MDMA, "Drugs Live," and a life update.

It's been a while.

Last summer, I became inspired to write an article about the potential benefits of the club drug, MDMA, otherwise known as Ecstasy or Molly. The blog post got turned into an article for my alma mater's science magazine, The Synapse, and was published a few months ago. With permission, I am cross-posting it here.

A quick life update for anyone who is interested will be at the bottom of this post.

In Europe and the United States, the drug known as ecstasy is the magic bullet that loosens the inhibitions of many dancers at all-night dance parties known as “raves.” Ecstasy—or “Molly” in its allegedly purer form—is a psychedelic drug with a signature high that produces an intense sensory experience coupled with feelings of euphoria and closeness with others. However, ecstasy's tendency to raise body temperatures and dehydrate users in over-packed, sweltering clubs creates a dangerous situation that troubles parents and politicians alike.

Though ecstasy has been the culprit behind some tragic deaths since its popularization in the mid-eighties, death and injury from ecstasy are relatively rare compared to other drugs scheduled I or II by the DEA. The number of emergency room visits per year resulting from the use of ecstasy are tens of thousands fewer than those due to the use of cocaine, heroin, and marijuana. Every year, the number of deaths from ecstasy are miniscule relative to tobacco- and alcohol-related deaths. Some experts believe that MDMA, the primary chemical constituent behind the ecstasy high, isn't the real danger of ecstasy. Instead, they believe that it is the crowded, hot dance floors combined with the effects of the many other substances ecstasy is famously adulterated with that puts users in danger.

Despite the risks, MDMA's signature high has not only beguiled party-goers. The drug has also intrigued many scientists with its potential therapeutic benefits. In hushed sessions behind closed doors, therapists in the seventies and eighties began to explore the drug's ability to release patients from painful emotions attached to traumatic experiences and to strengthen the therapist-patient alliance. Although the anecdotal evidence was in favor of MDMA as a therapeutic drug, no placebo-controlled clinical trials had been performed by 1985, which was when MDMA was on the table for scheduling by the DEA. Due to the lack of clinical data, and MDMA's perceived dangers in the club scene, the drug was labeled as Schedule 1: a harmful drug with no medical benefits. All research on the therapeutic effects of ecstasy were halted for the next two and a half decades.

Nevertheless, MDMA has only become more ubiquitous among young people since 1985, and the cries to research the actual effects of MDMA on the human body have gradually swelled to a dull roar. However, the US and British governments have little to no precedent for funding studies on MDMA in humans. In 2010, Channel 4 in London endowed Professors David Nutt and Val Curran with funding to begin the first fMRI study of MDMA's effects in the human brain. The results of the study were broadcast live in a TV special called Drugs Live: The Ecstasy Trial late last September.

In the trials, conducted in September 2011, 25 volunteers came in for testing twice. Each time a volunteer came in, they received either an 83 milligram dose of MDMA or a placebo. The study was double-blind, so neither the administrators nor the subjects knew which drug they were getting. 30 minutes after they took the pill, the volunteers entered a fMRI scanner, where they were monitored for 90 minutes while answering questions about their subjective experiences. Throughout this process, volunteers were also asked to recall positive and negative memories from their lives. After the volunteers came out of the scanner, they performed a task in which they rated the trustworthiness of various faces, testing their feelings of closeness with others.

Drugs Live features the experiences of five volunteers: an ordained priest, an ex-soldier, a journalist, an actor, and a former member of Parliament. The show itself consists of clips of the five volunteers' trials on ecstasy, interviews with them and members of the audience, a debate between David Nutt and his loudest dissenter, Andrew Parrott, short videos of recreational MDMA users out dancing or just enjoying a night in with friends, and a video of an illegal therapy session with MDMA. The program is punctuated by fleeting explanations of the results of the study, described by Nutt and host Jon Snow with the aid of a giant, plastic brain with flashing lights indicative of the various structures within.

