NOTES TO CHAPTER 1 137personhood” through brain scans, which do not photograph or film the brain in
action but rather statistically craft images of brain activity based on relative levels
of activation in different areas. Producing an fmri image involves many steps of
calculation, each of which involves a set of decisions, such as choosing statistical
thresholds, which influence the result. Further, deciding what those images mean
is a matter of interpretation. Scans often are read through reverse inference,
where particular cognitive processes are inferred from observed activations in
areas thought to be associated with such processes. Cordelia Fine (2011) ad-
dresses other methodological problems with brain scan research measuring sex
differences, including consistently small sample sizes, the difficulty of controlling
for bodily variables such as breathing rate and caffeine intake, and controversies
over statistical procedures.
9 For example, the corpus callosum, a bundle of nerve fibers that connect the two
hemispheres of the brain, and the cerebellum, located at the back of the brain,
are considered to have distinct trajectories. The former is thought to develop
“structurally throughout life, but most dramatically during childhood and
adolescence” (Luders et al. 2010, 10985), whereas the latter seems to be plastic
much longer, developing into the early twenties (Giedd 2004). The purportedly
less plastic corpus callosum has been associated in the literature with problem
solving, compared with the more plastic cerebellum, which has long been linked
to motor coordination and balance. The cerebellum’s role has more recently ex-
panded to include the coordination of cognitive as well as physical tasks.
10 For example, if the Supreme Court considers this knowledge in deciding whether
the execution of teenagers is unjust, as in Roper v. Simmons 2005.
11 Based on their review of the imaging literature that detects different task- related
patterns of activity in the brains of research subjects grouped by ses, as well
as their own experiments that use a battery of tests on children of low- and
middle- income backgrounds, they propose that ses affects primarily two of the
five (Noble et al. 2005) or seven (Farah, Shera, et al. 2006) brain systems they
identified.
12 Edward Taub’s controversial work offered surprising evidence of major cortical
remapping. To study the relation between sensory input and motor use, Taub
deafferented the limbs of rhesus and macaque monkeys to permanently cease the
feeling of stimuli in their arms. In the wake of a campaign by animal rights activ-
ists, the monkeys were removed from Taub’s lab. Over a decade later, when the
monkeys were euthanized, a group of researchers examined their somatosensory
cortices. They found that up to 14 mm of cortex that likely would have received
stimuli from the arms was instead receiving stimuli from the face (Pons et al.
1991). This was more extensive cortical remapping than ever documented before,
leading Taub to hypothesize that the plasticity involved not just the axons of neu-
rons in the cortex but the thalamus or brain stem, which would indicate a more
global mechanism of plasticity (Clifford 1999).
13 The researchers also experimented with using cognitive reinforcements to boost