138 NOTES TO CHAPTER 1
this topographic malleability, finding that attention to a task is a crucial factor in
transformations of the cortex (Merzenich 2012).
14 In lesion studies, which correlate structures with functions by examining the
behavioral impact of damage to particular brain areas, the hippocampus has long
been linked to spatial memory and navigation.
15 Their 2006 study compared taxi drivers with bus drivers (who, unlike taxi driv-
ers, follow planned routes and thus do not have to memorize a huge amount of
spatial information). In this study taxi drivers also measured comparatively more
gray matter volume in mid- posterior hippocampi and less volume in anterior
hippocampi. Interestingly, however, in a battery of tests, their performance on
tasks in acquiring new spatial information was poorer than that of the bus driv-
ers. To test this further, they took scans of seventy- nine trainees (and thirty- one
controls) over the three to four years they took to prepare for the examinations.
They found no differences in the structures of two regions of the hippocampus
at the start; later, however, they measured greater volume in the posterior hippo-
campus in trainees who passed the exam, but not in the controls or the trainees
who failed the exam (Maguire et al. 2011).
16 In the 2011 study Maguire et al. took scans of the hippocampi of seventy- nine
trainees (and thirty- one controls) over the three to four years they took to pre-
pare for the tests. They ended up with three groups: those who did not study at
all (since they were controls, not aiming to be taxi drivers), those who studied
and failed, and those who studied and passed. They found no differences in the
structures of the hippocampus between any of the groups at the start. Later, how-
ever, they measured greater volume in the posterior hippocampus in trainees
who passed the exam, but not in the controls or the trainees who failed the exam.
17 A 2011 review paper published in Frontiers in Neuroendocrinology, for exam-
ple, asserts that gender identity and sexual orientation are “programmed into
our brain during early [prenatal] development. There is no evidence that one’s
postnatal social environment plays a crucial role” (Bao and Schwabb 2011, 214).
Depending on whom you ask, male and female brains are very different, very
similar, or a little bit different. Anne Fausto- Sterling (2012) warns that many of
the reported differences, such as percentage of white matter versus gray matter
and relative size of the corpus callosum, hippocampus, and amygdala, disap-
pear when studies control for the relative size of the brain in men and women.
(Because of their larger body size, men’s brains are 10% bigger on average.) And
Cordelia Fine (2011) and Rebecca Jordan- Young (2010) caution that isolated re-
ports finding sex differences in the brain need to be assessed in conjunction with
others; many differences, such as the degree of lateralization across the right and
left hemispheres, disappear when examined across multiple studies.
18 Although the function of the straight gyrus is not settled in neuroscience, they
cite several fMRI studies that report activity in this area during social intelli-
gence tasks, as well as lesion studies that show deficits in social intelligence in
patients with brain damage in this area.