The symbol for love is the heart, but the brain may be more accurate.
- How love makes us feel can only be defined on an individual basis, but what it does to the body, specifically the brain, is now less abstract thanks to science.
- One of the problems with early-stage attraction, according to anthropologist Helen Fisher, is that it activates parts of the brain that are linked to drive, craving, obsession, and motivation, while other regions that deal with decision-making shut down.
- Dr. Fisher, professor Ted Fischer, and psychiatrist Gail Saltz explain the different types of love, explore the neuroscience of love and attraction, and share tips for sustaining relationships that are healthy and mutually beneficial.
Science has not yet reached a consensus on the nature of consciousness.
It's that intimate sense of personal awareness we carry around with us, and the accompanying feeling of ownership and control over our thoughts, emotions and memories.
Beliefs about consciousness can be roughly divided into two camps. There are those who believe consciousness is like a ghost in the machinery of our brains, meriting special attention and study in its own right. And there are those, like us, who challenge this, pointing out that what we call consciousness is just another output generated backstage by our efficient neural machinery.
Over the past 30 years, neuroscientific research has been gradually moving away from the first camp. Using research from cognitive neuropsychology and hypnosis, our recent paper argues in favour of the latter position, even though this seems to undermine the compelling sense of authorship we have over our consciousness.
And we argue this isn't simply a topic of mere academic interest. Giving up on the ghost of consciousness to focus scientific endeavour on the machinery of our brains could be an essential step we need to take to better understand the human mind.
Is consciousness special?
Our experience of consciousness places us firmly in the driver's seat, with a sense that we're in control of our psychological world. But seen from an objective perspective, it's not at all clear that this is how consciousness functions, and there's still much debate about the fundamental nature of consciousness itself.
One reason for this is that many of us, including scientists, have adopted a dualist position on the nature of consciousness. Dualism is a philosophical view that draws a distinction between the mind and the body. Even though consciousness is generated by the brain – a part of the body – dualism claims that the mind is distinct from our physical features, and that consciousness cannot be understood through the study of the physical brain alone.
MIT's Alex Byrne explains the philosophical underpinnings of the dualist position.
It's easy to see why we believe this to be the case. While every other process in the human body ticks and pulses away without our oversight, there is something uniquely transcendental about our experience of consciousness. It's no surprise that we've treated consciousness as something special, distinct from the automatic systems that keep us breathing and digesting.
But a growing body of evidence from the field of cognitive neuroscience – which studies the biological processes underpinning cognition – challenges this view. Such studies draw attention to the fact that many psychological functions are generated and carried out entirely outside of our subjective awareness, by a range of fast, efficient non-conscious brain systems.
Consider, for example, how effortlessly we regain consciousness each morning after losing it the night before, or how, with no deliberate effort, we instantly recognise and understand shapes, colours, patterns and faces we encounter.
Consider that we don't actually experience how our perceptions are created, how our thoughts and sentences are produced, how we recall our memories or how we control our muscles to walk and our tongues to talk. Simply put, we don't generate or control our thoughts, feelings or actions – we just seem to become aware of them.
The way we simply become aware of thoughts, feelings and the world around us suggests that our consciousness is generated and controlled backstage, by brain systems that we remain unaware of.
Our recent paper argues that consciousness involves no separate independent psychological process distinct from the brain itself, just as there's no additional function to digestion that exists separately from the physical workings of the gut.
While it's clear that both the experience and content of consciousness are real, we argue that, from a science explanation, they are epiphenomenal: secondary phenomena based on the machinations of the physical brain itself. In other words, our subjective experience of consciousness is real, but the functions of control and ownership we attribute to that experience are not.
Future study of the brain
Our position is neither obvious nor intuitive. But we contend that continuing to place consciousness in the driver's seat, above and beyond the physical workings of the brain, and attributing cognitive functions to it, risks confusion and delaying a better understanding of human psychology and behaviour.
