This blog reports new ideas and work on mind, brain, behavior, psychology, and politics - as well as random curious stuff. (Try the Dynamic Views at top of right column.)
Tuesday, August 28, 2007
Dramatic out of body demonstrations in normal subjects
Steven Fry's secret life of the manic-depressive
Monday, August 27, 2007
More on magic at Las Vegas
The four ages of functional neuroimaging
Really weird...
Friday, August 24, 2007
Changes in brain control circuits during human development
Human attentional control is unrivaled. We recently proposed that adults depend on distinct frontoparietal and cinguloopercular networks for adaptive online task control versus more stable set control, respectively. During development, both experience-dependent evoked activity and spontaneous waves of synchronized cortical activity are thought to support the formation and maintenance of neural networks. Such mechanisms may encourage tighter "integration" of some regions into networks over time while "segregating" other sets of regions into separate networks. Here we use resting state functional connectivity MRI, which measures correlations in spontaneous blood oxygenation level-dependent signal fluctuations between brain regions to compare previously identified control networks between children and adults. We find that development of the proposed adult control networks involves both segregation (i.e., decreased short-range connections) and integration (i.e., increased long-range connections) of the brain regions that comprise them. Delay/disruption in the developmental processes of segregation and integration may play a role in disorders of control, such as autism, attention deficit hyperactivity disorder, and Tourette's syndrome.
Fig. 2. (click to enlarge) Graphs formed from putative task-control regions in children, adolescents, and adults. ROI (regions of interest) locations are drawn to correspond to topographic brain locations. Right-sided ROIs are displayed on the right and anterior ROIs at the top of each graph. (A) rs-fcMRI revealed two separate control networks in adults as previously described (6). (B) The top 75 connections in adolescents revealed a similar two-component system as seen in adults; however, the dACC/msFC region was incorporated into the frontoparietal network. (C) The top 75 connections in children revealed a significant deviation from the adult architecture. The two networks were connected by a bridge connection (aPFC–dlPFC). The dACC/msFC region was incorporated into the frontoparietal network. Children lacked connections from the dlPFC to IPS and IPL. (D) Fit LOWESS curves of connection strength (r) versus age. As connection strength between the dACC/msFC region and the dF cortex decreased with age, correlation strength increased between the dACC/msFC and aI/fO regions. The aPFC region also decreased its connection strength with the dlPFC region with age but was already strongly connected to the aI/fO region in children. The strength of the aI/fO–aPFC connection was maintained into adulthood.
Fig. 3. (click to enlarge) Increased long-range and decreased short-range connectivity with age. Direct comparisons of all possible connections between adults and children were performed to test the statistical reliability of between-group differences. Both left- and right-hemisphere regions are placed on a transparent brain to aid with visualization. Red and blue lines highlight significant between-group differences for connections with an r ≥ 0.1 in either children or adults (i.e., absolute difference). Light blue and pink lines highlight connections present in both children and adults (r ≥ 0.1) that differed significantly in connection strength between groups (relative difference; P ≤ 0.05). (A) The segregation of the dACC/msFC region from the frontoparietal network (Fig. 2) was statistically significant, as was the disconnection of the aPFC from the dlPFC region (P ≤ 0.05). Most of the connections that "grew down" with age constituted short-range connections. Connections that "grew up" with age are faded to highlight this observation. (B) Connections between the dACC/msFC region and the cinguloopercular network that grew stronger with age were statistically significant (P ≤ 0.05). The connections of left dlPFC to left IPS and left frontal to left IPS were already present in children but significantly increased in strength with age. Most of the connections that "grew up" with age constituted long-range connections. Connections that "grew down" with age are faded to highlight this observation. Selected LOWESS curves are presented in A and B.
Live Longer - Don't Worry
Thursday, August 23, 2007
The Politics of God
The twilight of the idols has been postponed. For more than two centuries, from the American and French Revolutions to the collapse of Soviet Communism, world politics revolved around eminently political problems. War and revolution, class and social justice, race and national identity — these were the questions that divided us. Today, we have progressed to the point where our problems again resemble those of the 16th century, as we find ourselves entangled in conflicts over competing revelations, dogmatic purity and divine duty. We in the West are disturbed and confused. Though we have our own fundamentalists, we find it incomprehensible that theological ideas still stir up messianic passions, leaving societies in ruin. We had assumed this was no longer possible, that human beings had learned to separate religious questions from political ones, that fanaticism was dead. We were wrong.
