A bit of piano...

I thought I would punctuate the stream of 'serious' posts with a paste from my piano recordings, this being "Three Fantastic Dances" by Shostakovitch:

Most popular consciousness articles for February

From the ASSC downloads archive:
1. Koriat, A. (2006) Metacognition and Consciousness. In: Cambridge handbook
of consciousness. Cambridge University Press, New York, USA.http://eprints.assc.caltech.edu/175/
2. Sagiv, N. and Ward, J. (2006) Crossmodal interactions: lessons from synesthesia. In: Visual Perception, Part 2. Progress in Brain Research,
Volume 155.http://eprints.assc.caltech.edu/224
3. Seth, A.K. and Baars, B.J. (2005) Neural Darwinism and Consciousness. Consciousness and Cognition, 14. pp. 140-168.http://eprints.assc.caltech.edu/163/
4. Dehaene, S., Changeux, J.-P., Naccache, L., Sackur, J. and Sergent, C. (2006) Conscious, preconscious, and subliminal processing: a testable taxonomy. Trends in Cognitive Science, 10 (5). pp. 204-211.http://eprints.assc.caltech.edu/20/
5. Gennaro, R. J. (2007) Representationalism, peripheral awareness, and the transparency of experience. Philosophical Studies.http://eprints.assc.caltech.edu/218/

The maturing architecture of the brain's default network

From Raichle and others in the St. Louis group, an interesting story on the development of the brain network we most likely use for introspective mental activity:

In recent years, the brain's "default network," a set of regions characterized by decreased neural activity during goal-oriented tasks, has generated a significant amount of interest, as well as controversy. Much of the discussion has focused on the relationship of these regions to a "default mode" of brain function. In early studies, investigators suggested that, the brain's default mode supports "self-referential" or "introspective" mental activity. Subsequently, regions of the default network have been more specifically related to the "internal narrative," the "autobiographical self," "stimulus independent thought," "mentalizing," and most recently "self-projection." However, the extant literature on the function of the default network is limited to adults, i.e., after the system has reached maturity. We hypothesized that further insight into the network's functioning could be achieved by characterizing its development. In the current study, we used resting-state functional connectivity MRI (rs-fcMRI) to characterize the development of the brain's default network. We found that the default regions are only sparsely functionally connected at early school age (7–9 years old); over development, these regions integrate into a cohesive, interconnected network.


Figure legend - (click on figure to enlarge). Voxelwise resting-state functional connectivity maps for a seed region (solid black circle) in mPFC (ventral: –3, 39, –2). (A) Qualitatively, the rs-fcMRI map for the mPFC (ventral) seed region reveals the commonly observed adult connectivity pattern of the default network. The connectivity map in children, however, significantly deviates from that of the adults. Functional connections with regions in the posterior cingulate and lateral parietal regions (highlighted with blue open circles) are present in the adults but absent in children. (B) These qualitative differences between children and adults are confirmed by the direct comparison (random effects) between adults and children. mPFC (ventral) functional connections with the posterior cingulate and lateral parietal regions are significantly stronger in adults than children.

Analogies between cultural and genetic evolution - the case of polynesian canoes

Rogers and Ehrlich, in an open access article, have made an important contribution to understanding cultural evolution. Here are some clips from an accompanying commentary by Stephen Shennan, followed by the article abstract. The link to the article takes you to pictures of the canoe features studied.

In the most general terms, parallel mechanisms for inheritance, mutation, selection, and drift act on culture as they do on genes...In the case of culture, the inheritance mechanism is social learning: People learn ways to think and act from others...natural selection can also act on cultural attributes, in the sense that those individuals who inherit or acquire certain cultural attributes may have a greater probability of surviving and/or reproducing than those who do not; as a result, those cultural attributes will become increasingly prevalent. For example, it is clear that, in many parts of the world, adopting an agricultural rather than a hunting-and-gathering way of life led to greater reproductive success; as a result, the cultural traits that characterize agriculture spread and, in some cases, subsequently influenced genetic evolution [e.g., the ability to digest lactose]...It is also important to look at things from what Dawkins called "the meme's eye-view," the perspective of the cultural attributes themselves...in the case of the canoe attributes analyzed by Rogers and Ehrlich, these culturally transmitted features are the data that archaeologists and anthropologists have available...What Rogers and Ehrlich have done is make progress in this area by showing that variation that is believed to be under selection is patterned differently from other variation that is believed not to be under selection, or at least not in the same way. It seems to be more conservative and, therefore, under negative selection. Perhaps more surprisingly, they find that there is no correlation at all in the similarities between island groups in terms of functional canoe variation and the similarities based on symbolic variation. One might have expected some correlation, either because both would be affected by the distance between the islands, or because the process of island colonization by groups in canoes would have brought both their functional and their symbolic attributes. The fact that selection appears to have been sufficiently powerful to overwhelm evidence of descent history is extremely interesting and confirms the importance of regarding cultures not as hermetically sealed entities, a bit like species, but as bundles of distinct packages of traits affected by different forces

