Wednesday, April 30, 2008

Enhance your working intelligence with simple exercises...

Bakalar points to an interesting study by Jaeggi et al. showing that fluid intelligence (the kind of mental ability that allows us to solve new problems without having any relevant previous experience) can be enhanced by simple working memory training. It turns out that carefully structured training of the kind of memory that allows memorization of a telephone number just long enough to dial it enhances performance on standard tests of fluid intelligence. This suggests that fluid intelligence and working memory depend on the same brain circuitry.

Fairness activates brain reward circuitry.

Some interesting observations from Tabibnia et al. They:

...examined self-reported happiness and neural responses to fair and unfair offers while controlling for monetary payoff. Compared with unfair offers of equal monetary value, fair offers led to higher happiness ratings and activation in several reward regions of the brain. Furthermore, the tendency to accept unfair proposals was associated with increased activity in right ventrolateral prefrontal cortex, a region involved in emotion regulation, and with decreased activity in the anterior insula, which has been implicated in negative affect. This work provides evidence that fairness is hedonically valued and that tolerating unfair treatment for material gain involves a pattern of activation resembling suppression of negative affect.

Figure legend - Ventromedial prefrontal cortex (VMPFC), ventral striatum, and amygdala activation associated with fairness preference. The illustration (a) shows the location of clusters with significantly greater activation in response to fair compared with unfair offers.



Figure legend - Brain activation associated with the tendency to accept unfair offers. The illustrations show the location of areas in (a) left anterior insula and (c) right ventrolateral prefrontal cortex (right VLPFC) whose activation predicted this tendency.

Tuesday, April 29, 2008

More on language and perception...

Christine Kenneally writes a nice summary of current work on how language can nudge our perception. One interesting result demonstrates that labeling different categories enhances one's ability to discriminate between them. She discusses the work of Boroditsky mentioned in my Feb. 22 post, and work showing that in giving us symbols for spatial patterns, spatial language helps us carve up the world in specific ways. It appears that the ability to count is necessary to deal with large, specific numbers. And the only way to count past a certain point is with language.

The secret life of emotions.

Another demonstration that we can be nudged by unconscious emotional stimuli - that both global and specific emotional responses can be induced without awareness. From the discussion of an article with the title of this post from Ruys and Stapel, whose results show:

...that specific emotions can be elicited without conscious awareness of their cause...disgusting pictures (presented for 120 msec, not perceived) increased cognitive accessibility of disgust words and feelings of disgust. Similarly, fearful pictures increased cognitive accessibility of fear words and feelings of fear. When exposure to the priming stimuli was super-quick (40 msec), global mood, rather than a specific emotion, was evoked. These findings... empirically demonstrate (a) that specific emotions can be evoked without conscious awareness of their cause, (b) that unconscious exposure to emotion-eliciting pictures can evoke the specific corresponding emotion and does not evoke other emotions of similar valence, and (c) that unconscious emotion induction develops from elicitation of global affect to elicitation of specific emotions.

Monday, April 28, 2008

For a calm start to your week... some Debussy

Here is a second version (posted April 23, 2007) of the Debussy Reverie I initially put on YouTube Aug 29, 2006). I'm amazed that the first version has had ~90,000 viewings, and the second (made in response to comments on the first version) has had ~8,000.

A longevity-o-meter

Check out the "Vitality Compass" at the Blue Zones Community website. The results of a 2-3 minute quiz are based on a complex, 106-page algorithm developed by Dr. Robert Kane, a physician and a professor at the University of Minnesota School of Public Health. Here is my result (I'm 66 years old). Blue zone years refer to the number of years one has gained or lost given one's current behaviors.:

If you haven't OD'ed on the internet already....

Have a look at this site, which points to "20 websites that can change your life." (with 2 more added by feedback from viewers). Engaging a number of them (especially twitter) would appear to destroy any remnants of time or privacy that your life might contain.

Friday, April 25, 2008

Brain network disruption during aging.

Most work on brain changes with aging has focused on individual regions, especially those in the frontal lobe, which may shrink or lose activity even in the absence of disease. Andrews-Hanna et al. offer an important paper showing how long range interactions between brain regions are compromised with aging. The work looked at neural activity during a task in two large-scale networks that span the brain: the default network, used when we’re worrying, thinking of the past and future, or imagining people in our lives; and the attention network, used when we’re focusing on a specific task, such as word processing or math problems. The brain regions making up these systems were in sync in young people, but much less so, or not at all, in people over 60.


Figure - the younger brain, below, shows more synchronized activity than the older brain, above.

Thursday, April 24, 2008

Brain imaging can predict the mistakes you are about to make.

From Fountain's review of work by Eichele et al.:

...brain patterns start to change about 30 seconds before an error is committed... changes were seen in two brain networks. One, called the default mode region, is normally active when a person is relaxed and at rest. When a person is doing something, like playing the game, this region becomes deactivated...researchers found that in the time leading up to an error, the region became active again — the subject was heading toward a relaxed state...Another network in the right frontal lobe gradually became less active, the researchers found. This is an area in the brain thought to be related to cognitive control, Dr. Eichele said, to keeping “on task.”

...it might be possible someday to develop a warning system — perhaps by monitoring the brain’s electrical activity, which is more practical — that could be used by people doing monotonous or repetitive tasks. Such a system would alert users when they are heading for a harmful or costly, not to mention mindless, mistake.

Positive psychology - a new organization

Some of you might wish to check out the website of the new International Positive Psychology Association (IPPA). It's board includes Martin Seligman, Mihaly Csikszentmihalyi, Tal Ben-Shahar, etc. The organization seeks to promote the science and practice of positive psychology and to facilitate communication and collaboration among researchers and practitioners around the world. A first world congress is planned for June 2009 in Philadelphia.