The revival of political theology in the modern West is a humbling story. It reminds us that this way of thinking is not the preserve of any one culture or religion, nor does it belong solely to the past. It is an age-old habit of mind that can be reacquired by anyone who begins looking to the divine nexus of God, man and world to reveal the legitimate political order. This story also reminds us how political theology can be adapted to circumstances and reassert itself, even in the face of seemingly irresistible forces like modernization, secularization and democratization. Rousseau was on to something: we seem to be theotropic creatures, yearning to connect our mundane lives, in some way, to the beyond. That urge can be suppressed, new habits learned, but the challenge of political theology will never fully disappear so long as the urge to connect survives.
So we are heirs to the Great Separation only if we wish to be, if we make a conscious effort to separate basic principles of political legitimacy from divine revelation. Yet more is required still. Since the challenge of political theology is enduring, we need to remain aware of its logic and the threat it poses. This means vigilance, but even more it means self-awareness. We must never forget that there was nothing historically inevitable about our Great Separation, that it was and remains an experiment. In Europe, the political ambiguities of one religion, Christianity, happened to set off a political crisis that might have been avoided but wasn’t, triggering the Wars of Religion; the resulting carnage made European thinkers more receptive to Hobbes’s heretical ideas about religious psychology and the political implications he drew from them; and over time those political ideas were liberalized. Even then, it was only after the Second World War that the principles of modern liberal democracy became fully rooted in continental Europe.
As for the American experience, it is utterly exceptional: there is no other fully developed industrial society with a population so committed to its faiths (and such exotic ones), while being equally committed to the Great Separation. Our political rhetoric, which owes much to the Protestant sectarians of the 17th century, vibrates with messianic energy, and it is only thanks to a strong constitutional structure and various lucky breaks that political theology has never seriously challenged the basic legitimacy of our institutions. Americans have potentially explosive religious differences over abortion, prayer in schools, censorship, euthanasia, biological research and countless other issues, yet they generally settle them within the bounds of the Constitution. It’s a miracle.
...a number of Muslim thinkers around the world have taken to promoting a “liberal” Islam. What they mean is an Islam more adapted to the demands of modern life, kinder in its treatment of women and children, more tolerant of other faiths, more open to dissent. These are brave people who have often suffered for their efforts, in prison or exile, as did their predecessors in the 19th century, of which there were many. But now as then, their efforts have been swept away by deeper theological currents they cannot master and perhaps do not even understand. The history of Protestant and Jewish liberal theology reveals the problem: the more a biblical faith is trimmed to fit the demands of the moment, the fewer reasons it gives believers for holding on to that faith in troubled times, when self-appointed guardians of theological purity offer more radical hope. Worse still, when such a faith is used to bestow theological sanctification on a single form of political life — even an attractive one like liberal democracy — the more it will be seen as collaborating with injustice when that political system fails. The dynamics of political theology seem to dictate that when liberalizing reformers try to conform to the present, they inspire a countervailing and far more passionate longing for redemption in the messianic future. That is what happened in Weimar Germany and is happening again in contemporary Islam.
In the end, though, what happens on the opposite shore will not be up to us. We have little reason to expect societies in the grip of a powerful political theology to follow our unusual path, which was opened up by a unique crisis within Christian civilization. This does not mean that those societies necessarily lack the wherewithal to create a decent and workable political order; it does mean that they will have to find the theological resources within their own traditions to make it happen.
Our challenge is different. We have made a choice that is at once simpler and harder: we have chosen to limit our politics to protecting individuals from the worst harms they can inflict on one another, to securing fundamental liberties and providing for their basic welfare, while leaving their spiritual destinies in their own hands. We have wagered that it is wiser to beware the forces unleashed by the Bible’s messianic promise than to try exploiting them for the public good. We have chosen to keep our politics unilluminated by divine revelation. All we have is our own lucidity, which we must train on a world where faith still inflames the minds of men.
Two Books on Brain Plasticity
The book by Norman Doidge, "The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science" gives stories of numerous examples of neuroplasticity and rehabilitation among his own patients, as well as relating other case studies of recovery and conversations with neuroscientists.
