explain xkcd - User contributions [en]

Talk:2120: Brain Hemispheres

2019-03-08T03:13:28Z

Evilbob0:

https://en.wikipedia.org/wiki/Cerebral_hemisphere#Hemisphere_lateralization
If the left side controls the top half of the body, wouldn't that mean it also controls the right half? [[Special:Contributions/108.162.241.248|108.162.241.248]] 20:04, 6 March 2019 (UTC)
: It is uncontroversial that many senses and motoric functions are swapped between the right and left side. The anatomy of the nerve swaps can also be shown. But it is still under discussion, why evolution led to this swap (source: [https://en.wikipedia.org/wiki/Contralateral_brain Contralateral brain] and the even better organized German version [https://de.wikipedia.org/wiki/Kontralateralit%C3%A4t_des_Vorderhirns Kontralateralität des Vorderhirns]) Sebastian --[[Special:Contributions/172.68.110.46|172.68.110.46]] 08:41, 7 March 2019 (UTC)
: I'm referring exclusively to the hypothetical model posed by the comic; rather than the reality.

I don't think the sentence "all 3 claims are false" is accurate. I think the claim that the right side of your brain controls the left side of your body is accurate. It says so on the Wikipedia article mentioned and in several other sources. What the Wikipedia article disputes is whether or not "higher-level" functions are partitioned to one side of the brain. [[Special:Contributions/172.69.42.64|172.69.42.64]] 20:29, 6 March 2019 (UTC) Harrison
: With regard to the retina, the right half of the brain processes what the right half of each retina receives, and the left half processes what the left half of each retina receives (see e.g. [https://nba.uth.tmc.edu/neuroscience/m/s2/chapter15.html optic nerve]), but because our retina is behind the focal point of our lens so all the lightbeams cross and images hit the back of the eyeball upside-down and backwards, that means the halves of our brain process the opposite halves of what we see. But it's the same side of our body! I stopped learning neuroscience after we got to the optic nerve ;p [[Special:Contributions/108.162.221.95|108.162.221.95]] 21:48, 6 March 2019 (UTC)
: You must've stopped in the middle of the lesson, because the optic nerves split so that both brain halves get a copy of each eye. Your own link points it out in the figure as the "Optic chiasm".--[[User:Henke37|Henke37]] ([[User talk:Henke37|talk]]) 13:09, 7 March 2019 (UTC)
:: If you look closer, you can see how the left half of each eye (retina) goes only to the left half of the brain, and same for the right, even though both eyes do go to both sides. The split is by what is seen, not which eye sees it, which specially maps to the left side or right side of the eyeball. [[Special:Contributions/162.158.79.185|162.158.79.185]] 19:03, 7 March 2019 (UTC)

:I think the "right side of your brain controls the left side of your body" is NOT accurate, it's just closer to truth than the reverse. Some parts of perception and motor control are divided that way, but unless you have corpus callosotomy the high-level control is centralized and/or distributed regardless the side. Would be hard to synchronize both hands if not. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 02:05, 7 March 2019 (UTC)

Having survived an ischemic stroke on the left side of my brain, which temporarily paralyzed the right side of my body, this comic speaks to me like none other.

Is it possible that the title text is a reference to the whole "magnetic north is actually south" thing?
----You forgot to sign, dude ^^^---

Completely rewrote the explanation. There are two key phrases that were removed with the following justifications:

'''"left arm and left leg, and vice versa for the left half of the brain, and competing theories such as [https://arxiv.org/pdf/1003.1872.pdf these] [https://link.springer.com/article/10.1007%2FBF02972358 two] attempt to explain why this is the case."
'''
Those are not competing theories. It is the abandonment of one old theory in favor of a one that is better supported with evidence! It's like saying "There are competing theories of what an atom is actually made out of. One says that they are the smallest indivisible part of all matter. Another says that they are like plum-puddings with with a positive charge particle studded with negative charge corpsucles. And the last theory of what an atom is is a core particle with positive charge, made of many many smaller parts, surrounded by an probability/statistical cloud of negative particles which can act as both particles and waves and cannot have their speed and location determined at the same time.

... And if you think these are all "competing" and equally valid theories of what an atom is... I can not help you. Please... I don't know. Take a class or read a textbook or something. Good luck. May God have mercy on you.