The first major discovery presented in episode 1 is MDMA's effects on the neural circuit between the posterior cingulate cortex and the prefrontal cortex. This circuit is known to become overactive in people suffering from anxiety disorders and depression, and is believed to lead to the excessive rumination characteristic of mood disorders. Normally, the two nuclei fire in sync with one another, but MDMA releases a deluge of serotonin and causes the two nuclei to start firing out of line, hushing the circuit between them and alleviating anxiety, which leads to the characteristic euphoria of the drug.

After a clip showing a therapy session, in which a woman talks through her feelings towards her recently deceased, abusive father, Nutt walks toward the giant brain to explain how MDMA is helping this woman work through her traumatic memories. When a person recalls a traumatic memory, there is an activation of the amygdala and the prefrontal cortical region. According to Nutt, the prefrontal cortical region modulates the emotions associated with a particular memory, and MDMA works to dampen the firing of that region. Without the chatter of the emotional overlay, patients are better equipped to engage with and process those memories, making MDMA a particularly exciting potential therapy for post traumatic stress disorder.

Though the program opened with a claim of being politics-free, “unvarnished science,” many viewers felt that Drugs Live was more of a “pro-drugs” circus than a lucid exposition of the science behind MDMA. Indeed, there was little discussion of the negative aspects of MDMA, including the “Tuesday blues” experienced by one volunteer in the study and the overall negative experience the ex-soldier had during the trials. There was also little air time for the debate between Nutt, Curran, and Parrott, which some viewers with a scientific background were particularly interested in.

Perhaps the positive bias in Drugs Live is unsurprising to those who know David Nutt for famously suggesting that drugs like cannabis, ecstasy, and LSD were less dangerous than alcohol and tobacco while on the Advisory Council on the Misuse of Drugs. His comments were largely responsible for his subsequent firing from the Council.

Regardless of Nutt's personal opinions on illicit substances, the study performed in Drugs Live is still an exciting contribution to a sparse body of research on the effects of MDMA in humans. Many other studies on MDMA are funded by government agencies such as the National Institute on Drug Abuse (NIDA). These studies tend to be performed on animals with the intention of finding the harmful neurological effects of MDMA. Such studies have shown significant depletion of neurons that produce serotonin that lasts for years after a single round of MDMA administration. However, these single doses are given intravenously over the course of three or four days. Critics say such dosages are not representative of how the drug would be administered in therapy (a low dose taken orally once or twice in a patient's lifetime), nor do they reflect how most recreational users take ecstasy (taken orally once or twice a month.)

Studies on humans are often relegated to surveying cognitive faculties in recreational users of ecstasy, using hair and urine drug tests to determine what sorts of drugs subjects have been taking. There are many criticisms of these studies as well, many citing poor control for subjects who have taken ecstasy in combination with other drugs or alcohol. However, these studies still show many deficits in memory, as well as higher levels of anxiety in current and former ecstasy users. Theseresults foster skepticism for the therapeutic benefits of MDMA.

A viewer watching Drugs Live likely wouldn't catch the troublesome findings of such research on MDMA just from watching the few short minutes where Andrew Parrott attempted to explain it. This was one of many issues that commenters brought up about Drugs Live after it aired. Some criticized Channel 4 for not giving enough credit to its viewers for being able to hold their attention on scientific facts for more than a few seconds. It seemed as though the content of Drugs Live wasn't much different from that of ecstasy found on the street: very little though potent science adulterated with an abundance of questionable filler.

Life update: For anyone who is wondering what I've been up to this past year, I'm still writing! I have also been working a lot waiting tables to save up for graduate school. I will be beginning the science communication graduate program at University of California Santa Cruz in the fall. In addition, I have been writing for The Synapse, and I will be posting my newest article once it comes out in print!

Neuromagicology: At the Intersection of Art and Science

We all know how the cameras in our phones are only so good. The photos look grainy and the colors washed out. Compared to the naked eye, phone cameras don't seem to compare.

Well actually, the camera in your smartphone is 2 1/2 times better than your eye! In other words, if the resolution on your phone camera is 5 megapixels, the processing power of your eyes roughly equates to about 2 megapixels. But then, how is it the world around you looks so much sharper, richer, and full of color than the photos on your camera roll? It's because you have something your phone can't even begin to emulate, the brain.