Wednesday, April 23, 2008

An antidepressant enhances brain plasticity

The title of the article by Vetencourt et al. is "The Antidepressant Fluoxetine Restores Plasticity in the Adult Visual Cortex. " [Fluoxetine hydrochloride, i.e. Prozac, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class.] Here is their abstract:

We investigated whether fluoxetine, a widely prescribed medication for treatment of depression, restores neuronal plasticity in the adult visual system of the rat. We found that chronic administration of fluoxetine reinstates ocular dominance plasticity in adulthood and promotes the recovery of visual functions in adult amblyopic animals, as tested electrophysiologically and behaviorally. These effects were accompanied by reduced intracortical inhibition and increased expression of brain-derived neurotrophic factor in the visual cortex. Cortical administration of diazepam prevented the effects induced by fluoxetine, indicating that the reduction of intracortical inhibition promotes visual cortical plasticity in the adult. Our results suggest a potential clinical application for fluoxetine in amblyopia as well as new mechanisms for the therapeutic effects of antidepressants and for the pathophysiology of mood disorders.

Space versus body based number representation

Here is a fascinating bit of work from Brozzoli et al. showing how our touch perception can reveal the dominance of spatial over digital representation of numbers.

We learn counting on our fingers, and the digital representation of numbers we develop is still present in adulthood. Such an anatomy–magnitude association establishes tight functional correspondences between fingers and numbers. However, it has long been known that small-to-large magnitude information is arranged left-to-right along a mental number line. Here, we investigated touch perception to disambiguate whether number representation is embodied on the hand ("1" = thumb; "5" = little finger) or disembodied in the extrapersonal space ("1" = left; "5" = right). We directly contrasted these number representations in two experiments using a single centrally located effector (the foot) and a simple postural manipulation of the hand (palm-up vs. palm-down). We show that visual presentation of a number ("1" or "5") shifts attention cross-modally, modulating the detection of tactile stimuli delivered on the little finger or thumb. With the hand resting palm-down, subjects perform better when reporting tactile stimuli delivered to the little finger after presentation of number "5" than number "1." Crucially, this pattern reverses (better performance after number "1" than "5") when the hand is in a palm-up posture, in which the position of the fingers in external space, but not their relative anatomical position, is reversed. The human brain can thus use either space- or body-based representation of numbers, but in case of competition, the former dominates the latter, showing the stronger role played by the mental number line organization.

Tuesday, April 22, 2008

Testosterone predicts financial profitability

..at least on a stock trading floor in London. Dan Mitchell summarizes the work of Coats and Herbert, published in PNAS. Men with elevated levels of testosterone, the hormone associated with aggression, made more money. When the markets were more volatile, the men showed higher levels of the stress hormone cortisol. There is the minor question of which is cause and which is effect....

Mine is longer than yours....

The last game of the baby boomers: Who wins is not who has the most toys, but who lives longest. Check out this great New Yorker article by Michael Kinsley. And, by the way, you might refer back to my May 2, 2007 post on Gawande's excellent article on aging.

Stirring Dull roots with spring rain... at Twin Valley

I'm back in Madison, WI., at the old stone schoolhouse on Twin Valley road.



Monday, April 21, 2008

A mouse model for PTSD suggests a therapy

Pibiri et al. have performed experiments on mice that model the emotional hyper-reactivity (including enhanced contextual fear and impaired contextual fear extinction) that is observed in human post traumatic stress disorder (PTSD) patients. They suggest that activation of neuronal steroid synthesis might be useful in PTSD therapy. The edited abstract:

Mice subjected to social isolation (3–4 weeks) exhibit enhanced contextual fear responses and impaired fear extinction. These responses are time-related to a decrease of ... allopregnanolone (Allo) levels in selected neurons of the medial prefrontal cortex, hippocampus, and basolateral amygdala...In socially isolated mice, S-norfluoxetine, in doses that increase brain Allo levels but fail to inhibit serotonin reuptake, greatly attenuates enhanced contextual fear response. The drug SKF decreases corticolimbic Allo levels and enhances the contextual fear response in group housed mice... A recent clinical study reported that cerebrospinal fluid Allo levels also are down-regulated in human PTSD patients and correlate negatively with PTSD symptoms and negative mood. Thus, protracted social isolation of mice combined with tests of fear conditioning may be a suitable model to study emotional behavioral components associated with neurochemical alterations relating to PTSD. Importantly, selective brain steroidogenic stimulants such as S-norfluoxetine, which rapidly increase corticolimbic Allo levels, normalize the exaggerated contextual fear responses resulting from social isolation, suggesting that selective activation of neurosteroidogenesis may be useful in PTSD therapy.

8-month-old infants use intuitive statistics..

Here is a fascinating result from Xu and Garcia, a demonstration that our brains begin to employ statistics at a very young age. Here are some (slightly edited) clips from their paper:

One hallmark of human learning is that human learners are able to make inductive inferences given a small amount of data. Our hunter–gatherer ancestors may have tasted a few berries on a tree and then decided that all berries from the same kind of tree are edible. They may have encountered a few friendly people from a neighboring tribe and made the inference that people in that tribe are likely to be friendly in general. Once such generalizations are made, the inferences may go in the other direction as well. This type of statistical inference (going from samples to populations, and from populations to samples) is present in virtually every domain of learning, be it foraging, social interaction, visual perception, word learning, or causal reasoning . Inductive learning in general requires some understanding of intuitive statistics, perhaps a simpler version of what scientists do in laboratory experiments or field studies.