To better align psychology with the rest of the natural sciences, and to be consistent with how we understand and study processes like digestion and respiration, we favour a perspective change. We should redirect our efforts to studying the non-conscious brain, and not the functions previously attributed to consciousness.
This doesn't of course exclude psychological investigation into the nature, origins and distribution of the belief in consciousness. But it does mean refocusing academic efforts on what happens beneath our awareness – where we argue the real neuro-psychological processes take place.
Our proposal feels personally and emotionally unsatisfying, but we believe it provides a future framework for the investigation of the human mind – one that looks at the brain's physical machinery rather than the ghost that we've traditionally called consciousness.
A lab identifies which genes are linked to abnormal repetitive behaviors found in addiction and schizophrenia.
These behaviors, termed stereotypies, are also apparent in animal models of drug addiction and autism.
In a new study published in the European Journal of Neuroscience, researchers at the McGovern Institute for Brain Research have identified genes that are activated in the brain prior to the initiation of these severe repetitive behaviors.
"Our lab has found a small set of genes that are regulated in relation to the development of stereotypic behaviors in an animal model of drug addiction," says MIT Institute Professor Ann Graybiel, who is the senior author of the paper. "We were surprised and interested to see that one of these genes is a susceptibility gene for schizophrenia. This finding might help to understand the biological basis of repetitive, stereotypic behaviors as seen in a range of neurologic and neuropsychiatric disorders, and in otherwise 'typical' people under stress."
A shared molecular pathway
In work led by Research Scientist Jill Crittenden, scientists in the Graybiel lab exposed mice to amphetamine, a psychomotor stimulant that drives hyperactivity and confined stereotypies in humans and in laboratory animals and that is used to model symptoms of schizophrenia.
They found that stimulant exposure that drives the most prolonged repetitive behaviors led to activation of genes regulated by Neuregulin 1, a signaling molecule that is important for a variety of cellular functions including neuronal development and plasticity. Neuregulin 1 gene mutations are risk factors for schizophrenia.
The new findings highlight a shared molecular and circuit pathway for stereotypies that are caused by drugs of abuse and in brain disorders, and have implications for why stimulant intoxication is a risk factor for the onset of schizophrenia.
"Experimental treatment with amphetamine has long been used in studies on rodents and other animals in tests to find better treatments for schizophrenia in humans, because there are some behavioral similarities across the two otherwise very different contexts," explains Graybiel, who is also an investigator at the McGovern Institute and a professor of brain and cognitive sciences at MIT. "It was striking to find Neuregulin 1 — potentially one hint to shared mechanisms underlying some of these similarities."
Drug exposure linked to repetitive behaviors
Although many studies have measured gene expression changes in animal models of drug addiction, this study is the first to evaluate genome-wide changes specifically associated with restricted repetitive behaviors.
Stereotypies are difficult to measure without labor-intensive direct observation, because they consist of fine movements and idiosyncratic behaviors. In this study, the authors administered amphetamine (or saline control) to mice and then measured with photobeam-breaks how much they ran around. The researchers identified prolonged periods when the mice were not running around (i.e., were potentially engaged in confined stereotypies), and then they videotaped the mice during these periods to observationally score the severity of restricted repetitive behaviors (e.g., sniffing or licking stereotypies).
They gave amphetamine to each mouse once a day for 21 days and found that, on average, mice showed very little stereotypy on the first day of drug exposure but that, by the seventh day of exposure, all of the mice showed a prolonged period of stereotypy that gradually became shorter and shorter over the subsequent two weeks.
"We were surprised to see the stereotypy diminishing after one week of treatment. We had actually planned a study based on our expectation that the repetitive behaviors would become more intense, but then we realized that this was an opportunity to look at what gene changes were unique to that day of high stereotypy," says first author Jill Crittenden.
