We have shown previously that male rats develop a conditioned ejaculatory preference (CEP) for females scented with a neutral odor like almond or lemon that is paired with the male's post-ejaculatory reward state during their first and subsequent early sexual experiences. However, preexposing males to the neutral odor alone prior to its pairing with sexual reward results in latent inhibition. Here, we examined the phenomenon of unconditioned stimulus (US) preexposure, in which male rats were preexposed to the ejaculatory reward state either one or five times with scented (ScF) versus unscented (UnScF) females prior to multiple ejaculatory trials with females in the opposite condition (e.g., ScF preexposure received 10 subsequent ejaculatory trials with UnScF, whereas UnScF preexposure received 10 subsequent ejaculatory trials with ScF). As before, mate and partner preference was evaluated in an open field where each male had access to two females, one ScF and the other UnScF. Males that underwent five trials of preexposure did not display a CEP for either female. Conversely, males preexposed once to a ScF, and later trained with UnScF developed a preference for the latter, whereas males preexposed once to the UnScF, and then trained with ScF did not show a preference for any of the females. Subsequent exposure to the odor cue alone revealed different patterns of brain activation in areas related to sexual behavior that depended on the animal's group membership. Altogether, these findings demonstrate the pivotal role of first sexual experiences in the establishment of future sexual partner preference in the male rat, and suggest an innate preference for estrous odors over neutral odors that can become conditioned subsequently as predictors of sexual reward.

No abstract

Optic Pathway Gliomas (OPG) represent 4-6% of brain tumors in children. Treatment of optic pathway gliomas is prompted by neuroradiological evidence of tumor growth, usually associated with progressive visual loss. Despite therapy, approximately 40% will show visual deterioration. Treatment outcome is largely based on the preservation of vision. However, current visual fonction assessment is often unreliable in children with optic pathway gliomas who have limited collaboration. Thus, there is a need for new clinical tools to evaluate visual functions in these children. The_aim of the study was to assess the usefulness of steady-state visual evoked potentials as a tool to assess the integrity of the central and peripheral visual fields of children with optic pathway gliomas.Ten patients with optic pathway gliomas and 33 healthy controls (ages 3 to• 18 years) were tested using steady-state visual evoked potentials. The circular dart-board stimulus consisted of one central circle altemating at 16 reversals/second and one peripheral hoop alternating at 14.4 reversals/second, separated by ahoop of gray space. It was presented Iilonocularly at 30% and 96% contrasts.Results indicated that central signal-to-noise ratios were significantly lower in children with optic pathway gliomas compared to controls. However, no significant group difference was detected in the peripheral visual field.In conclusion, our study shows that steady-state visual evoked potentials could be useful in the clinical assessment and follow up of central visual • field deficits in uncooperative or non-verbal children but seems to have limited usefulness for the evaluation of peripheral visual field defièits. Additional studies are needed to identify • . testing parameters for full visual-field assessment.

No abstract

Background: Optic pathway gliomas (OPG) represent 5% of pediatric brain tumours. Visual acuity measures are used to evaluate treatment response. Current clinical tests to assess visual field integrity are subjective and require verbal cooperation. Thus, the objective of this study was to evaluate the clinical effectiveness of Steady State Visual Evoked Potentials (ssVEPs) to measure visual field integrity in a non-invasive and objective manner. Methods: SsVEPs were obtained in ten children with OPGs and 42 controls ages 3 to 21. The stimuli consisted of two circular dartboard patterns stimulating fovea and peripheral zones at two flickering frequencies, so that central and peripheral visual fields could be assessed simultaneously. The test consisted of eight stimuli presentations of 10 seconds. Results: Results indicate significantly lower ssVEP amplitudes in children with OPGs (M=2.52, 95% CI [1.13, 3.92]) compared to controls (M=13.26, 95% CI [8.85, 17.67]) in the central visual field (p=.021). However, no between group differences were detected in the peripheral field (p >.05). There were no significant differences between age groups (p>0.05). Conclusions: This objective, affordable, and non-invasive method appears to be effective in detecting central visual field deficits in children with OPGs rapidly and consistently.