Wednesday, August 22, 2007
What I totally do not get....a new book on consciousness
Below I give you the blurb on the book, and the problems I have with this are stated in the critical review just mentioned, some repeated below:
Bridging the gap between the world of science and the realm of the spiritual, B. Alan Wallace introduces a natural theory of human consciousness that has its roots in contemporary physics and Buddhism. Wallace’s "special theory of ontological relativity" suggests that mental phenomena are conditioned by the brain, but do not emerge from it. Rather, the entire natural world of mind and matter, subjects and objects, arises from a unitary dimension of reality that is more fundamental than these dualities, as proposed by Wolfgang Pauli and Carl Jung.My previous response:
To test his hypothesis, Wallace employs the Buddhist meditative practice of samatha, refining one’s attention and metacognition, to create a kind of telescope to examine the space of the mind. Drawing on the work of the physicist John Wheeler, he then proposes a more general theory in which the participatory nature of reality is envisioned as a self-excited circuit. In comparing these ideas to the Buddhist theory known as the Middle Way philosophy, Wallace explores further aspects of his "general theory of ontological relativity," which can be investigated by means of vipasyana, or insight, meditation. Wallace then focuses on the theme of symmetry in reference to quantum cosmology and the “problem of frozen time,” relating these issues to the theory and practices of the Great Perfection school of Tibetan Buddhism. He concludes with a discussion of the general theme of complementarity as it relates to science and religion.
The theories of relativity and quantum mechanics were major achievements in the physical sciences, and the theory of evolution has had an equally deep impact on the life sciences. Yet rigorous scientific methods do not yet exist to observe mental phenomena, and naturalism has its limits for shedding light on the workings of the mind. A pioneer of modern consciousness research, Wallace offers a practical and revolutionary method for exploring the mind that combines the keenest insights of contemporary physicists and philosophers with the time-honored meditative traditions of Buddhism.
The problem I think is that his analogy with other scientific revolutions fails on the issue of universality and ability to reproduce basic introspective observations. Galileo's and Darwin's observations and measurements can be reproduced by anyone in any culture having appropriate equipment. In the period after William James' challenge and before the behaviorists' 50+ year death grip on progress in psychology a number of groups pursuing an introspective approach could not agree on many basic observations (Wallace commented on, but did not really address this issue in the discussion period). The introspective and meditative approaches associated with many different cultures and religions don't seem remotely close to yielding a unified introspective description of consciousness and our mental processes that transcends their cultural origins in the way that astronomy and biology do.
Still, I think that the Buddha was the first great human biologist in his astute descriptions of levels of human behavior that corresponds roughly to stages in the biological evolution of our own brains and behavior (see my "Beast Within" essay). The mutual reinforcement of ancient introspective and modern scientific traditions yields some robustness, and perhaps the prospect of an eventual union of materialistic and mentalistic perspectives. Perhaps this will yield the "consciousness meter," analogous to a telescope or microscope, than we are now lacking.
Flipping switches in the brain with light.
A first step is establishing that it is possible to tweak a brain circuit by remote control and observe the corresponding behavioral changes in freely moving lab animals. On a recent Sunday at Stanford, Dr. Deisseroth and Feng Zhang, a graduate student, hovered over a dark brown mouse placed inside a white plastic tub. Through standard gene-manipulating tricks, the rodent had been engineered to produce channelrhodopsin only in one particular kind of neuron found throughout the brain, to no apparent ill effect....Mr. Zhang had implanted a tiny metal tube into the right side of the mouse’s partly shaved head...Now he carefully threaded a translucent fiber-optic cable not much wider than a thick human hair into that tube, positioned over the area of the cerebral cortex that controls movement...(then).. adjusted a key on a nearby laser controller box, and the fiber-optic cable glowed with blue light. The mouse started skittering in a left-hand spin, like a dog chasing its tail....“Turn it off, and then you can see him stand up,” Dr. Deisseroth continued. “And now turn it back on, and you can see it’s circling.”..Because the brain lacks pain receptors, the mouse felt no discomfort from the fiber optic, the scientists said, although it looked a tad confused. Scientists have long known that using electrodes to gently zap one side of a mouse’s motor cortex will make it turn the opposite way. What is new here is that for the first time, researchers can perturb specific neuron types using light.....