Don't believe me? Hold your arms straight out in front of you. Put the tips of your thumbs together with your index fingers pointed up towards the ceiling, so you're making mirrored L shapes, or one big U shape. Now close your left eye and look at the tip of your left index finger with your right eye. While looking at your left finger tip, focus your attention on your right finger tip. Did it disappear? If it didn't, wiggle it around a bit, and you'll see what I mean; you'll notice that it suddenly vanishes from sight.

That's because your right finger is sitting squarely in the blind spot of your right eye. There are no light-sensing photoreceptors there because that's where all the fibers that make up your optic nerve converge. It has been there all your life, yet you don't notice it until an illusion forces you to. You might have noticed that instead of your finger where it should have been, you just saw the wall or the computer screen or whatever your finger was in front of. What's going on here is the brain is "filling in" that blindspot with the stuff around it. Kind of like the clone stamp tool does in Photoshop.

Illusions reveal the "supreme achievement of the brain"

For a long time, illusions have been thought to be the tools to reveal the limitations of the visual system and show where the brain "got it wrong." Neuroscientists Stephen Macknik and Susana Martinez-Conde see it differently. They think illusions really reveal something special, magical even, about the brain. "This is one of the supreme achievements of the brain," says Stephen, "The brain has actually evolved these processes that are illusory for the purpose of improving vision."

Not only do these illusions show us the nature of our visual experience, but they can also tell us something about consciousness. Consciousness is the first person experience of your life in the world, and it is home grown in your brain. Your senses interact with the outside world and send electrical signals to your brain to make sense of them, but when you look at these sensory systems, "you realize that the information going [to the brain] is really quite deprived." When so little information goes in, the brain has to fill in the details. The so-called conscious part of your brain comes from a separate group of neurons that takes information from your sensory and cognitive systems, your memories, your attention and other systems, and cobbles it together to make a simulation of reality. As Stephen puts it,

That simulation of reality is the only thing you've ever interacted with, it's not that the real world isn't out there--it is--but you've never been there. You've only ever interacted with this simulation of reality that's put together from sparse information from the outside world and the rest is essentially confabulated, just like that blindspot is a confabulation of sorts.

From illusions to magic.

Stephen and Susana are very interested in how our attention and awareness, through the visual system, can be manipulated and what that manipulation says about the process--or confabulation--of consciousness. Illusions can certainly help, but they really only pertain to vision, not awareness and attention in particular. But while organizing a conference for the Association for the Scientific Study of Consciousness in Las Vegas, a little magic happened for Stephen and Susana.

They were brainstorming on how to generate public interest in the topic of consciousness, and they realized that they needed to study the artists of attention and awareness. But who would that be? "Finally it got through to us, Las Vegas spoke to us directly. It said, 'Magicians are the performance artists of attention and awareness.'"

Things took off from there. Stephen and Susana have worked with some great names in magic, like James Randi, Penn & Teller, and Apollo Robbins. Magicians, in the pursuit of bettering their art, have come up with some great theories about how the brain works that neuroscientists have yet to test in the lab. Having these theories before you start to research can also take years off the research process, and really help advance the field of awareness, cognition, and consciousness.

The intersection of art and science

Susana focuses her research on eye movements. There are two different types of eye movements, saccades (which I talked about before) and smooth pursuit. To see the difference. hold out your thumbs in front of you and look at your right thumb. Now try to move your eyes in a line from your right to your left thumb, and you'll notice that you can't do it. Your eyes seem to "skip" along a line to your left thumb. That skipping from point A to point B is called a saccade. Now look at your right thumb as you move slowly to your left, and now you can follow it smoothly, hence "smooth pursuit." So we've just demonstrated to ourselves that smooth pursuit eye movements are involuntary. Now for the Magic.