Xu and Garcia performed six experiments investigating whether 8-month-old infants are "intuitive statisticians." Their results show that, given a sample, the infants are able to make inferences about the population from which the sample had been drawn. Conversely, given information about the entire population of relatively small size, the infants are able to make predictions about the sample...This ability to make inferences based on samples or information about the population develops early and in the absence of schooling or explicit teaching. Human infants may be rational learners from very early in development.
Here is one of the experiments, which asked whether 8-month-old infants could use the information in a sample to make inferences about a larger population:
...8-month-old infants watched some events unfold on a puppet stage. Each infant was first given a set of six ping-pong balls in a small container to play with for a few seconds; half of the ping-pong balls were red, half were white. Then the infant was shown four familiarization trials. On each trial, a large box was brought onto the stage. The experimenter opened the front panel of the box and drew the infant's attention to the box. The box contained either mostly red ping-pong balls and a few white ping-pong balls or mostly white ping-pong balls and a few red ping-pong balls. The experimenter showed the infants these two displays alternately; thus the infants were equally familiarized with each display. Then the test trials began (see Fig. 1 for a schematic representation of the test events). On each test trial, the same box was brought onto the stage, its content not known to the infants. The experimenter shook the box for a few seconds, closed her eyes, reached into the top opening, and pulled out a ping-pong ball. She then placed it into a transparent sample display container next to the large box. A total of five ping-pong balls were drawn from the box, one at a time. In half of the test trials, a sample of four red and one white ping-pong balls were drawn. In the other half of the test trials, a sample of one red and four white ping-pong balls were drawn. After the five ping-pong balls were placed in the sample display container, the experimenter opened the front panel of the box to reveal its content. The infant's looking time was recorded. The experimenter then cleared the stage and started the next test trial until a total of eight test trials were completed. Only one outcome display was shown for each infant, either the mostly white or the mostly red one. On alternate test trials, the infants were shown the two samples (four red and one white or one red and four white). For an infant who saw the mostly red outcome display when the box was opened, the four red and one white sample was more probable and therefore expected, whereas the four white and one red ball sample was much less probable and therefore unexpected,{dagger} assuming each set was a random sample from the box. For an infant who saw the mostly white outcome display, the converse was true.


Figure - Schematic representation of the test events (Images 1, 3, and 5) The experimenter shook the box for a few seconds, closed her eyes, reached into the top opening, and pulled out a ping-pong ball. (Images 2, 4, and 6) She then placed the ball into a transparent sample display container next to the large box. Test outcomes are shown at the bottom.

The infants looked reliably longer at the unexpected outcome (M = 9.9s) than the expected outcome (M = 7.5 s). It appears that infants were able to predict the content of the box from which the samples had been drawn.

Friday, April 18, 2008

Even brief stress can zap your brain...

Well...to be sure, we're talking about rat brains, but the message is probably there for us as well. An interesting (and sobering) piece of work from Sapolsky's laboratory shows that a single dose of corticosterone, i.e. an increase in its levels of the sort that would be induced by temporary stress, is sufficient to induce the hyper-growth of nerve cell dendrites in the basolateral amygdala and heighten anxiety behaviors. Here is the complete abstract, followed by a figure from the paper:

Stress is known to induce dendritic hypertrophy in the basolateral amygdala (BLA) and to enhance anxiety. Stress also leads to secretion of glucocorticoids (GC), and the BLA has a high concentration of glucocorticoid receptors. This raises the possibility that stress-induced elevation in GC secretion might directly affect amygdaloid neurons. To address the possible effects of GC on neurons of amygdala and on anxiety, we used rats treated either acutely with a single dose or chronically with 10 daily doses of high physiological levels of corticosterone (the rat-specific glucocorticoid). Behavior and morphological changes in neurons of BLA were measured 12 days after the initiation of treatment in both groups. A single acute dose of corticosterone was sufficient to induce dendritic hypertrophy in the BLA and heightened anxiety, as measured on an elevated plus maze. Moreover, this form of dendritic hypertrophy after acute treatment was of a magnitude similar to that caused by chronic treatment. Thus, plasticity of BLA neurons is sufficiently sensitive so as to be saturated by a single day of stress. The effects of corticosterone were specific to anxiety, as neither acute nor chronic treatment caused any change in conditioned fear or in general locomotor activity in these animals.



Figure - Representative camera lucida drawing of neurons from animals treated either acutely (A) or chronically (B) with CORT (Right) compared with their respective vehicle-treated controls (i.e. injection without the hormone) (Left).

What do you see and not see?

Here is an update of a well known demonstration that I have used in my lectures (and in my "I-Illusion" web-lecture at dericbownds.net) - on what happens when you focus your attention.

Thursday, April 17, 2008

Money makes us happy...

In the Business section of the NY Times, Leonhardt points to a recent article by Betsey Stevenson and Justin Wolfers that disagrees with a classic paper published by Richard Easterlin in 1974, in which he argued that economic growth didn’t necessarily lead to more satisfaction. The prevailing idea as been that once a basic level of subsistence has been reached people care more about how much they make with respect to those around them than they do about their absolute level of income. An 'aspiration treadmill' makes people continuously dissatisfied (You own an iPod, now you want an iPod touch). Better public opinion data has been obtained over the past 34 years, and the bottom line is that income does matter, money indeed tends to bring happiness, even if it doesn’t guarantee it.

If anything...absolute income seems to matter more than relative income. In the United States, about 90 percent of people in households making at least $250,000 a year called themselves “very happy” in a recent Gallup Poll. In households with income below $30,000, only 42 percent of people gave that answer. But the international polling data suggests that the under-$30,000 crowd might not be happier if they lived in a poorer country.
Here is a summary graphic from Leonhardt's article (click to enlarge):

Brain changes in dyslexia - different in Hong Kong and Chicago

Siok et al show that the brain changes associated with dyslexia in an alphabetic versus an ideographic language can be different. In alphabetic language, a reader sees a letter and associates it with a sound. Chinese characters correspond to syllables and require much more memorization. Both Chinese and English dyslexics find it harder to make their way through even fairly simple written material. This study suggests that their brain mechanics as they try to read may be as different as Chinese is from English. Here is their abstract:

Developmental dyslexia is a neurobiologically based disorder that affects approximately 5–17% of school children and is characterized by a severe impairment in reading skill acquisition. For readers of alphabetic (e.g., English) languages, recent neuroimaging studies have demonstrated that dyslexia is associated with weak reading-related activity in left temporoparietal and occipitotemporal regions, and this activity difference may reflect reductions in gray matter volume in these areas. Here, we find different structural and functional abnormalities in dyslexic readers of Chinese, a nonalphabetic language. Compared with normally developing controls, children with impaired reading in logographic Chinese exhibited reduced gray matter volume in a left middle frontal gyrus region previously shown to be important for Chinese reading and writing. Using functional MRI to study language-related activation of cortical regions in dyslexics, we found reduced activation in this same left middle frontal gyrus region in Chinese dyslexics versus controls, and there was a significant correlation between gray matter volume and activation in the language task in this same area. By contrast, Chinese dyslexics did not show functional or structural (i.e., volumetric gray matter) differences from normal subjects in the more posterior brain systems that have been shown to be abnormal in alphabetic-language dyslexics. The results suggest that the structural and functional basis for dyslexia varies between alphabetic and nonalphabetic languages.

