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BackgroundIn many songbirds the larger vocal repertoire of males is associated with sexual dimorphism of the vocal control centers and muscles of the vocal organ, the syrinx. However, it is largely unknown how these differences are translated into different acoustic behavior.Methodology/Principal FindingsHere we show that the sound generating structures of the syrinx, the labia and the associated cartilaginous framework, also display sexual dimorphism. One of the bronchial half rings that position and tense the labia is larger in males, and the size and shape of the labia differ between males and females. The functional consequences of these differences were explored by denervating syringeal muscles. After denervation, both sexes produced equally low fundamental frequencies, but the driving pressure generally increased and was higher in males. Denervation strongly affected the relationship between driving pressure and fundamental frequency.Conclusions/SignificanceThe syringeal modifications in the male syrinx, in concert with dimorphisms in neural control and muscle mass, are most likely the foundation for the potential to generate an enhanced frequency range. Sexually dimorphic vocal behavior therefore arises from finely tuned modifications at every level of the motor cascade. This sexual dimorphism in frequency control illustrates a significant evolutionary step towards increased vocal complexity in birds.

The detection of suboptimal effort has become crucial in clinical neuropsychological practice in order to make accurate diagnoses, prognoses, and referrals. Symptom Validity Testing (SVT) has been the most commonly utilized model for assessing effort, and frequently includes recognition memory tasks. Some conflicting views on this model purport, however, that measures of effort gathered from a recognition memory paradigm do not necessarily extend to effort in other cognitive domains and other areas of performance. The present study sought to investigate whether performance on an SVT measure, which utilizes recognition memory, the TOMM, could predict performance on other measures that do not evaluate recognition memory or just memory per se in a group of mildly traumatic brain-injured litigants. Results indicated that poor performance on the TOMM was significantly correlated with poorer performance on the WAIS-R and the HRNB-A. Further, experimental exploration of these results indicated that the overall neuropsychological performance of litigants with suboptimal effort was poorer than what is generally expected from mild TBI individuals, and was also lower than the other mild TBI examinees in the study, who were not classified by the TOMM as exhibiting suboptimal effort. These findings support the proposition that poor effort as measured by recognition memory effort measures is not restricted to recognition and memory measures. In fact, in the present study it appears that a poor performance on the TOMM is predictive of a generalized poorer performance on standardized measures such as the WAIS-R and the HNRB-A.

In 1948 one of us (O.S.) proposed a new method of treatment, abdominoperineal resection, for patients with congential megacolon. Since then, 483 patients have been treated by 13 pediatric surgeons in Chicago and Boston using this technique. Two hundred and eight-two of the patients were last interviewed and examined more than 5 years after the resection. There were 16 postoperative deaths (3.3%) and 6 late deaths (1.2%) from enterocolitis. Both early and late complications were infrequent and are discussed in detail. Almost 90% of the patients reported that they now have normal bowel habits. None of the patients developed urinary incontinence or impotence, although ten patients (2.1%) reported permanent fecal soiling. This is the first large group of patients treated for congenital megacolon who have been followed to adulthood. The low incidence of postoperative complications and minimal frequency of long-term complications indicate that the abdominoperineal resection is a safe, effective method of treatment for congenital megacolon.