'''Similarly, many people incorrectly argue that different parts of the brain control logic and emotion, due to the importance of the [https://www.sciencedirect.com/science/article/pii/S0028393211000285?via%3Dihub left] brain for language processing.
'''
Removed and replaced it with a better explanation. Not technically "incorrectly argue". There is basis for which the arguments are founded.

--[[User:Evilbob0|Evilbob0]] ([[User talk:Evilbob0|talk]]) 03:12, 8 March 2019 (UTC)

Talk:2120: Brain Hemispheres

2019-03-08T03:12:34Z

Evilbob0:

https://en.wikipedia.org/wiki/Cerebral_hemisphere#Hemisphere_lateralization
If the left side controls the top half of the body, wouldn't that mean it also controls the right half? [[Special:Contributions/108.162.241.248|108.162.241.248]] 20:04, 6 March 2019 (UTC)
: It is uncontroversial that many senses and motoric functions are swapped between the right and left side. The anatomy of the nerve swaps can also be shown. But it is still under discussion, why evolution led to this swap (source: [https://en.wikipedia.org/wiki/Contralateral_brain Contralateral brain] and the even better organized German version [https://de.wikipedia.org/wiki/Kontralateralit%C3%A4t_des_Vorderhirns Kontralateralität des Vorderhirns]) Sebastian --[[Special:Contributions/172.68.110.46|172.68.110.46]] 08:41, 7 March 2019 (UTC)
: I'm referring exclusively to the hypothetical model posed by the comic; rather than the reality.

I don't think the sentence "all 3 claims are false" is accurate. I think the claim that the right side of your brain controls the left side of your body is accurate. It says so on the Wikipedia article mentioned and in several other sources. What the Wikipedia article disputes is whether or not "higher-level" functions are partitioned to one side of the brain. [[Special:Contributions/172.69.42.64|172.69.42.64]] 20:29, 6 March 2019 (UTC) Harrison
: With regard to the retina, the right half of the brain processes what the right half of each retina receives, and the left half processes what the left half of each retina receives (see e.g. [https://nba.uth.tmc.edu/neuroscience/m/s2/chapter15.html optic nerve]), but because our retina is behind the focal point of our lens so all the lightbeams cross and images hit the back of the eyeball upside-down and backwards, that means the halves of our brain process the opposite halves of what we see. But it's the same side of our body! I stopped learning neuroscience after we got to the optic nerve ;p [[Special:Contributions/108.162.221.95|108.162.221.95]] 21:48, 6 March 2019 (UTC)
: You must've stopped in the middle of the lesson, because the optic nerves split so that both brain halves get a copy of each eye. Your own link points it out in the figure as the "Optic chiasm".--[[User:Henke37|Henke37]] ([[User talk:Henke37|talk]]) 13:09, 7 March 2019 (UTC)
:: If you look closer, you can see how the left half of each eye (retina) goes only to the left half of the brain, and same for the right, even though both eyes do go to both sides. The split is by what is seen, not which eye sees it, which specially maps to the left side or right side of the eyeball. [[Special:Contributions/162.158.79.185|162.158.79.185]] 19:03, 7 March 2019 (UTC)

:I think the "right side of your brain controls the left side of your body" is NOT accurate, it's just closer to truth than the reverse. Some parts of perception and motor control are divided that way, but unless you have corpus callosotomy the high-level control is centralized and/or distributed regardless the side. Would be hard to synchronize both hands if not. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 02:05, 7 March 2019 (UTC)

Having survived an ischemic stroke on the left side of my brain, which temporarily paralyzed the right side of my body, this comic speaks to me like none other.

Is it possible that the title text is a reference to the whole "magnetic north is actually south" thing?
----You forgot to sign, dude ^^^---

Completely rewrote the explanation. There are two key phrases that were removed with the following justifications:

'''"left arm and left leg, and vice versa for the left half of the brain, and competing theories such as [https://arxiv.org/pdf/1003.1872.pdf these] [https://link.springer.com/article/10.1007%2FBF02972358 two] attempt to explain why this is the case."
'''
Those are not competing theories. It is the abandonment of one old theory in favor of a one that is better supported with evidence! It's like saying "There are competing theories of what an atom is actually made out of. One says that they are the smallest indivisible part of all matter. Another says that they are like plum-puddings with with a positive charge particle studded with negative charge corpsucles. And the last theory of what an atom is is a core particle with positive charge, made of many many smaller parts, surrounded by an probability/statistical cloud of negative particles which can act as both particles and waves and cannot have their speed and location determined at the same time.