Wednesday, April 16, 2008

Release of creativity by frontotemporal dementia

An article by Sandra Blakeslee describes FTD, or frontotemporal dementia, through which some patients have become gifted in landscape design, piano playing, painting and other creative arts as their disease progressed. The composer Ravel composed “Bolero” in 1928, when he was 53 and began showing signs of this illness with spelling errors in musical scores and letters. The structure and repetition of this musical piece is mirrored by the graphic shown here, an image of a migraine by Anne Adams,a bench scientist with FTD who became drawn to structure and repetition. Enhanced artistic abilities arise when frontal brain areas decline and posterior regions take over. Injury or disintegration of dominant inhibitory frontal cricuits appears to release or disinhibit activity in other areas. The result of compromising one part of the brain can be to induce other parts to remodel and become stronger.

Emotion enhancing learning and memory - a mechanism

Emotion enhances our ability to form vivid memories of even trivial events. Eric Nestler points to a study by Hu et al. that links this behavioral outcome to its molecular cause. They

...elucidated a molecular mechanism by which emotional stress and arousal promote long-term memory formation. In doing so, they brought together two well-characterized phenomena: that noradrenaline stimulates memory formation in the brain's hippocampus, and that the trPublish Postafficking of a type of glutamate receptor is important for a form of plasticity in the same brain region.

Malinow's team shows that, by stimulating noradrenaline release in the hippocampus, emotional stress leads to phosphorylation of glutamate receptors. This boosts the incorporation of these receptors at the synapse — the junction between nerve cells — which, in turn, enhances synaptic function and improves memory formation. Crucially, mice with a mutation that prevents phosphorylation of the relevant part of the glutamate receptor do not show noradrenaline-mediated memory enhancement.

Impressively, this study begins with a clinically important phenomenon — memory enhancement by emotional stress — and establishes a detailed biological pathway that underlies a behavioural endpoint in an animal model.

Tuesday, April 15, 2008

Negligent mouse moms - a model for humans?

From the laboratory of my Univ. of Wisconsin Zoology colleague Steve Gammie, along with Anthony Auger in the Psychology Department, an interesting account of a mouse model for human maternal neglect: a strain of mice that exhibit unusually high rates of maternal neglect, with approximately one out of every five females failing to care for her offspring. By comparing the good mothers to their less attentive relatives, this group has found that negligent parenting seems to have both genetic and non-genetic influences, and may be linked to dysregulation of the brain signaling chemical dopamine. In more detail, they:

...examined brain activity in neglectful and nurturing mice. c-Fos expression was significantly elevated in neglectful relative to nurturing mothers in the CNS, particularly within dopamine associated areas, such as the zona incerta (ZI), ventral tegmental area (VTA), and nucleus accumbens. Phosphorylated tyrosine hydroxylase (a marker for dopamine production) was significantly elevated in ZI and higher in VTA (although not significantly) in neglectful mice. Tyrosine hydroxylase levels were unaltered, suggesting a dysregulation of dopamine activity rather than cell number. Phosphorylation of DARPP-32, a marker for dopamine D1-like receptor activation, was elevated within nucleus accumbens and caudate-putamen in neglectful versus nurturing dams.

Enhancing our memories with brain implants.

Here are some interesting speculations by Gary Marcus on enhancing our memory - possibly through the use of computer chips as brain implants which combine cue-driven promptings similar to human memory with the location-addressability of computers. He does a nice job of distinguishing the differences in memory storage between our brains and computers.

Monday, April 14, 2008

Language evolution and the arcuate fasciculus

Did language evolve gradually via communication precursors in the primate lineage or did it arise spontaneously through a fortuitous confluence of neuroanatomical changes that are found only in humans? Rilling et al., reviewed by Ghazanfar, have used diffusion-tensor imaging to track putative differences in white matter connectivity between the frontal and temporal lobes, a pathway that is essential for language, by comparing humans, chimpanzees and macaque monkeys. They focused on the arcuate fasciculus,the fiber tract connecting the temporal to the frontal lobes in humans, which is essential for language in humans. Lesions to this pathway result in conduction aphasia, in which, among other deficits, patients can comprehend speech, but cannot repeat what was said. Rilling et al found that the organization of cortical terminations between the temporal and frontal lobes was strongly modified in the course of human evolution, and, crucially, this modification was gradual. They also noted a prominent temporal lobe projection of the human arcuate fasciculus that is much smaller or absent in nonhuman primates. This human specialization may be relevant to the evolution of language.


Figure from the News and Views summary by Ghazanfar (click to enlarge) - Chimpanzees are phylogenetically between macaques and humans in the primate lineage, and the similarly 'in between' pattern of their arcuate pathway terminations strongly suggest a gradual evolution of this pathway.(a) Changing patterns of connections between frontal cortical areas and the temporal lobe in humans, chimpanzees and macaque monkeys. AS, arcuate sulcus; CS, central sulcus; IFS, inferior frontal sulcus; IPS, intraparietal sulcus; PS, principal sulcus; PrCS, precentral sulcus; STS, superior temporal sulcus. (b) The voice area in the rhesus macaque relative to other auditory cortical areas and where the voice area would be if it were in a similar location as the human voice area. LS, lateral sulcus; IOS, inferior occipital sulcus; STS, superior temporal sulcus; other labels refer to cytoarchitectonic areal designations. The lateral sulcus is cut open to reveal the superior temporal plane. In this plane, the core region is thought to contain 'primary-like' areas, responding best to pure tones, whereas the surrounding belt areas are more responsive to complex sounds. The voice area in macaques is anterior to the core and belt regions. INS, insula; IT, inferotemporal cortex; Tpt, temporoparietal area.

Neuroenhancement - continued....

