“
“After natural menopause in women, androstenedione becomes the primary hormone secreted by the residual follicle-depleted ovaries. In two independent studies, in rodents that had undergone ovarian follicular depletion, we found that higher endogenous

serum androstenedione levels correlated with increased working memory errors. This led to the hypothesis that higher androstenedione levels impair memory. The current study directly tested this hypothesis, examining the cognitive effects of exogenous androstenedione administration in rodents. Middle-aged ovariectomised rats received vehicle or one of two doses of androstenedione. Rats were tested on a spatial working and reference memory maze battery including the water-radial arm maze, Morris water APO866 chemical structure maze (MM) and delay match-to-sample task. Androstenedione at the highest dose impaired reference memory as well as the ability to maintain performance as memory demand was elevated. Selleck AZD0530 This was true for both high temporal demand memory retention of one item of spatial information, as well as the ability to handle multiple items of spatial working memory information. We measured glutamic acid decarboxylase (GAD) protein in multiple brain regions to determine

whether the gamma-aminobutyric acid (GABA) system relates to androstenedione-induced memory impairments. Results showed that higher entorhinal cortex GAD levels were correlated with worse MM performance, irrespective of androstenedione treatment. These findings suggest that androstenedione, the main hormone produced by the follicle-depleted ovary, is detrimental to working memory, reference memory and memory retention. Furthermore, while spatial reference memory performance might be related to the GABAergic system, it does not appear to be altered with androstenedione administration, at least Pyruvate dehydrogenase at the doses used in the current study. “
“Damage to cerebral systems is frequently followed by the emergence of compensatory mechanisms,

which serve to reduce the effects of brain damage and allow recovery of function. Intrinsic recovery, however, is rarely complete. Non-invasive brain stimulation technologies have the potential to actively shape neural circuits and enhance recovery from brain damage. In this study, a stable deficit for detecting and orienting to visual stimuli presented in the contralesional visual hemifield was generated by producing unilateral brain damage of the right posterior parietal and contiguous visual cortical areas. A long regimen of inhibitory non-invasive transcranial direct-current stimulation (cathodal tDCS, 2 mA, 20 min) was applied to the contralateral (intact) posterior parietal cortex over 14 weeks (total of 70 sessions, one per day, 5 days per week) and behavioral outcomes were periodically assessed. In three out of four stimulated cats, lasting recovery of visuospatial function was observed.