The Rogers and Ehrlich abstract:

It has been claimed that a meaningful theory of cultural evolution is not possible because human beliefs and behaviors do not follow predictable patterns. However, theoretical models of cultural transmission and observations of the development of societies suggest that patterns in cultural evolution do occur. Here, we analyze whether two sets of related cultural traits, one tested against the environment and the other not, evolve at different rates in the same populations. Using functional and symbolic design features for Polynesian canoes, we show that natural selection apparently slows the evolution of functional structures, whereas symbolic designs differentiate more rapidly. This finding indicates that cultural change, like genetic evolution, can follow theoretically derived patterns.

Amazing Images...

From the Wellcome Image Awards Gallery:

A new brain book...

The new book "Brain Rules" looks interesting, it appears to be an enlightened self-help manual based on basics of brain function.

Our motor adaptation as a process of reoptimization.

Because I'm a classical pianist and am continually trying to optimize the motor performance involved, I'm fascinated by articles like this one by Izawa et al. They oppose the common assumption that the goal of motor adaptation is to compensate for some perturbation by returning to a previous baseline condition assumed to be optimal. Here is their abstract:

Adaptation is sometimes viewed as a process in which the nervous system learns to predict and cancel effects of a novel environment, returning movements to near baseline (unperturbed) conditions. An alternate view is that cancellation is not the goal of adaptation. Rather, the goal is to maximize performance in that environment. If performance criteria are well defined, theory allows one to predict the reoptimized trajectory. For example, if velocity-dependent forces perturb the hand perpendicular to the direction of a reaching movement, the best reach plan is not a straight line but a curved path that appears to overcompensate for the forces. If this environment is stochastic (changing from trial to trial), the reoptimized plan should take into account this uncertainty, removing the overcompensation. If the stochastic environment is zero-mean, peak velocities should increase to allow for more time to approach the target. Finally, if one is reaching through a via-point, the optimum plan in a zero-mean deterministic environment is a smooth movement but in a zero-mean stochastic environment is a segmented movement. We observed all of these tendencies in how people adapt to novel environments. Therefore, motor control in a novel environment is not a process of perturbation cancellation. Rather, the process resembles reoptimization: through practice in the novel environment, we learn internal models that predict sensory consequences of motor commands. Through reward-based optimization, we use the internal model to search for a better movement plan to minimize implicit motor costs and maximize rewards.

Relativity of space, time and magnitude representation in our brains

Here are some simple and elegant experiments that shows how relativistic our time sense is. Our two cerebral hemispheres expand (right hemisphere) or contract (left hemisphere) time perception when acting alone, and then let magnitude cues in the stimulus influence perceived time when acting together. Vicario et al. investigated whether duration judgments of digit visual stimuli were biased depending on the side of space where the stimuli were presented (i.e. to which hemisphere) and on the magnitude of the stimulus itself:

Different groups of healthy subjects performed duration judgment tasks on various types of visual stimuli. In the first two experiments visual stimuli were constituted by digit pairs (1 and 9), presented in the centre of the screen or in the right and left space. In a third experiment visual stimuli were constituted by black circles. The duration of the reference stimulus was fixed at 300 ms. Subjects had to indicate the relative duration of the test stimulus compared with the reference one. The main results showed that, regardless of digit magnitude, duration of stimuli presented in the left hemispace is underestimated and that of stimuli presented in the right hemispace is overestimated. On the other hand, in midline position, duration judgments are affected by the numerical magnitude of the presented stimulus, with time underestimation of stimuli of low magnitude and time overestimation of stimuli of high magnitude. These results argue for the presence of strict interactions between space, time and magnitude representation on the human brain.