Nature magazine continues its coverage of reactions to an December article on cognitive-enhancing drugs. Here is the PDF of a summary.

Friday, April 11, 2008

Light deprivation damages neurons and causes depression

Experiments from Gonzalez and Aston-Jones on how light deprivation damages monoamine neurons and produces a depressive behavioral phenotype in rats:

Light is an important environmental factor for regulation of mood. There is a high frequency of seasonal affective disorder in high latitudes where light exposure is limited, and bright light therapy is a successful antidepressant treatment. We recently showed that rats kept for 6 weeks in constant darkness (DD) have anatomical and behavioral features similar to depressed patients, including dysregulation of circadian sleep–waking rhythms and impairment of the noradrenergic (NA)-locus coeruleus (LC) system. Here, we analyzed the cell viability of neural systems related to the pathophysiology of depression after DD, including NA-LC, serotoninergic-raphe nuclei and dopaminergic-ventral tegmental area neurons, and evaluated the depressive behavioral profile of light-deprived rats. We found increased apoptosis in the three aminergic systems analyzed when compared with animals maintained for 6 weeks in 12:12 light-dark conditions. The most apoptosis was observed in NA-LC neurons, associated with a significant decrease in the number of cortical NA boutons. Behaviorally, DD induced a depression-like condition as measured by increased immobility in a forced swim test (FST). DD did not appear to be stressful (no effect on adrenal or body weights) but may have sensitized responses to subsequent stressors (increased fecal number during the FST). We also found that the antidepressant desipramine decreases these neural and behavioral effects of light deprivation. These findings indicate that DD induces neural damage in monoamine brain systems and this damage is associated with a depressive behavioral phenotype. Our results suggest a mechanism whereby prolonged limited light intensity could negatively impact mood.

Thursday, April 10, 2008

Leaving Austin...


This morning I hit the road again, leaving the family home to drive back to Madison Wisconsin. I may miss tomorrow's blog post. The picture shows a partial skyline of downtown Austin, taken from across Lady Bird Johnson Lake.

Rationalization of our choices - statistics rather than psychology?

Tierny has done it again - a really really kewl article on what appears to be an error in some classical psychological experiments on cognitive dissonance and rationalization. He provides online exercises you can do. Those early experiments suggested choice rationalization: Once we reject something, we tell ourselves we never liked it anyway (and thereby spare ourselves the painfully dissonant thought that we made the wrong choice). It turns out that in the free-choice paradigm used to test our tendency to rationalize decisions, any bias or slight preference for one of the initial choices can lead to results on subsequent choices that are explained by simple statistics rather than a psychological explanation. The article is worth a careful read...

Wednesday, April 09, 2008

Episodic-like memory in rats - not like humans

Until recent experiments showing that scrub jays remember where and when they cached or discovered foods of differing palatability, it had been thought that episodic memory - defined as ability to remember an event (what) as well as where and when it happened - was confined to humans. Memory for 'when' observed in scrub jays has been taken to suggest that animals can mentally travel in time or locate a past event within a temporal framework of hours and days. Roberts et al. point out that:

An alternative possibility is that, instead of remembering when an event happened within a framework of past time, animals are keeping track of how much time has elapsed since caching or encountering a particular food item at a particular place and are using elapsed time to indicate return to or avoidance of that location. The cues of when and how long ago are typically confounded in studies of episodic-like memory. Thus, animals might be remembering how long ago an event occurred by keeping track of elapsed time using accumulators, circadian timers, their own behavior, or the strength of a decaying memory trace. If this is the case, then episodic-like memory in animals may be quite different from human episodic memory in which people can reconstruct past experiences within an absolute temporal dimension.
Their experiments show that this is the case.
Three groups of Long-Evans hooded rats were tested for memory of previously encountered food. The different groups could use only the cues of when, how long ago, or when + how long ago. Only the cue of how long ago food was encountered was used successfully. These results suggest that episodic-like memory in rats is qualitatively different from human episodic memory.

Creating Musical Variation

Here is a clip from a very interesting perspectives piece on approaches to creating musical variation, by Diana S. Dabby in the April 4 issue of Science:

In the 21 letters that Mozart wrote to his friend Michael Puchberg between 1788 and 1791, there exist at least 24 variants of the supplication "Brother, can you spare a dime?" Mozart ornaments his language to cajole, flatter, and play on Puchberg's sympathies. He varies his theme of "cash needed now" in much the same way an 18thcentury composer might dress a melody in new attire by weaving additional notes around its thematic tones in order to create a variation. Such ornamentation could enliven and elaborate one or more musical entities, as can be heard in the Haydn F Minor Variations (1793) (mp3 file of theme, mp3 file of variation). The Haydn represents one of the most popular forms of the 18th and 19th centuries--variations on original or borrowed themes. Yet myriad variation techniques existed besides ornamentation, including permutation and combination, as advocated by a number of 18th-century treatises. More recently, fields such as chaos theory have allowed composers to create new kinds of variations, some of which are reminiscent of earlier combinatorial techniques.

In a broad context, variation refers to the technique of altering musical material to create something related, yet new. Recognizing its importance to composers, the 20th-century composer and teacher Arnold Schoenberg defined variation as "repetition in which some features are changed and the rest preserved". He wrote numerous examples showing how a group of four notes, each having the same duration, can be varied by making rhythmic alterations, adding neighboring notes, changing the order of the notes, and so on (see the figure, panels A to C). Changing the order of the notes reflects the 18th-century practice of ars combinatoria. Joseph Riepel advocated a similar approach (see the figure, panel D).


Figure - Idea and variations. Variation techniques illustrated by Schoenberg, Riepel, and a chaotic mapping example. Schoenberg offers numerous ways to vary a given four-note group, shown in the first measure of each line. (A) Rhythmic changes. (B) Addition of neighboring notes. (C) Changing the original order. (D) One of many examples given by Riepel of ars permutatoria, a branch of ars combinatoria, where six permutations of the notes A B C are given (15). Note that Riepel writes above the staff the German musical spelling of the notes so that "B" translates to B-flat. (E) The first measure of a Bach prelude (pitches only) followed by the first measure of a variation generated by the chaotic mapping.

