Brainiac
Orbital dynamics, environmental heterogeneity, and the evolution of the human brain
Matt Grove
Intelligence, September-October 2012, Pages 404-418
Abstract:
Many explanations have been proposed for the evolution of our anomalously large brains, including social, ecological, and epiphenomenal hypotheses. Recently, an additional hypothesis has emerged, suggesting that advanced cognition and, by inference, increases in brain size, have been driven over evolutionary time by the need to deal with environmental complexity. The essential logic is that orbital variables have affected the quantity of solar energy reaching the earth, thus creating climatic changes that posed adaptive challenges to ancestral humans. Larger-brained humans were better equipped to deal with such changes, and proliferated accordingly, leading to the observed trajectory of increasing brain size. Though cross-citation remains rare, researchers from areas as apparently disparate as philosophy and botany are ultimately reaching similar conclusions. In order to test the validity of hypotheses linking encephalisation to climatic variability in the human lineage, the endocranial volumes of 180 fossil human skulls spanning the last 3.2 million years were collated from the literature and regressed upon a series of palaeoclimatic variables, including the amplitudes of the orbitally induced eccentricity, obliquity, and precession cycles. Multiple regression analyses demonstrate that the minimum amplitude of the eccentricity cycle explains 43% of the variance in endocranial capacity, with two further climatic variables accounting for a further 16%. These results are discussed in relation to the increasing weight of evidence that suggests that climatic instability may have played a significant part in the evolution of advanced cognition in both humans and other animals.
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Next-Generation Digital Information Storage in DNA
George Church, Yuan Gao & Sriram Kosuri
Science, forthcoming
Abstract:
Digital information is accumulating at an astounding rate, straining our ability to store and archive it. DNA is among the most dense and stable information media known. The development of new technologies in both DNA synthesis and sequencing make DNA an increasingly feasible digital storage medium. Here, we develop a strategy to encode arbitrary digital information in DNA, write a 5.27-megabit book using DNA microchips, and read the book using next-generation DNA sequencing.
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Intelligence and Homosexuality
Satoshi Kanazawa
Journal of Biosocial Science, September 2012, Pages 595-623
Abstract:
The origin of preferences and values is an unresolved theoretical problem in behavioural sciences. The Savanna-IQ Interaction Hypothesis, derived from the Savanna Principle and a theory of the evolution of general intelligence, suggests that more intelligent individuals are more likely to acquire and espouse evolutionarily novel preferences and values than less intelligent individuals, but general intelligence has no effect on the acquisition and espousal of evolutionarily familiar preferences and values. Ethnographies of traditional societies suggest that exclusively homosexual behaviour was probably rare in the ancestral environment, so the Hypothesis would predict that more intelligent individuals are more likely to identify themselves as homosexual and engage in homosexual behaviour. Analyses of three large, nationally representative samples (two of which are prospectively longitudinal) from two different nations confirm the prediction.
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Testosterone levels in healthy men are related to amygdala reactivity and memory performance
Sandra Ackermann et al.
Psychoneuroendocrinology, September 2012, Pages 1417-1424
Abstract:
Testosterone is a steroid hormone thought to influence both emotional and cognitive functions. It is unknown, however, if testosterone also affects the interaction between these two domains, such as the emotional arousal-induced enhancement of memory. Healthy subjects (N = 234) encoded pictures taken from the International Affective Picture System (IAPS) during functional magnetic resonance imaging (fMRI) and underwent a free recall test 10 min after memory encoding. We show that higher endogenous testosterone levels at encoding were associated with higher arousal ratings of neutral pictures in men. fMRI analysis revealed that higher testosterone levels were related to increased brain activation in the amygdala during encoding of neutral pictures. Moreover, endogenous testosterone levels were positively correlated with the number of freely recalled neutral pictures. No such relations were found in women. These findings point to a male-specific role for testosterone in enhancing memory by increasing the biological salience of incoming information.
