Brains on Brains Week 2: Synaptic Transmission

_____________________________________________________________________________________________________________________________________

 

The blog “A Plastic Journey: Introspection of Brains Learning About Brains” delves into the qualia, feelings and thoughts brought forth in the authors’ brains upon learning about the human brain and its functions. The blog will follow loosely the structure of the course “NBE-E4210 – Structure and operation of the human brain.” The blog is written in the form of a fact-filled, loopy and introspective story. [Logo: Oxford University Press (2018).]

______________________________________________________________________________________________________________________________________

I came to the course as a doctoral student of new media. I study virtual reality, a trendy field where concepts like immersion, perception and embodiment all seem to point towards the need to understand not just human psychology, but the underlying principles that make us (or / and our brains) what we are. Like so many other disciplines, media research has also gained an enormous new insight into human mind through the advancements in neuroscience. While the course book, lectures and everything else seem overwhelming for someone coming from “outside”, professor Ilmoniemi’s introduction lecture’s figure two we already cited in this blog (the brain operates on multiple scales) puts it all in place. Media research operates usually somewhere between language, behaviour and society, so it’s just wise to venture into the molecular and cellular levels too. This week’s theme, synaptic transmission, was a good example of something totally groundbreaking for me.

Probably the easiest and most common knowledge part of the chapter 5 were the neuromuscular junctions. Being more accessible to researchers and having direct effects on bodily functions it’s no wonder many synaptic transmission mechanics were first understood here, before central nervous system. This is also the area most people understand to some extent even without any training in neuroscience. But of course the lecture and the book were mostly focused on synaptic transmissions in CNS.

In addition to the general understanding of the chemical and electrical synapses and the chemistry and physics behind them, some learning highlights for this week included the role of SNARE proteins in binding and fusion of membranes. The delivery of vesicles to presynaptic membrane is key to fast working synaptic transmission. The cooperation of v-SNARES of vesicles and t-SNARES of the outer membrane makes sure that the vesicle “docks” where it should. Although it wasn’t discussed during the lecture, the book’s explanation of botulinum toxins and how they function anchored the mechanism of synaptic transmission very firmly into my memory.

Examples like this are valuable because sometimes it’s easier to remember a certain mechanic by learning conditions where it doesn’t work as intended. To make it short, botulinum toxins are enzymes that destroy certain SNARE proteins, disrupting the transmitter release. Another poison affecting the transmitter release is latrotoxin, which eliminates acetylcholine release in neuromuscular junction. I actually encountered a black widow spider recently while working abroad, and got a colourful description of the symptoms of it’s bite from a lady who was nice enough to take it away from my room. Now I know that nausea, muscle cramps and dizziness are actually swollen axon terminals and missing synaptic vesicles. Another fun animal from the same region, black mamba (dendroaspis polylepis), uses a venom that is a combination of many different toxins. One part of the cocktail, dendrotoxin, interferes with neuromuscular junction transmission through various mechanisms, including by inhibiting potassium channels at pre- and post-synaptic levels, enhancing ACh release from nerve terminals.

Still, for me the most wondrous detail has to be the temporal scale these things happen. We can’t “sense” our own synaptic transmissions in any relevant way, because everything happens in the scale of milliseconds to be useful for us when navigating in human scale world. This reminds me of the discussion about free will: if everything that makes us think and act happens so fast, are we actually the authors of our thoughts or just merely witnessing them rising in our consciousness? I’m sure this is something we can discuss later in the course, but for me chapter 5 gave many new reasons to speculate this.

 

SOURCES

Bear, M.F., Connors, B., Paradiso, M. 2015. Neuroscience: Exploring the Brain. 4th Edition. Lippincott, Williams & Wilkins.

Brylla C., Kramer M. (ed.) 2018. Cognitive Theory and Documentary Film. Palgrave Macmillan, Cham

Grabowski, M (ed.) 2014. Neuroscience and Media: New Understandings and Representations. Routledge.

Harris, S. 2012. Free will. New York, Free Press.

Ranawaka, U. K., Lalloo, D. G., & de Silva, H. J. 2013. Neurotoxicity in Snakebite—The Limits of Our Knowledge. PLoS Neglected Tropical Diseases, 7/(10).  http://doi.org/10.1371/journal.pntd.0002302

Posted by Free Willy

About Free Willy

The blog "A Plastic Journey: Introspection of Brains Learning About Brains" delves into the qualia, feelings and thoughts brought forth in the authors' brains upon learning about the human brain and its functions. The blog will follow loosely the structure of the course "NBE-E4210 - Structure and operation of the human brain." The blog is written in the form of a fact-filled, loopy and introspective story.
This entry was posted in Uncategorized. Bookmark the permalink.

Leave a Reply