Limitless: How can we unlock the full potential of the brain?

The trailer for the movie "Limitless" depicts a young writer who starts taking a drug that his drug dealer tells him will unlock the other 80% of his brain. The character, portrayed by Bradley Cooper, becomes fantastically intelligent and quickly wealthy and famous. Could this happen? Not so sure. A number of smart drugs, memory enhancers and “nootropic” supplements have been shown to slightly improve memory, motivation, attention and concentration. Vitamins B and C, folate, Omega-3, Ginkgo biloba, other herbals and proprietary blends of these like “Focus Factor” seem to help cognitive function. Central nervous system stimulants like caffeine, Adderall and Ritalin are more powerful, and have proven effects on mental ability, but it is not completely clear how any of these increase mental through-put. Some increase the effects of certain neurochemicals, some dilate blood vessels, some stimulate nerve growth, and most cause neurons to work harder. Simply put, most neurotropic drugs give the brain more energy to power its searches for appropriate memories. Does this mean that the brain is being used more, or that more of the brain is being used?

Is it true that humans only use 20% of their brain? No one can be sure because there is actually no way of knowing quite what this statement is trying to say. It is clearly not true that large portions of our cortex remain unused. If you watch the video results of an fMRI scan you will see that as a person does various tasks and is exposed to various stimuli, virtually the entire cortical surface will light up at one time or another. It is true that at any one time, only a small fraction of the neurons in the brain are being used maximally. But this is a good thing because the unused neurons would insert inappropriate and superfluous content that would be distracting and would take away from the specificity of thought.

It is helpful that we only use a limited percentage of our brains at a time. The brain has dozens of dedicated processing areas, each fine-tuned to solve particular problems, most of which would be irrelevant to a specific task at hand. In fact, much of the brain is designed around quieting or inhibiting extraneous stimuli so that only the most pertinent things can make it into consciousness. Your mind is able to do its work without distractions because your brain is constantly suppressing activation in areas that may seem to hold pertinent memories, but have proven in the past to be misleading. Arguing that we would be better off using 100% of our brain is like arguing that it is better to use each of the tools in a Swiss Army knife, at the same time, for the same project, all at once.

Brain researchers like Karl Lashley, in the 1950s were confused by certain experimental results and were falsely led to assume that the entire cortex of the brain was undifferentiated and that individual areas do not specialized in specific tasks or activities. Outdated principles, such as “mass action” and “equipotentiality” conceptualized the cortex as a homogenous pool of neurons where function could not be localized. Lashley and other neuroscientists of his day saw the individual tools of the brain's Swiss Army knife as interchangeable and able to be summed together. These conceptualizations were wrong but probably contributed greatly to the 10% myth.  In fact, it would follow logically from his principles that if specific brain areas do not have particular jobs and if we only use a small minority of brain cells at any time, that we could increase mental ability simply by increasing the number of active areas. Too bad it isn't that easy.

Activating inappropriate memories will not increase intelligence, but how about increasing the span of activity of the most relevant memories? As we think, we hold and let go of certain memories. If we could increase the time that certain helpful memories are activated and available to working memory then this, I believe, would increase intelligence. The brain area to target in order to do this would be the prefrontal cortex. I think that the movie Limitless, does an amazing job of portraying the effects of prolonged prefrontal activation or “hyperfrontality.”

The best kind of neurotropic drug that I can imagine would increase activity in the lateral prefrontal cortex. This would make it so that one was able to drag even more of their visual and verbal imagery with them through time. The PFC is like a switchboard with contacts in all kinds of other brain areas. The harder the PFC works, the longer various representations and subroutines can be maintained. In some senses, this WOULD allow someone to use more of their brain. Using time and mental resources to recall deactivated memories is like trying to use your fingernails to pry out the implements of a Swiss Army knife. Increasing PFC activity though, would be akin to having the most recently used tools in the knife unsheathed and ready for implementation.

Stress Primes You for Negative Thinking

I watched a great animated movie last night, "All Star: Superman." In it, Lois Lane visits Superman at his fortress of solitude for the first time but disappointingly she starts acting bizarre. She becomes highly nervous and begins to assume that Superman brought her there to experiment on her. After planning frantically to defend herself, she grabs a kryptonite laser from his arsenal and blasts him with it.