A fiery piano performance...

This makes me cringe..... On March 8, pianist Yosuke Yamashita donned a fireproof suit and played a burning piano on a beach in Ishikawa prefecture. The improvised jazz performance went for about 10 minutes until the flames rendered the piano silent.

In Most Species, Faithfulness Is a Fantasy

This post has the title of a great article by Natalie Angier in the NYTimes Science section. Elliot Spitzer was doing nothing that hasn't been done by males and females of thousands of other species - representatives of every taxonomic twig on the great tree of life.

Even the “oldest profession” that figured so prominently in Mr. Spitzer’s demise is old news. Nonhuman beings have been shown to pay for sex, too. Reporting in the journal Animal Behaviour, researchers from Adam Mickiewicz University and the University of South Bohemia described transactions among great grey shrikes, elegant raptorlike birds with silver capes, white bellies and black tails that, like 90 percent of bird species, form pair bonds to breed. A male shrike provisions his mate with so-called nuptial gifts: rodents, lizards, small birds or large insects that he impales on sticks. But when the male shrike hankers after extracurricular sex, he will offer a would-be mistress an even bigger kebab than the ones he gives to his wife — for the richer the offering, the researchers found, the greater the chance that the female will agree to a fly-by-night fling.

In another recent report from the lubricious annals of Animal Behaviour entitled “Payment for sex in a macaque mating market,” Michael D. Gumert of Hiram College described his two-year study of a group of longtailed macaques that live near the Rimba ecotourist lodge in the Tanjung Puting National Park of Indonesia. Dr. Gumert determined that male macaques pay for sex with that all-important, multipurpose primate currency, grooming. He saw that, whereas females groomed males and other females for social and political reasons — to affirm a friendship or make nice to a dominant — and mothers groomed their young to soothe and clean them, when an adult male spent time picking parasites from an adult female’s hide, he expected compensation in the form of copulation, or at the very least a close genital inspection. About 89 percent of the male-grooming-female episodes observed, Dr. Gumert said in an interview from Singapore, where he is on the faculty of Nanyang Technological University, “were directed toward sexually active females” with whom the males had a chance of mating.

Influence of language on brain activity underlying perceptual decisions

Following up on my Feb. 22 post on the same topic, I pass on the abstract of work by Tan et al., showing that language-processing areas of the brain are directly involved in visual perceptual decisions:

Well over half a century ago, Benjamin Lee Whorf [Carroll JB (1956) Language, Thought, and Reality: Selected Writings of Benjamin Lee Whorf (MIT Press, Cambridge, MA)] proposed that language affects perception and thought and is used to segment nature, a hypothesis that has since been tested by linguistic and behavioral studies. Although clear Whorfian effects have been found, it has not yet been demonstrated that language influences brain activity associated with perception and/or immediate postperceptual processes (referred hereafter as "perceptual decision"). Here, by using functional magnetic resonance imaging, we show that brain regions mediating language processes participate in neural networks activated by perceptual decision. When subjects performed a perceptual discrimination task on easy-to-name and hard-to-name colored squares, largely overlapping cortical regions were identified, which included areas of the occipital cortex critical for color vision and regions in the bilateral frontal gyrus. Crucially, however, in comparison with hard-to-name colored squares, perceptual discrimination of easy-to-name colors evoked stronger activation in the left posterior superior temporal gyrus and inferior parietal lobule, two regions responsible for word-finding processes, as demonstrated by a localizer experiment that uses an explicit color patch naming task. This finding suggests that the language-processing areas of the brain are directly involved in visual perceptual decision, thus providing neuroimaging support for the Whorf hypothesis.

Figure legend (Click on figure to enlarge it). Brain activations elicited by color perception and explicit color naming. (A and B) Areas showing significant activation during perceptual discrimination of easy-to-name colors in comparison with perceptual discrimination of hard-to-name colors. A and B are lateral view and axial sections, respectively. Two regions of greatest interest are the left posterior superior temporal gyrus (BA 22; x = –57, y = –38, z = 18) and the left inferior parietal lobule (BA 40; x = –61, y = –32, z = 27). (C and D) Percentage BOLD signal change (± SEM) at voxels of maximal difference between the two color-discrimination conditions in the two regions of interest. (E and F) Areas showing significant activation in explicit color naming against color word naming as baseline. E and F are lateral view and axial sections, respectively. The left posterior superior temporal gyrus and the left inferior parietal lobule are critically engaged by the color naming task.

