王佩怡的部落格

Color perception shifts from right brain to left

RANDOLPH E. SCHMID, AP Science Writer

WASHINGTON – Learning the name of a color changes the part of the brain that handles color perception. Infants perceive color in the right hemisphere of the brain, researchers report, while adults do the job in the brain's left hemisphere.

Testing toddlers showed that the change occurred when the youngsters learned the names to attach to particular colors, scientists report in Tuesday's edition of Proceedings of the National Academy of Sciences.

"It appears, as far as we can tell, that somehow the brain, when it has categories such as color, it actually consults those categories," Paul Kay of the department of linguistics, University of California, Berkeley, said in a telephone interview.

He said the researchers did a similar experiment with silhouettes of dogs and cats with the same result -- once a child learns the name for the animal, perception moves from the right to the left side of the brain.

"It's important to know this because it's part of a debate that's gone on as long as there has been philosophy or science, about how the language we speak affects how we look at the world," Kay said. Indeed, scholars continue to discuss the comparative importance of nature versus nurture.

The researchers studied the time it took toddlers to begin eye movement toward a colored target in either their left or right field of vision to determine which half of the brain was processing the information.

The research was funded by the National Science Foundation.

On the Net:

PNAS: http://www.pnas.org

http://news.yahoo.com/mp/1689/20081118;_ylt=Ak9Rikqcq.N.rK.eMAsXCeYbr7sF

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Scientists Closing in on Theory of Consciousness       解釋「意識」的兩個理論

Tanya Lewis, 07/30/14

Probably for as long as humans have been able to grasp the concept of consciousness, they have sought to understand the phenomenon.

Studying the mind was once the province of philosophers, some of whom still believe the subject is inherently unknowable. But neuroscientists are making strides in developing a true science of the self.

Here are some of the best contenders for a theory of consciousness.

Cogito ergo sum

Not an easy concept to define, consciousness has been described as the state of being awake and aware of what is happening around you, and of having a sense of self. [Top 10 Mysteries of the Mind]

The 17th century French philosopher René Descartes proposed the notion of "cogito ergo sum" ("I think, therefore I am"), the idea that the mere act of thinking about one's existence proves there is someone there to do the thinking.

Descartes also believed the mind was separate from the material body -- a concept known as mind-body duality -- and that these realms interact in the brain's pineal gland. Scientists now reject the latter idea, but some thinkers still support the notion that the mind is somehow removed from the physical world.

But while philosophical approaches can be useful, they do not constitute testable theories of consciousness, scientists say.

"The only thing you know is, 'I am conscious.' Any theory has to start with that," said Christof Koch, a neuroscientist and the chief scientific officer at the Allen Institute for Neuroscience in Seattle.

Correlates of consciousness

In the last few decades, neuroscientists have begun to attack the problem of understanding consciousness from an evidence-based perspective. Many researchers have sought to discover specific neurons or behaviors that are linked to conscious experiences.

Recently, researchers discovered a brain area that acts as a kind of on-off switch for the brain. When they electrically stimulated this region, called the claustrum, the patient became unconscious instantly. In fact, Koch and Francis Crick, the molecular biologist who famously helped discover the double-helix structure of DNA, had previously hypothesized that this region might integrate information across different parts of the brain, like the conductor of a symphony.

But looking for neural or behavioral connections to consciousness isn't enough, Koch said. For example, such connections don't explain why the cerebellum, the part of the brain at the back of the skull that coordinates muscle activity, doesn't give rise to consciousness, while the cerebral cortex (the brain's outermost layer) does. This is the case even though the cerebellum contains more neurons than the cerebral cortex.

Nor do these studies explain how to tell whether consciousness is present, such as in brain-damaged patients, other animals or even computers. [Super-Intelligent Machines: 7 Robotic Futures]

Neuroscience needs a theory of consciousness that explains what the phenomenon is and what kinds of entities possess it, Koch said. And currently, only two theories exist that the neuroscience community takes seriously, he said.

Integrated information

Neuroscientist Giulio Tononi of the University of Wisconsin-Madison developed one of the most promising theories for consciousness, known as integrated information theory.

Understanding how the material brain produces subjective experiences, such as the color green or the sound of ocean waves, is what Australian philosopher David Chalmers calls the "hard problem" of consciousness. Traditionally, scientists have tried to solve this problem with a bottom-up approach. As Koch put it, "You take a piece of the brain and try to press the juice of consciousness out of [it]." But this is almost impossible, he said.

In contrast, integrated information theory starts with consciousness itself, and tries to work backward to understand the physical processes that give rise to the phenomenon, said Koch, who has worked with Tononi on the theory.

The basic idea is that conscious experience represents the integration of a wide variety of information, and that this experience is irreducible. This means that when you open your eyes (assuming you have normal vision), you can't simply choose to see everything in black and white, or to see only the left side of your field of view.

Instead, your brain seamlessly weaves together a complex web of information from sensory systems and cognitive processes. Several studies have shown that you can measure the extent of integration using brain stimulation and recording techniques.

The integrated information theory assigns a numerical value, "phi," to the degree of irreducibility. If phi is zero, the system is reducible to its individual parts, but if phi is large, the system is more than just the sum of its parts.

This system explains how consciousness can exist to varying degrees among humans and other animals. The theory incorporates some elements of panpsychism, the philosophy that the mind is not only present in humans, but in all things.

An interesting corollary of integrated information theory is that no computer simulation, no matter how faithfully it replicates a human mind, could ever become conscious. Koch put it this way: "You can simulate weather in a computer, but it will never be 'wet.'"

Global workspace

Another promising theory suggests that consciousness works a bit like computer memory, which can call up and retain an experience even after it has passed.

Bernard Baars, a neuroscientist at the Neurosciences Institute in La Jolla, California, developed the theory, which is known as the global workspace theory. This idea is based on an old concept from artificial intelligence called the blackboard, a memory bank that different computer programs could access.

