Lesion studies.

Read Also

 Experimental lesions in normal male and female animals sometimes give sex-specific results.    For example, it makes a difference whether female mammals are pregnant or not.   Pregnant females seem to manifest better cognitive recovery from brain lesions than do non-pregnant mammals.  In fact,  females seem to frequently recover better from brain lesions in general.   This effect has been observed following prenatal frontal lobe brain lesions in primates (monkeys) and following lesions of a brain nucleus called the globus pallidus in rats lesioned during adulthood.  The human female also has a better neurodevelopmental, cognitive, and school outcome following extreme premature birth  or extremely low birth weight.  A meta-analysis of previously published results has found that women have a better recovery than men on both the Performance IQ (PIQ) and on the Verbal IQ (VIQ) scales following unilateral brain lesions.  The same effect has been observed in children. We have seen that interesting such findings are pointing toward the frontal lobes as a brain volume which is different in function in the two sexes. Patricia Goldman-Rakic found that cognitive impairments due to very precocious frontal lesions emerge earlier (in adolescence) in male than female monkeys.   The same researcher found that performance on one of the frontal lobe tasks was improved by injections of androgens in both male and female monkeys.  The task consisted of a test of the ability to maintain a discrimination and produce a discriminative response after an interval of time.    In another chapter of this book I mention sex differences in the composition of frontal lobe tissue in humans.  Finally,  recall that I found that men were superior on the Porteus Mazes test,  a test reputed to reflect frontal lobe functioning (though it also loads heavily on visuospatial processing).    Some researchers have even reported sex-specific effects of brain lesions on behaviors that are gender-specific in normal animals.    Hippocampal lesions and lesions of the ventromedial nucleus of the hypothalamus as well as of the septum,   all limbic structures,   have produced sex-specific changes in rodents.   Further research is required to determine whether there exist brain nuclei that could be termed «female»  or «male».