The authors compared gene expression changes in the brains of mice treated with amphetamine for one day, seven days, or 21 days. They hypothesized that the gene changes associated specifically with high-stereotypy-associated seven days of drug treatment were the most likely to underlie extreme repetitive behaviors and could identify risk-factor genes for such symptoms in disease.
A shared anatomical pathway
Previous work from the Graybiel lab has shown that stereotypy is directly correlated to circumscribed gene activation in the striatum, a forebrain region that is key for habit formation. In animals with the most intense stereotypy, most of the striatum does not show gene activation, but immediate early gene induction remains high in clusters of cells called striosomes. Striosomes have recently been shown to have powerful control over cells that release dopamine, a neuromodulator that is severely disrupted in drug addiction and in schizophrenia. Strikingly, striosomes contain high levels of Neuregulin 1.
"Our new data suggest that the upregulation of Neuregulin-responsive genes in animals with severely repetitive behaviors reflects gene changes in the striosomal neurons that control the release of dopamine," Crittenden explains. "Dopamine can directly impact whether an animal repeats an action or explores new actions, so our study highlights a potential role for a striosomal circuit in controlling action-selection in health and in neuropsychiatric disease."
Patterns of behavior and gene expression
Striatal gene expression levels were measured by sequencing messenger RNAs (mRNAs) in dissected brain tissue. mRNAs are read out from "active" genes to instruct protein-synthesis machinery in how to make the protein that corresponds to the gene's sequence. Proteins are the main constituents of a cell, thereby controlling each cell's function. The number of times a particular mRNA sequence is found reflects the frequency at which the gene was being read out at the time that the cellular material was collected.
To identify genes that were read out into mRNA before the period of prolonged stereotypy, the researchers collected brain tissue 20 minutes after amphetamine injection, which is about 30 minutes before peak stereotypy. They then identified which genes had significantly different levels of corresponding mRNAs in drug-treated mice than in mice treated with saline.
A wide variety of genes showed modest mRNA increases after the first amphetamine exposure, which induced mild hyperactivity and a range of behaviors such as walking, sniffing, and rearing in the mice.
By the seventh day of treatment, all of the mice were engaged for prolonged periods in one specific repetitive behavior, such as sniffing the wall. Likewise, there were fewer genes that were activated by the seventh day relative to the first treatment day, but they were strongly activated in all mice that received the stereotypy-inducing amphetamine treatment.
By the 21st day of treatment, the stereotypy behaviors were less intense, as was the gene upregulation — fewer genes were strongly activated, and more were repressed, relative to the other treatments. "It seemed that the mice had developed tolerance to the drug, both in terms of their behavioral response and in terms of their gene activation response," says Crittenden.
"Trying to seek patterns of gene regulation starting with behavior is correlative work, and we did not prove 'causality' in this first small study," explains Graybiel. "But we hope that the striking parallels between the scope and selectivity of the mRNA and behavioral changes that we detected will help in further work on the tremendously challenging goal of treating addiction."
This work was funded by the National Institute of Child Health and Human Development, the Saks-Kavanaugh Foundation, the Broderick Fund for Phytocannabinoid Research at MIT, the James and Pat Poitras Research Fund, The Simons Foundation, and The Stanley Center for Psychiatric Research at the Broad Institute.
Because of our ability to think about thinking, "the gap between ape and man is immeasurably greater than the one between amoeba and ape."
- Self-awareness — namely, our capacity to think about our thoughts — is central to how we perceive the world.
- Without self-awareness, education, literature, and other human endeavors would not be possible.
- Striving toward greater self-awareness is the spiritual goal of many religions and philosophies.
The following is an excerpt from Dr. Stephen Fleming's forthcoming book Know Thyself. It is reprinted with permission from the author.
I now run a neuroscience lab dedicated to the study of self-awareness at University College London. My team is one of several working within the Wellcome Centre for Human Neuroimaging, located in an elegant town house in Queen Square in London. The basement of our building houses large machines for brain imaging, and each group in the Centre uses this technology to study how different aspects of the mind and brain work: how we see, hear, remember, speak, make decisions, and so on. The students and postdocs in my lab focus on the brain's capacity for self-awareness. I find it a remarkable fact that something unique about our biology has allowed the human brain to turn its thoughts on itself.