Anything from the appearance of a person's face to a memory of childhood can be loaded into the brain's blackboard, where it can be sent to other brain areas that will process it. According to Baars' theory, the act of broadcasting information around the brain from this memory bank is what represents consciousness.

The global workspace theory and integrated information theories are not mutually exclusive, Koch said. The first tries to explain in practical terms whether something is conscious or not, while the latter seeks to explain how consciousness works more broadly.

"At this point, both could be true," Koch said.

Follow Tanya Lewis on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

Editor's Recommendations

http://www.livescience.com/47096-theories-seek-to-explain-consciousness.html

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However, the word “process” here is used as a verb. As such, an agent, i.e., someone, something, or some organ or organs has to DO the “processing.”

As far as I know, the commonly accepted neurological theory stipulates that our bodily organs other than the brain can only “sense”, i.e., receive and transmit external stimuli, signals if you will, via neurons, synapses, and associated chemicals. When the stimuli reach the particular cortical area, the neurons there will DO the “processing”; and this particular cortical area (in conjunction with other relevant cortical areas) will issue certain response which in turn is transmitted via another set of neurons, synapses, and associated chemicals to our limbs and/or organs. These limbs and/or organs will then carry out or execute the said response.

There are reported cases when the first neural path described above gets blocked somehow, the person will not “feel” anything; hence, she/he will exhibit no response emotional or otherwise.

Now, “commonly accepted” in no way imply that the theory is correct or true. However, it does entail:

a.     It has not been falsified or proven wrong;

b.     It has produced practical applications benefiting us. For example, drugs and/or operations that treat headache, depression, anxiety, sleeplessness, etc.

Unless someone can identify the “who” or “what” that is doing the “processing”, I would take the aforementioned “meditational observation” with a grain of salt.

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Hard to explain; however, this is observed in meditation

Brain is more complicated. Emotional responses are processed before reaches the brain

為天地立心,為生民立命.為往聖繼絕學,為萬世開太平!

Study cracks how the brain processes emotions

Melissa Osgood, Media Relations Office, Cornell University, 07/09/14

Although feelings are personal and subjective, the human brain turns them into a standard code that objectively represents emotions across different senses, situations and even people, reports a new study by Cornell University neuroscientist Adam Anderson.

“We discovered that fine-grained patterns of neural activity within the orbitofrontal cortex, an area of the brain associated with emotional processing, act as a neural code which captures an individual’s subjective feeling,” says Anderson, associate professor of human development in Cornell’s College of Human Ecology and senior author of the study. “Population coding of affect across stimuli, modalities and individuals,” published online in Nature Neuroscience.

Their findings provide insight into how the brain represents our innermost feelings – what Anderson calls the last frontier of neuroscience – and upend the long-held view that emotion is represented in the brain simply by activation in specialized regions for positive or negative feelings, he says.

“If you and I derive similar pleasure from sipping a fine wine or watching the sun set, our results suggest it is because we share similar fine-grained patterns of activity in the orbitofrontal cortex,” Anderson says.

“It appears that the human brain generates a special code for the entire valence spectrum of pleasant-to-unpleasant, good-to-bad feelings, which can be read like a ‘neural valence meter’ in which the leaning of a population of neurons in one direction equals positive feeling and the leaning in the other direction equals negative feeling,” Anderson explains.

For the study, the researchers presented participants with a series of pictures and tastes during functional neuroimaging, then analyzed participants’ ratings of their subjective experiences along with their brain activation patterns.

Anderson’s team found that valence was represented as sensory-specific patterns or codes in areas of the brain associated with vision and taste, as well as sensory-independent codes in the orbitofrontal cortices (OFC), suggesting, the authors say, that representation of our internal subjective experience is not confined to specialized emotional centers, but may be central to perception of sensory experience.

They also discovered that similar subjective feelings – whether evoked from the eye or tongue – resulted in a similar pattern of activity in the OFC, suggesting the brain contains an emotion code common across distinct experiences of pleasure (or displeasure), they say. Furthermore, these OFC activity patterns of positive and negative experiences were partly shared across people.

“Despite how personal our feelings feel, the evidence suggests our brains use a standard code to speak the same emotional language,” Anderson concludes.

Media note: Images and the paper can be downloaded at, https://cornell.box.com/Emotion

http://mediarelations.cornell.edu/2014/07/09/study-cracks-how-the-brain-processes-emotions/

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Your Brain Is On the Brink of Chaos

Neurological evidence for chaos in the nervous system is growing.

Kelly Clancy, 07/10/14

In one important way, the recipient of a heart transplant ignores its new organ: Its nervous system usually doesn’t rewire to communicate with it. The 40,000 neurons controlling a heart operate so perfectly, and are so self-contained, that a heart can be cut out of one body, placed into another, and continue to function perfectly, even in the absence of external control, for a decade or more. This seems necessary: The parts of our nervous system managing our most essential functions behave like a Swiss watch, precisely timed and impervious to perturbations. Chaotic behavior has been throttled out.

Or has it? Two simple pendulums that swing with perfect regularity can, when yoked together, move in a chaotic trajectory. Given that the billions of neurons in our brain are each like a pendulum, oscillating back and forth between resting and firing, and connected to 10,000 other neurons, isn’t chaos in our nervous system unavoidable?

The prospect is terrifying to imagine. Chaos is extremely sensitive to initial conditions -- just think of the butterfly effect. What if the wrong perturbation plunged us into irrevocable madness? Among many scientists, too, there is a great deal of resistance to the idea that chaos is at work in biological systems. Many intentionally preclude it from their models. It subverts computationalism, which is the idea that the brain is nothing more than a complicated, but fundamentally rule-based, computer. Chaos seems unqualified as a mechanism of biological information processing, as it allows noise to propagate without bounds, corrupting information transmission and storage.

The brain’s main function is to protect us, like an umbrella, from chaos.

