Category: Article
The Hand That Never Was: Supernumerary Phantom Limbs
In early 2007, a 64-year-old Swiss woman was admitted to the emergency room of a local hospital after having suffered a moderate right hemispheric stroke. Several days following her hospitalization, the woman began to experience what she described to her physicians as a “pale,” “transparent” arm that began at her elbow, which she could move and utilize to complete actions. The phenomenon the Swiss woman experienced was a Supernumerary Phantom Limb (SPL), which is characterized by the sensation of possessing an extra limb that did not exist previously. Though uncommon, conditions such as SPL and phantom limb (the sensation that a missing limb is still attached to the body) typically arise due to some form of insult to the somatosensory region of the brain or from the removal or lack of body parts.
The third arm illusion at the Karolinska Institute in Stockholm, Sweden.
In the healthy brain, multisensory circuits organize visual, tactile, and proprioceptive inputs to the brain in order to compose a somatotopic map of which body parts are inherently our own. However, even the normal brain can be manipulated into believing in the existence of an extra limb. More
“Out, damned spot! Out, I say!”
Lady Macbeth
For those of you who’ve forgotten or perhaps even repressed your memories of high school English class, the line in the title is the cry of the power-hungry and all-around homicidal maniac Lady Macbeth, the female lead in Shakespeare’s great tragedy, Macbeth. After having committed regicide so that her husband may become king, she becomes convinced that she cannot wash King Duncan’s blood from her hands. Thoughts are soliloquized, guilt is manifested in madness, and archetypes are born.
Curtain. More
Our Attraction to the End
Since the beginning of time, there have been theories on how the world will end. One fairly recent theory is that the end of the world will occur on December 21, 2012 when the Mayan Long Count calendar ends. Although scholars reject the theory that any catastrophic event is scheduled for this date, arguing that the significance of the date has been misinterpreted, many people still believe it’s coming. Movies, countless online forums and a good number of books talk about the apocalypse that is supposed to be arriving.
It makes you wonder what makes people obsess over these end-of-the-world scenarios after they’re given facts proving that it won’t happen. In an article published in Scientific American, Michael Moyer suggests that we are constantly trying to predict our demise because we have a need to explain things that are not in our control. Our brains are always searching for patterns in order to interpret the significance of events that occur in the natural world. Sociologist, John Hall, explains in his book, Apocalypse: From Antiquity to the Empire of Modernity, that, “After events like 9/11 and the Great Recession, as well as technological disasters like the BP oil spill, people begin to wonder—not just people who are fringe zealots or crazies—whether modern society is any longer capable of solving its problems.” Therefore, Moyer suggests, people are more willing to believe that the end of the world is coming because of a psychological need to explain why these events are happening.
Michael Shermer, editor in chief of Skeptic Magazine, agrees with Moyer, saying that the mind is always creating patterns based on events, meaningful or not. This explains why some people are so willing to believe doomsday scenarios when they hear them. He adds that people will opt to believe that a proposed danger is real when it actually isn’t because it is the safer course. He gives the example of Lucy the hominid who hears a noise while walking on the plains of Africa. She has two choices; she could assume that it was just grass rustling because of the wind or that is was a predator. The safer choice would be to assume that she was in danger, even if she wasn’t, in order to save her life. He suggests that this habit of assuming the worst to stay out of danger evolved into our pattern-seeking habits, causing us to predict catastrophic events based on potentially meaningless events. Research done by Jennifer Whitson, an assistant professor at the University of Texas at Austin, supports this claim, suggesting that a decreased sense of control causes people to look for patterns in order to regain order and control as well as to find solutions to the problem.
Eternal Fascinations with the End: Why We're Suckers for Stories of Our Own Demise – Scientific American
A video and transcript of Michael Shermer's talk
Feeling Powerless? Do I have a Conspiracy Theory For You - Newsweek
"Rage" Stimulating Neurons Have Their Own Little Fight Club in the Amygdala
Ever been in a situation where you had to deal with someone/something that just really PISSED YOU OFF!? Of course you have. After all, we're all human; we've all felt that terrible tingle of insatiable rage wash over us from time to time. It's a pretty intense emotion, sometimes even frightening in its potential to completely change your whole disposition from that of a mild mannered undergrad to a rampaging Hulk wannabe. Even more interesting (and a bit more terrifying perhaps) is how such an big emotion like anger can be generated by such a tiny section of your brain!
