A number of interesting pieces in this set of articles. As ever, the default mode network continues to be garnering attention with a new article looking at the influence of heredity on the functional connectivity of the network (1). We also learn that this network can be robustly reproduced (17). Given how important this network appears to be for social cognition, future extensions of this line of research will be of great use to political science. And, we have a couple of other pieces using functional connectivity analysis of subcortical regions (15, 16). We also get a fascinating view of an entire network of cells in the brain that had usually been thought of as acting individually (12). On the topic of networks, the piece showing that an amoeba can effectively design a rail system is pretty fascinating (10, 11).
Ernst Fehr’s new paper on the role of testosterone shows how misconstrued it has been in common understanding and how it can play a prosocial role (7, 8). And, a bit more evidence on the antisocial role that amphetamines can play (2).
The most interesting “big idea” in the set is Karl Friston’s attempt to develop a unified theory of the brain based upon the minimization of free-energy (20-23). One of my concerns about how the neuroscience literature develops is that usually researchers are focused on leaves and not trees or forests. It is great to see a luminary like Friston attempting a big picture view.
Finally, let me draw your attention to a review of some of the work on race and the brain (24).
1) Glahn et al. Genetic control over the resting brain. P Natl Acad Sci (2010) vol. 107 (3) pp. 1223-1228
2) Liu et al. Nucleus accumbens dopamine mediates amphetamine-induced impairment of social bonding in a monogamous rodent species. P Natl Acad Sci (2009) pp.
3) Kwok. Five hard truths for synthetic biology. Nature (2010) vol. 463 (7279) pp. 288-90
4) Aspinall. A route to more tractable expert advice. Nature (2010) vol. 463 (7279) pp. 294-5
5) Daar. Books & Arts: Vision of a personal genomics future. Nature (2010) vol. 463
6) Benton. Evolutionary biology: New take on the Red Queen. Nature (2010) vol. 463 (7279) pp. 306-7
7) Eisenegger et al. Prejudice and truth about the effect of testosterone on human bargaining behaviour. Nature (2010) vol. 463 (7279) pp. 356-9
8) Fehr. Making the paper: Ernst Fehr. Nature (2010) vol. 463 (7279) pp. 268-268
9) Mervis. Science indicators. Trends document China’s prowess. Science (2010) vol. 327 (5964) pp. 407
10) Marwan. Systems biology. Amoeba-inspired network design. Science (2010) vol. 327 (5964) pp. 419-20
11) Tero et al. Rules for biologically inspired adaptive network design. Science (2010) vol. 327 (5964) pp. 439-42
12) Giaume et al. Astroglial networks: a step further in neuroglial and gliovascular interactions. Nat Rev Neurosci (2010) vol. 11 (2) pp. 87-99
13) Diekelmann and Born. The memory function of sleep. Nat Rev Neurosci (2010) vol. 11 (2) pp. 114-26
14) Zilles and Amunts. Centenary of Brodmann’s map – conception and fate. Nat Rev Neurosci (2010) vol. 11 (2) pp. 139-45
15) Doron and Goelman. Evidence for asymmetric intra substantia nigra functional connectivity-application to basal ganglia processing. Neuroimage (2010) vol. 49 pp. 2940-2946
16) Robinson et al. Metaanalytic connectivity modeling: Delineating the functional connectivity of the human amygdala. Human Brain Mapping (2009) vol. 31 (2) pp. 173-184
17) Meindl et al. Test-retest reproducibility of the default-mode network in healthy individuals. Human Brain Mapping (2010) vol. 31 (2) pp. 237-246
18) Bogacz et al. The neural basis of the speed-accuracy tradeoff. Trends Neurosci (2009) pp.
19) Schauer. Neuroscience, Lie-Detection, and the Law: Contrary to the prevailing view, the suitability of brain-based lie-detection for courtroom or forensic use should be determined according to legal and not scientific standards. Trends Cogn Sci (2010) pp.
20) Friston. The free-energy principle: a unified brain theory?. Nat Rev Neurosci (2010) vol. 11 (2) pp. 127-38
21) Friston. The free-energy principle: a rough guide to the brain?. Trends Cogn Sci (2009) vol. 13 (7) pp. 293-301
22) Thornton. Some puzzles relating to the free-energy principle: comment on Friston. Trends Cogn Sci (2009) pp.
23) Friston. Some free-energy puzzles resolved: response to Thornton. Trends Cogn Sci (2009) pp.