At the same time, chaos has its advantages. On a behavioral level, the arms race between predator and prey has wired erratic strategies into our nervous system.¹ A moth sensing an echolocating bat, for example, immediately directs itself away from the ultrasound source. The neurons controlling its flight fire in an increasingly erratic manner as the bat draws closer, until the moth, darting in fits, appears to be nothing but a tumble of wings and legs. More generally, chaos could grant our brains a great deal of computational power, by exploring many possibilities at great speed.

Motivated by these and other potential advantages, and with an accumulation of evidence in hand, neuroscientists are gradually accepting the potential importance of chaos in the brain.

Chaos is not the same as disorder. While disordered systems cannot be predicted, chaos is actually deterministic: The present state of the system determines its future. Yet even so, its behavior is only predictable on short time scales: Tiny differences in inputs result in vastly different outcomes. Chaotic systems can also exhibit stable patterns called “attractors” that emerge to the patient observer. Over time, chaotic trajectories will gravitate toward them. Because chaos can be controlled, it strikes a fine balance between reliability and exploration. Yet because it’s unpredictable, it’s a strong candidate for the dynamical substrate of free will.

The similarity to random disorder (or stochasticity) has been a thorn in the side of formal studies of chaos. It can be mathematically tricky to distinguish between the two -- especially in biological systems. There are no definite tests for chaos when dealing with multi-dimensional, fluctuating biological data. Walter Freeman and his colleagues spearheaded some of the earliest studies attempting to prove the existence of chaos in the brain, but came to extreme conclusions on limited data. He’s argued, for example, that neuropil, the extracellular mix of axons and dendrites, is the organ of consciousness -- a strong assertion in any light. Philosophers soon latched onto these ideas, taking even the earliest studies at face value. Articles by philosophers and scientists alike can be as apt to quote Jiddu Krishnamurti as Henri Poincaré, and chaos is often handled with a semi-mystical reverence.^{2, 3}

As a result, researchers must tread carefully to be taken seriously. But the search for chaos is not purely poetic. The strongest current evidence comes from single cells. The squid giant axon, for example, operates in a resting mode or a repetitive firing mode, depending on the external sodium concentration. Between these extremes, it exhibits unpredictable bursting that resembles the wandering behavior of a chaotic trajectory before it settles into an attractor. When a periodic input is applied, the squid giant axon responds with a mixture of both oscillating and chaotic activity.⁴ There is chaos in networks of cells, too. The neurons in a patch of rat skin can distinguish between chaotic and disordered patterns of skin stretching.⁵

More evidence for chaos in the nervous system can be found at the level of global brain activity. Bizarrely, an apt metaphor for this behavior is an iron slab.⁶ The electrons it contains can each point in different directions (more precisely, their spins can point). Like tiny magnets, neighboring spins influence each other. When the slab is cold, there is not enough energy to overcome the influence of neighboring spins, and all spins align in the same direction, forming one solid magnet. When the slab is hot, each spin has so much energy that it can shrug off the influence of its neighbor, and the slab’s spins are disordered. When the slab is halfway between hot and cold, it is in the so-called “critical regime.” This is characterized by fluctuating domains of same-spin regions which exhibit the highest possible dynamic correlations -- that is, the best balance between a spin’s ability to influence its neighbors, and its ability to be changed.

The critical state can be quite useful for the brain, allowing it to exploit both order and disorder in its computations -- employing a redundant network with rich, rapid chaotic dynamics, and an orderly readout function to stably map the network state to outputs. The critical state would be maintained not by temperature, but the balance of neural excitation and inhibition. If the balance is tipped in favor of more inhibition, the brain is “frozen” and nothing happens. If there is too much excitation, it will descend into chaos. The critical point is analogous to an attractor.

But how can we tell whether the brain operates at the critical point? One clue is the structure of the signals generated by the activity of its billions of neurons. We can measure the power of the brain’s electrical activity at different oscillation frequencies. It turns out that the power of activity falls off as the inverse of the frequency of that activity. Once referred to as 1/f “noise,” this relationship is actually a hallmark of systems balanced at their critical point.⁷ The spatial extent of regions of coordinated neuronal activity also depend inversely on frequency, another hallmark of criticality. When the brain is pushed away from its usual operating regime using pharmacological agents, it usually loses both these hallmarks,^{8, 9} and the efficiency of its information encoding and transmission is reduced.¹⁰

The philosopher Gilles Deleuze and psychiatrist Felix Guattari contended that the brain’s main function is to protect us, like an umbrella, from chaos. It seems to have done so by exploiting chaos itself. At the same time, neural networks are also capable of near-perfect reliability, as with the beating heart. Order and disorder enjoy a symbiotic relationship, and a neuron’s firing may wander chaotically until a memory or perception propels it into an attractor. Sensory input would then serve to “stabilize” chaos. Indeed, the presentation of a stimulus reduces variability in neuronal firing across a surprising number of different species and systems,¹¹ as if a high-dimensional chaotic trajectory fell into an attractor. By “taming” chaos, attractors may represent a strategy for maintaining reliability in a sensitive system.¹² Recent theoretical and experimental studies of large networks of independent oscillators have also shown that order and chaos can co-exist in surprising harmony, in so-called chimera states.¹³

The current research paradigm in neuroscience, which considers neurons in a snapshot of time as stationary computational units, and not as members of a shifting dynamical entity, might be missing the mark entirely. If chaos plays an important role in the brain, then neural computations do not operate as a static read-out, a lockstep march from the transduction of photons to the experience of light, but a high-dimensional dynamic trajectory as spikes dance across the brain in self-choreographed cadence.

