- Chemical Synapses: the most common of those found in the human brain, have a miniscule gap (called the “synaptic cleft”) between the pre- and post-synaptic neurons. Amongst this gap, chemicals that are produced in the soma of the cell, called Neurotransmitters are released by way of exocytosis ( a fancy word for membranous sacks releasing) into this small gap between neurons, and some are received (by way of receptors) into the post-synaptic cell, of which this process can either decrease or increase the potential (disparity between positive and negative charge amongst the inside and outside of the cell) and influence any further electrical, action potentials (the “firing” of the cell). Furthermore, the electrical current that caused the neurotransmitters to be released in the pre-synaptic cell, is released outside of the cell. There are a plethora of neurotransmitters and a nerve cell only makes/diffuses a specific neurotransmitter, already implicating a great diversity of neurons…which we will delve into later in this answer…
- Electrical Synapses: less common than chemical synapses, and have ion channels that connect the pre- and post- synaptic cells (i.e. there is a continuity between the two cells). Electrical transmissions are extremely rapid and typically bi-directional. The process of which can be shown below, and involves the transmission of an electrical current via “gap junction” channels that are highly conductive and low-resistant to electricity. Furthermore, in the post-synaptic cell features non-gated channels by which some of the electrical current will escape, reducing the electrical potential within the cell.
(a) Electrical Synapse (b) Chemical Synapse
Now onto the true answer to the question, what is the purpose of these dang things?
Perhaps the most notable reason I could think of for the purpose of this is that of the purpose of sustainability and efficiency in the process of chemical neuro-transmission. The chemical synapse requires more processes than that of an electrical synapse, ( binding of neurotransmitters to vesicles, releasing of neurotransmitters into synaptic cleft, diffuse across cleft, potentially recycling through process of reuptake, etc… i.e: more processes than the simpler electrical synapse)…
Now, imagine a electrical current going through a small pre-synaptic cell, it reaches the synapse and “sees” (bare with me on the lack of technicality) a large post-synaptic cell, how is the subsequent, smaller electrical current going to achieve the threshold and initiate an action potential? Through chemical diffusion of thousands of neurotransmitters diffusing across this small synaptic cleft, of which permit amplification of the synaptic response, enabling a smaller pre-synaptic cell to trigger an action potential in a potentially, much larger post-synaptic cell. This further hints at the fact that there is such a immense diversity of neurons… that a synapse can efficiently and functionally connect different shaped, sized, etc. neurons and have neurotransmitters serve as the liaisons (in transmitting information) between the two different shaped, sized, neurons further hints at its purpose, especially as brains (cerebral cortices, specifically) have augmented in complexity over thousands and thousands of years.
Essentially, a synapse provides the most biologically efficient, robust, versatile (synapses can be modified) mechanism for information to be transmitted chemically and electrically in the brain…
Other reasons for which there is a synaptic gap would include ():
- For chemical synapses, the synaptic gap ensures a unidirectional flow of electrical impulses.
- Permits a ‘refractory period’ of which the process of action potentials is bounded by a upper limit due to limit on neurotransmitter resourcers.. This ensues in sensory adaptation, e.g: you are not constantly stimulated because your shorts are touching your skin…
- Permits impulses to be distributed across multiple post-synaptic neurons and vice versa, multiple impulses can converge at a synapse…
- Further permit spatial summation (many pre-synaptic neurons’ impulses converge on a singular post-synaptic neuron reaching its threshold and firing an action potential) and temporal summation (a rapidly firing, single, pre-synaptic neuron causes a post-synaptic neuron to fire an action potential) … ensuing in the grading of neural responses (i,e.: too “low” or “infrequent”, not important => don’t transmit).
My answer, to:on Quora…
When you exercise and close your eyes, you will lose a great sense of balance, as vision is crucial for proper balance and posture. However, despite your eyes being closed, your Visual Cortex will still be active, perhaps not as active as before, but active nonetheless, as you will be visualizing and creating some semblance of your surroundings based on visual memories. Also, the visual system is highly connected to other regions of the brain that are responsible for balance and sensory-motor coordination, as will be discussed further in this answer.
On the other hand, neural activity will most likely increase in the other areas responsible for sensory-motor coordination such as the semicircular canals that comprise your vestibular sense which can best be described in this paper called “Balanced Vision: How the Visual and Vestibular Systems Interact:”
“Sometimes called the “balance system,” the vestibular system is located in the inner ear. It is the first fully myelinated sensorimotor system of the human body, and is fully functional at birth, because the mother’s movements during pregnancy stimulate vestibular development in the fetus.
The job of the vestibular system is to sense changes in motion. It is not a motion detector, but rather more of an accelerometer of sorts. It senses both linear and rotational acceleration/deceleration and gravity. It lets us know our position with gravity and whether or not we are moving. It registers linear motion through the utricles (mostly horizontal), and saccules (mostly vertical), which together make up organs called otoliths. Registration of rotary motion is through the six semicircular canals.
