THE PHENOMENON OF BRAIN PLASTICITY 41tiple neural ontologies that are brought forth in particular research pro-
grams, which themselves may affect the structures and functions they seek
to measure. This leads to the second issue. The specificity of matter must
be explored without accepting the naïve position that what neuroscientific
research uncovers is given by nature alone. The brain isn’t plastic because
we say it is, to paraphrase Barad (2007), and the ways we know its plasticity
do not determine them. But the differential differences of plasticity, the way
its differences matter, are entangled with our efforts to know it. In this sense
the plastic brain is materially- discursively performative.
In his essay on Henri Bergson, James (1909) argued that the concepts
we use to grasp reality fail to reflect its fluid nature. “The essence of life is
its continuously changing character,” he wrote, “but our concepts are all
discontinuous and fixed, and the only mode of making them coincide with
life is arbitrarily supposing positions of arrest therein” (cited in B. Rubin
2013).^26 One could argue that this epistemic limitation applies to all efforts
to describe the biosocial world, but it is especially paradoxical with respect
to neural plasticity. Neuroscientific research on plasticity fosters an appre-
ciation of the brain as a fluid becoming that constantly transforms itself in
relation with the world, but it also imposes various moments of arrest. The
uneven economies of plasticity allow researchers to identify distinct pat-
terns and configurations in the brain, which are not necessarily understood
to be permanent, but nonetheless gain duration in part through their influ-
ence on future trajectories. Efforts to depict brains as biosocial also rely on
a parallel effort to fix persons in social categories, statistical aggregates, or
populations that can be mapped onto the brain. The resultant neural phe-
notypes may resist biological determinism, but they do not auto^ matically
resolve the attendant problems of reification and essentialism. The mea-
surement of human difference through biosocial plasticity can require cuts
that belie biosocial complexity and that (mis)construe the experience of
individuals and groups as homogenous and predictable.
The significance of this cannot be fully appreciated through a critique
that addresses neurobiology only in terms of its epistemic constructs. Nor
can it be grasped through the assumption that the materiality of the brain
simply escapes its measurement and representation. James (1909) writes
that concepts “are not part of reality, not real positions taken by it,” and