While hundreds of millions of dollars are being funneled into building the connectome -- a neuron-by-neuron map of the brain -- scientists like Eve Marder have argued that, due to the complexity of these circuits, a structural map alone will not get us very far. Functional connections can flicker in and out of existence in milliseconds. Individual neurons appear to change their tuning properties over time^{14, 15} and thus may not be “byte-addressable” -- that is, stably represent some piece of information -- but instead operate within a dynamic dictionary that constantly shifts to make room for new meaning. Chaos encourages us to think of certain disorders as dynamical diseases, epileptic seizures being the most dramatic example of the potential failure of chaos.¹⁶ Chaos might also serve as a signature of brain health: For example, researchers reported less chaotic dynamics in the dopamine-producing cells of rodents with brain lesions, as opposed to healthy rodents, which could have implications in diagnosing and treating Parkinson’s and other dopamine-related disorders.¹⁷

Economist Murray Rothbard described chaos theory as “destroying math from within.” It usurps the human impulse to simplify, replacing the clear linear relationships we seek in nature with the messy and unpredictable. Similarly, chaos in the brain undermines glib caricatures of human behavior. Economists often model humans as “rational agents”: hedonistic calculators who act for their future good. But we can’t really act out of self-interest -- though that would be a reasonable thing to do -- because we are terrible at predicting what that is. After all, how could we? It’s precisely this failure that makes us what we are.

Kelly Clancy studied physics at MIT, then worked as an itinerant astronomer for several years before serving with the Peace Corps in Turkmenistan. As a National Science Foundation fellow, she recently finished her PhD in biophysics at the University of California, Berkeley. She will begin her postdoctoral research at Biozentrum in Switzerland this fall.

References

1. Humphries, D.A. & Driver, P.M. Protean defence by prey animals. Oecologia 5, 285–302 (1970).

2. Abraham, F.D. Chaos, bifurcations, and self-organization: dynamical extensions of neurological positivism. Psychoscience 1, 85-118 (1992).

3. O’Nuallain, S. Zero power and selflessness: what meditation and conscious perception have in common. Cognitive Science 4, 49-64 (2008).

4. Korn, H. & Faure, P. Is there chaos in the brain? II. Experimental evidence and related models. Comptes Rendus Biologies 326, 787–840 (2003).

5. Richardson, K.A., Imhoff, T.T., Grigg, P. & Collins, J.J. Encoding chaos in neural spike trains. Physical Review Letters 80, 2485–2488 (1998).

6. Beggs, J.M. & Timme, N. Being critical of criticality in the brain. Frontiers in Physiology 3, 1–14 (2012).

7. Bak, P., Tang, C. & Wiesenfeld, K. Self-organized criticality: an explanation of 1/f noise. Physical Review Letters 59, 381–384 (1987).

8. Mazzoni, A. et al. On the dynamics of the spontaneous activity in neuronal networks. PLoS ONE 2 e439 (2007).

9. Beggs, J.M. & Plenz, D. Neuronal avalanches in neocortical circuits. Journal of Neuroscience 23, 11167–11177 (2003).

10. Shew, W.L., Yang, H., Yu, S., Roy, R. & Plenz, D. Information capacity and transmission are maximized in balanced cortical networks with neuronal avalanches. Journal of Neuroscience 31, 55–63 (2011).

11. Churchland, M.M. et al. Stimulus onset quenches neural variability: a widespread cortical phenomenon. Nature Neuroscience 13, 369–378 (2010).

12. Laje, R. & Buonomano, D.V. Robust timing and motor patterns by taming chaos in recurrent neural networks. Nature Neuroscience 16, 925–933 (2013).

13. Kuramoto, Y. & Battogtokh, D. Coexistence of coherence and incoherence in nonlocally coupled phase oscillators: a soluble case. Nonlinearity 26, 2469-2498 (2002).

14. Margolis, D.J. et al. Reorganization of cortical population activity imaged throughout long-term sensory deprivation. Nature Neuroscience 15, 1539–1546 (2012).

15. Ziv, Y. et al. Long-term dynamics of CA1 hippocampal place codes. Nature Neuroscience 16, 264–266 (2013).

16. Schiff, S.J. et al. Controlling chaos in the brain. Nature 370, 615–620 (1994).

17. di Mascio, M., di Giovanni, G., di Matteo, V. & Esposito, E. Decreased chaos of midbrain dopaminergic neurons after serotonin denervation. Neuroscience 92, 237–243 (1999).

http://nautil.us/issue/15/turbulence/your-brain-is-on-the-brink-of-chaos

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Is the Claustrum the Key to Consciousness?

Klaus M. Steifel, 05/27/14

Editor's Note: This article was originally published at The Conversation.

Consciousness is one of the most fascinating and elusive phenomena we humans face. Every single one of us experiences it but it remains surprisingly poorly understood.

That said, psychology, neuroscience and philosophy are currently making interesting progress in the comprehension of this phenomenon.

The main player in this story is something called the claustrum. The word originally described an enclosed space in medieval European monasteries but in the mammalian brain it refers to a small sheet of neurons just below the cortex, and possibly derived from it in brain development.

The cortex is the massive folded layer on top of the brain mainly responsible for many higher brain functions such as language, long-term planning and our advanced sensory functions.

The location of the claustrum (blue) and the cingulate cortex (green), another brain region likely to act as a global integrator. The person whose brain is shown is looking to the right (see the inset in the top right corner). Brain Explorer, Allen Institute for Brain Science

Interestingly, the claustrum is strongly reciprocally connected to many cortical areas. The visual cortex (the region involved in seeing) sends axons (the connecting “wires” of the nervous system) to the claustrum, and also receives axons from the claustrum.

The same is true for the auditory cortex (involved in hearing) and a number of other cortex areas. A wealth of information converges in the claustrum and leaves it to re-enter the cortex.

The connection

Francis Crick – who together with James Watson gave us the structure of DNA – was interested in a connection between the claustrum and consciousness.

In a recent paper, published in Frontiers in Integrative Neuroscience, we have built on the ideas he described in his very last scientific publication.

Crick and co-author Christoph Koch argued that the claustrum could be a coordinator of cortical function and hence a “conductor of consciousness”.