Apollo Robbins is a professional thief. His act involves very close-range sleight of hand where he pick-pockets from people right before their eyes. Through his art, he noticed that if he moves his hand in a straight line from someone's pocket, people will look at where the hand is going to go, and then immediately back to the pocket through saccadic movement, and that this is a good way to distract someone, or trick them into thinking that he stole something from that pocket when he really didn't. But when he moves his hand in an arch people have to use smooth pursuit to follow his hand, and they don't look back to the pocket at the end.

Apollo's observations led Susana and Stephen to think that perhaps smooth pursuit and saccadic movements affect attention differently, and prompted them to do a study. They found that with straight arm movement away from the pocket from which an item was "stolen," the attention of the thief-ee is directed through saccadic motions from the pocket to Apollo's hand, making the pocket the last place where the thief-ee had their attention, and thus they look back at it. But smooth pursuit eye movement directs attention to the hand as it moves away from the pocket, and there's enough time in between that the pocket isn't the next logical point of attention anymore.

And that isn't the only example, either. Magicians will "use humor in order to, basically, get away with magical murder. If they get people to laugh, their attention is suppressed." When you think about it, this might seem obvious, but there actually isn't any literature in neuroscience on the emotional modulation of attention. Studies on PTSD and anxiety get at the idea, few have looked at the effect of emotions other than fear on attention.

Sleights of Mind

In their book, Sleights of Mind: What The Neuroscience of Magic Reveals About Our Every Day Deceptions, Stephen Macknik and Susana Martinez-Conde explore just that. They look at how magicians intrinsically understand the mechanisms of our attention and awareness and what their manipulation of those mechanisms can tell us about how our brain constructs our sense of reality from sensory stimuli.

Not only is this book very educational, but it's fun! Sleights of Mind is just as much about magic as it is about neuroscience. It's a great read for anyone, regardless of their background in science, who wants to know more about the brain and how it can be hacked. To order the book, and see some really awesome videos, illusions, and more, visit sleightsofmind.com!

Blindsight and Consciousness, what can we learn from the blindsighted?

If there were ever a perfect example of an oxymoron, the term blindsight would be it.

Other than the best oxymoron ever, what is blindsight?  Alan Cowey, in his 2010 review article, The blindsight saga, describes it as such:

It is the ability of patients with absolute, clinically established, visual field defects caused by occipital cortical damage to detect, localize, and discriminate visual stimuli despite being phenomenally visually unaware of them.

In simpler terms, it's the ability to sense the presence of objects in one's visual field without consciously seeing them the way normal sighted people do.  While it would be a stretch to call blindsight a superpower, the visual capabilities of a person with blindsight could be considered akin to those of Dare Devil.  Blindsighted people often are able to identify visual stimuli, although they deny having a conscious experience of actually seeing anything.

In this video, a blindsighted patient is able to navigate a field of obstacles successfully, even though he can't see them.

How does blindsight happen?  It is a fairly unique condition; not all people who are blind possess blindsight.  It occurs in patients who become blind in part or all of their visual field after suffering damage to the primary visual cortex, known as V1.

The primary visual cortex (V1) highlighted in yellow.  The bottom view is from a mid-section of the brain, the top view is from the outside.  In both views, your eyes would be on the left.  Source.

Becoming totally "cortically blind," as is the case for the patient in the video above, is actually pretty rare (thankfully), so most patients with blindsight are only blind in part of their visual field, while the rest of  the field remains normally sighted.

A controversial subject

Blindsight has drawn a lot of controversy among researchers.  Since the hallmark trait of blindsight is responsiveness to visual stimuli without the conscious experience of perceiving it, it makes animal studies a little difficult.  You can observe where a cortically blind animal turns its attention when presented a stimulus, but you can't ask it if it actually saw anything.  So researchers interested in getting at the question of what people with blindsight actually do or do not experience have a relatively small pool of subjects they can perform research on.

