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Cianci Melo-Carrillo

Dr. Eric Raymer

Frontiers of Science

December 8th 2015

Return to Immaturity: Neuroplasticity’s Future

The “Astonishing Hypothesis” that our identity results from the interactions within the

brain left me with the ominous feeling that perhaps I experience the outside world solely based

on my neural connections. By further studying the concept of neuroplasticity, I have confirmed

my ominous feeling but have also understood that the experiences which I choose to participate

reciprocally change even the most primitive neural connections. Solely observing the effects of

the brain on behavior or experiences on the brain limits our ability to understand either since the

two processes do not act independently.

Garcia-Segura in Hormones and the Mutable Brain relays that processes such as hormone

production, feelings, emotions, behavior, and cognition only contribute to brain plasticity, but do

not cause brain plasticity. The process of plasticity occurs independently of anything else—

something that Garcia-Segura attributes to plasticity being an innate procedure. It surprised me to

learn about the brain’s quick modification in the “hammered arm” trick, but to see the brain’s

plasticity as pre-programmed to modify perceptions such as that of one’s own arm shocked me.

It appears to almost be as if the brain foresees having to changing neural connections, therefore,

having an independent system of modification.

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Hormones and the Mutable Brain proceeds to describes two processes of neuroplasticity:

modification and neurogenesis. Early investigators Cajal and Hebb both presented ideas about

how experience modifies existing neural connections. Most beautifully, Cajal presents that

cerebral cortex as a “garden filled with trees, the pyramidal cells, which, thanks to intelligent

culture, can multiply their branches, sending their roots deeper and producing more and more

varied and exquisite flowers and fruits.” Modification is the only process of neuroplasticity for

Cajal in this passage, since without “intelligent culture,” there would be no one to maintain the

“garden.” Hebb echoes Cajal’s flowery language by concluding that long term changes in

synaptic efficacy are associated with repeated neuronal activity. To me, this the most obvious

and accessible aspects of neural plasticity, that habit and our intellectual environments affects

our neural connections. Our ability to affect our neural plasticity (but not cause it) provides me

with a more optimistic view of the “Astonishing Hypothesis.” While I might not have control

over what Garcia-Segura calls metaplasticity—or the process that controls plasticity—I do have

control over which intellectual environments and habits I can pursue. By “willfully” placing

myself in a situation that aids modification through neural plasticity, I can indirectly affect the

process which shapes my brain to view experiences in a certain way.

In Spatial Integration and Cortical Dynamics (Charles Gilbert et Al.), the modification

aspect of neuroplasticity surprisingly affects one the most primeval brain locations: the primary

visual cortex. In Smart Sparrow, we were introduced to the monkey visual cortex experiment in

which it was found that certain neurons were specialized in perceiving certain shapes or aspects

of an object. Logically it would be assumed that if a part of the visual cortex were lesioned, the

function those neurons would be lost. Charles Gilbert and colleagues incredibly found that

arboratization occurred in surrounding axons, meaning that old pathways were replaced by

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newer surrounding ones. Through observing the plasticity resulting from lesioning the retina, the

study concludes that “even in adulthood, brain plasticity results from a continuing process of

experience-dependent synaptogenesis.” Even the most primeval brain locations are affected by

experience in adulthood.

Neurogenesis, or the creating of new brain cells, works at a slow pace in comparison to

the almost immediate effects of modification neuroplasticity (Charles Gilbert et. Al). Recent

research in this process of neuroplasticity attempts to change the speed of this process by altering

alleles or artificially disrupting receptors such as the PirB which are involved in blocking

neuroplasticity. Returning to the cortical representation of visual information, David Bochner

and colleagues change the PirB receptor of blinded mice. They concurrently track the progress of

mice that are reforming binocular vision through modification, and mice whose PirB receptors

have been altered under the hypothesis that “if adult neural circuits could be returned to an

immature state, critical periods might be effectively reopened, facilitating recovery after nervous

system damage.” Their experiment effectively resulted in the extending of critical periods for the

mice, which allowed them to recover more quickly. Richard Sapp believes that artificial

neurogenesis contains the future of many treatments for diseases and disorders including

Alzheimer’s disease.

While the authors see these results as beneficial and capable of leading to new treatments,

this creates an insidious feeling inside of me. My discussion of an optimistic view on the

“Astonishing hypothesis” was based on having control of the types of experiences, but not on the

metaplasticity processes. By being able to extend critical periods, normal metaplasticity is altered

to allow for a return to a state of immaturity; this has implications in our fundamental

knowledge, which means that our sense of self could also be completely vulnerable. The

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prospect of being able to change that which we learned during our developmental years appeals

to those that see a larger potential inside of their minds, but this desire assumes that there is an

ideal mind or experience lens that one should aim for. There is a difference between aiming for

an ideal while keeping one’s individuality, and becoming an “ideal” by modifying one’s

individuality.

The thought of ideal “forms” stems from Plato and inspires modern day science. Physics

seeks to explain natural behavior through laws, effectively creating a form for which natural

history should be explained. The physics equivalent of altering metaplasticity would be

modifying the universe to fit the form of laws which you wish to place it in. Would it make the

understanding of the universe simpler? Yes. It would not bring nearly the amount of satisfaction

that having a goal to reach a form of beauty would, similar to our ideal as students to become an

ideal academic with our good “habits of mind” which exist because of our understanding of

change as gradual and not instantaneous.

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Works Cited

Bice, Travis. "Neural Plasticity." History of Neuroscience. Univerisity of Wisconsin, n.d. Web. 7

Dec. 2015.

Bochner, D. N., R. W. Sapp, J. D. Adelson, S. Zhang, H. Lee, M. Djurisic, J. Syken, Y. Dan, and

C. J. Shatz. "Blocking PirB Up-regulates Spines and Functional Synapses to Unlock Visual

Cortical Plasticity and Facilitate Recovery from Amblyopia." Science Translational Medicine

6.258 (2014): n. pag. Web.

Garcia-Segura, Luis Miguel. Hormones and Brain Plasticity. Oxford: Oxford UP, 2009. Print.

Gilbert, Charles D., Aniruddha Das, Minami Ito, Mitesh Kapadia, and Gerald Westheimer.

"Spatial Integration and Cortical Dynamics." National Academy of Sciences United States of

America (1996): n. pag. Web.