Such percepts as colour, form, sound, body position and social relations are all represented in different parts of the cortex. How are they bound to a unified experience of consciousness? Wouldn’t a region exerting a (even limited) central control over all these cortical areas be highly useful?

This is what Crick and Koch suggested when they hypothesised the claustrum to be a “conductor of consciousness”. But how could this hypothesis about the claustrum’s role be tested?

Plant power alters the mind

Enter the plant Salvia divinorum, a type of mint native to Mexico. The Mazatecs civilisation’s priests would chew its leaves to get in touch with the gods.

It’s a powerful psychedelic, but not of the usual type. Substances such as LSD and psylocibin (the active compound in “magic” mushrooms) mainly act by binding to the serotonin neuromodulator receptor proteins.

It is not completely understood how these receptors bring about altered states of consciousness, but a reduction of the inhibitory (negative feedback) communication between neurons in the cortex likely plays a role.

In contrast, Salvia divinorum acts on the kappa-opiate receptors. These are structurally related, but their activation has quite different effects than the mu-opiate receptors which bind substances such as morphine or heroin.

In contrast to the mu-opiate receptors, which are involved in the processing of pain, the role of the kappa-opiate receptors is somewhat poorly understood.

Where are these kappa-opiate receptors located in the brain? You might have guessed it, they are most densely concentrated in the claustrum (and present at lower densities in a number of other brain regions such as the frontal cortex and the amygdala).

So, the activity of Salvia likely inhibits the claustrum via its activation of the kappa-opiate receptors. Consuming Salvia might just cause the inactivation of the claustrum necessary to test Crick and Koch’s hypothesis.

Any volunteers?

Did we administer this psychedelic to a group of volunteers to then record their hallucinations and altered perceptions? Well, no. To get ethics approval for such an experiment with a substance outlawed in Australia would be near impossible.

While Salvia is not known to be toxic or addictive, the current societal climate is not very sympathetic towards psychoactive substances other than alcohol.

But fortunately we had an alternative. The website Erowid.org hosts a database of many thousand trip reports, submitted by psychedelic enthusiasts, describing often in considerable detail what went on in their minds when consuming a wide selection of substances.

We analysed trip reports from this website written by folks who had consumed Salvia divinorum and, for comparison, LSD.

We found that subjects consuming Salvia were more likely to experience a few select psychological effects:

l   they were more likely to believe they were in an environment completely different from the physical space they were actually in

l   they often believed to be interacting with “beings” such as hallucinated dead people, aliens, fairies or mythical creatures

l   the often reported “ego dissolution”, a variety of experiences in which the self ceased to exist in the user’s subjective experience.

… and this means?

Altered surroundings, other beings and ego dissolution – this surely hints at a disturbance of the “conductor of consciousness”, as expected if the conductor claustrum is perturbed by Salvia divinorum.

If a region central to the integration of consciously represented information is disturbed in its function, we would expect fundamental disturbances in the conscious experience. The core of a person’s consciousness seems to be altered by Salvia divinorum, rather than merely some distortions of vision or audition.

We believe that the psychological effects of Salvia divinorum, together with the massive concentration of the kappa-opiate receptors (the target molecules of Salvia divinorum) in the claustrum support its role as a central coordinator of consciousness.

It’s worth noting that our results were not black-and-white. The users of LSD also experienced (albeit to a lesser degree) translation into altered environments, fairies and ego dissolution.

This, together with a review of the literature convinced us that the claustrum is one of the conductors of consciousness, with brain areas cingulate cortex and pulvinar likely being the other ones.

Still, the claustrum appears to be special in the brain’s connectivity and we think that Salvia can inactivate it. We hope that the experimental neuroscience community will take advantage of the window into the mind which this unique substance provides.

http://www.realclearscience.com/articles/2014/05/27/is_the_claustrum_the_key_to_consciousness_108673.html

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A Fundamental Theory to Model the Mind

Jennifer Ouellette, 04/03/14

In 1999, the Danish physicist Per Bak proclaimed to a group of neuroscientists that it had taken him only 10 minutes to determine where the field had gone wrong. Perhaps the brain was less complicated than they thought, he said. Perhaps, he said, the brain worked on the same fundamental principles as a simple sand pile, in which avalanches of various sizes help keep the entire system stable overall -- a process he dubbed “self-organized criticality.”

As much as scientists in other fields adore outspoken, know-it-all physicists, Bak’s audacious idea -- that the brain’s ordered complexity and thinking ability arise spontaneously from the disordered electrical activity of neurons -- did not meet with immediate acceptance.

But over time, in fits and starts, Bak’s radical argument has grown into a legitimate scientific discipline. Now, about 150 scientists worldwide investigate so-called “critical” phenomena in the brain, the topic of at least three focused workshops in 2013 alone. Add the ongoing efforts to found a journal devoted to such studies, and you have all the hallmarks of a field moving from the fringes of disciplinary boundaries to the mainstream.

“How do we know that the creations of worlds are not determined by falling grains of sand?” -- Victor Hugo, “Les Misérables”

In the 1980s, Bak first wondered how the exquisite order seen in nature arises out of the disordered mix of particles that constitute the building blocks of matter. He found an answer in phase transition, the process by which a material transforms from one phase of matter to another. The change can be sudden, like water evaporating into steam, or gradual, like a material becoming superconductive. The precise moment of transition -- when the system is halfway between one phase and the other -- is called the critical point, or, more colloquially, the “tipping point.”

Classical phase transitions require what is known as precise tuning: in the case of water evaporating into vapor, the critical point can only be reached if the temperature and pressure are just right. But Bak proposed a means by which simple, local interactions between the elements of a system could spontaneously reach that critical point -- hence the term self-organized criticality.