Until quite recently, however, this all seemed like nonsense. As the nineteenth-century French philosopher Auguste Comte put it: "The thinking individual cannot cut himself in two — one of the parts reasoning, while the other is looking on. Since in this case the organ observed and the observing organ are identical, how could any observation be made?" In other words, how can the same brain turn its thoughts upon itself?
Comte's argument chimed with scientific thinking at the time. After the Enlightenment dawned on Europe, an increasingly popular view was that self-awareness was special and not something that could be studied using the tools of science. Western philosophers were instead using self-reflection as a philosophical tool, much as mathematicians use algebra in the pursuit of new mathematical truths. René Descartes relied on self-reflection in this way to reach his famous conclusion, "I think, therefore I am," noting along the way that "I know clearly that there is nothing that can be perceived by me more easily or more clearly than my own mind." Descartes proposed that a central soul was the seat of thought and reason, commanding our bodies to act on our behalf. The soul could not be split in two — it just was. Self-awareness was therefore mysterious and indefinable, and off-limits to science.
We now know that the premise of Comte's worry is false. The human brain is not a single, indivisible organ. Instead, the brain is made up of billions of small components — neurons — that each crackle with electrical activity and participate in a wiring diagram of mind-boggling complexity. Out of the interactions among these cells, our entire mental life — our thoughts and feelings, hopes and dreams — flickers in and out of existence. But rather than being a meaningless tangle of connections with no discernible structure, this wiring diagram also has a broader architecture that divides the brain into distinct regions, each engaged in specialized computations. Just as a map of a city need not include individual houses to be useful, we can obtain a rough overview of how different areas of the human brain are working together at the scale of regions rather than individual brain cells. Some areas of the cortex are closer to the inputs (such as the eyes) and others are further up the processing chain. For instance, some regions are primarily involved in seeing (the visual cortex, at the back of the brain), others in processing sounds (the auditory cortex), while others are involved in storing and retrieving memories (such as the hippocampus).
In a reply to Comte in 1865, the British philosopher John Stuart Mill anticipated the idea that self-awareness might also depend on the interaction of processes operating within a single brain and was thus a legitimate target of scientific study. Now, thanks to the advent of powerful brain imaging technologies such as functional magnetic resonance imaging (fMRI), we know that when we self-reflect, particular brain networks indeed crackle into life and that damage or disease to these same networks can lead to devastating impairments of self-awareness.
I often think that if we were not so thoroughly familiar with our own capacity for self-awareness, we would be gobsmacked that the brain is able to pull off this marvelous conjuring trick. Imagine for a moment that you are a scientist on a mission to study new life-forms found on a distant planet. Biologists back on Earth are clamoring to know what they're made of and what makes them tick. But no one suggests just asking them! And yet a Martian landing on Earth, after learning a bit of English or Spanish or French, could do just that. The Martians might be stunned to find that we can already tell them something about what it is like to remember, dream, laugh, cry, or feel elated or regretful — all by virtue of being self-aware.
I find it a remarkable fact that something unique about our biology has allowed the human brain to turn its thoughts on itself.
But self-awareness did not just evolve to allow us to tell each other (and potential Martian visitors) about our thoughts and feelings. Instead, being self-aware is central to how we experience the world. We not only perceive our surroundings; we can also reflect on the beauty of a sunset, wonder whether our vision is blurred, and ask whether our senses are being fooled by illusions or magic tricks. We not only make decisions about whether to take a new job or whom to marry; we can also reflect on whether we made a good or bad choice. We not only recall childhood memories; we can also question whether these memories might be mistaken.
