J. p. SEGUNDO, C. GALEANO, J. A. SOMMER-SMITH AND j. A. ROIG 287 



were painful and cortical responses were dependent (in part or in roto) 

 on pain-producing centripetal volleys, it should be kept in mind that any 

 ofFort to establish the behavioural (and, we may add, subjective) correlates 

 to cerebral action potentials is ' ... bound to be tentative' (Morison, 

 Dempsey and Morison, 1941). Therefore, experiments described in this 

 presentation cannot be construed as evidence that, after trainnig, T 

 application blocked afferent volleys initiated by SS and, consequently, 

 cats experienced less pain and relaxed; discussion of this possibility would 

 be entirely conjectural. 



In spite of the previous cautious remarks, two main conclusions may 

 justifiably be drawn from these experiments. In the first place, that within 

 certain limits, conduct and electrographic changes induced by sub- 

 cutaneous, presumably painful stimuli are subject to variations, 'spon- 

 taneous' or provoked. In the second place, that learned issues established 

 through adequate training are significant m the determination of induced 

 oscillations. Similar deductions may issue from experiments in which 

 painful excitation became the conditioned signal for feeding and, con- 

 comitantly, discomfort-suggesting manifestations were lessened (Pavlov, 

 1941). 



Suggestion and hypnosis have been used for centuries by physicians 

 and the laity to alleviate pain and its consequences: it is perhaps within 

 this labile range confirmed experimentally and by way of mechanisms 

 related to those mobilized in chronicallv implanted cats, that pain effects 

 are vulnerable to such pocn^ly understood but frequently effective measures. 



SUMMARY 



Experiments were performed on cats with chronically implanted 

 electrodes in which application and substraction of prolonged subcutan- 

 eous stimuli (SS) induced variable but characteristic electrographic (in 

 somatic sensory cortex) and behavioural patterns. During training stage I, 

 a tone (T) was presented repeatedly until rendered inoperant (habituation). 

 During stage II, SS was consistently interrupted 2-5 seconds after T initia- 

 tion. 



A learning process was established by this 'reinforcement' of indifferent 

 T with interruption of pain and cats eventually came to react to T m a 

 consistent fashion. Behavioural responses to T initiation (during SS) 

 resembleci those to SS substraction (without previous T) and consisted in 

 head, eye and or limb movements, frequently carrying from a 'tense' to a 

 'relaxed, natural' position. 



