Previous research on healthy individuals reported improvements in balance control following a purported ankle proprioception-training program. The training may have resulted in a general rather than a specific enhancement of ankle proprioception. To test this hypothesis, subjects were constrained at the hips and trunk with a custom-made thoracolumbosacral orthosis and performed a one-leg standing test with eyes closed and head tilted back, so that they had to rely primarily on their ankle musculature to keep their balance. Subjects were retested after training on the BAPS three times a week for 4 weeks, following the training recommendations of the manual. Subjects' bodies were not constrained during the training. Analysis showed that subjects made improvements during training in performing more difficult tasks on the board. On the one-leg test, however, there were no improvements in sway velocity, number of touchdowns, or falls relative to pretest scores. Improvements observed during training likely resulted from diffuse enhancement of proprioception in other body segments such as the knees, hips, spine, and upper extremities. A training program in control of general balance does not specifically target ankle proprioception.

In the African cichlid fish, Haplochromis burtoni, males are either territorial or nonterritorial. Territorial males suppress reproductive function in the nonterritorial males, and have larger gonads and larger gonadotropin-releasing hormone- (GnRH) containing neurons in the preoptic area (POA). We describe an experiment designed to establish the causal relationship between large GnRH neurons and large testes in these males by determining the feedback effects of gonadal sex steroids on the GnRH neurons. Territorial males were either castrated or sham-operated, 4 weeks after which they were sacrificed. Circulating steroid levels were measured, and the GnRH-containing neurons were visualized by staining sagittal sections of the brains with an antibody to salmon GnRH. The soma areas of antibody-stained neurons were measured with a computer-aided imaging system. Completely castrated males had markedly reduced levels of circulating sex steroids [11-ketotestosterone (11KT) and testosterone (T)], as well as 17 beta-estradiol (E2). POA GnRH neurons in castrates showed a significant increase in mean soma size relative to the intact territorial males. Hence, in mature animals, gonadal steroids act as a brake on the growth of GnRH-containing neurons, and gonadal products are not responsible for the large GnRH neurons characteristic of territorial males.

Adult males of the African cichlid fish Haplochromis burtoni are either territorial or nonterritorial. In nature and aquaria, only territorial males breed and they have markedly more developed testes than do nonterritorial males. Territorial males are clearly dominant over nonterritorial males of the same age and size, and also exhibit higher levels of aggression. In this study, territorial males were gonadectomized in order to assess the effects of lowered androgen levels on their aggression and dominance status. Completely castrated males showed a pronounced reduction in both testosterone and 11‐ketotestosterone, as well as significantly lower aggression scores than sham‐operated males. Partially castrated males (> 0.005 g gonadal tissue remaining at autopsy) exhibited intermediate levels of both androgen levels and aggression. Surprisingly, in dyadic encounters with normal nonterritorial males of the same size, castrated territorial males retained their dominance despite decreased androgen levels and aggression.

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