Then, of course, there's the fact that whatever blindsighted patients report as their experiences of blindsight must be taken with the grain of salt as all experience is subjective.  Some patients report that, even though they didn't see anything, they have a feeling that "something happened."  The question, then is, is this feeling essentially visual in nature?  Did it come about due to light scattering from the stimulus into their seeing field?  Or did the subject report a feeling of something happening because that's what he or she felt that the researchers were looking for?  The answers to these questions have proven to be extremely difficult to tease apart.  Regardless, the fact that some patients have "feelings" when presented a stimulus and others do not requires that blindsight be split into two categories: type 1, no awareness at all; and type 2, awareness without visual experience.

Even in patients with type 2 blindsight, the awareness of the stimuli isn't always consistent.  But we can still learn something here.  In one task, patient GY was asked to discriminate between the presence or absence of a stimulus and then wager money on his answer.  Incorrect wagers would be subtracted from his winnings, thus prompting him to only wager high when he was very confident of his answer.  When he felt that he was aware of the stimulus, despite not seeing anything, he wagered high and was correct more than 90% of the time.  When he didn't report any awareness, he wagered low, as would be expected.  But he was correct more often than could be explained by chance, suggesting that even without awareness, he was still able to perceive visual stimuli.

Total cortical blindness

Let's re-visit the patient in the video, TN.  After successive strokes, TN's primary visual cortex was completely destroyed, as was later verified by both structural and functional MRIs.  Something helpful at least came of TN's misfortune, in that he gave researchers De Gelder et al a rare chance to study a person with total cortical blindness.  The video above is truly astonishing because, at first glance, it looks like he is able to avoid obstacles without the use of a cane or any outside guidance.

Nevertheless, this video is not without its critics.  The first that springs to mind is echolocation, a capability that has been shown in other blind people.*  The researchers recognized that this could not be ruled out, but many critics of the research suggested that not enough attention was paid to the possibility of echolocation anyway.  Other critics say that TN could have been unconsciously processing auditory signals from the researcher shadowing him (to make sure he didn't stumble or fall), and that those aided in his navigation.

TN's contributions to blindsight research don't just end with that video.  TN also demonstrated affective blindsight, or the ability to discriminate between emotional stimuli in a physiological sense.  Researchers Gonzalez-Andino et al showed TN pictures of various facial expressions and monitored his brain activity via an EEG.  Without any awareness of the stimuli whatsoever, the researchers were able to localize changes in the electrical activity of parts of the brain associated with emotional stimuli, such as the right amygdala, in TN.  In these trials, TN was also not asked to guess at the nature of the stimuli, either, so the results suggest some perceptual ability without any conscious awareness at all.

Conclusions: what blindsight can tell us about consciousness

It is extremely important to note that all studies on blindsight and consciousness are done with very small sample sizes.  Most studies are case studies that focus on the abilities of only one patient.  Because of this, everything that we can say about blindsight must be taken with a grain of salt.  There simply aren't enough subjects with blindsight to tell us very much with any certainty about the nature of consciousness and vision.  Nevertheless, some results are so provocative that they can at least give us clues and ideas about where consciousness in vision lies in the brain, and can give us leads for further and more focused studies in the future.

It has become clear that blindsighted patients' vision is certainly unlike normal vision, and obviously unlike total blindness.  There is definitely some ability in patients to perceive objects, even if the true nature of that ability remains murky.  And it's the murkiness of that ability that makes blindsight so tantalizing to researchers interested in the neural mechanisms of consciousness.  How can one see without actually seeing?  That is the big question.  The visual pathway is certainly very complex, but the blindsighted just may be able to tell us what aspects of that pathway give rise to the conscious experience of sight, and wouldn't that be so cool?

*While looking for the video about Ben Underwood, I found out that just a few years after the original news spot was filmed, he sadly died of cancer.  You can read more about him and his life here.

References:

Cowey, A.  (2010).  The blindsight saga.  Experimental Brain Research 200:3-24.

de Gelder, B.; Tamietto, M.; van Boxtel, G.; Goebel, R.; Sahraie, A.; van den Stock, J.; Stienen, B.; Weiskrantz, L.; Pegna, A.  (2008).  Intact navigation skills after bilateral loss of striate cortex.  Current Biology 18,24:1128-1129.