Stimulation of the otoliths releases serotonin producing calmness, relaxation and lowered tone. Stimulation of the semicircular canals releases adrenaline producing excitation, arousal and increased tone.”
and in areas of muscular proprioception and your kinesthetic sense. Kinesthetic sense can best be clarified in this article :
[The Kinesthetic sense is] the sense that tells a home-run hitter that the ball will go out of the park, because he hit the ball just right & he knows before the crowd does that the ball is on the way to the bleachers. The proprioceptors in his muscles as he swings the bat send information to his brain, which puts together all the sensory input and formulates based on past experience what feels right. Someone like Sadaharu Oh, the Japanese baseball player who holds the all-time world record of 868 home runs, would have an excellent sense of what it feels like to hit a home run. Like kinesthetic sense, proprioception describes how much we know about where we are in space and where all of our parts are in relationship to each other.
Our kinesthetic sense helps us move with greater precision, avoid injuries, and be fully present in the moment. This awareness assists us in healing by enabling us to both consciously & unconsciously direct our energy and healing activities like fluid and chemical exchanges more effectively to an injured area. All sorts of factors will influence human proprioception. The neural pathways in the brain give us an almost unconscious sense of the right sequence of muscle contractions that will cause our foot to take a step. Microscopic sensory receptors throughout our bodies send information. Our mind sorts through and processes this information in a complex way that science is only beginning to understand fully. One thing is clear – greater body awareness leads to improved function and better overall health.
The neural pathways of kinesthetic sense become more ingrained through repetition. It can be a challenging process to overcome habits or tendencies ingrained in movement patterns. One movement pattern will feel more “normal” or “right” because it is customary… With practice and with time movement training helps develop greater awareness.”
While your vision has been deemed the most “significant contributor to balance”, without it, it would be logical that neural activity would still occur in the Visual Cortex (for the aforementioned reasons), but perhaps not at such copious metabolic rates, and neural activity would continue (if not, augment) in other areas responsible for sensory-motor coordination, particularly the vestibular sense and proprioception and kinesthetic networks of the brain.
Where to Begin?
So, this past summer, I began a “soul search,” in that I wanted to attempt to find answers to the following questions:
- What is the purpose of my life?
- What do I see myself doing for the remainder of my limited time on this planet?
Unfortunately, or perhaps fortunately, I have not really answered these questions, trying various avenues, various methodologies, and going through some interesting (to say the least) experiences. In this post, I hope to detail the “Recent Failures” and the impact on my “soul search” and how I rebounded, in several parts, this being the initial, and first.
Introduction to Failurology [a.k.a The Beginning of Summer]:
It was the beginning of June, exams were complete, both AP and Honors, and summer was approaching, meaning no more schoolwork (other than the usual “summer assignments,” which I always have found to be quite interesting), and I was ready to spend my summer, learning…
Wait? What? Yes, indeed, I was ready and prepared to delve into various classes and go to a STEM Pre-College at my local university. However, due to my recent hospital bills (apparently spine surgery is pretty expensive) and my single mother’s intensive work schedule, I found myself confined to my house… No external access to the physical world, just myself and the vast Internet.
S0, I self-enrolled in courses through iTunes U, Udacity, and Coursera, in attempt to both broaden and specify my knowledge base. I self-enrolled in Physics, Statistics, Machine Learning, Algorithms, Artificial Intelligence Courses, and pretty much anything else that sounded “cool” to me. By the end of the first couple weeks of Summer, I [self] “dropped-out” of many of the rudimentary courses, narrowed my “soul-search” down to one primary option, and “Check 1″ of my Checklist… done!
I wished it was that simple. However, I did narrow down my life’s dedication, or perhaps better known as the cliche terms “passion” and/or “interest.” This being, Neuroscience, the Computational Kind… Now, this was just an idea, akin to the typical conversation:
- “Hey what do you want to be when you grow up? “
- “Well, you know, a Computational Neuroscientist!”
[Thought in other persons' head]: It’ll be something different in a month or two…
Though, Computational Neuroscience, and Neuroscience in general, intrigues me beyond comprehension, as there is just something about the brain, the mystery, the complexity, it is quite exhilarating, if I may say so myself. Now, it is great to have an idea, a notion of what you may want to do, but I realized, “Hey, I need to do something…,” so I went straight to my favorite social network Quora and asked this question. This led me to two great things, one, a volunteer opportunity for Eyewire.org thanks to a truly wonderful person and awesomely active user of Quora named Amy Robinson. The second led me to realize, I could attempt to get an internship at my local university at a neuroscience lab. Now, this realization, is where the failure and subsequent recovery begin.