Legend: Light stimulation every 200 milliseconds generates electrical activity, right, in an area of the brain associated with depression.
At Stanford, Dr. Deisseroth’s group has identified part of a brain circuit, in the hippocampus, that is underactive in rats, with some symptoms resembling depression. The neural circuit’s activity — and the animals’ — perked up after antidepressant treatment, in findings reported last week in the journal Science. Now the team is examining whether they can lift the rats’ low-energy behavior by using channelrhodopsin to rev up the sluggish neural zone...
The Stanford group has sent DNA copies of the “on” and “off” light-switch genes to more than 175 researchers eager to try them in all stripes of electrically excitable cells, from insulin-releasing pancreas cells to heart cells.
Tuesday, August 21, 2007
Imaging Depression
Neuroimaging studies of humans with major depressive disorder have largely pointed to prefrontal sites, especially implicating an area in the midline subgenual anterior cingulate cortex, often denoted as area 25 (see the figure. Not only does this region appear abnormal on structural and functional scans, but also it is enriched with the serotonin transporter, a target for many antidepressant drugs. Individuals inheriting a risk allele within the promoter of the serotonin transporter gene have reduced volume of area 25 and reduced functional coupling of this region to the amygdala, a subcortical region implicated in the regulation of emotion. An initial study of treatment-resistant depressed patients reports that deep brain stimulation adjacent to area 25 relieves the symptoms of major depressive disorder.
Male sexual behavior circuits in female brains...
In mice, pheromone detection is mediated by the vomeronasal organ and the main olfactory epithelium. Male mice that are deficient for Trpc2, an ion channel specifically expressed in VNO neurons and essential for VNO sensory transduction, are impaired in sex discrimination and male–male aggression. We report here that Trpc2-/- female mice show a reduction in female-specific behaviour, including maternal aggression and lactating behaviour. Strikingly, mutant females display unique characteristics of male sexual and courtship behaviours such as mounting, pelvic thrust, solicitation, anogenital olfactory investigation, and emission of complex ultrasonic vocalizations towards male and female conspecific mice. The same behavioural phenotype is observed after VNO surgical removal in adult animals, and is not accompanied by disruption of the oestrous cycle and sex hormone levels. These findings suggest that VNO-mediated pheromone inputs act in wild-type females to repress male behaviour and activate female behaviours. Moreover, they imply that functional neuronal circuits underlying male-specific behaviours exist in the normal female mouse brain.There is some controversy over whether this result is unique to inbred laboratory mouse strains, so Dulac is now breeding wild mice with the Trpc2-mutant mice, to experiment with a 'wilder' version.
Monday, August 20, 2007
Happiness Tips
* 1. Give yourself permission to be human. When we accept emotions — such as fear, sadness, or anxiety — as natural, we are more likely to overcome them. Rejecting our emotions, positive or negative, leads to frustration and unhappiness.
* 2. Happiness lies at the intersection between pleasure and meaning. Whether at work or at home, the goal is to engage in activities that are both personally significant and enjoyable. When this is not feasible, make sure you have happiness boosters, moments throughout the week that provide you with both pleasure and meaning.
* 3. Keep in mind that happiness is mostly dependent on our state of mind, not on our status or the state of our bank account. Barring extreme circumstances, our level of well being is determined by what we choose to focus on (the full or the empty part of the glass) and by our interpretation of external events. For example, do we view failure as catastrophic, or do we see it as a learning opportunity?
* 4. Simplify! We are, generally, too busy, trying to squeeze in more and more activities into less and less time. Quantity influences quality, and we compromise on our happiness by trying to do too much.
* 5. Remember the mind-body connection. What we do — or don't do — with our bodies influences our mind. Regular exercise, adequate sleep, and healthy eating habits lead to both physical and mental health.
* 6. Express gratitude, whenever possible. We too often take our lives for granted. Learn to appreciate and savor the wonderful things in life, from people to food, from nature to a smile.