Gonzalez-Andino, S.L.; de Perlata Menendez, R.G.; Khateb, A.; Landis, T.; Pegna, A. (2009). Electrophysiological correlates of affective blindsight.  NeuroImage 44:581-589.

How film makers are using your own imagination to scare you

Happy Halloween!  It's a time of costumes, candy, and for those more thrill-seeking types, horror movies.

Personally, I'm a total wimp when it comes to scary movies.  Show me anything that's even trying and failing to be scary, and it will still scare me.  So that got me thinking, why is it you can walk into a movie feeling like this:

See this:

And suddenly feel like this:

After all, there's nothing inherently scary about that image.  It's just a forest at night.  But it's the fact that it's a forest at night in a scary movie that has me sitting on the edge of my seat.  This is a phenomenon called priming, wherein the fact that I know that this is a scary movie and scary things will happen will make me more likely to "fill in the blanks" of that scene with my imagination.  In other words, since I know something scary will probably happen soon after being presented the visual stimulus of the dark forest, I will begin to look for something to scare me in the scene when nothing inherently scary is there at all, while still proceeding to scare the living daylights out of myself.

Movie Magic!

Film makers are very, very aware of this phenomenon and they love to exploit it.  After all, it makes their job a lot easier.  If you can scare yourself by just imagining what's happening off-screen, then the film makers don't have to go through all the trouble and expense of actually showing you, and your imagination will almost always come up with something more horrifying than what they can show you on screen, anyway.  Movies like Paranormal Activity and The Blair Witch Project capitalize on this by showing you shaky, home-movie style shots and lots and lots of scenery without ever showing you the source of the threat throughout most of the movie.  The idea is that by presenting these otherwise neutral scenes with the implication of a threat intensifies the emotional reaction of the audience.

The Science

So what's actually going on in your brain while this is happening?  A recent study in Social Cognitive and Affective Neuroscience aimed to figure that out.  Researchers observed subjects' brain activity in a fMRI as they read two different types of sentences; one which implied a fearful situation, and another which was neutral.  In the fearful type of sentence, none of the individual words themselves were inherently fearful--that is to say that there were no words like "threat" or "hurt" or the like.  An example of one of the fearful sentences used in the study is "The boy was never found again."

In the next trial, the researchers showed the subjects neutral images (like a boy on a beach) and paired them with the fearful and non-fearful sentences.  In a final trial, the subjects were shown the images again, but without the sentences to see if the emotional memory of the images with the sentences would carry over without the presentation of the sentence.

The Results

When subjects were presented a fearful or non-fearful sentence with and without a picture, there were higher levels of activation in subjects presented a fearful sentence with and without a picture than in subjects shown non-fearful sentences with and without pictures.  These areas of activation were the middle temporal gyri, the temporal poles, and the left inferior frontal gyrus, which are associated with language processing and understanding.

Brain activity in people presented with fearful sentences

The researchers also found an additive effect in the right temporal pole when subjects were shown a fearful sentence with a picture (the right black bar) than when subjects were shown a fearful sentence alone (the left black bar).

The temporal poles, which are the front-most projections of the temporal lobe, are still poorly understood in their function.  However, they are connected to many structures in the brains emotional, or limbic, system and they have been implicated in the processing of emotion, and binding emotions to linguistic and visual stimuli (such as associating a fearful looking face with feeling fearful yourself).

So far, one brain structure has been conspicuously absent from this study on fear: the amygdala.  The amygdala is often referred to as the "fear center" of the brain, so why has it been so quiet up till now?  It would appear that the visual stimulus is necessary in this case to cause the amygdala to react to the fearful sentence.  Subjects who were shown fearful sentences with images had higher levels of activation in the right amygdala, whereas subjects who were shown fearful sentences without images had no activity above baseline in the amygdala.  This would imply that the amygdala does not necessarily interpret emotional salience from language alone, leading the researchers to conjecture that perhaps the amygdala can only be activated in this context with linguistic-emotional binding input from the temporal poles.

