation to the soliton model"

Master’s thesis by

Rolf Justesen Pedersen

Membrane Biophysics Group,

Niels Bohr Institute,

University of Copenhagen

Supervisor: Thomas Heimburg

December 20, 2010

http://www.membranes.nbi.dk/thesis-pdf/2011_Masters_RolfPedersen.pdf