Brain Mechanisms

Conclusion. The ultimate test of the present model is the extent to which it can serve to stimulate and guide future experiments that can further our understanding of the brain mechanisms of behavior. Having already seen a great deal of progress in the field since I began my research fifteen years ago, I am confident that we will be that much further ahead in another fifteen years. I am proud to have participated with my many distinguished commentators in this process. New data are mentioned in the commentaries that begin to force revision of, the model. Gandelman mentions evidence that prolactin is not the critical hormone for maternal aggression in mice. And the Blanchards have found that septal lesions, contrary to what I might have predicted, do not abolish ultrasound during shock-induced fighting. Berntson proposes new and intriguing experiments on the role of the paleocerebellum in the integration of behavior. Yutzey proposes new experiments to clarify the role of the septum and hippocampus in submission and defense. And Karli has undertaken a renewed attack upon the brain mechanisms of aggression at the single unit level.

I am particularly intrigued by the possibilities of extrapolating from the behavior of rats and cats to that of other vertebrates. But such extrapolation is hazardous as several commentators correctly observe. I appreciate the comments of Andrew that I have "effectively re-interpreted" his data on the chick, although the effect of midbrain lesions is much more complicated than I had indicated. From recent unpublished work on motivational systems in stumptail macaques, I agree with Delgado that in primates "the essential factors determining an animal's response (defense and submission) are hierarchical position and social context, not familiarity," However, I hope to show in a future publication that this difference between rodents and primates reflects a rather simple change in the nature of the inputs to the consociate modulator. And regarding extrapolation to humans, I agree with Eichelman and Fraczek that human aggressive behavior is far more complex than that of other vertebrates. Human aggression has been transformed by many cultural factors such as the development of institutions and economic systems and the elaboration of motor patterns with tools and language. Knowing this, we have a moral obligation to avoid oversimplified phylogenetic extrapolations (which may be "particularly provocative" as noted by Brain), and we should make it clear that such human phenomena as crime, revolution, and war are not the inevitable results of neural circuitry.