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The Effects of Socio-Economic Status on Infant Attention
Melissa Clearfield & Kelly Jedd
Infant and Child Development, forthcoming
Abstract:
The development of visual attention is a key component of cognitive functioning in infancy and childhood. By the time children in poverty reach school, deficits in attention are readily apparent; however, when these attention delays manifest is unknown. The current study tested attention longitudinally at 6, 9 and 12 months in infants from high-socio-economic status (SES) and low-SES families. Infants were tested in a free play attention task in both simple and complex conditions, and two measures each of attention and inattention were scored. High-SES infants showed greater attention overall and greater increases in attention when the stimuli were more complex. Low-SES infants showed higher inattention than their high-SES peers at all ages and were less likely to modulate their attention on the basis of stimulus complexity. Thus, by 6 months of age, low-income infants already show deficits in attention. Results are discussed in terms of adaptability, implications for social development and attention interventions.
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Joanne Ruthsatz & Jourdan Urbach
Intelligence, September-October 2012, Pages 419-426
Abstract:
Child prodigies are unusual for their early and exceptional adoption of what are traditionally thought of as adult abilities. As part of an effort to better understand the underpinnings of these extraordinary individuals' talent, the researcher examined the cognitive and developmental profiles of eight child prodigies by taking their developmental histories and administering the Stanford-Binet 5th ed. full scale intelligence test and the Autism-Spectrum Quotient (AQ). The collected data reveals a startling picture. While each of the prodigies demonstrated an at least moderately elevated level of intelligence, the prodigies' full scale IQ scores were not consistently on the extreme end of the spectrum. What was consistently extraordinary, however, was the child prodigies' working memory scores-a category in which every prodigy tested in the 99th percentile. Additional results suggest a previously unknown connection between child prodigies and autism. The prodigies' family histories yielded an unlikely number of autistic relatives. And the child prodigies received elevated AQ scores with respect to attention to detail, a trait associated with autism. The prodigies did not, however, display many of the other traits typically associated with autism. This result raises the possibility of a moderated autism that actually enables the prodigies' extraordinary talent.
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Global Connectivity of Prefrontal Cortex Predicts Cognitive Control and Intelligence
Michael Cole et al.
Journal of Neuroscience, 27 June 2012, Pages 8988-8999
Abstract:
Control of thought and behavior is fundamental to human intelligence. Evidence suggests a frontoparietal brain network implements such cognitive control across diverse contexts. We identify a mechanism - global connectivity - by which components of this network might coordinate control of other networks. A lateral prefrontal cortex (LPFC) region's activity was found to predict performance in a high control demand working memory task and also to exhibit high global connectivity. Critically, global connectivity in this LPFC region, involving connections both within and outside the frontoparietal network, showed a highly selective relationship with individual differences in fluid intelligence. These findings suggest LPFC is a global hub with a brainwide influence that facilitates the ability to implement control processes central to human intelligence.
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Fraser Lauchlan, Marinella Parisi & Roberta Fadda
International Journal of Bilingualism, forthcoming
Abstract:
The research reports on a study investigating the cognitive benefits of bilingualism in children who speak the minority languages of Sardinian and Scottish Gaelic, in addition to their respective ‘national' languages of Italian and English. One hundred and twenty-one children, both bilingual and monolingual, were administered a series of standardised cognitive ability tests targeted at the four areas that have been previously shown to be advantageous to bilingual children in the literature, namely, cognitive control, problem-solving ability, metalinguistic awareness and working memory. The bilingual children significantly outperformed the monolingual children in two of the four sub-tests, and the Scottish children significantly outperformed the Sardinian children in one of the sub-tests. The differences found were largely due to the superior performance of the Scottish bilingual children who receive a formal bilingual education, in contrast to the Sardinian bilingual children who mostly only speak the minority language at home. The implications of the results are discussed.
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Brief wakeful resting boosts new memories over the long term
Michaela Dewar et al.
Psychological Science, forthcoming
Abstract:
Taking a brief wakeful rest after new verbal learning enhances memory for several minutes. Here we explored the possibility of extending this rest-induced memory enhancement over much longer periods. Participants were presented with two stories, one of which was followed by a 10-min period of wakeful resting, the other by a 10-min period of spot the difference games. Wakeful resting led to significant memory improvement after 15-30 min and after 7 days (Experiment 1). This striking 7-day memory improvement was demonstrated even when no story retrievals were imposed in the interim (Experiment 2). The degree to which prose can be remembered after 7 days is affected significantly by the cognitive activity that one engages in shortly after new learning. We hypothesise that wakeful resting after new learning allows new memory traces to be consolidated better and hence to be retained for much longer.