Tuesday, April 08, 2008

Simple curves can influence whether we see happy or sad faces.

Here is an interesting bit of work from Xu et al. showing that adaptation to simple stimuli (like the shape of a mouth) that are processed early in the visual hierarchy can influence our perception of higher level perceptions (i.e., of faces) that are analyzed at higher levels of the visual hierarchy. Thus adaptation to a concave (sad) cartoon mouth shape makes subsequent perception more likely to report a happy face, and vice versa. Their abstract:

Adaptation is ubiquitous in sensory processing. Although sensory processing is hierarchical, with neurons at higher levels exhibiting greater degrees of tuning complexity and invariance than those at lower levels, few experimental or theoretical studies address how adaptation at one hierarchical level affects processing at others. Nevertheless, this issue is critical for understanding cortical coding and computation. Therefore, we examined whether perception of high-level facial expressions can be affected by adaptation to low-level curves (i.e., the shape of a mouth). After adapting to a concave curve, subjects more frequently perceived faces as happy, and after adapting to a convex curve, subjects more frequently perceived faces as sad. We observed this multilevel aftereffect with both cartoon and real test faces when the adapting curve and the mouths of the test faces had the same location. However, when we placed the adapting curve 0.2° below the test faces, the effect disappeared. Surprisingly, this positional specificity held even when real faces, instead of curves, were the adapting stimuli, suggesting that it is a general property for facial-expression aftereffects. We also studied the converse question of whether face adaptation affects curvature judgments, and found such effects after adapting to a cartoon face, but not a real face. Our results suggest that there is a local component in facial-expression representation, in addition to holistic representations emphasized in previous studies. By showing that adaptation can propagate up the cortical hierarchy, our findings also challenge existing functional accounts of adaptation.

Here are some examples of face stimuli used in the studies, in which subjects were experiments as well as naive subjects:


Figure - Examples of the face stimuli used in this study. a, Cartoon faces used in experiment 1, generated with our anti-aliasing program. The mouth curvature varied from concave to convex to produce sad to happy expressions. b, Ekman faces used in experiment 2. The first (sad) and last (happy) images were taken from the Ekman PoFA database, and the intermediate ones were generated with MorphMan 4.0. c, MMI faces used in experiments 3 and 4. The first (sad), middle (neutral), and last (happy) images were taken from the MMI face database, and the other images were generated with MorphMan 4.0.

Our Racist, Sexist Selves

Kristof has a great Op-Ed piece int he Sunday NYTimes with the title of this post. You should check out the psychological experiments that you can do online. You may think you are not prejudiced, but these "implicit attitude tests" might show otherwise.

Monday, April 07, 2008

The Amazing Aging Brain

Check out this interesting site, illustrating how the brain changes on aging.

The social cognitive neuroscience of business organizations

Jumping on the bandwagon of getting cognitive neuroscience into business and marketing, there is a special issue of the Annals of the New York Academy of Sciences which offers one open access article by Klein and D'Desposito, "Neurocognitive Inefficacy of the Strategy Process." Their abstract (written in business-speak gobbledegook, but content can be extracted):

The most widely used (and taught) protocols for strategic analysis—Strengths, Weaknesses, Opportunities, and Threats (SWOT) and Porter's (1980) Five Force Framework for industry analysis—have been found to be insufficient as stimuli for strategy creation or even as a basis for further strategy development. We approach this problem from a neurocognitive perspective. We see profound incompatibilities between the cognitive process—deductive reasoning—channeled into the collective mind of strategists within the formal planning process through its tools of strategic analysis (i.e., rational technologies) and the essentially inductive reasoning process actually needed to address ill-defined, complex strategic situations. Thus, strategic analysis protocols that may appear to be and, indeed, are entirely rational and logical are not interpretable as such at the neuronal substrate level where thinking takes place. The analytical structure (or propositional representation) of these tools results in a mental dead end, the phenomenon known in cognitive psychology as functional fixedness. The difficulty lies with the inability of the brain to make out meaningful (i.e., strategy-provoking) stimuli from the mental images (or depictive representations) generated by strategic analysis tools. We propose decreasing dependence on these tools and conducting further research employing brain imaging technology to explore complex data handling protocols with richer mental representation and greater potential for strategy creation.

The spiritual side of atheism

This from Andrew Sullivan's blog.

Friday, April 04, 2008

Report from the road - Central Texas Bluebonnets

From the drive into Austin Texas yesterday, the roadsides (seeded with wildflowers by Lady Bird Johnson) were a riot of spring flowers at their peak. (Click to enlarge).

The social brain in adolescence - a review

In a recent Nature Reviews Neuroscience, Sarah-Jayne Blakemore does a summary of changes in the social brain during adolescence and I put down here the slightly edited capsule summary and one summary figure that offers a review of the relevant brain structures:

The 'social brain', the network of brain regions involved in understanding other people, includes the medial prefrontal cortex (mPFC) and the posterior superior temporal sulcus (pSTS). These regions are key to the process of mentalizing — that is, the attribution of mental states to oneself and to other people...Recent functional neuroimaging studies have shown that activity in parts of the social brain during social cognitive tasks changes during adolescence... activity in the PFC during face-processing tasks increases from childhood to adolescence and then decreases from adolescence to adulthood. Consistent with this, activity in the mPFC during mentalizing tasks decreases between adolescence and adulthood.

The prefrontal cortex is one of the brain regions that undergo structural development, including synaptic reorganization, during adolescence. Synaptic density, reflected in grey-matter volume in MRI scans, decreases during adolescence...Synaptic reorganization in the PFC might underlie the functional changes that are seen in the social brain during adolescence, as well as the social cognitive changes during this period.


Figure - Regions that are involved in social cognition include the medial prefrontal cortex (mPFC) and the temporoparietal junction (TPJ), which are involved in thinking about mental states, and the posterior superior temporal sulcus (pSTS), which is activated by observing faces and biological motion. Other regions of the social brain on the lateral surface are the inferior frontal gyrus (IFG) and the interparietal sulcus (IPS). Regions on the medial surface that are involved in social cognition include the amygdala, the anterior cingulate cortex (ACC) and the anterior insula (AI).

