A Study of the Extracellular Stretch Receptor Neuronal Response Under Influence of External Electric Fields

The present study is concerned with the effects of externally imposed electric fields on the neuronal response of the crayfish stretch receptor body. Preliminary studies concerning the effects of external fields on single cell activity have been made by Terzuolo and Bullock (8) and Hause (7). In these studies, the external fields were found to alter the ongoing neuronal activity. The transcranial application of AC electric fields for the purposes of inducing electroanesthesia or electrosleep results in a diffuse alteration of the ongoing population activity (EEG) (1,2,3). Brain tissue, which is electrochemically active, appears to undergo significant structural changes in response to these externally applied currents, i.e., the distribution of the synaptic vesicles appears to be affected (4.), suggesting an effect at the synaptic level. Application of transcortical DC fields affects the cortical neuronal activity en masse (6.) Although the groww activity is altered by diffuse currents, it would appear that the interactions take place at the cellular level. Thus, investigations of the single cell phenomenon are of primary importance. The stretch receptor neuronal body of the crayfish offers a relatively convenient experimental means to evaluate the modifications in the single cell response caused by externally imposed electric fields. The studies of Terzuolo, Bullock and Hause are based upon this stretch receptor neuron. Application of the external fields is found to modulate the ongoing activity of the neuronal body. Diffenent orientations of field yield variable rates of firing (8). This afferent neuronal body has also been seen to occasionally manifest the group discharge phenomenon. These group discharges are also modified by externally applied fields. On the whole, the modulative effects exerted by external fields may be helpful in understanding the neuronal response behavior. The present study endeavors to further explore the effects of external electric fields on the spontaneous neuronal response. Time variant external DC fields have been employed for this purpose