This is the case in humans as well; sex hormone levels in male and female fetuses and infants differ, and both androgen receptors and estrogen receptors have been identified in brains. Several sex-specific genes not dependent on sex steroids are expressed differently in male and female human brains. Structural sex differences begin to be recognizable by 2 years of age, and in adult men and women include size and shape of corpus callosum (larger in women) and fasciculae connecting each hemisphere internally (larger in men), certain hypothalamic nuclei, and the gonadotropin feedback response to estradiol . [ citation needed ]
Past-year use of synthetic cannabinoids (K2/herbal incense, sometimes called "fake weed" or "synthetic marijuana") has dropped significantly in the six years since the survey began tracking use of these substances. Since 2011, reported use among 12th graders has dropped from percent to percent. Use has also fallen from percent to percent among 8th graders and from percent to percent among 10th graders since 2012. In recent years, use of another synthetic drug called "bath salts" (technically, synthetic cathinones) among youth has become a concern. The MTF survey began tracking past-year synthetic cathinone use in 2012, and since then, there has been a decrease among 12th graders from percent to percent in 2017. Use among 10th graders has declined to percent from a peak of percent in 2013.
assortment , hash , hodgepodge , hotchpotch , jumble , medley , mélange , mishmash , motley , patchwork , potpourri , variety ;