Genetic changes that influence memory
Knowing which genes contribute to natural variation in learning and memory would help us understand how differences in these cognitive traits evolve among populations and species. We show that a natural polymorphism at the foraging (for) locus, which encodes a cGMP-dependent protein kinase (PKG), affects associative olfactory learning in Drosophila melanogaster. In an assay that tests the ability to associate an odor with mechanical shock, flies homozygous for one natural allelic variant of this gene (forR) showed better short-term but poorer long-term memory than flies homozygous for another natural allele (fors). The fors allele is characterized by reduced PKG activity. We showed that forR-like levels of both short-term learning and long-term memory can be induced in fors flies by selectively increasing the level of PKG in the mushroom bodies, which are centers of olfactory learning in the fly brain. Thus, the natural polymorphism at for may mediate an evolutionary tradeoff between short- and long-term memory. The respective strengths of learning performance of the two genotypes seem coadapted with their effects on foraging behavior: forR flies move more between food patches and so could particularly benefit from fast learning, whereas fors flies are more sedentary, which should favor good long-term memory.
Followup on male promiscuity...
The Median, the Math and the Sex
By GINA KOLATA
David Gale, eminent emeritus mathematics professor at the University of California, Berkeley, member of the National Academy of Sciences, household name in certain rarefied circles, wanted to sound off about sex surveys. Over and over again, he said, they report results that logic dictates can’t be right. The total number of sex partners for men, he said, must equal the total number for women.
So when I said I’d write about that for The New York Times, he was delighted. Do you think I’ll get a response, he asked?
Little did he know. The moment the article hit The Times’s Web site last weekend, the e-mail messages flew and a discussion ensued that might be bewildering to the nonmathematician.
Gotcha, readers said: Data in one of the surveys cited, they said, reported the median numbers of sexual partners — and Dr. Gale’s argument, they said, only holds for the average number of partners.
Some were polite. Andrew Odlyzko, a mathematician at the University of Minnesota, wrote, “David Gale’s argument is unimpeachable” but there is this problem of medians.
Others were blunt: “Theorem: Professor Gale never went to prom. Proof: His High School Prom Theorem fatally assumes that everyone has a partner for every dance and no one ever sits out. The alternative is he has confused medians (at issue in the article) with means (averages, not middle-points in data), a rather elementary mistake for an emeritus professor of mathematics at Berkeley.”
The problem, Dr. Gale says, is that people leapt to conclusions. He had looked at the actual data from the survey citing medians and found that it could not possibly be correct. Of course he knew the difference between a median and a mean.
He wrote an explanation to send out to his numerous correspondents. But the e-mail messages kept coming.
A few correspondents, at least, were gracious. James Smith, an economist at the RAND Corporation, replied: “Yes, my point was only that of a nerd,” he wrote. “I have no doubt that the puzzle you pointed out is indeed true and cannot be explained away by medians and means.”
For the unconvinced, Dr. Gale’s response:
What I did was to get a copy of the C.D.C. report and use the data in its tables. The C.D.C. groups people into four groups and gives percentage of men and women in each group
From these figures you can estimate the total partners claimed by each sex. I got between 40 percent and 75 percent more male than female partners depending on how you guess the average on each interval. Thus, the raw data is inconsistent (so it doesn’t matter whether you take averages or medians or any other statistic).
I hope this clarifies.
Friday, August 17, 2007
Dan Koshland on scientific discovery - his Cha-Cha-Cha theory
Scientific discoveries are the steps--some small, some big--on the staircase called progress, which has led to a better life for the citizens of the world. Each scientific discovery is made possible by the arrangement of neurons in the brain of one individual and as such is idiosyncratic. In looking back on centuries of scientific discoveries, however, a pattern emerges which suggests that they fall into three categories--Charge, Challenge, and Chance--that combine into a "Cha-Cha-Cha" Theory of Scientific Discovery. (Nonscientific discoveries can be categorized similarly.)
"Charge" discoveries solve problems that are quite obvious--cure heart disease, understand the movement of stars in the sky--but in which the way to solve the problem is not so clear. In these, the scientist is called on, as Nobel laureate Albert Szent-Györgyi put it, "to see what everyone else has seen and think what no one else has thought before." Thus, the movement of stars in the sky and the fall of an apple from a tree were apparent to everyone, but Isaac Newton came up with the concept of gravity to explain it all in one great theory.