It turns out that she was exposed to some chemicals that increased activity in her amygdala. At that point, it all made sense to me. Even though Lois Lane is kind and thoughtful, she has the potential to become paranoid when severely stressed. She didn't have a good reason to suspect Superman of foul play, but when our amygdala is activated, we often trust it unquestioningly. We do this because it is so often right. The amygdala has a mind of its own. It unconsciously listens to many other brain areas and takes cues from the environment about when to be scared. We accept its messages as a type of foreboading intuition.

When activity in the amygdala increases, and the adrenal glands begin to release adrenaline and cortisol, the brain becomes primed for negative thinking. It is like your brain is retuned to perceive things as troublesome or upsetting. This is the opposite of a manic episode where someone with mania might perceive everything as a happy, lucky coincidence. A friend of mine who has experienced mania told me that for two days it felt like all of the cars of the freeway moved to let him through, like everyone was agreeable and like everything was going his way. When I start to feel that everything is going poorly I try to remember this - that neurochemicals can paint over reality.

I have noticed recently, that if one thing stresses me out, I am much more likely to get stressed out about other, completely unrelated things. I might get upset about an unfortunate circumstance and then wear cynical glasses for a full hour afterwards. One could say that this "displaced" negative thinking is not logical. It may be evolutionarily logical to be prepared for the worst during bad times, but from a modern, practical perspective it is illogical to generalize anxiety to whatever your mind turns to.

Remember, cortisol is high in the morning, so don't give morning stressors the attention that they feel they should be given. Also, remember Lois Lane, and make sure that one unfortunate circumstance doesn't lead to a domino effect of paranoia. Nowadays, I try to notice when I carry negativity over, from one thought to another. When I can notice it I try to tell myself that the negativity may feel valid and intense but it is probably just residual and misattributed emotion.

Is Dreaming Similar to a Lobotomized State?

Freeman performing a trans-orbital lobotomy in 1949

I had a dream last night where an old friend from high school asked me, “what brain areas are involved in creating the thoughts we have during dreams?” I got a little excited and began to tell him that all of the posterior areas contribute but that the anterior, frontal areas are pretty much turned off. Actually, the prefrontal cortex (PFC) is the main area that is conspicuously missing during dreaming. It allows planning, self-organization and forethought, things that most dreaming is devoid of. Responding to the friend in my dream I rattled off a few names of areas that are turned on during dreaming: “the occipital visual cortex, the temporal auditory cortex, the limbic system, the somatesthetic…” But midsentence I realized that “somatesthetic” wasn’t a real word. It was a blurted-out mixture of somatosensory and somesthetic – a mistake I would never make during waking life. That I mispronounced this name so unhesitatingly clued me in to the fact that I was in the middle of a dream, not my high school cafeteria.

I was operating off-the-cuff, without inhibition or care for correctness. I made this mistake because my PFC was down. A funny thing about lucid dreaming is that thinking too hard after one realizes they are in a dream often catapults the PFC into full metabolic swing and the person into full consciousness. This is exactly what happened to me. Attempting to muster the cognitive wherewithal to correct my misstatement pulled me out of my dream and suddenly I found myself lying in bed in the dark muttering the word “somatosensory.” After tossing for a few minutes, thinking about the role of the PFC in sleep and wakefulness, I realized that, while dreaming, people operate as if they didn’t have a prefrontal cortex. It seems that the experience of dreaming replicates many of the elements of what it would feel like to be lobotomized. Patients that undergo a lobotomy have their PFC severed from the rest of their brain which causes them to act impulsive, eccentric and whimsical, to have a short attention span and poor reasoning ability. Honestly, this is how I behave while dreaming.  

Lying in bed I came to the conclusion that lobotomized people probably feel and act as if they are in a dream state all of the time. Further, because other mammals have disproportionately small PFCs relative to humans (nonmammals don’t even have them), the experience of being another mammal may feel a little like dreaming. Further still, the way I act in my dreams would probably be very similar to how I would act if I were actually lobotomized. If a mid-century doctor plunged an ice pick slightly above and a few inches past each of my eye balls, and wiggled the thing around a little severing the connections between my PFC and the rest of my brain, I might just walk around rattling off over-simplified explanations in ways that that dream-people wouldn’t blink at but real people would institutionalize me for.

The Unconscious Mind is Like a Little Animal Inside of Our Heads

I have given a lot of thought in the past to the nature and extent of two things: 

1) the intelligence of small animals, and 

2) the intelligence of our unconscious mind. 