Excited and hyped, I began to research Neuroscience Labs, who either utilized computational modeling, or were involved in biophysics, or the neuroscience behind learning and memory, as neuronal computation and synaptic plasticity are the most intriguing. As I searched, hours on end, for relevant Labs, I found one, of which was researching Reelin signaling, and ApoE genes and their roles in Alzheimer’s. This didn’t quite suite my desires, but I maintained an “open” mind and decided to investigate a little further, and per the answer by another awesome Quora user (who is a neuroscientist), named Colin Gerber. Who would aid in my letter to the aforementioned lab, something I am extremely thankful for, I read their publications, got quite interested into the basis of Alzheimer’s Disease, and was immensely excited, so within a week, after attempting to absorb as much information as I possibly could about the Disease, I sent the e-mail/letter…
I never received a response, even after a follow-up e-mail and with no phone number, I was slightly dismayed, perhaps I was too naive, too young, or [insert generic predisposition about 16-year-old teenage males here]. However, as Mr. Gerber, advised me not to get discouraged, I would overcome this personal failure, and move on.
Critical Lessons of First Failure:
1) Always remain open to doing things that may have not been your first or second choices… they may soon become it. As a result of my research into Alzheimer’s, I continue to study it, have been greatly interested in it, and is now one of my “first” or “seconds” of my Preferences.
2) Support, Support, Support. Someone who encourages you, advises you, create opportunities for you; these people are crucial to overcoming failure and pressing the “reset” button, or in the case of Amy Robinson, provide a “start” button. Value, appreciate, and surround yourselves with these people, as you can not do everything on your own. These people were those of my mother, Colin Gerber, and Amy Robinson. Thanks again!
End of Part 1…
So, for the past week or two, I have coding up my own blog, one iteration via Flask, a Python Microframework, and the other via Ruby on Rails, the infamous and widely-used web application platform for the beautiful Ruby programming language. While, I learned a lot, about Ruby, Ruby on Rails, and continued my investigation into HTML5 and CSS3, I realized that while I could create a more minimal, Content Management System, akin to WordPress.com (without the PHP and certain design ugliness), I could just host my own domain on WordPress and then update the CSS and fonts, therefore that is probably what I am going to do, in attempt to create the most beautiful, minimal, and user-friendly blog, but then, again… I am rather unpredictable.
Hope you enjoy…
The Blue Brain Project will most likely be able to simulate a “cortical column of best fit” analogous to a line of best fit, in which they will integrate and decide on the known neurobiological data, patterns, and essentially model such, attempting to create something that behaves as the brain as much as possible given our current understandings. However, due to the unknowns of the brain, in what pattern neurons are connected and the subsequent role/processes of these synapses (rewiring, reconnection, and regeneration) their resulting project, of which they may present as the first simulated, virtual brain, will not be completely comparable to the mammalian counterpart of their simulation (whether it be rat, human, etc.) and in that respect (given their relative time range) the project will most likely not work to the standard of creating a 1:1, entirely accurate, simulation of the brain through their extreme, ambitious form of Reductionism.
Virtual Brain of Best Fit:
What will come out of this, hopefully…
Regardless of whether they succeed or not (and how they will measure such? Turing Test?), hopefully the Blue Brain/ Human Brain Project will breed a robust, well-architected, and adaptable foundation for future data and neuroscientific progress to be integrated when made in the coming decades.
Now, without a doubt, any development amongst this project, be it successful in fulfilling the goal of the actual project or not, will be progress to the field of neuroscience in one way or another. But, one would remain skeptical that brain simulation through computational methods and reductionism would breed a clearer understanding of the 3 pounds of flesh in our skull, as a compromise will have to be made, from a computational perspective (power, energy consumption, expense), preventing true simulation of the brain, hence the “brain of best fit” analogy, modifying a computer to behave as close to the brain. Moreover, I do not believe that this project will breed insight on the organic brain, but breed insight on how to create better simulations of our Central Nervous System in the decades to come.
For more: Quora Answer
Due to various injuries and subsequent academic intensity (make-up work, exams, etc.) I have not been able to post on my beloved blog as much as I wish I could, however, with the commencement of summer break, I hope I can continue my studies in neuroscience and programming and really have a good, learning-intensive time away from school, of which I hope I can post more frequently and sustain a more lively and interesting blog.
For my dedicated followers, I am going to start a book called The Quest for Consciousness by the much venerated Christof Koch, in which I hope to share a basic summary over each chapter, as well as just share my sporadic thoughts on each chapter. Hope you find it interesting!
Related Info: http://www.youtube.com/watch?v=QJA5NYoDeO4
Several posts this week noted how we are failing with the nurturing, facilitating, and direct teaching of creativity within school environments.
New research reveals a global creativity gap in five of the world’s largest economies, according to the Adobe® State of Create global benchmark study. The research shows 8 in 10 people feel that unlocking creativity is critical to economic growth and nearly two-thirds of respondents feel creativity is valuable to society, yet a striking minority – only 1 in 4 people – believe they are living up to their own creative potential.