Self-awareness also enables us to understand that other people have minds like ours. Being self-aware allows me to ask, "How does this seem to me?" and, equally importantly, "How will this seem to someone else?" Literary novels would become meaningless if we lost the ability to think about the minds of others and compare their experiences to our own. Without self-awareness, there would be no organized education. We would not know who needs to learn or whether we have the capacity to teach them. The writer Vladimir Nabokov elegantly captured this idea that self-awareness is a catalyst for human flourishing:
"Being aware of being aware of being. In other words, if I not only know that I am but also know that I know it, then I belong to the human species. All the rest follow s— the glory of thought, poetry, a vision of the universe. In that respect, the gap between ape and man is immeasurably greater than the one between amoeba and ape."
In light of these myriad benefits, it's not surprising that cultivating accurate self-awareness has long been considered a wise and noble goal. In Plato's dialogue Charmides, Socrates has just returned from fighting in the Peloponnesian War. On his way home, he asks a local boy, Charmides, if he has worked out the meaning of sophrosyne — the Greek word for temperance or moderation, and the essence of a life well lived. After a long debate, the boy's cousin Critias suggests that the key to sophrosyne is simple: self-awareness. Socrates sums up his argument: "Then the wise or temperate man, and he only, will know himself, and be able to examine what he knows or does not know…No other person will be able to do this."
Likewise, the ancient Greeks were urged to "know thyself" by a prominent inscription carved into the stone of the Temple of Delphi. For them, self-awareness was a work in progress and something to be striven toward. This view persisted into medieval religious traditions: for instance, the Italian priest and philosopher Saint Thomas Aquinas suggested that while God knows Himself by default, we need to put in time and effort to know our own minds. Aquinas and his monks spent long hours engaged in silent contemplation. They believed that only by participating in concerted self-reflection could they ascend toward the image of God.
A similar notion of striving toward self-awareness is seen in Eastern traditions such as Buddhism. The spiritual goal of enlightenment is to dissolve the ego, allowing more transparent and direct knowledge of our minds acting in the here and now. The founder of Chinese Taoism, Lao Tzu, captured this idea that gaining self-awareness is one of the highest pursuits when he wrote, "To know that one does not know is best; Not to know but to believe that one knows is a disease."
Today, there is a plethora of websites, blogs, and self-help books that encourage us to "find ourselves" and become more self-aware. The sentiment is well meant. But while we are often urged to have better self-awareness, little attention is paid to how self-awareness actually works. I find this odd. It would be strange to encourage people to fix their cars without knowing how the engine worked, or to go to the gym without knowing which muscles to exercise. This book aims to fill this gap. I don't pretend to give pithy advice or quotes to put on a poster. Instead, I aim to provide a guide to the building blocks of self-awareness, drawing on the latest research from psychology, computer science, and neuroscience. By understanding how self-awareness works, I aim to put us in a position to answer the Athenian call to use it better.
Two different studies provide further evidence of the efficacy of psychedelics in treating depression.
- A phase 2 clinical trial by Imperial College London found psilocybin to be as effective at treating depression as escitalopram, a commonly prescribed antidepressant.
- A different study by the University of Maryland showed that blocking the hallucinogenic effects of magic mushrooms in mice did not reduce the antidepressant effect.
- Combined, these studies could lead to new ways of applying psychedelics to patient populations that don't want to trip.
Due to stigma, their illegal status and difficulty in finding control groups, research with psychedelics has been a challenge. But research increasingly shows that this class of drug has legitimate medicinal uses, and they may be just as good or even better than more traditional therapies.
Now, the Centre for Psychedelic Research at Imperial College London reports in the New England Journal of Medicine that when pitted against escitalopram (brand name: Lexapro), psilocybin was as effective as the popular SSRI (selective serotonin reuptake inhibitor) in treating moderate to severe depression. Perhaps most significantly, these results were obtained when comparing 6 weeks of daily doses of escitalopram to just two administrations of psilocybin.