Think of sand running from the top of an hourglass to the bottom. Grain by grain, the sand accumulates. Eventually, the growing pile reaches a point where it is so unstable that the next grain to fall may cause it to collapse in an avalanche. When a collapse occurs, the base widens, and the sand starts to pile up again -- until the mound once again hits the critical point and founders. It is through this series of avalanches of various sizes that the sand pile -- a complex system of millions of tiny elements -- maintains overall stability.

While these small instabilities paradoxically keep the sand pile stable, once the pile reaches the critical point, there is no way to tell whether the next grain to drop will cause an avalanche -- or just how big any given avalanche will be. All one can say for sure is that smaller avalanches will occur more frequently than larger ones, following what is known as a power law.

Bak introduced self-organized criticality in a landmark 1987 paper -- one of the most highly cited physics papers of the last 30 years. Bak began to see the stabilizing role of frequent smaller collapses wherever he looked. His 1996 book, “How Nature Works,” extended the concept beyond simple sand piles to other complex systems: earthquakes, financial markets, traffic jams, biological evolution, the distribution of galaxies in the universe -- and the brain. Bak’s hypothesis implies that most of the time, the brain teeters on the edge of a phase transition, hovering between order and disorder.

The brain is an incredibly complex machine. Each of its tens of billions of neurons is connected to thousands of others, and their interactions give rise to the emergent process we call “thinking.” According to Bak, the electrical activity of brain cells shift back and forth between calm periods and avalanches -- just like the grains of sand in his sand pile -- so that the brain is always balanced precariously right at that the critical point.

A better understanding of these critical dynamics could shed light on what happens when the brain malfunctions. Self-organized criticality also holds promise as a unifying theoretical framework. According to the neurophysiologist Dante Chialvo, most of the current models in neuroscience apply only to single experiments; to replicate the results from other experiments, scientists must change the parameters -- tune the system -- or use a different model entirely.

Self-organized criticality has a certain intuitive appeal. But a good scientific theory must be more than elegant and beautiful. Bak’s notion has had its share of critics, in part because his approach strikes many as ridiculously broad: He saw nothing strange about leaping across disciplinary boundaries and using self-organized criticality to link the dynamics of forest fires, measles and the large-scale structure of the universe -- often in a single talk. Nor was he one to mince words. His abrasive personality did not endear him to his critics, although Lee Smolin, a physicist at the Perimeter Institute for Theoretical Physics, in Canada, has chalked this up to “childlike simplicity,” rather than arrogance. “It would not have occurred to him that there was any other way to be,” Smolin wrote in a remembrance after Bak’s death in 2002. “Science is hard, and we have to say what we think.”

Nonetheless, Bak’s ideas found fertile ground in a handful of like-minded scientists. Chialvo, now with the University of California, Los Angeles, and with the National Scientific and Technical Research Council in Argentina, met Bak at Brookhaven National Laboratory around 1990 and became convinced that self-organized criticality could explain brain activity. He, too, encountered considerable resistance. “I had to put up with a number of critics because we didn’t have enough data,” Chialvo said. Dietmar Plenz, a neuroscientist with the National Institute of Mental Health, recalled that it was impossible to win a grant in neuroscience to work on self-organized criticality at the time, given the lack of experimental evidence.

Since 2003, however, the body of evidence showing that the brain exhibits key properties of criticality has grown, from examinations of slices of cortical tissue and electroencephalography (EEG) recordings of the interactions between individual neurons to large-scale studies comparing the predictions of computer models with data from functional magnetic resonance (fMRI) imaging. “Now the field is mature enough to stand up to any fair criticism,” Chialvo said.

One of the first empirical tests of Bak’s sand pile model took place in 1992, in the physics department of the University of Oslo. The physicists confined piles of rice between glass plates and added grains one at a time, capturing the resulting avalanche dynamics on camera. They found that the piles of elongated grains of rice behaved much like Bak’s simplified model.

Most notably, the smaller avalanches were more frequent than the larger ones, following the expected power law distribution. That is, if there were 100 small avalanches involving only 10 grains during a given time frame, there would be 10 avalanches involving 100 grains in the same period, but only a single large avalanche involving 1,000 grains. (The same pattern had been observed in earthquakes and their aftershocks. If there are 100 quakes measuring 6.0 on the Gutenberg-Richter scale in a given year, there will be 10 7.0 quakes and one 8.0 quake.)

Chialvo envisions self-organized criticality providing a broader, more fundamental theory for neuroscientists, like those found in physics.

Ten years later, Plenz and a colleague, John Beggs, now a biophysicist at Indiana University, observed the same pattern of avalanches in the electrical activity of neurons in cortical slices -- the first key piece of evidence that the brain functions at criticality. “It was something that no one believed the brain would do,” Plenz said. “The surprise is that is exactly what happens.” Studies using magnetoencephalography (MEG) and Chialvo’s own work comparing computer simulations with fMRI imaging data of the brain’s resting state have since added to the evidence that the brain exhibits these key avalanche dynamics.

But perhaps it is not so surprising. There can be no phase transitions without a critical point, and without transitions, a complex system -- like Bak’s sand pile, or the brain -- cannot adapt. That is why avalanches only show up at criticality, a “sweet spot” where a system is perfectly balanced between order and disorder, according to Plenz. They typically occur when the brain is in its normal resting state. Avalanches are a mechanism by which a complex system avoids becoming trapped, or “phase-locked,” in one of two extreme cases. At one extreme, there is too much order, such as during an epileptic seizure; the interactions among elements are too strong and rigid, so the system cannot adapt to changing conditions. At the other, there is too much disorder; the neurons aren’t communicating as much, or aren’t as broadly interconnected throughout the brain, so information can’t spread as efficiently and, once again, the system is unable to adapt.

A complex system that hovers between “boring randomness and boring regularity” is surprisingly stable overall, said Olaf Sporns, a cognitive neuroscientist at Indiana University. “Boring is bad,” he said, at least for a critical system. In fact, “if you try to avoid ever sparking an avalanche, eventually when one does occur, it is likely to be really large,” said Raissa D’Souza, a complex systems scientist at the University of California, Davis, who simulated just such a generic system last year. “If you spark avalanches all the time, you’ve used up all the fuel, so to speak, and so there is no opportunity for large avalanches.”

