Abstract: Effects of stimulating the cervicodorsal and dorsolaterai funiculi on transection and isolation preparations were compared in anesthetized and immobilized cats in terms of field potentials recorded from the lumbar enlargement with microelectrode.Similarly, typical field potentials were recorded from both the cervicodorsal and dorsolateral funiculi rostral and caudal to the dorsal column on transection preparation. On isolation preparation, however, typical fieldpotentials could be evoked only by stimulation of the dorsal columns caudal to the dorsal transection and smaller potentials by stimulation of the rostral end; whereas no detectable potentials could be recorded from stimulation of the dorsolateral funiculi rostral and caudal to the transection.The results show that the natural gap between spinal funiculi and the funicular transection itself are not sufficient to prevent the spread of stimulating current; this can effectively be done only by funicular dissection and the placement of an electrical barrier between the funiculi. It is thus supposed that electrical stimulatior on the transection preparation may lead to misidentification of spinal projection neurons; while isolation preparation can be used to effectively identify single and double spinal projection neurons.