... And if you think these are all "competing" and equally valid theories of what an atom is... I can not help you. Please... I don't know. Take a class or read a textbook or something. Good luck. May God have mercy on you.

'''Similarly, many people incorrectly argue that different parts of the brain control logic and emotion, due to the importance of the [https://www.sciencedirect.com/science/article/pii/S0028393211000285?via%3Dihub left] brain for language processing.
'''
Removed and replaced it with a better explanation. Not technically "incorrectly argue". There is basis for which the arguments are founded.
--[[User:Evilbob0|Evilbob0]] ([[User talk:Evilbob0|talk]]) 03:12, 8 March 2019 (UTC)

Talk:2120: Brain Hemispheres

2019-03-08T03:11:16Z

Evilbob0:

2120: Brain Hemispheres

2019-03-08T02:56:35Z

Evilbob0: /* Explanation */

{{comic
| number = 2120
| date = March 6, 2019
| title = Brain Hemispheres
| image = brain_hemispheres.png
| titletext = Neurologically speaking, the LEFT hand is actually the one at the end of the RIGHT arm.
}}

==Explanation==
{{incomplete|Created by an AUTONOMOUS LEG and a CHICKEN. The links "these", "two", and "left" are nonsense for a reader, please explain the content and provide a link-text revealing the title ot something similar of the linked article. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

As a general rule, each cerebral hemisphere (half of the brain) innervates (feeds/supplies/controls) the contralateral (opposite side) portion of the body. So things on the left half of the body are controlled by the right side of the brain and vice-versa. As previously noted however, this is simply a rough approximation. As all things biology, God (or evolution, or pick your deity/creator of choice) enjoys unnecessary convolution [citation needed]; as always to most biology "rules" there are exceptions.

A notable exception are the cranial nerves; some do not decussate (cross over) as would be predicted from the rule above and directly innervate the ipsilateral (same side) side (eg abducens CN6). And of course, many cranial nerves innervate both ipsilateral and contralateral sides. This phenomenon is often seen, when everything is working properly, in things like the pupillary reflex (when you shine a bright light in one eye, both eyes' pupils constrict)

While the motor and sensation aspects of nerve innervation have been relatively well-established from studies, experiments, and dissections, (mostly through knockout(what happens to function if I damage/remove this part of the brain?) or stimulation studies) there is probably always going to be an exception, as you might imagine. Any number of factors may cause deviation from the normal physiology: trauma, disease, congenital birth defects, brain plasticity, etc.

With less concrete aspects of human brain function, such as logic, emotion, language processing, and creativity, establishing which brain hemisphere has control is obviously more complicated. Because a lot of these are higher order functions (these are things you tend to learn, develop, and obtain as you grow into an adult from a neonate), establishing which hemisphere has control of which function are obviously more complicated. Due again to brain plasticity or other factors, different developing brains may grow to wire control of these functions differently. So while studies have established which hemisphere is more likely to be involved with which function (eg left with language processing), again mostly through knockout studies, these generalizations are not necessarily true for every individual.

Randall spoofs these by suggesting that the right brain instead controls the upper torso. This would suggest that your left leg moves independently of your brain. To explain the areas of the body controlled by both halves of the brain, Randall declares those sections "disputed," echoing a note added on maps that must display a border which is part of a {{w|territorial dispute}}. This suggests that the halves of your brain fight for control of the region, and is also described similarly to two countries disputing territory. Alternatively, there would be cooperative shared control (= dual control).