D’Souza’s research applies these dynamics to better understand power outages across the electrical grid. The brain, too, needs sufficient order to function properly, but also enough flexibility to adapt to changing conditions; otherwise, the organism could not survive. This could be one reason that the brain exhibits hallmarks of self-organized criticality: It confers an evolutionary advantage. “A brain that is not critical is a brain that does exactly the same thing every minute, or, in the other extreme, is so chaotic that it does a completely random thing, no matter what the circumstances,” Chialvo said. “That is the brain of an idiot.”

When the brain veers away from criticality, information can no longer percolate through the system as efficiently. One study (not yet published) examined sleep deprivation; subjects remained awake for 36 hours and then took a reaction time test while an EEG monitored their brain activity. The more sleep-deprived the subject, the more the person’s brain activity veered away from the critical balance point and the worse the performance on the test.

Another study collected data from epileptic subjects during seizures. The EEG recordings revealed that mid-seizure, the telltale avalanches of criticality vanished. There was too much synchronization among neurons, and then, Plenz said, “information processing breaks down, people lose consciousness, and they don’t remember what happened until they recover.”

Chialvo envisions self-organized criticality providing a broader, more fundamental theory for neuroscientists, like those found in physics. He believes it could be used to model the mind in all its possible states: awake, asleep, under anesthesia, suffering a seizure, and under the influence of a psychedelic drug, among many others.

This is especially relevant as neuroscience moves deeper into the realm of big data. The latest advanced imaging techniques are capable of mapping synapses and monitoring brain activity at unprecedented resolutions, with a corresponding explosion in the size of data sets. Billions of dollars in research funding has launched the Human Connectome Project -- which aims to build a “network map” of neural pathways in the brain -- and the Brain Research Through Advancing Innovative Neurotechnologies (BRAIN), dedicated to developing new technological tools for recording signals from cells. There is also Europe’s Human Brain Project, working to simulate the complete human brain on a supercomputer, and China’s Brainnetome project to integrate data collected from every level of the brain’s hierarchy of complex networks.

But without an underlying theory, it will be difficult to glean all the potential insights hidden in the data. “It is fine to build maps and it is fine to catalog pieces and how they are related, so long as you don’t lose track of the fact that when the system you map actually functions, it is in an integrated system and it is dynamic,” Sporns said.

“The structure of the brain -- the precise map of who connects with whom -- is almost irrelevant by itself,” Chialvo said -- or rather, it is necessary but not sufficient to decipher how cognition and behavior are generated in the brain. “What is relevant is the dynamics,” Chialvo said. He then compared the brain with a street map of Los Angeles containing details of all the connections at every scale, from private driveways to public freeways. The map tells us only about the structural connections; it does not help predict how traffic moves along those connections or where (and when) a traffic jam is likely to form. The map is static; traffic is dynamic. So, too, is the activity of the brain. In recent work, Chialvo said, researchers have demonstrated that both traffic dynamics and brain dynamics exhibit criticality.

Sporns emphasizes that it remains to be seen just how robust this phenomenon might be in the brain, pointing out that more evidence is needed beyond the observation of power laws in brain dynamics. In particular, the theory still lacks a clear description for how criticality arises from neurobiological mechanisms -- the signaling of neurons in local and distributed circuits. But he admits that he is rooting for the theory to succeed. “It makes so much sense,” he said. “If you were to design a brain, you would probably want criticality in the mix. But ultimately, it is an empirical question.”

This article was reprinted on ScientificAmerican.com.

https://www.simonsfoundation.org/quanta/20140403-a-fundamental-theory-to-model-the-mind/

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A Patient’s Bizarre Hallucination Points to How the Brain Identifies Places

Genevieve Bookwalter, 04/15/14

Dr. Pierre Mégevand was in the middle of a somewhat-routine epilepsy test when his patient, a 22-year old man, said Mégevand and his medical team looked like they had transformed into Italians working at a pizzeria -- aprons and all. It wasn’t long, the patient said, before the doctors morphed back into their exam room and business-casual attire. But that fleeting hallucination -- accompanied by earlier visions of houses, a familiar train station and the street where the patient grew up -- helped verify that a certain spot, in a certain fold in the brain, is a crucial node in the brain’s process of recognizing places.

In the 1950s, the Canadian neurosurgeon Wilder Penfield made a set of remarkable observations in the course of operating on epilepsy patients. As he moved a stimulating electrode around parts of the temporal and frontal lobes of the brain to locate the source of a patient’s seizures, the patients sometimes reported vivid hallucinations. The work was an early contribution to scientists’ understanding of which parts of the brain do what.

Since then, researchers have developed new methods like fMRI for studying the human brain in action without picking up a scalpel. These tools have given them a much better understanding of how the brain is organized -- suggesting, for example, that one particular patch of the temporal cortex specializes in processing faces, while another nearby patch specializes in places. Very few studies, however, have tested these findings by stimulating those parts of the brain to see what people experience.

In the new study, Mégevand and colleagues report what happened when they stimulated a brain region thought to be important for the perception of places -- the so-called parahippocampal place area -- in one particular patient.

“At first we were really stunned. It was the first time in 70 patients that someone gave such a detailed, specific report,” said Mégevand, a post-doctoral research fellow at The Feinstein Institute for Medical Research in Manhasset, New York.

His team’s findings appear in the April 16 issue of The Journal of Neuroscience. The patient’s hallucinations came as Mégevand and his medical team were tickling electrodes they had placed in his brain in search of the origin of his epilepsy, which had been difficult to control. The patient had started suffering epileptic seizures after contracting West Nile virus when he was 10.