Preschool children's narratives predict later math performance

In a Nature journal club note, Devlin points out work by O'Neill and colleagues, who examined whether language development in preschool children might be a predictor of later math ability, given that early aptitude for arithmetic is not a terribly good indicator of future math performance.

O'Neill and her team showed three- and four-year-old children a picture book and asked them to tell a story about what they saw...narrative measures of conjunction use, event content, perspective shift, and mental state reference were significantly predictive of later Math scores. The sophistication with which the children told their stories was important. The most significant feature of this sophistication was children's ability to switch perspectives as they related the stories. Crucially, this correlation pertained not to later performance in reading, spelling or general knowledge, but to future mathematical ability.

Thursday, April 03, 2008

Report from the road...



My first day on the road to Austin, TX. (see April 1 post) ended at Waklulla Springs State Park in the Florida panhandle, staying overnight in the Park Lodge. The second night has been at L'auberge Casino in Lake Charles, Louisiana (the room sans gambling)...heading out for the Cajun Trail along the coast today.

Runner's High - endorphin release finally demonstated

It has long been assumed that strenuous exercise causes chemical changes in the brain, particularly the release of endorphins, the brain’s naturally occurring opiates. The problem with this idea, from Kolata's review, has been:

...that it was not feasible to do a spinal tap before and after someone exercised to look for a flood of endorphins in the brain. Researchers could detect endorphins in people’s blood after a run, but those endorphins were part of the body’s stress response and could not travel from the blood to the brain. They were not responsible for elevating one’s mood. So for more than 30 years, the runner’s high remained an unproved hypothesis.
Boecker et al. used a synthetic opioid labelled with fluorine isotope ([18F]FDPN), visible in positron emission brain scans (PET scans), which binds to brain opioid receptors. Less of this compound was found bound to several brain sites important in mood control after running, because those site had become occupied by endogenous opioids during the running. The current affective states before and after running as well as before the resting PET scan were evaluated with Visual Analog Mood Scales - subjects rated different items (sadness, tension, fear, anger, confusion, fatigue, happiness, and energy. This yielded the VAS euphoria scale referenced in the figure. VAS ratings of euphoria are inversely correlated with [18F]FDPN binding. Here is that figure, followed by the full abstract from the article.

Figure - Correlation of opioidergic binding in runners with VAS ratings of euphoria. Statistical parametric maps of the regression analysis (regions where VAS ratings of euphoria are inversely correlated with [18F]FDPN binding) in standard stereotactic space (Montreal Neurological Institute [MNI] space) are overlaid in color on axial slices of a skull-stripped normalized brain.
The abstract:
The runner's high describes a euphoric state resulting from long-distance running. The cerebral neurochemical correlates of exercise-induced mood changes have been barely investigated so far. We aimed to unravel the opioidergic mechanisms of the runner's high in the human brain and to identify the relationship to perceived euphoria. We performed a positron emission tomography "ligand activation" study with the nonselective opioidergic ligand 6-O-(2-[18F]fluoroethyl)-6-O-desmethyldiprenorphine ([18F]FDPN). Ten athletes were scanned at 2 separate occasions in random order, at rest and after 2 h of endurance running (21.5 ± 4.7 km). Binding kinetics of [18F]FDPN were quantified by basis pursuit denoising (DEPICT software). Statistical parametric mapping (SPM2) was used for voxelwise analyses to determine relative changes in ligand binding after running and correlations of opioid binding with euphoria ratings. Reductions in opioid receptor availability were identified preferentially in prefrontal and limbic/paralimbic brain structures. The level of euphoria was significantly increased after running and was inversely correlated with opioid binding in prefrontal/orbitofrontal cortices, the anterior cingulate cortex, bilateral insula, parainsular cortex, and temporoparietal regions. These findings support the "opioid theory" of the runner's high and suggest region-specific effects in frontolimbic brain areas that are involved in the processing of affective states and mood.



Infants to adults, color perception switches from right to left hemisphere

An interesting article by Franklin et al. shows that our perception of color categories (CP) starts in the right hemisphere, but then switches to the left hemisphere as it develops the lexical color codes of language. They suggest that language-driven CP in adults may not build on prelinguistic CP, but that language instead imposes its categories on a left hemisphere that is not categorically prepartitioned.

Wednesday, April 02, 2008

The 'size' of an odor can influence our reaching to grasp an object.

An nice example from Tubaldi et al. of multisensory integration. They find that olfactory information contains highly detailed information able to elicit the planning for a reach-to-grasp movement suited to interact with the evoked object. From their paper:

The size of the object evoked by the odour has the potential to modulate hand shaping. Importantly, the fact that ‘size’ olfactory information modulates the hand at the level of individual digits (and not only the thumb-index distance as previously reported) leads to two important considerations in terms of sensorimotor transformation. First, from a perceptual perspective, the representation evoked by the odour seems to contain highly detailed information about the object (i.e., volumetric features rather than a linear dimension such as the thumb-index distance). If olfaction had provided a blurred and holistic object's representation (i.e., a low spatial-resolution of the object's image), then the odour would have not affected the hand in its entirety. Second, from a motor perspective, the olfactory representation seems to be mapped into the action vocabulary with a certain degree of reliability. The elicited motor plan embodies specific and selective commands for handling the ‘smelled’ object, and it is fully manageable by the motor system. Therefore, it is not an incomplete primal sketch which only provides a preliminary descriptive in the terms of motor execution.
Some of the details:
When the odour was ‘large’ and the visual target was small, only one finger joint (i.e., the mcp joint of the ring finger) was affected by the olfactory stimulus. In contrast, the influence of the ‘small’ odour on the kinematics of a reach-to-grasp movement towards a large target was much more evident and a greater number of joints were mobilized. This seems to suggest that planning for a reach-to-grasp movement on the basis of a ‘small’ odour when the target is large poses more constraints than when the odour is ‘large’ and the movement is directed towards a small target. Our proposal is that the motor plan elicited by the odour has to be modified according to the visual target. However such reorganization could be more easily managed without compromising object grasp when the odour is ‘large’ and the visual target is small than vice versa.