"Challenge" discoveries are a response to an accumulation of facts or concepts that are unexplained by or incongruous with scientific theories of the time. The discoverer perceives that a new concept or a new theory is required to pull all the phenomena into one coherent whole. Sometimes the discoverer sees the anomalies and also provides the solution. Sometimes many people perceive the anomalies, but they wait for the discoverer to provide a new concept. Those individuals, whom we might call "uncoverers," contribute greatly to science, but it is the individual who proposes the idea explaining all of the anomalies who deserves to be called a discoverer.
"Chance" discoveries are those that are often called serendipitous and which Louis Pasteur felt favored "the prepared mind." In this category are the instances of a chance event that the ready mind recognizes as important and then explains to other scientists. This category not only would include Pasteur's discovery of optical activity (D and L isomers), but also W. C. Roentgen's x-rays and Roy Plunkett's Teflon. These scientists saw what no one else had seen or reported and were able to realize its importance.
There are well-known examples in each one of the Cha-Cha-Cha categories (see the figure). Two conclusions are immediately apparent. The first is that the original contribution of the discoverer can be applied at different points in the solution of a problem. In the Charge category, originality lies in the devising of a solution, not in the perception of the problem. In the Challenge category, the originality is in perceiving the anomalies and their importance and devising a new concept that explains them. In the Chance category, the original contribution is the perception of the importance of the accident and articulating the phenomenon on which it throws light.
Second, most important discoveries are usually not solved in one "Eureka" moment, as movie scripts sometimes suggest. True, there are moments in which a scientist has been mulling over various facts and problems and suddenly puts them all together, but most major discoveries require scientists to make not one but a number of original discoveries and to persist in pursuing them until a discovery is complete. Thus, to solidify his theory of gravity, Newton developed calculus and laws of physics that he described in his Principia. In a modern example, Michael Brown and Joseph Goldstein not only studied the metabolism of cholesterol but also discovered the role of lipoprotein receptors and the movement of key proteins from the outside to the interior of cells. Great discoveries are frequently covered in textbooks with a single word or phrase, but the concepts actually become solidified as scientific understanding by a series of discoveries.
It is also pertinent to define "the prepared mind" that is required for all of these innovations. Such a mind must be curious and knowledgeable. Curious refers to the fact that the individual is interested in phenomena and is constantly seeking to understand and explain them. Knowledgeable means that the individual has a background of facts and theories as a fertile incubator into which the new facts can fall.
The Cha-Cha-Cha Theory pertains to small everyday findings by scientists as well as the big discoveries that appear in history books. When, for example, a researcher discovers a new chemical isolated from a plant, there is so much understood today that the "charge" to that scientist is to find the formula and structure of the compound. There are now many ways to find the structure of an unknown chemical. Along the way there may be anomalous results that present challenges to the scientist and unexpected findings that must be interpreted by the prepared mind. So each of these represent real discoveries, not as big as a theory of gravity, but important just the same.
Finally, scientific discoveries are not that different from nonscientific discoveries. In the earliest days, there was an obvious "charge" for a set of rules to guide conduct in the close environment of a village that led to social customs and religious guidelines such as the Ten Commandments. As more complex societies emerged, the idea of a democratic vote probably resulted from a "charge" that saw the importance of getting consensus. The Magna Carta and the Bill of Rights came out of "challenges" to an entrenched social system. So when Einstein said that scientific thinking and general thinking were not that different, he probably meant that the patterns of thought of those with "prepared minds" in government and law operated by some of the same general principles as science, even though the methods of science and law are very different.
Someday we may understand the arrangement of neurons in the brain enough to understand how originality can arise. A wild guess would be that the brain of a discoverer has a greater tendency than the average individual to relate facts from highly separate compartments of the brain to each other. As a step to making that Herculean problem tractable, we can at least follow the traditions of scientific reductionism and use the Charge, Challenge, and Chance categories to make the interpretation of brain imaging experiments easier to analyze.
Monkeys prefer silence...