In this patient, Mégevand’s collaborator, Ashesh Mehta, director of epilepsy surgery at the Feinstein Institute, drilled tiny holes in the skull through which he inserted 2-inch long electrodes and guided them to specific points on unique folds in the brain tissue. Even with that level of precision, results can be difficult to reproduce from patient to patient, Mehta says. That’s because everyone’s brain is different, and a variation of millimeters can make a certain hallucination-producing spot hard to pinpoint across patients.

“What was groundbreaking was everything worked the way it was supposed to work,” Mehta said.

The research follows that of Stanford University neurologist Josef Parvizi, who two years ago showed that electrodes placed another spot in the brain were crucial in a patient’s processing of faces.

That study includes a video of the patient’s reaction (below). “You just turned into somebody else. Your face metamorphosed,” the patient marveled. “That was a trip.” Parvizi published another study last year showing that stimulating yet another part of the brain “gave patients the will to persevere hardship.”

This type of ongoing research “is a perfect way for us to explore the functional architecture of the human brain,” Parvizi said. He describes the Feinstein Institute team’s paper as “elegant,” but stresses that the findings do not prove that certain parts of the brain are entirely responsible for the processing of faces, places or anything else. Instead, he says, it only shows that these spots are critical links in networks of neurons responsible for a certain task.

Back in New York, Mehta says he expects to make additional discoveries as his team continues their epilepsy research and treatment. “As we’re stimulating more and more of the brain, we’re finding more unique little spots,” he said.

Still, with these findings come more questions.

For example, Mégevand says, was the pizzeria hallucination the result of an electrode placed partly between neurons that process faces, and those that process places? The patient owned a pizzeria with his family, he says. So was that scene part of an old memory, or something he’d never seen before? Those are questions Mégevand says he hopes to answer going forward.

“If he had been working in a sushi place, maybe we would have been wearing different garb,” Mégevand chuckled.

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http://www.wired.com/2014/04/pizzeria-hallucination-place-brain/

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Chattering brain cells hold the key to the language of the mind

Kate Jeffery, 03/12/14

Let’s say Martians land on the Earth and wish to understand more about humans. Someone hands them a copy of the Complete Works of Shakespeare and says: “When you understand what’s in there, you will understand everything important about us.”

The Martians set to work – they allocate vast resources to recording every detail of this great tome until eventually they know where every “e”, every “a”, every “t” is on every page. They remain puzzled, and return to Earth. “We have completely characterised this book,” they say, “but we still aren’t sure we really understand you people at all.”

The problem is that characterising a language is not the same as understanding it, and this is the problem faced by brain researchers too. Neurons (brain cells) use language of a kind, a “code”, to communicate with each other, and we can tap into that code by listening to their “chatter” as they fire off tiny bursts of electricity (nerve impulses). We can record this chatter and document all its properties.

We can also determine the location of every single neuron and all of its connections and its chemical messengers. Having done this, though, we still will not understand how the brain works. To understand a code we need to anchor that code to the real world.

Place, memory and administration

We easily anchor Shakespeare’s code (we find out that “Juliet” refers to a specific young woman, “Romeo” to a specific young man) but can we do this for the brain? It seems we can. By recording the chatter of neurons while animals (and sometimes humans) perform the tasks of daily life, researchers have discovered that there are regions where the neural code relates to the real world in remarkably straightforward ways.

The best known of these is the code for “place”, discovered in a small and deeply buried part of the brain called the hippocampus. A given hippocampal neuron starts chattering furiously whenever its owner (rat, mouse, bat, human) goes to a particular place. Each neuron tends to be most excited at a particular place (near the door, halfway along a wall) and so a large collection of neurons can, between them, be ready to “speak up” for any place in the environment. It is as if these neurons encode space, to form something akin to a mental map.

To determine where you are, you simply consult your hippocampus and see which neuron is active. (In practice, of course, many neurons will be active in that place and not just one – otherwise every time a neuron died you would lose a small piece of your map.) These neurons in the hippocampus are called “place neurons”, and are remarkable entities that form the foundation not only for our mental map of the space around us, but also for memories of the events that occur in that space – a kind of biographical record. Their importance is evident in the terrible disorientation and amnesia that result from their degeneration in Alzheimer’s disease. When the brain loses its link to its place in the world, and to its past, its owner loses all sense of self.

There are many other neurons in the brain whose code seems decipherable. Neurons that activate when facing a particular direction, or near a wall, or when you see your grandmother … Gradually we are piecing together the network of nodes in the brain that connect the inner code to the world outside.

This is not all that neurons do, of course. Much of the brain is involved with internal “administration”. For example, a large part of the frontal lobe (the brain behind the forehead) is involved in making decisions – how to prioritise activities, what to do next, and so on. Many neurons, scattered throughout the brain, have housekeeping duties to do with maintaining the code, improving and refining it, preserving the relevant parts as memory and discarding the rest.

Some of the most numerous neurons seem simply to have the job of suppressing their neighbours, so that the neural conversation, as it were, does not degenerate into the equivalent of uncontrollable shouting (which, in technical terms, we recognise as epilepsy).

Still room for psychology

It is clear that to understand the brain we need to investigate all aspects of its functioning, not just those that relate to internal administration but also those that connect to the outside world.

We need to determine how brain activity relates to what the brain’s owner is thinking, feeling and doing with respect to the world outside that brain – that is, we need to anchor the code to the real world.

For this, we need scientists who study thoughts, feelings and behaviour – psychologists – as much as we need those who study anatomy and physiology. Study of the brain requires investigation at all levels – otherwise, we will have a complete characterisation, but no understanding, of this remarkable organ.

Decoding the brain, a special report produced in collaboration with the Dana Centre, looks at how technology and person-to-person analysis will shape the future of brain research.

Kate Jeffery receives, or have received, funding for her work from the BBSRC, MRC, Wellcome trust and European Commission FP7. She is a non-shareholding director of the biomedical instrumentation company Axona Ltd, which makes data acquisition systems for in vivo electrophysiological recording

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