Reality getting to you?

Perhaps try escaping into one of these devices? (I don't think I'll go there just yet....)

The brain and emotion-laden images: two pathways

A collaborative study has considered several models that might explain why our behavior can be rapidly influenced by an emotional stimulus (a snake like shape that we jump away from) before the stimulus has been fully processed (and we realize that it is a coil of rope). Information influences action before perception is complete. The data can only be accounted for by a two-pathway architecture by which emotional visual information proceeds more directly via one pathway to the amygdala (and thus influences action) and at the same time more slowly by the second conventional visual pathway that establishes the perception of the actual nature of the stimulus. I'm showing here the abstract and then the basic figure describing the models.

Visual attention can be driven by the affective significance of visual stimuli before full-fledged processing of the stimuli. Two kinds of models have been proposed to explain this phenomenon: models involving sequential processing along the ventral visual stream, with secondary feedback from emotion-related structures ("two-stage models"); and models including additional short-cut pathways directly reaching the emotion-related structures ("two-pathway models"). We tested which type of model would best predict real magnetoencephalographic responses in subjects presented with arousing visual stimuli, using realistic models of large-scale cerebral architecture and neural biophysics. The results strongly support a "two-pathway" hypothesis. Both standard models including the retinotectal pathway and nonstandard models including cortical–cortical long-range fasciculi appear plausible.

Tested models. (Click on image to enlarge) a, Basic components of the generic model, including all the possible types of connections used in this report, within and between two connected regions. Top, Cortical regions are modeled as three layered columns with three types of neuronal populations (pyramidal, excitatory spiny, and inhibitory interneurons), connected through intrinsic and extrinsic (feedforward and backward) connections. Bottom, The dynamics is mathematically expressed at the level of neural populations and is defined by nonlinear differential equations in which the change of state of each unit dxi/dt depends on its current state xi(t); thalamic inputs ui(t); average firing rate of afferents S(xj(t – {delta}ij)); transmission delays {delta}ij; forward, backward, and intrinsic effective connectivity matrices CF, CB, Ci, and other parameters. The MEG signal M is assumed to be related to the local average current density x generated by pyramidal populations through a linear forward model M = GX. b, Lateral, mesial, and ventral views of the mapping of the regions of interest common to all models on a reference cortical tessellation [for color code, see c (top row)]. c, Schematic representation of the architecture of the tested models. All the models share the same basic layout (see text). Null model, Simple feedforward model. Model 1, Adjunction of connectivity modulation. Model 2 (2-stage model), Adjunction of local feedbacks. Model 3 (2-stage model), Adjunction of long-range feedbacks from structures of the AAS (anterior affective system). Model 4 (2-pathway model), Adjunction of a direct subcortical retinotectal short-cut pathway to the AAS. Model 5 (2-pathway model), Alternative short-cut pathways to the AAS via the inferior longitudinal and frontal–occipital fasciculi. Model 6 (2-pathway model), Combination of models 4 and 5. Orange circles, "Synapses" at which modulation by emotional competence of the stimuli is implemented.

Awaress and attention: different brain processes

Most of the proposed neural correlates of visual awareness do not explicitly distinguish top-down attention from awareness per se. However, several authors have started to point at the need to disambiguate visual awareness and spatial attention. Experimental evidence supporting their possible neural dissociation has remained sparse. Such evidence is now provided by a nice piece of work from Wyart and Tallon-Baudry:

To what extent does what we consciously see depend on where we attend to? Psychologists have long stressed the tight relationship between visual awareness and spatial attention at the behavioral level. However, the amount of overlap between their neural correlates remains a matter of debate. We recorded magnetoencephalographic signals while human subjects attended toward or away from faint stimuli that were reported as consciously seen only half of the time. Visually identical stimuli could thus be attended or not and consciously seen or not. Although attended stimuli were consciously seen slightly more often than unattended ones, the factorial analysis of stimulus-induced oscillatory brain activity revealed distinct and independent neural correlates of visual awareness and spatial attention at different frequencies in the gamma range (30–150 Hz). Whether attended or not, consciously seen stimuli induced increased mid-frequency gamma-band activity over the contralateral visual cortex, whereas spatial attention modulated high-frequency gamma-band activity in response to both consciously seen and unseen stimuli. A parametric analysis of the data at the single-trial level confirmed that the awareness-related mid-frequency activity drove the seen–unseen decision but also revealed a small influence of the attention-related high-frequency activity on the decision. These results suggest that subjective visual experience is shaped by the cumulative contribution of two processes operating independently at the neural level, one reflecting visual awareness per se and the other reflecting spatial attention.