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Relations between preschool attention span-persistence and age 25 educational outcomes
Megan McClelland et al.
Early Childhood Research Quarterly, forthcoming
Abstract:
This study examined relations between children's attention span-persistence in preschool and later school achievement and college completion. Children were drawn from the Colorado Adoption Project using adopted and non-adopted children (N = 430). Results of structural equation modeling indicated that children's age 4 attention span-persistence significantly predicted math and reading achievement at age 21 after controlling for achievement levels at age 7, adopted status, child vocabulary skills, gender, and maternal education level. Relations between attention span-persistence and later achievement were not fully mediated by age 7 achievement levels. Logistic regressions also revealed that age 4 attention span-persistence skills significantly predicted the odds of completing college by age 25. The majority of this relationship was direct and was not significantly mediated by math or reading skills at age 7 or age 21. Specifically, children who were rated one standard deviation higher on attention span-persistence at age 4 had 48.7% greater odds of completing college by age 25. Discussion focuses on the importance of children's early attention span-persistence for later school achievement and educational attainment.
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IQs predict differences in the technological development of nations from 1000 BC through 2000 AD
Richard Lynn
Intelligence, September-October 2012, Pages 439-444
Abstract:
National IQs and measures of technological development given by Comin, Easterly and Gong (2010) are presented for 133 nations for the year 1000 BC, for 134 nations for 0 AD, for 120 nations for 1500 AD and for 133 nations for 2000 AD. It is shown that national IQs are significantly correlated with national differences in technological development at 0.42 in 1000 BC, 0.18 in 0 AD, 0.63 in 1500 D, and 0.75 in 2000 AD.
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Supervisory experience at work is linked to low rate of hippocampal atrophy in late life
Chao Suo et al.
NeuroImage, forthcoming
Abstract:
Cultivation of an active cognitive lifestyle, including diverse and challenging educational, occupational and cognitively-loaded leisure activities may be protective against development of dementia but the mechanisms underlying this link are not clear. We used the Lifetime Experiences Questionnaire (LEQ) to assess the structural brain correlates of cognitive lifestyle in the Sydney Memory and Aging Study, a large population-based cohort of originally 1037 non-demented elderly aged over 70 years of age. After excluding those without structural Magnetic Resonance Image data or Mild Cognitive Impairment at their most recent assessment, 151 cognitively intact subjects were studied. Whole-brain voxel based morphometric analysis found that higher total Lifetime Experiences Questionnaire scores are linked with increased grey matter volume in the medial temporal lobe, especially in the hippocampus. Through a series of more specific analyses, we found that supervisory and managerial experience in midlife was the dominant contributor to this effect. Furthermore, in those with longitudinal neuroimaging data (N = 91), we measured hippocampal structural changes over a 2-3 year period by gold-standard manual tracing. The rate of hippocampal atrophy in late-life in those with high level supervisory experience in midlife was five-times slower than those with no midlife supervisory experience (p < 0.001). Individual differences in intracranial volume, age, gender, physical activity, depressive symptoms, or apolipoprotein ε4 genetic status could not explain these findings, nor could specific lifestyle patterns in late life. For the first time, we reveal that managerial and supervisory experience during our working life is connected to hippocampal integrity after retirement, some 20-30 years later. Our results stimulate several questions about the nature of work-related effects on longterm behaviour, structural neuroplasticity and neuroprotection, and may help explain differences in dementia-risk based on cognitive lifestyle.
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Individual differences in working memory capacity predict sleep-dependent memory consolidation
Kimberly Fenn & David Hambrick
Journal of Experimental Psychology: General, August 2012, Pages 404-410
Abstract:
Decades of research have established that "online" cognitive processes, which operate during conscious encoding and retrieval of information, contribute substantially to individual differences in memory. Furthermore, it is widely accepted that "offline" processes during sleep also contribute to memory performance. However, the question of whether individual differences in these two types of processes are related to one another remains unanswered. We investigated whether working memory capacity (WMC), a factor believed to contribute substantially to individual differences in online processing, was related to sleep-dependent declarative memory consolidation. Consistent with previous studies, memory for word pairs reliably improved after a period of sleep, whereas performance did not improve after an equal interval of wakefulness. More important, there was a significant, positive correlation between WMC and increase in memory performance after sleep but not after a period of wakefulness. The correlation between WMC and performance during initial test was not significant, suggesting that the relationship is specific to change in memory due to sleep. This suggests a fundamental underlying ability that may distinguish individuals with high memory capacity.