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:[Cueball is shown with the right half of his brain (on the viewer's left) colored in orange and the left half (on the viewer's right) in iris blue. An iris blue box is overlaid over the right half of the body (on the viewer's left), and an orange box is overlaid over the top half. The boxes are overlapping in a greenish color on the upper right quarter of the body (on the viewer's left).]
:'''Neuroscience Fact:'''
:[An arrow pointing to the iris blue rectangle on top with the text above:]
:The ''left'' half of the brain actually controls the ''right'' half of the body...
:[An arrow pointing to the orange rectangle at the right, the text reads:]
:...while the ''right'' half of the brain actually controls the ''top'' half of the body.
:[An arrow pointing to the overlapping area (the top left body from the viewers perspective) with the text below:]
:Disputed/dual control
:[An arrow pointing to Cueball's left leg area (on the viewer's right), not highlighted by any color, and the text is:]
:This leg is fully autonomous

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Comics featuring Cueball]]
[[Category:Biology]]

2049: Unfulfilling Toys

2018-09-21T20:10:18Z

Evilbob0:

{{comic
| number = 2049
| date = September 21, 2018
| title = Unfulfilling Toys
| image = unfulfilling_toys.png
| titletext = We were going to do a falling-apart Rubik's cube that was just 27 independent blocks stuck together with magnets, but then we realized it was actually really cool and even kind of worked, so we cut that one.
}}

==Explanation==
{{incomplete|Created by a Stretch Armstrong made out of hard plastic. Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

This comic lists and illustrates a number of classic toys that are missing a key piece or attribute that makes them work and/or that makes them unique. As such, they are not much fun{{Citation needed}}.

====Rigid Slap Bracelet====
Slap Bracelets are flexible bars that when you hit them on your arm they twist and become a bracelet. A rigid one would not twist and would be deeply frustrating and painful.

====Sealed Stomp Rocket====
A stomp rocket has a rubber pouch full of air, connected via a hose to a cylinder containing a tightly-fitting rocket on a stick. By stomping on the pouch, the air is forced into the cylinder launching the rocket into the air. By sealing the air channel, the rocket would stay in the cylinder and the person would just be bounced into the air by the pouch -- acting like the world's smallest bouncy house -- or the pouch will burst rending the toy even more useless.

====Pump-only Supersoaker====
A supersoaker is a water gun that works by first pumping air into the gun, which introduces air pressure next to the water, then releasing the water using the gun's trigger -- the extra pressure from the pumped air makes the water go much further than a regular water gun. In this version, the water cannot be released, so the fun part of the water gun -- getting to spray your friends -- isn't there.

====Glass Glow Stick====

In a classic glow-stick, made of flexible plastic, one much first bend it enough to break the glass cylinder inside. This allows the chemicals inside to mix and begin glowing within the plastic tube. If the entire tube were made of actual glass, however, it would not only shatter into many sharp glass pieces, but would also cover the hands of the unfortunate user with a mixture of harmful chemicals.

====Wingless Sky Dancer====

In the traditional toy, a doll or figure with folded-up wings sits on top of a hand-held device with a wrapped string or other mechanism that lets it spin the doll very fast. As the doll spins, centrifugal force causes the wings to unfold and provide lift, and the doll rises up in the air and flies, spinning, sometimes going quite high. Without the wings, the doll will spin but otherwise remain flightless.

====No-strings-attached Yo-yo====
In a traditional yo-yo, one attaches a string to their finger and the other end of the string is loosely attached to the yo-yo, such that it will hold the yo-yo but the yo-yo can still spin. In this case, the string is included but not attached to the yo-yo, so the yo-yo, when it reaches the end of the string, will keep going instead of coming back to the person or spinning at the end of the string.

This one actually exists and some people are even quite good at it. See https://www.youtube.com/watch?v=t5P-fdrlBg8 for example. Although some may argue that this is less a "stringless yo-yo" and more of a "stickless [https://en.wikipedia.org/wiki/Diabolo diabolo (Chinese yo-yo)]"

====Title-text: Falling-Apart Rubik's cube====
In order to build the magnetic Rubik's cube, you would need to embed magnets (like the little hockey-puck shaped ones for magnetic bulletin boards) in the the uncolored (inward-facing) sides of each cube. You would need to take care to have the correct pole of each magnet facing outward in order for it to work, but you can achieve that by having the corners and the central outside cubes use one pole (say north) facing outward and have the edge and center (hidden) cube use the other pole (say south) facing outward. In that way each piece would be attracted to its correct neighboring piece and if you rotated a side, it would resist turning until you got half way around, then it would be drawn into the correct new position.

This also exists, is rather functional, and is the only way to make fun Rubik's cube shapes such as 1x5x5. See: https://www.youtube.com/watch?v=Xb8ENlS-5Go

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Ponytail]]
{{comic discussion}}