Upset? Reduce your blood pressure by switching to 3rd person view.

How we view our own stories, immersed within them or viewing them as outside observer, can have a big effect on our ability to change (see 5/30/07 post). Negative feelings and stress are known to enhance vulnerability to cardiac disease, and a problem with ruminating over these negative feelings or events is that the effort can backfire, and instead maintain or enhance negativity. Ayduk and
Kross ask whether the outcome of self analysis depends on the type of self-perspective that is adopted, self-immersed (1st person) or self-distanced (3rd person).

Their experiments recruited 90 undergraduates who:

...were cued to recall an experience when they were angry and indicated that they had recalled an appropriate experience by pressing the space bar (i.e., recall phase); the computer recorded their recall times. Then they were told, "Go back to the time and place of the conflict and see the scene in your mind's eye." They were then randomly assigned to one of two perspective conditions (the manipulation phase). In the self-immersed condition, participants were told: "Relive the situation as if it were happening to you all over again … Reexperience the interaction as it progresses in your mind's eye."

In the self-distanced condition, participants were told: "Take a few steps back … . Move away from the situation to a point where you can now watch the conflict from a distance … . Watch the conflict unfold as if it were happening all over again to the distant you. Replay the interaction as it progresses in your mind's eye."

At the end students filled out a questionnaires (the recovery phase) rating the extent to which and the intensity with which they re-experienced their original feelings during the experiment. Blood pressure (mean arterial pressure, or MAP) was monitored throughout the three phases of the experiments.

The authors expected and found no difference between the two groups in MAP reactivity during recall. In contrast, participants in the self-distanced group showed lower MAP reactivity than those in the self-immersed group during both the manipulation and the recovery phases of the experiment. (That is, they were more chilled out, had lower blood pressure.)

Watching yourself during a brain stroke...

This widely circulating video has some fascinating insights into the experience of having a stroke. Jill Bolte Taylor gives an very simplified description of left versus right hemisphere function and then describes the consequences of a hemmorage in her left hemisphere that formed a large clot pressing against the language area. She watched a flickering back and forth between having a self with thoughts and a la-la land or nirvana of pure awareness as she gradually lost motor and sensory control :

Our innate number sense.

Jim Holt has written an excellent article in the New Yorker focusing on the work of Stanislas Dehaene, who argues that humans (and higher animals) have an inbuilt “number sense” capable of some basic calculations and estimates. Evidence from cognitive deficits in brain-damaged patients has shown that we have a sense of number that is independent of language, memory, and reasoning in general.
When we see numerals or hear number words, our brains appear to automatically map them onto a number line that grows increasingly fuzzy above 3 or 4. A few chunks from Holt's article:

... it is generally agreed that infants come equipped with a rudimentary ability to perceive and represent number. (The same appears to be true for many kinds of animals, including salamanders, pigeons, raccoons, dolphins, parrots, and monkeys.) And if evolution has equipped us with one way of representing number, embodied in the primitive number sense, culture furnishes two more: numerals and number words. These three modes of thinking about number, Dehaene believes, correspond to distinct areas of the brain. The number sense is lodged in the parietal lobe, the part of the brain that relates to space and location; numerals are dealt with by the visual areas; and number words are processed by the language areas.