The amygdala also has an interesting role in the third trial of this experiment.  Researchers showed subjects pictures that were either previously paired with a fearful sentence, a non-fearful sentence, or no sentence at all, and monitored activity in their right and left amygdalae.  Pictures that had been previously shown with a fearful sentence led to a higher level of activation in the subjects' amygdalae than did pictures that were previously shown with a non-fearful sentence or no sentence at all.  This is in line with other evidence to show the role of the amygdala in emotional memory.  That is to say that when the image was previously shown with the fearful sentence, it was "tagged" by the brain as emotionally salient.  The presentation of the image again, even without the fearful component, will bring up the emotional flavor of the image, and lead to higher levels of activation in the amygdala.

Our brains are excellent at drawing connections between various stimuli in our environment.  We can take inherently un-emotional words, phrases, and images and combine them to form context and illicit emotion.  So the next time you go see a horror movie, take a moment to observe how artfully (or perhaps artlessly) the movie is taking advantage of and manipulating your own imagination to scare you even more.

Images courtesy of ragemaker, we <3 it, and Social Cognitive and Affective Neuroscience
Reference:
Willems, R.M.; Clevis, K.; Hagoort, P.  (2011) Add a picture for suspense: neural correlates of the interaction between language and visual information in the perception of fear.  Social Cognitive and Affective Neuroscience, 6(4), 404-416.

The Stopped Clock Illusion

Everyone can relate to this. You're in class, at work, waiting for something... you look at the clock and that first second that goes by seems to take forever. Then every second after that appears to progress normally. Why is that?

This is due to a phenomenon called saccadic masking or saccadic suppression. A saccade is the rapid movement of your eyes from one point of attention to another. To demonstrate this to yourself, hold out your two thumbs in front of you, and try to move your eyes smoothly from your right thumb to your left. You'll notice that your eyes don't move smoothly. Instead, they jump to points between your two thumbs along the way.

Saccades allow us to make a mental map of our surroundings and all the points of interest within it.  This is because the part of your retina directly behind your pupil, the fovea is packed with receptors that enhance visual acuity.

Cross-section of the eye, Wikimedia.

When you look around, your eyes don't span smoothly across the scene in front of you. Instead they move in saccades, quickly directing your fovea from one object of interest (the sharp corner of that table that you don't want to walk into) to another (that cute guy/girl waiting for you at the other end of the room). Saccades also occur when focusing on the details of a single image, as demonstrated by these eye movement traces of subjects as they examined the bust of Nefertiti.

Source: MIT

What you don't notice in between these saccades is well, anything.  The saccade itself is so fast that your brain doesn't have enough time to process the information coming to it to make a clear image.  A blurry image isn't too helpful and would probably just give you motion sickness.  In fact, the shaky "hand-held" camera effects in the movie Cloverfield did just that to many of its viewers.

So then what does your brain do with the information sent to it during a saccade?  Nothing; this is what is meant by the terms, saccadic suppression and saccadic masking mentioned earlier.  Even though the eyes are sending information to the brain, the brain does not process the information, leaving you effectively blind during a saccade. However, saccades are not so fast that you wouldn't notice the lapse in vision. What's going on? You don't actually perceive being blind during a saccade but you also don't see the blurry image, so what are you seeing?

It turns out that once you've fixed your fovea on an object, your brain actually tells you that you've been looking at it from the beginning of the saccade.  You don't notice this difference in timing at all, unless of course that object of your gaze actually keeps time.  So even though you're focused on the clock for only a second, your brain is telling you that you've been focusing on the clock for the 1,000 milliseconds it takes the second hand to move plus the time it took for your eyes to move to the clock.

On average, a saccade takes about 100 milliseconds, or about 10% of one second. So if you happen to look at a clock right at the beginning of a new second, it will appear to take 10% longer than normal, resulting in the famous illusion known as Chronostasis, or the stopped clock illusion.

Lucid dreams

xkcd

Most of the time, when we dream we are not consciously aware that we are dreaming.  Despite the often fantastic circumstances of the dream, we accept that the events and experiences that are happening to us are real.  At least until we wake up.