When a preceding odour elicits a motor plan which is congruent with the motor plan subsequently established for the visual target, the kinematic patterning is magnified. Therefore, the grasp plan triggered by the olfactory stimulus primed the grasp plan established for the visual target. This effect was evident at the very beginning of the movement, fading away during the second phase of the movement. For both the incongruent conditions the conflict between the ‘olfactory’ and the ‘visual’ grasp plans lasted for the entire movement duration. Importantly, and again in contrast with what reported for the incongruent conditions, an odour of a similar ‘size’ than the visual target, does not alter hand synergies with respect to when no-odour is presented. This indicates that when the ‘size’ of the odour and the size of the visual target match, the integration of the two modalities reinforces the grasp plan, the established synergic pattern is more ‘protected’ and it does not change. Having two sources carrying similar information leads to a more stable and coherent action.

Antidepressant effects of eating less.

I notice that when I get paranoid about my weight creeping up and suddenly eat less for several days, my general mood improves considerably.... I wonder if the chemistry described in these (admittedly more extreme) experiments on rodents done by Lutter et al. is what is going on. The experiments deal with the orexin neuropeptides, which can stimulate food seeking activity in mice and decrease anxiety-like behaviors in helplessness and social defeat model of stress. (Decreased levels of orexin-A have been reported in the CSF of suicidal patients with major depressive disorder, supporting chronic social defeat stress as a model of major depression.) The title of the article is "Orexin Signaling Mediates the Antidepressant-Like Effect of Calorie Restriction" Here is the abstract:

During periods of reduced food availability, animals must respond with behavioral adaptations that promote survival. Despite the fact that many psychiatric syndromes include disordered eating patterns as a component of the illness, little is known about the neurobiology underlying behavioral changes induced by short-term calorie restriction. Presently, we demonstrate that 10 d of calorie restriction, corresponding to a 20–25% weight loss, causes a marked antidepressant-like response in two rodent models of depression and that this response is dependent on the hypothalamic neuropeptide orexin (hypocretin). Wild-type mice, but not mice lacking orexin, show longer latency to immobility and less total immobility in the forced swim test after calorie restriction. In the social defeat model of chronic stress, calorie restriction reverses the behavioral deficits seen in wild-type mice but not in orexin knock-out mice. Additionally, chronic social defeat stress induces a prolonged reduction in the expression of prepro-orexin mRNA via epigenetic modification of the orexin gene promoter, whereas calorie restriction enhances the activation of orexin cells after social defeat. Together, these data indicate that orexin plays an essential role in mediating reduced depression-like symptoms induced by calorie restriction.

Tuesday, April 01, 2008

MindBlog hits the road....

I'm loading boxes into my Honda Civic, leaving my condo in paradise (Fort Lauderdale) to return to Madison, Wisconsin via Austin, Texas - where I visit my son and his wife who live in the family house in which I grew up. It is a week or two early to return to Wisconsin, but I've decided I should symbolically share the suffering by arriving for the last gasp of a winter that has deposited 107 inches of snow on my Twin Valley home.

I've decided to take a leisurely tourist drive, tonight staying in the Wakula Springs State Park in the Florida panhandle, at the Wakula Springs Lodge, an example of Mediterranean Revival architecture built in 1937 by Edward Ball, who established the Wakula Springs wildlife preserve in 1934. After driving along Florida's Gulf coast Wednesday I'm heading on to Lake Charles, Louisiana, and crashing at the L'Augerge Du Lac casino. Thursday morning I will take the "Creole Trail" along the Louisiana Gulf coast into Texas, and then head on to Austin. I'm not sure what my internet status will be. I have asked a friend to post some blog drafts I've prepared ahead. It would be therapeutic for me to be off the grid for a few days.......

Mind Reading with fMRI

From the Nature Editor's summary:

Recent functional magnetic resonance imaging (fMRI) studies have shown that, based on patterns of activity evoked by different categories of visual images, it is possible to deduce simple features in the visual scene, or to which category it belongs. Kay et al. take this approach a tantalizing step further. Their newly developed decoding method, based on quantitative receptive field models that characterize the relationship between visual stimuli and fMRI activity in early visual areas, can identify with high accuracy which specific natural image an observer saw, even for an image chosen at random from 1,000 distinct images. This prompts the thought that it may soon be possible to decode subjective perceptual experiences such as visual imagery and dreams, an idea previously restricted to the realm of science fiction.
The abstract from Kay et al., followed by one figure:
A challenging goal in neuroscience is to be able to read out, or decode, mental content from brain activity. Recent functional magnetic resonance imaging (fMRI) studies have decoded orientation, position, and object category from activity in visual cortex. However, these studies typically used relatively simple stimuli (for example, gratings) or images drawn from fixed categories (for example, faces, houses), and decoding was based on previous measurements of brain activity evoked by those same stimuli or categories. To overcome these limitations, here we develop a decoding method based on quantitative receptive-field models that characterize the relationship between visual stimuli and fMRI activity in early visual areas. These models describe the tuning of individual voxels for space, orientation and spatial frequency, and are estimated directly from responses evoked by natural images. We show that these receptive-field models make it possible to identify, from a large set of completely novel natural images, which specific image was seen by an observer. Identification is not a mere consequence of the retinotopic organization of visual areas; simpler receptive-field models that describe only spatial tuning yield much poorer identification performance. Our results suggest that it may soon be possible to reconstruct a picture of a person's visual experience from measurements of brain activity alone.


Figure Legend - The experiment consisted of two stages. In the first stage, model estimation, fMRI data were recorded while each subject viewed a large collection of natural images. These data were used to estimate a quantitative receptive-field model for each voxel. In the second stage, image identification, fMRI data were recorded while each subject viewed a collection of novel natural images. For each measurement of brain activity, we attempted to identify which specific image had been seen. This was accomplished by using the estimated receptive-field models to predict brain activity for a set of potential images and then selecting the image whose predicted activity most closely matches the measured activity.