Dehaene has been able to bring together the experimental and the theoretical sides of his quest, and, on at least one occasion, he has even theorized the existence of a neurological feature whose presence was later confirmed by other researchers. In the early nineteen-nineties, working with Jean-Pierre Changeux, he set out to create a computer model to simulate the way humans and some animals estimate at a glance the number of objects in their environment. In the case of very small numbers, this estimate can be made with almost perfect accuracy, an ability known as “subitizing” (from the Latin word subitus, meaning “sudden”). Some psychologists think that subitizing is merely rapid, unconscious counting, but others, Dehaene included, believe that our minds perceive up to three or four objects all at once, without having to mentally “spotlight” them one by one. Getting the computer model to subitize the way humans and animals did was possible, he found, only if he built in “number neurons” tuned to fire with maximum intensity in response to a specific number of objects. His model had, for example, a special four neuron that got particularly excited when the computer was presented with four objects. The model’s number neurons were pure theory, but almost a decade later two teams of researchers discovered what seemed to be the real item, in the brains of macaque monkeys that had been trained to do number tasks. The number neurons fired precisely the way Dehaene’s model predicted—a vindication of theoretical psychology. “Basically, we can derive the behavioral properties of these neurons from first principles,” he told me. “Psychology has become a little more like physics.”

Innate fear of snakes in young humans

Monkeys very rapidly learn to fear snakes simply from seeing another monkey react fearfully to the presence of a snake. There has been a question of whether our human aversion to snake forms requires such learning, or might develop autonomously. Experiments by LoBue and DeLoache support the idea that our visual systems employ an innate developmental sequence to develop a heightened awareness of snake like forms very early in development, independent of actual direct or indirect experience of snakes. 3-5 year olds preferentially attended to snake pictures, even compared with pictures of caterpillars (as well as pictures of flowers or frogs), and this preference was the same in the presence or absence of previous exposure to snakes or snake images.
A preschool child identifying the single flower target among eight snake distractors by touching the flower image on a touch-screen monitor.

Why smoking pot chills you out...

The title of the article by Phan et al. in J. Neuroscience is "Cannabinoid Modulation of Amygdala Reactivity to Social Signals of Threat in Humans" and their abstract says it clearly:

The cannabinoid (CB) system is a key neurochemical mediator of anxiety and fear learning in both animals and humans. The anxiolytic effects of {Delta}9-tetrahydrocannabinol (THC), the primary psychoactive ingredient in cannabis, are believed to be mediated through direct and selective agonism of CB1 receptors localized within the basolateral amygdala, a critical brain region for threat perception. However, little is known about the effects of THC on amygdala reactivity in humans. We used functional magnetic resonance imaging and a well validated task to probe amygdala responses to threat signals in 16 healthy, recreational cannabis users after a double-blind crossover administration of THC or placebo. We found that THC significantly reduced amygdala reactivity to social signals of threat but did not affect activity in primary visual and motor cortex. The current findings fit well with the notion that THC and other cannabinoids may have an anxiolytic role in central mechanisms of fear behaviors and provide a rationale for exploring novel therapeutic strategies that target the cannabinoid system for disorders of anxiety and social fear.


Figure - THC effects on amygdala activation. A, B, Statistical t maps overlaid on a canonical brain rendering (MNI coronal y-plane = 0) showing right lateral amygdala activation to threat (>nonthreat) faces is present during the PBO session but absent during the THC session. C, Statistical t map overlaid on a canonical brain rendering (MNI coronal y-plane = 0) showing greater threat-related amygdala reactivity in the PBO relative to the THC session (PBO > THC). For additional information, see Results. Statistical t score scale is shown at the bottom of the brain rendering. R, Right.

The Genetics of Personality and Well-Being

Some support for our folk wisdom that happiness is a personal(ity) thing: Weiss et al. have used standard verbal and written questionnaires to examine personality and subjective well-being in 973 twin pairs. The written personality questionnaire used the five factor model (FFM) rating neuroticism, extraversion, openness to experience, agreeableness, and conscientiousness. Numerous studies of personality have shown that genetic effects account for approximately 50% of the variance in these FFM domains. The 'happiness' measure was by a telephone interview that asked three questions: how satisfied participants were with life at the present, how much control subjects felt they had over their lives, and how satisfied they were with life overall.

They found that the genetic structure of the FFM and subjective well-being could be modeled without genetic influences specific to subjective well-being. Subjective well-being was genetically indistinct from personality traits, especially those reflecting, in part, emotional stability (low neuroticism), social and physical activity (high extraversion), and constraint (high conscientiousness). The close genetic relationship between positive personality traits and happiness traits is the mirror image of comorbidity in psychopathology. Weiss et al. suggest that their findings indicate that subjective well-being is linked to personality by common genes and that personality may form an "affective reserve" relevant to set-point maintenance and changes in set point over time.