Lucid dreaming, or the awareness that one is dreaming, is a fairly well-known, and well-documented phenomenon.  Most people report having at least one lucid dream in their life, but for the most part they are considered to be very rare occurrences in the overall population.  However, lucid dreaming was not always a well-accepted fact of life, and of course is still contested by some sleep researchers today.

The term, "lucid dreaming" was originally coined by the Dutch psychiatrist, Frederik van Eeden in 1913,  but reports of lucid dreaming have been documented since Aristotle's time.  For the better part of the history of research on dreams and sleep many people believed that lucid dreams were not dreams at all, but were the result of brief moments of consciousness due to transitory awakenings that are common during REM sleep.

Then along came Alan Worsley.

Alan Worsley is a bit of a lucid dreaming celebrity in the field.  A graduate student in psychology, Worsley had been developing his own ability to dream lucidly.  He was able to plan experiments while awake, and then recall and carry out the protocol once dreaming.

During REM sleep, your body paralyzes the motor activity eminating from the spinal cord.  This is thought to be because during dreaming motor activities are initiated in the brain in response to dream stimuli, but then they are not propagated beyond the spinal cord so that this (usually) doesn't happen:

However, it is known that not all motor functions are cut off during dreaming.  The most obvious being the eye muscles (hence, Rapid Eye Movement) and respiratory muscles.  Alan Worsley used this information to signal to an observer in the lab that he was dreaming and aware of it by moving his eyes left and right a pre-agreed upon number of times.  By carrying out this procedure with no lapse in sleep activity (as monitored on an electroencephalogram (or EEG)), Worsley effectively proved that lucid dreaming is a physiological reality.

Since Worsely many people have become skilled in lucid dreaming, and indeed it has become accepted as a skill that most people can learn with practice and patience.  For most people, lucid dreams initiate when something in the dream is so outside the normal realm of reality that it becomes abundantly clear to the dreamer that he or she is dreaming.  You may think that something like a blue whale passing overhead like a blimp might be the sort of stimulus needed to induce that sort of awareness, but really it may in fact be something more mundane that suddenly jolts you into awareness.  In the clip from Waking Life that I posted a couple weeks ago, one of the characters suggests turning a light switch off and on.  In fact, this is a common method used by lucid dreamers to test waking vs. dreaming states of consciousness.  Worsley and other lucid dreamers often report that light levels are hard to adjust in dreams, so turning a light switch on and off is a quick and easy way to test if you are dreaming.  If it's a habit you can build in waking life, then you may find one day you try it and the results aren't what you expect, and from there it could be reasonable to conclude that you're dreaming.

Lucid dreaming can also be used as a valuable tool for studying consciousness and its properties both in the waking world and the dream world.  In particular, it's interesting to test what can be done in the dream world.  Since it exists purely in the mind, one would think that lucid dreaming allows you total control over the circumstances of your dream and you can essentially play God.  But in practice, most people seem to have limits to control over their dreams.  The light switch is one example, and reflections in a mirror are another.

In one study, dreamers were asked to find a mirror and view their reflection, and then to try and walk through the mirror.  Most participants could find the mirror and view their reflection with ease, however most participants also reported distortion in the image they saw in the mirror.  When they tried to walk through it, slightly less than half were successful in doing so.  What was on the other side varied from person to person.  One participant reported coming up from the bottom of a lake after entering the mirror.  Others reported moving through the mirror but then ending up back in the same room.

While this is cool and all, the fact still remains that most of the participants could not walk through the mirror.  Why?  It's a dream so anything should be possible.  That's something we generally believe even when dreaming non-lucidly.

The element of control may be in some way related to the level of lucidity.  Up until now I have been talking about lucid dreaming as a distinctly different type of dreaming from non-lucid dreaming.  But modern research shows that there is a continuum between states of lucidity in dreaming, and that this continuum affects the ability of the dreamer's control over the events of the dream.  Theoretically, if one can learn to dream lucidly, one could probably learn to master control over the events in the dream once lucidity is achieved.  And then who knows what you could be capable of.

But first, just try to turn the lights on and off.