Today I realized that these two things share many similarities. The subconscious pathways in our heads that affect our behavior, and even our thoughts without us knowing, are the primary pathways that determine behavior in many animals. This is part of the reason why less intelligent animals can think and behave but not be consciously aware of themselves. I have wondered for a long time whether our unconscious processes are sufficient or intelligent enough to constitute a separate mind or a true entity apart from our conscious mind. I am starting to think that they are - at least in the same sense that unaware animals are.

The Binding Problem

The binding problem is an issue in theoretical neuroscience that arises because of the lack of clarity about how two features of the same object are bound together in the brain leading to a single, coherent perception. Most neuroscientists in this area assume that individual features of sensory stimuli correspond to tiny assemblies of cells in the brain. These neural assemblies specialize in representing specific features and will become active if you perceive this feature, or even if you simply imagine it. For example, if one sees a blue, wrinkled glove, neural assemblies that correspond to blue, wrinkled and glove would all be activated simultaneously. The coactivation of these assemblies, and all of the other assemblies responsible for other features of the glove, would create a unified picture of a single object. The question is though, how do these assemblies take discrete, individual features and combine them to make one perception?

It is thought that when assemblies that correspond to the same perception are coactivated they send electric messages back and forth. They also recruit other areas that get involved in these informational oscillations. When these assemblies oscillate in synchrony they are thought to bind features such as contour, shape, motion, color, depth and other aspects into a composite image. These electrical oscillations alone cannot adequately explain how conscious perception arises in the brain but they give clues about how we perceive multiple objects. 

Another very similar problem in feature binding is the superposition catastrophe. This is where you have multiple objects, each with their own features, and you are able to keep track of the features of each object. Imagine that you are looking at a green raccoon and a yellow hippo. If all of the assemblies that correspond to these animals and colors must fire simultaneously, then how can you discern that the raccoon is green and the hippo is yellow? How can you tell that the raccoon is not yellow? One way of solving this problem is to assume that we have dedicated assemblies for green raccoons and yellow hippos and that these can become activated at the same time without confusing their contents. This is an unreasonable hypothesis though because most of us have never seen or imagined these animals. If we had dedicated assemblies for every combination of features in our memory the total number of necessary assemblies would be astronomical, and would require far more neurons than we can hold in our heads. Neuroscientists are starting to think that perhaps the assemblies for green and raccoon are activated simultaneously, the assemblies yellow and hippo as well, but that the two pairs are activated out of sync with each other. In other words, the assemblies for green, those for raccoon, and all of the other assemblies and networks associated with these, but not with yellow hippos, fire neural messages back and forth with each other at their own tempo that is distinct from the timing of other activities that are going on in the brain. Such amalgams of associated assemblies are often called modules in the literature. The ability of the brain to compartmentalize features into modules allows the segregation of information which in turn allows the perception of multiple objects, each with their own features. 

Modules of neural assemblies are thought to contribute to conscious perceptions and are thought to interact with other modules to create behavior. If they could be visualized these modules would not appear as neat, uniform structures in the brain, but would probably be messy, wiry structures that criss-cross between a variety of brain areas. It is not as easy to visualize the neural assemblies. Some may involve neurons that are clustered very close together yet others may be more distributed. It is thought that assemblies have to fire back and forth very fast (around 40 Hz or 40 times per second) to bind together to form a module. Experiments have shown that when someone is experiencing an optical illusion, that illusorily associated features bind together. Interestingly, it has also been shown that when someone cannot perceive a hidden image, that the features necessary to see the image are either not activated or not bound. In other words, in order to notice something you have to bind its features together and when we are fooled we bind the wrong features.

A Partial Solution to the Binding Problem:

I don't believe that there is a superposition catastrophe. To posit one you must assume that in higher brain centers, the physical location and orientation of the two, differently colored objects are lost. I think that the higher-order associative areas may not code this information but that the primary and secondary visual areas (which the association areas continually interact with) do because they are organized retinotopically and would be able to keep the objects, and their respective features (such as color), consistent without mixing things up. This is akin to having a TV in your head, as long as you are watching the TV, you cannot forget the colors of different objects. Certainly, this occipital "TV" is erased every 250 ms due to the fact that its outputs amount to transient "sensory memory" but if the higher association areas bind to the right elements, they can keep them active on this TV for as long as they are either visually rehearsed or committed to memory.