The amygdala, nexus of RAGE and mystery
Despite the nigh inevitable incorporation of the frontal lobe in interpreting and modulating emotional responses, when it comes to generating many of the basic motivated behaviors to which mammals are bound (anger, fear, attraction, hunger/thirst, etc.) the amygdala is usually the primary suspect (or at least an important accomplice). The amygdala itself is a tiny, almond shaped bundle of neurons and fiber tracts located deep within the temporal lobes (usually near the end of the hippocampus). Countless studies from emotion-based research have targeted the amygdala as a playing a minor role in memory and, most famously, as a hot spot for emotional response. Despite all this work, researchers are still relatively hazy as to how the amygdala is able to help us feel such different emotions as fear, anger and so on. However, recent research from the Howard Hughes Medical Institute at Caltech may be starting to turn all of our uncertainty about the amygdala around, as well as shedding some light on the specific neuronal origins of our most primal emotions.
Yes, this actually is what activating those cells does to mice (minus the personality disorder)
Current investigations from the labs of Dayu Lin and David Anderson have led to the discovery of what seems to be a subset of neurons in the amygdala that exclusively help generate aggression in mice. Upon activation, these "rage" neurons (or "fight cells" as Anderson has dubbed them) can turn an otherwise docile male mouse into a hyper-aggressive brawler. Indeed, the effects are so strong that the mice can be induced to attack females and other males (usually castrated) that would otherwise not be viewed as a threat. Talk about domestic violence! To tease apart the action and sensitivity of these cells even more, Anderson and his team genetically modified a strain of these mice to express fight cells that respond to pulses of laser light. Upon shining this light in the eyes of mutated mice, an aggressive response in the presence of females, castrated males and even a rubber glove was able to be stimulated!
In the midst of all this bio-molecular wizardry, Anderson and his team stumbled across another interesting discovery: a population of "mate" stimulating cells that seems to be closely knit with the fight cells in the amygdala. As the name may imply, mate cells seem to play a large role in inducing and modulating sexual behavior. Interestingly though, upon analyzing the brains of modified mice, after having previously been induced to attack a rubber glove (or something similar) and then allowed to mate, Anderson's team that a healthy amount of fight cells were activated in concert with mate cells as the mice where engaging in sexual activity.
The fight cells' corner of the amygdala
It is this latest discovery that Anderson and his team have expressed the most excitement about, specifically because of its implications for potential remediation of violent sex offenders and predators who may be suffering from a massive "cross-wiring" of the fight cells and mate cells in their amygdalar/temporal regions. If enough homology can be drawn between these cells and their specific pathways in the mouse brain with that of the human brain, perhaps the future work of Hughes center could produce ways to untangle these connections and offer both sex offenders (and the general public) alternative solutions to their deeply ingrained problems.
Small Part of Brain Itching for a Fight - Science News
Are you and your significant other meant to be?
Well, no one truly knows the answer to that question until they're looking back on their life and reminiscing about the time they spent with their partner. However, a new theory suggests that certain subtleties in language style can determine compatibility between two people. This includes speaking as well as personal writing styles, from Facebook chat to an essay sample.
Researchers have postulated that the use of common words called "function words", including 'me', 'a', 'and', 'but', as well as a number of other prepositions, pronouns, adverbs, etc. can at least estimate the compatibility of a couple. These researchers have devised an equation using the basic-level function words to determine "language style matching" (LSM). A higher LSM means more compatible writing styles, and ergo, a more compatible couple.
A study that analyzed the writing styles of online chats of various couples over the course of ten days revealed much about this theory. According to an article about this study in The Daily Telegraph, "almost 80 percent of the couples whose writing style matched were still dating three months later, compared with approximately 54 percent of the couples who did not match as well."
An online LSM generator has been created by this team of researchers. You can go to this site and insert various writing samples from IM chats to poetry. But this is not solely to determine compatibility in a relationship; you are able to compare writing styles of strangers, friends, and even two of your own pieces. I've tried it and find it to be intriguing at least. In no way would I assert that this is a completely accurate way to determine personality similarity, but it seems to me that it has some logic to it and is not as absurd as I had originally expected.
Language Style Matching Predicts Relationship Initiation and Stability- Association for Psychological Science
Scientists find true language of love - The Telegraph
Just Keep Swimming…
Finding Nemo's Marlin
In Disney/Pixar's "Finding Nemo," Marlin and Dory are swimming through murky waters en route to Sydney Harbor. Marlin suddenly exclaims, "Wait, I have definitely seen this floating speck before. That means we've passed it before and that means we're going in circles and that means we're not going straight!" - and he is probably right.
Is it really possible that when we cannot see where we are going, we actually travel in circles? Souman et al. tested this belief through a variety of experiments. They found in all cases that when deprived of a visual stimulus, it is actually impossible to travel in a straight line.
