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.

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.

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.

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.

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.

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...

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.

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.

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.

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.