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The present paper considers recent progress in our understanding of the afferent/ascending neural pathways and neural circuits of interoception. Of particular note is the extensive role of rostral neural systems, including cortical systems, in the recognition of internal body states, and the reciprocal role of efferent/descending systems in the regulation of those states. Together these reciprocal interacting networks entail interoceptive circuits that play an important role in a broad range of functions beyond the homeostatic maintenance of physiological steady-states. These include the regulation of behavioral, cognitive, and affective processes across conscious and nonconscious levels of processing. We highlight recent advances and knowledge gaps that are important for accelerating progress in the study of interoception. The nervous system receives ascending communication of interoceptive signals originating from the periphery via chemoreceptor, mechanoreceptor, and osmoreceptor pathways, several of which were discovered only recently. Visceral systems and associated interoceptive signals are regulated in part by descending central nervous system (CNS) control of the autonomic nervous system, yielding a reciprocal circuit that regulates bodily organs and a wide array of motor, cognitive, and affective processes. A gap in our understanding of how interoceptive signals are relayed through the CNS from the body centers on inputs to the nucleus tractus solitarius and higher relay pathways. The neural circuits of interoception are important for behavioral, cognitive, and emotional regulation across conscious and nonconscious levels of processing. [ABSTRACT FROM AUTHOR]

Prader-Willi syndrome (PWS) is characterized by morbid obesity and abnormal appetite. It has been suggested that appetite is reduced by the administration of the opioid antagonist, naloxone. This has led to the hypothesis that appetite disturbance is a consequence of an abnormal hypothalamic response to appetite effects of endogenous opiates and opiate antagonist may be a useful treatment. To characterize the feeding patterns of PWS children and test this hypothesis, we administered an appetite test to 10 PWS children and 9 obese control children. We also examined the effects of naloxone on eating behavior of the children with PWS. While initial rate of eating did not differ, the PWS group showed a much delayed satiety resulting in a longer period of food intake. No difference in food intake was observed with naloxone (1.6 mg im, 30 mm before the feeding test) treatment as compared with saline treatment. [ABSTRACT FROM AUTHOR]

Criticizes an article which declared that only naturalistic studies can inform about the cognitive process that are sensitive to natural selection. Definition of a naturalistic study versus an artificial task for probing defined cognitive functions; Criticisms of other studies done on behavioral genetics. INSET: Reply.

Abstract: In mammals, empathy is crucial for living in social groups and caring for others. In this paper, we consider the structural and functional organization of empathy. We propose that empathy subsumes a variety of neurobiological processes and partially dissociable information processing subsystems, each of which has a unique evolutionary history. Even the most advanced and flexible forms of empathy in humans are built on more basic forms and remain connected to core subcortical and neurohormonal mechanisms associated with affective communication, parental care and social attachment processes. Considering empathy within a framework that recognizes both the continuities and the changes within a phylogenetic perspective provides a richer understanding of empathy and related neurobehavioral processes. [Copyright &y& Elsevier]