Crossing the Nodes of Ranvier

There were many things that struck me as I read through the Neurobiology textbook and related the physical and electrical structures and impulses of the brain to our other readings on computer networking, ecosystems, and the rhetorical situation. Most importantly, unlike a computer system, the brain is constantly adjusting according to a symbiotic feedback loop between the organism and its environment. It is far more complex than a computer system that uses binary logic to make decisions between inputs. In the brain, whose model is no longer thought of as a computer network or system of file drawers, the neuro-plasticity lasts a lifetime, and the experiences of the organism have a real physical impact on the network of neurons, which in turn governs memory, learning, thought, and systems. The movement of electrical impulses — action potentials — through the network physically changes the cell structures. The transmission itself actualizes the potential and creates the capacity for future transmission.

I was immediately struck by the language used by the researchers that mimics communication and rhetoric: neurons communicate constantly, they can listen and speak at the same time. In the computer networking materials I read at the beginning of the semester, this dual capacity was spoken of as something that evolved in networking: originally the cabling only allowed for taking turns — a node had to listen and receive before it could speak — but the development of fiber-optic cabling allowed for parallel pathways of outgoing and incoming information, what was described as listening and speaking. But the brain is different, and here I’m thinking of Latour’s concept of intermediary vs. mediator. In a computer network, the information is relayed without change, although it could be amplified by a particular node to have a larger reach. In the brain, the information is transformative as it moves along the network of neurons. In a computer network, packets of information are bundled and labeled for a particular recipient that takes a predetermined action. In the brain, the neurotransmitters mediate between the pre-synaptic and post-synaptic terminals, effecting change as a result of their interaction. This change is not merely for the current transmission, but it creates the possibility for future transmissions, strengthening and building a pattern. In this sense the movement itself creates the pathways, inscribing the network. The brain controls behavior and behavior makes the brain. They are in a co-creative loop that sets up the potentials for the next scenario encountered.

The relationship between the regulation of potassium and sodium drives the movement of these electrical impulses, which were termed “action potential” down the neuron.  I began to wonder if my 9 p.m. salt cravings have to do with sustaining mental energy and concentration. Then I ate a big bowl of popcorn and figured I should get a banana.

As the scientists discussed the brain as being a link between the outside world and regulated internal behavior, I started thinking about the brain as a boundary object. I also started thinking about it as an ecosystem on the forage- eat- poop loop. The brain takes in information, processes it, then makes outputs. It is its own system, within the system of the body, in constant interface with external systems. I became consumed with the thought of the brain as a rhetor, and the action inside the brain as mimicking the movement in a rhetorical situation. The pre-synaptic terminals as the rhetor, the audience as the post-synaptic terminals, and the discourse or message traveling across the synapse via a medium — a selected and appropriate neurotransmitter. The magic happens in the exchange, where, based on the intensity of the message, the receptors can be “keyed up” or stimulated in such a way that they repeat or escalate the message, depending on how it is interpreted. One neuron firing — one instance of discourse — can cause a single other neuron to fire or thousands of them.

As the chapter discussed the movement of the electrical impulses along the Sheaths of Myelin covering the neurons, jumping tiny gaps called the Nodes of Ranvier, I was envisioning a Rider of Rohan galloping along, the ground lighting up under the horse’s feet,  jumping the ravines (synapses) to continue to relay the message. (Must have been the word “Ranvier” that put me into the fantasy realm of Dagohir or Isengard).

There is fruit to this notion of an impulse being an “action potential” in the network, and to the idea of vescicles holding a variety of (genre) neurotransmitters, waiting for a particular exigence that would allow them to be deployed. There is also fruit to the idea that the post-synaptic receptors are predisposed to accept particular neurotransmitters, but that this can be altered by changing the strength and type of the action potential signal. The imbalance of sodium and potassium creates “membrane potential” which cannot reach stasis — an inside/outside imbalance is necessary for the communication to take place. These ideas bring me back to discussions about the rhetorical situation, which is predicated on tension and creating an opening to receive the message.

I have not gotten as far as I should have in the Castells reading. It is fascinating! Castells notion of  simultaneous communication networks that are more than mere “horizontal” and “vertical” but a convergence of autonomous content creation that he terms “mass self-communication” (xxx) is amazing. This jives with the notion of the brain creating and reinforcing the pathways and potentialities. Castells says that communication (discourse?) is “self-generated in content, self-directed in emission, and self-selected in reception” (xxx) and distributed in a many-t0-many multimodal model. So individuals are the creators and they create the collective perception and reality that is a conglomerate of individual perceptions and affected by the messages they come in contact with.  The question is, how do people come together as communities? How do they find commonality among their individual experiences and interpretations? Is there a way for the network to unite the fragmented post-modern society?

References

Annenberg Learner. “Unit 10: Neurobiology.” Rediscovering Biology. 2014. Web. 31 March 2014.

Pictures:

Minion Loves Bananas: http://minionslovebananas.com/galleries-images-wallpapers/

Rohan Rider: http://www.onrpg.com/articles/news/lotro-unveils-riders-of-rohan-expansion-details/