Read the full article that I wrote on this topic here:

http://www.sciencedirect.com/science/article/pii/S0031938416308289

Grandmother Cells

 


The term "grandmother cell" was coined by Jerry Lettvin in 1969 to describe a hypothetical neuron that can be shown to represent a specific psychological concept. This cell would become active every time a person thinks about a complex thing, such as his or her grandmother. The question was: Are there any cells, anywhere in the brain, that are dedicated specificlly to processing information about one's grandmother? It seems that this may be the case despite the fact that neuroscientists were convinced, for decades, that this was a gross oversimplification.

It is known that millions of cells work together to help us visualize even the most simplistic visual objects. The retinas of the eyes relay information about what we look at to early visual processing areas in the back of the head. This data passes through a series of neural areas before objects are recognized. These areas, which have been fine-tuned by life experience, act as filters that allow the visual data to matchup against the brain's best existing representation of what is being seen. In this sense, when we see, we are not really looking at what is out there, but instead piecing together a collage of things that we know to try to recreate the scene. When our brain does this, large numbers of neurons in the simple visual areas that correspond to the lines and contours of what we are seeing send their information to a smaller number of more complex neurons that deal with shape and form. These neurons, in turn, converge on even smaller populations of neurons that code for recognizable objects like people, cars and animals. It is thought that populations of cells, in these high-order processing regions, can be dedicated to processing very specific objects. Grandmother cells are the theoretical limit to this convergence where the activities of a large interconnected structure of networks meet together to activate a single neuron that in some senses, holds much of the information of the entire network (because much of the network must be activated for it to fire).

Some cells that come close to meeting the requirements of a grandmother cell have been found. One study by Rodrigo Quiroga and colleagues used patients undergoing treatment for epilepsy where 100 tiny electrodes were implanted in their brains. Each subject saw around 100 images of famous people, places and things. Overall, almost 1,000 neurons were sampled and 132 of these reacted to at least one of the images. The objects that elicited increased activity were used in another round of recognition except different images of these objects were shown. For example, if a head-on photo of a truck elicited a response, then a profile picture might be shown next. The researchers were able to find grandmother-like cells in some of the participants. One female participant had a neuron that only responded to the actress Jennifer Aniston. The neuron did not respond to other pictures, even of similar-looking female actresses, with one exception. This neuron responded to some pictures of Lisa Kudrow, Jennifer’s costar on the show Friends.

Another female participant had a neuron that responded only to Halle Berry. Pictures of the actress, a line drawing, a profile, even the words of her name, all made this neuron fire. These neurons were generally in convergence areas – such as the hippocampus- where a lot of processing, in areas such as vision and audition, meet up. This neuron must have been highly tuned, not only to the physical aspects of Halle, but to the abstract representation of her overall persona because even a picture of Halle’s catwoman character made the neuron fire despite the fact that she was masked.

Early critics of the idea pointed out that there are not enough neurons in the brain to account for every possible sensory object in one-to-one correspondence. Grandmother cells don’t necessarily work this way though. It seems that sensory objects are represented by networks of neurons many of which overlap and intersect. The individual neurons that make up these networks usually have the capacity to contribute toward the perception and recognition of several different objects of sensation. The further down the processing stream these neurons lie - the closer in the brain they are to the retinal inputs - the more fundamental they are in the process of recognition and the more objects they contribute to. The contribution of an individual neuron is actually very weak. One neuron usually does not have the capacity to send a global message that can be perceived consciously. In fact, many, many neurons would have to be removed to abolish the ability to recognize your grandmothers. Even more (tens of thousands or perhaps millions), would have to be removed to ensure that you could not remember anything about your grandmothers.

Experience fine-tunes neurons and the inputs that they are receptive to. The brain will even tune some neurons so narrowly that they become dedicated processing specialists for things that you recognize frequently, especially things that you see over and over again. They may not become active to every representation of a grandmother, they may become active to totally unrelated representations and there may be a number of them in each person’s brain, that vary in their responsivity to grandmothers. Even so, grandmother cells, at least loosely defined, do seem to exist. It is probably a safe bet that the cartoon drawing of a grandmother at the beginning of this entry activated some of the same cells in your brain that respond uniquely to images of your parent’s mothers.

Quiroga, R. Q., Reddy, L., Kreiman, G., Koch, C. & Fried, I. 2005. Invariant visual representation by single neurons in the human brain. Nature 435: 1102-1107.



Read the full article that I wrote on this topic here:

http://www.sciencedirect.com/science/article/pii/S0031938416308289