Investigation of the amygdaloid and olfactory electrographic response in the cat after toxic dosage of lidocaine

Abstract

Evidence has been presented concerning the effects of afferent inputs on the amygdaloid hypersynchronous electrographic discharge in the cat after toxic doses of lidocaine HCl. The study was divided into three parts consisting of chronically implanted animals, cerveau isolé preparations and midbrain-deafferented preparations with the reticular core intact. A brief description of each preparation is included. From the results of this study these conclusions can be drawn: 1. 1. The electrographic pattern change is not evident in high midbrain transected (cerveau isolé) cat preparations. 2. 2. The pattern change in the midbrain-deafferented cat preparation (with reticular core intact) is essentially identical to that seen in the normal chronic cat. 3. 3. Olfactory inputs are essential to this hypersynchronous amygdaloid pattern change, with this alteration appearing initially in the olfactory apparatus, then spreading synchronously to the amygdala and hippocampus. From this study, it would appear that possible noxious afferent inputs are not implicated but that olfaction is involved in the genesis of this response to toxic doses of lidocaine HCl. It is also apparent that either an activated cerebrum or an intact reticular core is essential to the genesis of this electrographic pattern change. Based on these findings, one may conclude that the amygdaloid hypersynchronous electrographic response to toxic levels of local anesthetics results from a lowering of the threshold of the olfactory system and subsequent lowering of the amygdaloid threshold to these olfactory inputs by lidocaine HCl. © 1970.