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Was pre-modern man a child? The quintessence of the psychometric and developmental approaches
Georg Oesterdiekhoff
Intelligence, September-October 2012, Pages 470-478
Abstract:
The essay integrates the psychometric intelligence approach with the cognitive-developmental approach or the stage theory erected by Piaget and his disciples. The latter led to Piagetian Cross-Cultural Psychology and the accumulation of an immense body of data. It shows that different IQ levels are indicative of the peculiar stages of cognitive and personality development that characterize pre-modern and modern societies, that is, the distinction between pre-formal and formal thinking. It reveals the true significance of low IQ scores and the rise of scores, known as Flynn effect, among modern populations. The result is a Historical Anthropology that illuminates social evolution, history, law, economics, politics, morals, etc. This new anthropology contradicts the "official spirit" of the humanities and social sciences of the past decades, both its "cultural relativism" and "universality of rationality". It resurrects the leading pre-war theories, which were based on developmental approaches, and improves, enlarges, and elaborates them.
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Helen Cheng & Adrian Furnham
Journal of Vocational Behavior, forthcoming
Abstract:
This study explored a longitudinal data set of nearly 5000 adults examining the effects of childhood cognitive ability (measured at age 11), parental social class (measured at birth), and personality on current occupational prestige (all measured at age 50), taking account the effects of education and the previous occupational levels (both measured at age 33). Participants' levels of occupational attainment significantly went up from age 33 to age 50. Correlational analysis showed childhood cognitive ability, parental social class, education and occupation, and personality traits (intellect, conscientiousness, extraversion, emotional stability) were all significantly associated with current occupational prestige. The strongest correlates of current occupational levels were educational qualifications, followed by childhood cognitive ability, parental social class, and personality traits. Structural equation modelling showed that for the change of occupation over seventeen years, the strongest predictor was education, followed by childhood intelligence. Personality traits (extraversion, conscientiousness, and intellect) had modest but significant influence in the upgrading of occupational attainment over the period of time, and parental social status predicted occupational change mediated through education and initial occupational levels. Education and childhood intelligence are more powerful predictors of current occupational prestige than personality factors or family social background. The implications for policy making and equal opportunities for education are discussed.
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D.M. Curlik & T.J. Shors
Neuropharmacology, forthcoming
Abstract:
New neurons are produced each day in the hippocampus through the process of neurogenesis. Both mental and physical training can modify this process by increasing the number of new cells that mature into functional neurons in the adult brain. However, the mechanisms whereby these increases occur are not necessarily the same. Physical activity, especially aerobic exercise greatly increases the number of new neurons that are produced in the hippocampal formation. In contrast, mental training via skill learning increases the numbers that survive, particularly when the training goals are challenging. Both manipulations can increase cognitive performance in the future, some of which are reportedly mediated by the presence of new neurons in the adult hippocampus. Based on these data, we suggest that a combination of mental and physical training, referred to here as MAP training, is more beneficial for neuronal recruitment and overall mental health than either activity alone.
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Pulmonary Function as a Cause of Cognitive Aging
Charles Emery, Deborah Finkel & Nancy Pedersen
Psychological Science, forthcoming
Abstract:
Human aging is associated with decline in cognitive and physical functioning. Although pulmonary function predicts long-term performance (up to 10 years) on measures of cognitive function, recent data suggest the opposite relationship: Cognitive decline predicts self-reported physical limitations. In the study reported here, we utilized dual-change-score models to determine the directional relationship between pulmonary and cognitive function. Our sample consisted of 832 participants (ages 50-85 years at baseline), who were assessed in up to seven waves of testing across 19 years as part of the longitudinal Swedish Adoption/Twin Study of Aging. Changes in pulmonary function led to subsequent changes in fluid cognitive function, specifically, in tasks reflecting psychomotor speed and spatial abilities. There was no evidence that declines in cognitive function led to subsequent declines in pulmonary function. Thus, these data indicate a directional relationship from decreased pulmonary function to decreased cognitive function, a finding that underscores the importance of maintaining pulmonary function to ensure cognitive performance.
