Though its existence has been known for well over 30 years, only recently has the supplementary motor area (SMA) and its role in the cortical organization of movement come to be examined in detail by neuroscientists. Evidence from a wide variety of investigational perspectives is reviewed in an attempt to synthesize a conceptual framework for understanding SMA function. It is suggested that the SMA has an important role to play in the intentional process whereby internal context influences the elaboration of action. It may be viewed as phylogenetically older motor cortex, derived from anterior cingulate periarchicortical limbic cortex, which, as a key part of a medial premotor system, is crucial in the “programming” and fluent execution of extended action sequences which are “projectional” in that they rely on model-based prediction. This medial system can be distinguished from a lateral premotor system postulated to have evolved over phylogeny from a different neural source. An anatomico-physiologic model of the medial premotor system is proposed which embodies the principles of cyclicity and reentrance in the process of selecting those neural components to become active in conjunction with the performance of a particular action. The postulated dynamic action of this model in the microgenesis of a discrete action is outlined. It is concluded that although there is a great deal to be learned about the SMA, a convergence of current evidence can be identified. Such evidence suggests that the SMA plays an important role in the development of the intention-to-act and the specification and elaboration of action through its mediation between medial limbic cortex and primary motor cortex.

Males are selectively afflicted with the neurodevelopmental and psychiatric disorders of childhood, a broad and virtually ubiquitous phenomenon that has not received proper attention in the biological study of sex differences. The previous literature has alluded to psychosocial differences, genetic factors and elements pertaining to male “complexity” and relative immaturity, but these are not deemed an adequate explanation for selective male affliction. The structure of sex differences in neurodevelopmental disorders is hypothesized to contain these elements: (1) Males are more frequently afflicted, females more severely; (2) disorders arising in females are largely mediated by the genotype; in males, by a genotype by environment interaction; (3) complications of pregnancy and delivery occur more frequently with male births; such complications are decisive and influence subsequent development. We hypothesize that there is something about the male fetus that evokes an inhospitable uterine environment. This “evocative principle” is hypothesized to relate to the relative antigenicity of the male fetus, which may induce a state of maternal immunoreactivity, leading either directly or indirectly to fetal damage. The immunoreactive theory (IMRT) thus constructed is borrowed from studies of sex ratios and is the only explanation consistent with negative parity effects in the occurrence of pregnancy complications and certain neurodevelopmental disorders. Although the theory is necessarily speculative, it is heuristic and hypotheses derived from it are proposed; some are confirmed in the existing literature and by the authors' research.

There seem to be two kinds of pain: fundamental “sensory” pain, the intensity of which is a direct function of the intensity of various pain stimuli, and “psychological” pain, the intensity of which is highly modifiable by such factors as hypnotism, placebos, and the sociocultural setting in which the stimulus occurs.

Physiological, cognitive, and behavioral theories of pain each have their own view of the nature of the two kinds of pain. According to physiological theory and cognitive theory, “psychological” pain and “sensory” pain are both internal processes, with the former influencing the latter as central processes influence peripheral processes. According to behavioral theory, “sensory” pain is a reflex (a respondent) while “psychological” pain is an instrumental act (an operant). Behavioral theory claims that neither kind of pain is an internal process — that both are overt behaviors.

Although both physiological theory and cognitive theory agree with common sense that pain is internal, they disagree with commonsense intuitions at other points. They are no better at explaining the subjective experience of pain than is behavioral theory. They have not generated treatments for pain that are superior to those generated by behavioral theory. There is no basis for the frequent claim by antibehaviorist philosophers and psychologists that behaviorism, because it cannot explain pain, is less capable of explaining mental phenomena than physiology or cognition.