Cognitive scientists Joshua McDermott of the Massachusetts Institute of Technology in Cambridge and Marc Hauser of Harvard University put tamarins and marmosets in an apparatus with two chambers, each rigged to play music whenever an animal entered. In one experiment, the musical choices were a flute lullaby (65.26 beats per minute) and Alec Empire's electronic techno hit "Nobody Gets Out Alive" (369.23 beats per minute). The monkeys spent an average of about two-thirds of their time on the lullaby side, showing that they prefer slower tempos. But when given the choice of silence, lullabies, or a Mozart concerto, they spent most of their time avoiding music altogether. A similar experiment with eight humans showed a distinct preference for music--especially lullabies--over silence, the authors report in the September issue of Cognition.
"The observations suggest that only humans have a natural, or innate, inclination to engage with music," says Isabelle Peretz of the University of Montreal in Canada, who has concluded from studies of people with amusia (tone deafness) that humans have special brain pathways for music (Science, 1 June 2001, p. 1636). McDermott and Hauser--who earlier found that monkeys have no preference between harmonious and dissonant music--suggest that humans' music responses may reflect a "unique evolutionary history of selection" for cognitive processes linked to emotion and motivation.
Thursday, August 16, 2007
Most popular consciousness papers for July 2007
1. Windt, Jennifer Michelle and Metzinger, Thomas (2006) The philosophy of
dreaming and self-consciousness: What happens to the experiential subject
during the dream state? In: The new science of dreaming (1505 downloads from
18 countries). http://eprints.assc.caltech.edu/200/
2. Rosen, Alan and Rosen, David B. (2006) The Design of a
Sensation-generating Mechanism in the Brain: A first step towards a
quantitative definition of consciousness. In: Consciousness and Cognition
(1030 downloads from 20 countries). http://eprints.assc.caltech.edu/195/
3. Sagiv, Noam and Ward, Jamie (2006) Crossmodal interactions: lessons from
synesthesia. In: Visual Perception, Part 2 (873 downloads from 17
countries). http://eprints.assc.caltech.edu/224/
4. Koriat, A. (2006) Metacognition and Consciousness. In: Cambridge handbook
of consciousness. CUP (801 downloads from 17 countries).
http://eprints.assc.caltech.edu/175/
5. Robbins, Stephen E (2006) Bergson and the holographic theory of mind.
Phenomenology and the Cognitive Sciences, 5. pp. 365-394 (762 downloads from
14 countries). http://eprints.assc.caltech.edu/206
Notice that many of this year's conference presentations and related
material can now be found in the archive - for example, this year's William
James Prize winner Sid Kouder's paper: Kouider, Sid and Dehaene, Stanislas
and Jobert, Antoinette and Le Bihan, Denis (2007) Cerebral Bases of
Subliminal and Supraliminal Priming during Reading. Cerebral Cortex, 17 (9).
pp. 2019-2029. ( http://eprints.assc.caltech.edu/321)
Sugar more rewarding than cocaine...
Background: Refined sugars (e.g., sucrose, fructose) were absent in the diet of most people until very recently in human history. Today overconsumption of diets rich in sugars contributes together with other factors to drive the current obesity epidemic. Overconsumption of sugar-dense foods or beverages is initially motivated by the pleasure of sweet taste and is often compared to drug addiction. Though there are many biological commonalities between sweetened diets and drugs of abuse, the addictive potential of the former relative to the latter is currently unknown.Thus, they demonstrate (at least in rats) that:
Principal finding: ...when rats were allowed to choose mutually-exclusively between water sweetened with saccharin–an intense calorie-free sweetener–and intravenous cocaine–a highly addictive and harmful substance–the large majority of animals (94%) preferred the sweet taste of saccharin. The preference for saccharin was not attributable to its unnatural ability to induce sweetness without calories because the same preference was also observed with sucrose, a natural sugar. Finally, the preference for saccharin was not surmountable by increasing doses of cocaine and was observed despite either cocaine intoxication, sensitization or intake escalation–the latter being a hallmark of drug addiction.
...intense sweetness can surpass cocaine reward, even in drug-sensitized and -addicted individuals.And speculate:
...that the addictive potential of intense sweetness results from an inborn hypersensitivity to sweet tastants. In most mammals, including rats and humans, sweet receptors evolved in ancestral environments poor in sugars and are thus not adapted to high concentrations of sweet tastants. The supranormal stimulation of these receptors by sugar-rich diets, such as those now widely available in modern societies, would generate a supranormal reward signal in the brain, with the potential to override self-control mechanisms and thus to lead to addiction.