THE PHENOMENON OF BRAIN PLASTICITY 23in brain function and structure. They argue that social forces, rather than
evolutionary ones, are the cause of neurobiological difference.
The move to read plasticity through the lens of gender socialization,
alongside efforts to discover a neural phenotype of poverty and other bio-
social research programs, underscores the necessity to theorize plasticity
not as a social construction, nor as an unmediated matter of fact, but rather
as a jointly ontological and epistemological concern, one whose agentic
implications are not immediately straightforward. I make this case below,
but first I offer a brief (and necessarily partial) description of neuroscien-
tific research on plasticity, which suggests that it cannot be understood as
generic or monolithic. Plasticity is neither an undisputable fact with a sin-
gular meaning nor a mere social construction. Rather, it refers to multiple
materialities that are entangled with specific research questions, practices
of scientific measurement, and ideas about development, environmental
context, and biosociality. The promise of neural plasticity depends in part
on how it is defined and measured.
Plasticities of the Brain
Plasticity has some shared meanings across different knowledge sites, but
also gains significance and weight in particular contexts (Jordan- Young 2014;
Kraus 2012; Pitts- Taylor 2010; B. Rubin 2009). At the start of modern neuro-
science, the concept of plasticity emerged to address how neurons’ connec-
tions with each other are related to the brain’s activity. In the mid- twentieth
century, this synaptic or “functional” plasticity often was elaborated in con-
trast to the apparently fixed structural organization of the brain. Evidence
of the mature brain’s ability to rewire and reshape itself in response to new
stimuli and activity has more recently led to biosocial models of brain
structure as well as function. This history should not be conceived in a tel-
eological fashion, where the brain is merely awarded greater plasticity over
time. Even in the current moment, when neural plasticity is more broadly
recognized than ever before, the brain does not appear to be globally or
monolithically plastic. Rather, in different research programs plasticity is
unevenly distributed across developmental time scales, various regions of
the brain, and even potentially between persons.