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Structural changes after videogame practice related to a brain network associated with intelligence
Roberto Colom et al.
Intelligence, September-October 2012, Pages 479-489
Abstract:
Here gray and white matter changes after four weeks of videogame practice were analyzed using optimized voxel-based morphometry (VBM), cortical surface and cortical thickness indices, and white matter integrity computed from several projection, commissural, and association tracts relevant to cognition. Beginning with a sample of one hundred young females, twenty right handed participants were recruited for the study and assigned to a practice or a control group carefully matched by their general cognitive ability scores. After the first scan, the practice group played ‘Professor Layton and The Pandora's Box' 4 h per week during four weeks. A second scan was obtained at the end of practice and intelligence was measured again. Image analyses revealed gray and white matter changes in the practice group. Gray matter changes theoretically relevant for intelligence were observed for the practice group mainly in frontal clusters (Brodmann areas 9 and 10) and also in smaller parietal and temporal regions. White matter findings were focused in the hippocampal cingulum and the inferior longitudinal fasciculus. These gray and white matter changes presumably induced by practice did not interact with intelligence tests' scores.
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When Less Is More: Evidence for a Facilitative Cathodal tDCS Effect in Attentional Abilities
Michal Weiss & Michal Lavidor
Journal of Cognitive Neuroscience, September 2012, Pages 1826-1833
Abstract:
Many previous studies reported that the hyperpolarization of cortical neurons following cathodal stimulation (in transcranial direct current stimulation) has resulted in cognitive performance degradation. Here, we challenge this assumption by showing that cathodal stimulation will not always degrade cognitive performance. We used an attentional load paradigm in which irrelevant stimuli are processed only under low but not under high attentional load. Thirty healthy participants were randomly allocated into three interventional groups with different brain stimulation parameters (active anodal posterior parietal cortex [PPC], active cathodal PPC, and sham). Cathodal but not anodal stimulation enabled flanker processing even in high-loaded scenes. A second experiment was carried out to assert whether the improved flanker processing under cathodal stimulation is because of altered attention allocation between center and surround or, alternatively, enhanced attentional resources. In this experiment, the flanker was presented centrally. The results of Experiment 2 replicated Experiment 1's finding of improved flanker processing. We interpret the results from these two experiments as evidence for the ability of cathodal stimulation to enhance attentional resources rather than simply change attention allocation between center and periphery. Cathodal stimulation in high-loaded scenes can act like a noise filter and may in fact enhance cognitive performance. This study contributes to understanding the way the PPC is engaged with attentional functions and explains the cathodal effects, which thus might lead to more efficient brain stimulation protocols.
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Sleep Improves Memory: The Effect of Sleep on Long Term Memory in Early Adolescence
Katya Trudeau Potkin & William Bunney
PLoS ONE, August 2012
Abstract:
Sleep plays an important role in the consolidation of memory. This has been most clearly shown in adults for procedural memory (i.e. skills and procedures) and declarative memory (e.g. recall of facts). The effects of sleep and memory are relatively unstudied in adolescents. Declarative memory is important in school performance and consequent social functioning in adolescents. This is the first study to specifically examine the effects of normal sleep on auditory declarative memory in an early adolescent sample. Given that the majority of adolescents do not obtain the recommended amount of sleep, it is critical to study the cognitive effects of normal sleep. Forty male and female normal, healthy adolescents between the ages of ten and fourteen years old were randomly assigned to sleep and no sleep conditions. Subjects were trained on a paired-associate declarative memory task and a control working memory task at 9am, and tested at night (12 hours later) without sleep. The same number of subjects was trained at 9pm and tested 9am following sleep. An increase of 20.6% in declarative memory, as measured by the number correct in a paired-associate test, following sleep was observed compared to the group which was tested at the same time interval without sleep (p<0.03). The performance on the control working memory task that involved encoding and memoranda manipulation was not affected by time of day or relationship to sleep. Declarative memory is significantly improved by sleep in a sample of normal adolescents.