The first set of experiments had participants travel through a wood without visual impediments (such as blindfolds). One set of subjects traveled through the woods when it was cloudy, the second set when it was sunny. All of the cloudy group walked in circles and walked in areas that they had previously been, without noticing they had crossed a previous path. In contrast, all of the subjects who could see the sun were able to maintain a course that was relatively straight and had no circles.
The experiment was also performed on blindfolded subjects in an open field.
Paths of Blindfolded Subjects
The blue paths correspond to the subjects that walked on cloudy days. Their paths are mostly curved with many circles. The small straight areas of walking are most likely caused by the setup of the trial - participants walked for a period of time, then were unblindfolded and allowed to walk to the starting point of the next walking block. Even so, when blindfolded, lack of a visual stimulus when blindfolded always resulted in walking in curved motions or in circles. This contrasts the yellow path; this subject walked on a sunny day, and maintained a straight course for a long distance.
What causes this strange phenomenon? Could it perhaps be subtle differences in leg length that introduce a bias to walk in one direction, thus accounting for the circular motion? Nope - the circle directions were still random. Adding shoe soles to add a more than subtle difference in leg length didn't make a difference: the participants continued to walk in random circles.
Perhaps the only explanation is that our vision is so necessary for our daily lives that our body randomizes without it. This idea is demonstrated in studies in which subjects are kept in a room with constant lighting: their biological clocks become completely randomized with no night and day inputs. More studies should be performed to truly understand the importance of the visual system. Since we rely so heavily on vision, is it natural for movements to become randomized without it? Do those who are blind from birth experience the same walking in circles phenomenon? For now, the conclusion here is that the sensory systems are complex and there is still much work to be done in understanding this strange phenomenon. So, if you ever find yourself lost in murky Australian waters, you probably should not just keep swimming, but rather, ask a friendly passing whale for directions.
A Mystery: Why Can't We Walk Straight? : Krulwich Wonders... - NPR
Walking Straight into Circles - Current Biology
Memory 101: Understanding How We Remember
Do you ever wonder how you are able to remember the name of your third-grade teacher, or the skills you use to ride a bike, or even lines from your favorite movie? Well, if you haven't then you should, because it takes the workings of many regions of our brain to combine all the different aspects of one memory into a cohesive unit.
The first step in this complex process deals with our perceptions and senses. Think about the last time you visited the beach. Recall the sound of the wind and birds, the sight of the sun and ocean, the smell of the salt water and the feeling of the hot sand and shells underfoot. Your brain merges all of these different perceptions together, crafting them into the "memory" that we are able to recall.
All of these separate sensations travel to the part of our brain called the hippocampus. Along with the frontal cortex, the hippocampus plays a huge part in our memory system. These two regions decide what is worth remembering and then store this information throughout the brain.
Perception starts the processes leading up to encoding and storage, which takes place through our brains' synapses (or the gaps between neurons). Through these synapses, neurons are able to electrically and chemically transmit information between themselves. When an electric pulse is fired across the gap, it triggers the release of chemical messengers called neurotransmitters.
Here is a clear view of communication between neurons through the releasing of neurotransmitters over the synapse.
From there, the spread of information begins. The neurotransmitters diffuse to neighboring cells and attach to them, forming thousands of links. All of these cells process and organize the information as a network. Similar areas of information are connected and are constantly being reorganized as our brain processes more and more.
Changes are reinforced with use. So let's say you are learning to play a sport. The more you practice, the stronger the rewiring and connections will become, thus allowing the brain to do less work as the initiation of pulses becomes easier with repetitive firing. This is how you get better at a certain task and are able to perform at a higher level without making as many mistakes. But again, because our brain never stops the process of input and output, practice needs to be constant in order to promote strong information retention.
Knowing all of this, it probably comes as no surprise that the most basic function for ensuring proper memory encoding is to pay specific attention to what you are doing. We are exposed to thousands of things in very short amounts of time, so the majority of it is ignored. If we pay more attention to select, specific bits of information, we'll have a higher potential to remember certain things (try it out for yourself in lecture).
Since the actual process has been discussed, we'll go into greater detail about the types of memory we have and how they differ. There are three basic memory types that act as a filter systems for what we find important. This is based on what we need to know and for how long we need to know it.
The first is sensory memory, which is basically ultra-short-term memory. It is based off of input from the five senses and usually lasts a few seconds or so. An example would be looking at a car that passes by and remembering what color it was based on that split second intake. The effect is vaguely lingering, and is forgotten almost instantly.
Short-term memory is the next category. People sometimes refer to it as "the brain's Post-it note". It has the ability to retain around seven items of information for about less than a minute. Some examples would include telephone numbers or even a sentence that you quickly glance over (such as this one). You have to remember what is being said at the beginning to understand the context. Likewise, numbers are usually better remembered, and have longer staying power in the brain, when split up (800-493-2751 instead of 8004932751 for instance).
