No abstract

Previous research has shown that exposure to testicular hormones during the peri-pubertal period of life has long-term, organizational effects on adult sexual behaviour and underlying neural mechanisms in laboratory rodents. However, the organizational effects of peri-pubertal testicular hormones on other aspects of behaviour and brain function are less well understood. Here, we investigated the effects of manipulating peri-pubertal testicular hormone exposure on later behavioural responses to novel environments and on hormone receptors in various brain regions that are involved in response to novelty. Male rodents generally spend less time in the exposed areas of novel environments than females, and this sex difference emerges during the peri-pubertal period. Male Lister-hooded rats (Rattus norvegicus) were castrated either before puberty or after puberty, then tested in three novel environments (elevated plus-maze, light–dark box, open field) and in an object/social novelty task in adulthood. Androgen receptor (AR), oestrogen receptor (ER1) and corticotropin-releasing factor receptor (CRF-R2) mRNA expression were quantified in the hypothalamus, hippocampus and medial amygdala. The results showed that pre-pubertally castrated males spent more time in the exposed areas of the elevated-plus maze and light–dark box than post-pubertally castrated males, and also confirmed that peri-pubertal hormone exposure influences later response to an opposite-sex conspecific. Hormone receptor gene expression levels did not differ between pre-pubertally and post-pubertally castrated males in any of the brain regions examined. This study therefore demonstrates that testicular hormone exposure during the peri-pubertal period masculinizes later response to novel environments, although the neural mechanisms remain to be fully elucidated.

This pilot study examines the use of surgical instrument tracking and motion analysis in objectively measuring surgical performance. Accuracy of objective measures in distinguishing between surgeons of different levels was compared to that of subjective assessments. Twenty-four intraoperative video clips of mastoidectomies performed by junior residents (n = 12), senior residents (n = 8), and faculty (n = 4) were sent to otolaryngology programs via survey, yielding 708 subjective ratings of surgical experience level. Tracking software captured the total distance traveled by the drill, suction irrigator, and patient’s head. Measurements were used to predict surgeon level of training, and accuracy was estimated via area under the curve (AUC) of receiver operating characteristic curves. Key objective metrics proved more accurate than subjective evaluations in determining both faculty vs resident level and senior vs junior resident level. The findings of this study suggest that objective analysis using computer software has the potential to improve the accuracy of surgical skill assessment.