Robin Carhart-Harris, head of the center who has published over 100 papers on psychedelics, is confident this study represents another step forward in applying psychedelics to mental health treatment protocols while also reducing fears a lot of citizens have around these substances. In a press release, he said:
"One of the most important aspects of this work is that people can clearly see the promise of properly delivered psilocybin therapy by viewing it compared with a more familiar, established treatment in the same study. Psilocybin performed very favorably in this head-to-head."
Credit: Robin Carhart-Harris et al, NEJM, 2021.
As depicted above, the phase 2 clinical trial included 59 volunteers. The escitalopram (control) group received six weeks of daily escitalopram in addition to two tiny (1-mg) doses of psilocybin — a dose so low that it is unlikely to produce hallucinogenic effects. The psilocybin (experimental) group received two 25-mg doses of psilocybin three weeks apart with placebo given on all the other days.
At the end of the study, both groups saw a decrease in depressive symptoms, though the results were not statistically significant. (That isn't necessarily bad because if the two drugs have similar effects, then they would not produce statistically significant results. Still, a larger study is needed to confirm that psilocybin is "just as good as" escitalopram.)
Additionally, several other outcomes favored psilocybin over escitalopram. For instance, 57 percent in the psilocybin group saw a remission of symptoms compared to 28 percent in the escitalopram group. This result was significant.
Psychedelics without tripping
As psychedelics become decriminalized and potentially legalized for therapeutic use, however, a large population of people might desire the antidepressant effects without the hallucinations. For example, the psychedelic ibogaine may be useful for treating addiction, so the company Mindmed is developing an analog that works without producing the unwanted hallucinogenic side effects.
A new research article, published in the journal PNAS, investigated the antidepressant effects of psilocybin on a group of chronically stressed mice. (Under immense stress, mice develop something resembling human depression.) As with humans, depressed mice lose a sense of joy, which can be assessed by determining their preference for sugar water over tap water. Normal mice prefer sugar water, but depressed mice simply don't care.
Once the mice were no longer juicing up on the sweetened water, the team dosed them with psilocybin alongside a drug called ketanserin, a 5-HT2A serotonin receptor antagonist that eliminates psychedelic effects. Within 24 hours of receiving the dose, the mice were rushing back to the sugar water, indicating that tripping is not necessary for psilocybin to work as an antidepressant.
While the team is excited about these results, they realize it needs to be replicated in a different population.
"The possibility of combining psychedelic compounds and a 5-HT2AR antagonist offers a potential means to increase their acceptance and clinical utility and should be studied in human depression."
Photo: Cannabis_Pic / Adobe Stock
The future of psychedelic therapy
Psychedelics such as psilocybin and LSD have a long track record of efficacy in clinical trials and anecdotal experiences. Almost all volunteers of the famous Marsh Chapel experiment claimed their experience on Good Friday in 1962 was one of the most significant events of their lives — and this was a quarter-century after the fact. A more recent, controlled study found that a single dose of psilocybin showed antidepressant effects six months later.
Proponents of macrodosing and ritualistic experiences sometimes argue that the full-blown mystical trip is the therapy, though this is anecdotal, not clinical research. As the Maryland team noted, a number of people are contraindicated for psychedelics, whether through a family history of schizophrenia or current antidepressant treatments.
Senior author Scott Thompson is excited for future research on this topic. As he said of his team's findings:
"The psychedelic experience is incredibly powerful and can be life-changing, but that could be too much for some people or not appropriate… These findings show that activation of the receptor causing the psychedelic effect isn't absolutely required for the antidepressant benefits, at least in mice."
Hopefully, with more research occurring in psychedelics than even in the 1950s (when studies predominantly relied on anecdotal evidence and little government support), the longstanding stigmatization of psychedelics is beginning to recede. This could open up new possibilities for both clinical research and, for those curious about the ritual effects, a continuation of introspective experiences.
Stay in touch with Derek on Twitter and Facebook. His most recent book is "Hero's Dose: The Case For Psychedelics in Ritual and Therapy."