Repetition and conscious effort to retain information leads to the transformation of short-term memory into long-term memory. By rehearsing information without interference or disturbances, one is better able to remember things and ingrain them into his/her brain. This is a gradual process, but it proves why studying is important! Unlike the other two memory categories, long-term memory has the ability to retain unlimited amounts of information for a seemingly indefinite amount of time.
This diagram shows a more complex view of the major memory types and their subdivisions.
A piece of information must pass from both sensory and short-term memory to successfully be encoded in long-term memory. Failure to do so generally leads to the phenomenon known as "forgetting", something that many of us are all too familiar with ironically enough!
To give a common example of long-term encoding and memory retrieval, consider trying to recall where you have put your keys down. First, you must register where you are putting your keys and attention while putting them down so that you can remember later. Accomplishing all of this helps a memory to be stored, retained, and ready for retrieval when necessary.
Forgetting may deal with distraction, or simply just failure to properly retrieve a memory. That being said, it should be noted that there is no predisposition to having a "good" or a "bad" memories. Most people are good at remembering certain things (numbers, procedures and mechanisms for example) better than others (names, phrases, or even entire plays) and vice versa. It all depends on where you are able to focus your interests and your attention.
Hopefully, you will be able to remember some of this so that you can use your understanding of the complexities of the brain and memory encoding to your advantage. After all, your brain does all the hard work for you! Now you just need to pay attention and focus on what you find important and what you want to remember to best suit your own needs.
How Human Memory Works - Discovery Health
Types of Memory - The Human Memory
How Does Human Memory Work? - USATODAY.com
Connectomics is the name. Connections are the game.
You are unique, just like everyone else.
Connectomics is the study of the structural and functional connections among brain cells; its product is the "connectome," a detailed map of those connections. The idea is that such information will be monumental in our understanding of the healthy and diseased brain. Sebastian Seung thinks that a complete connectome of the human brain will be one of the great prizes in 21st-century neuroscience.
Efforts to construct brain connectomes are split into two categories: ones that use imaging techniques like MRI, PET, and DT, thus focusing on macroscopic connections or tracts; and those that use electron microscopy to map the tinniest of axons (0.2-20 microns in diameter) and individual synapses.
While this may sound daunting, it also seems the obvious thing to do in order to really understand how the brain works. After all, don’t all our memories, personalities, and behaviors dependent on the structure of the brain, down to the microscopic level? So why is connectomics so new? Because the three-pound enigma that can contemplate all things big and small – from protons and electrons, to planets and stars, to galaxies and the whole universe – contains more parts than anything we’ve ever studied before. The human brain, we’ve been told, holds 100 billion neurons, with close to one quadrillion synaptic connections total; storing all of that information in one brain would take one Exabyte of data (that’s one trillion Gigabytes).
Jeff Lichtman and colleages at Harvard remain hopeful. They are developing novel tools to automate the tedious task of scanning brain slices. They expect the connectome to reveal differences in the way healthy and diseased brains are wired.
The effort is laudable, considering its scope and ambition, but it begs the question: does all behavior, experience, perception, etc depend on the structure of synapses and connectivity of neurons? More pointedly, does structure determine all function – chemical and electrical? Sure, larger synapses or more dendritic spines make stronger connections and more efficient transmission of information, but a snap-shot connectome won’t take into account temporal dynamics and enzymatic processes, which play a big role in the active brain.
In his TED talk, Sebastian Seung says that to test the hypothesis that “I am my connectome,” we could try to read out memories from someone’s connectome. But memories are not just synaptic connections – they are also assemblies of neurons in time or firing sequence. The connectome does not take those into account. And Seung fails to explain how we could actually verify any of those personal memories, since current methods of constructing a connectome involve cutting the brain into thousands of 30-micron slices.
If we could devise some non-invasive methods to construct a human connectome at the synapse level, what ethical issues would we face? Could a personal connectome be the ultimate breach of privacy? Could it redefine or “undefine” what we consider to be normal brains/mental states?
Constructing a comprehensive human connectome is a great challenge. A bigger challenge would be to model the electrical dynamics of the 100 billion human neurons. But perhaps the most important quest for neuroscience isn’t building a connectome, but learning how neuronal activity creates experience.
Neurocartography - Narayanan Kasthuri and Jeff Lichtman via NIH Public Access
Sebastian Seung: I am my connectome - TED.com
Seeking the Connectome, a Mental Map, Slice by Slice - NYTimes.com