24) Ito and Bartholow. The neural correlates of race. Trends Cogn Sci (2009) vol. 13 (12) pp. 524-31
25) Vogeley and Roepstorff. Contextualising culture and social cognition. Trends Cogn Sci (2009) vol. 13 (12) pp. 511-6
26) Passingham et al. Medial frontal cortex: from self-generated action to reflection on one’s own performance. Trends Cogn Sci (2009) pp.
The default-mode network, a coherent resting-state brain network, is thought to characterize basal neural activity. Aberrant default- mode connectivity has been reported in a host of neurological and psychiatric illnesses and in persons at genetic risk for such illnesses. Whereas the neurophysiologic mechanisms that regulate default- mode connectivity are unclear, there is growing evidence that genetic factors play a role. In this report, we estimate the importance of genetic effects on the default-mode network by examining covariation patterns in functional connectivity among 333 individuals from 29 randomly selected extended pedigrees. Heritability for default-mode functional connectivity was 0.424 ± 0.17 (P = 0.0046). Although neuroanatomic variation in this network was also heritable, the genetic factors that influence default-mode functional connectivity and gray-matter density seem to be distinct, suggesting that unique genes influence the structure and function of the network. In contrast, significant genetic correlations between regions within the network provide evidence that the same genetic factors contribute to variation in functional connectivity throughout the default mode. Specifically, the left parahippocampal region was genetically correlated with all other network regions. In addition, the posterior cingulate/precuneus region, medial prefrontal cortex, and right cerebellum seem to form a subnetwork. Default-mode functional connectivity is influenced by genetic factors that cannot be attributed to anatomic variation or a single region within the network. By establishing the heritability of default-mode functional connectivity, this experiment provides the obligatory evidence required before these measures can be considered as endophenotypes for psychiatric or neurological illnesses or to identify genes influencing intrinsic brain function.
The prairie vole (Microtus ochrogaster) is a socially monogamous rodent species that forms pair bonds after mating, a behavior in which central dopamine (DA) has been implicated. Here, we used male prairie voles to examine the effects of drug exposure on pair bonding and related neural circuitry. In our first experiment, amphetamine (AMPH) motivated behavior was examined using a conditioned place preference (CPP) paradigm and was shown to be mediated by activation of D1-like DA receptors. Next, we examined the effects of repeated AMPH exposure on pair bonding. Intact and saline pretreated control males displayed mating-induced partner preferences, whereas males pretreated with AMPH at the doses effective to induce CPP failed to show mating-induced partner preferences. Such AMPH treatment also enhanced D1, but not D2, DA receptor expression in the nucleus accumbens (NAcc). Furthermore, pharmacological blockade of D1-like DA receptors in the NAcc rescued mating-induced partner preferences in AMPH-treated males. Together, our data indicate that repeated AMPH exposure may narrow the behavioral repertoire of male prairie voles via a DA receptor-specific mechanism in the NAcc, resulting in the impairment of pair bond formation.
To read some accounts of synthetic biology, the ability to manipulate life seems restricted only by the imagi- nation. Researchers might soon program cells to produce vast quantities of biofuel from renewable sources, or to sense the presence of toxins, or to release precise quantities of insulin as a body needs it — all visions inspired by the idea that biologists can extend genetic engineering to be more like the engineering of any hardware. The for- mula: characterize the genetic sequences that perform needed functions, the ‘parts’, com- bine the parts into devices to achieve more complex functions, then insert the devices into cells. As all life is based on roughly the same genetic code, synthetic biol- ogy could provide a toolbox of reusable genetic compo- nents — biological versions of transistors and switches — to be plugged into circuits at will.
There are mathematically advanced ways to weigh and pool scientific advice. They should be used more to quantify uncertainty and improve decision-making.
Book review of The Language of Life: DNA and the Revolution in Personalized Medicine by Francis Collins.
Biologists have assumed that natural selection shapes larger patterns of evolution through interactions such as competition and predation. These patterns may instead be determined by rare, stochastic speciation.
Both biosociological and psychological models, as well as animal research, suggest that testosterone has a key role in social interactions. Evidence from animal studies in rodents shows that testosterone causes aggressive behaviour towards conspecifics. Folk wisdom generalizes and adapts these findings to humans, suggesting that testosterone induces antisocial, egoistic, or even aggressive human behaviours. However, many researchers have questioned this folk hypothesis, arguing that testosterone is primarily involved in status-related behaviours in challenging social interactions, but causal evidence that discriminates between these views is sparse. Here we show that the sublingual administration of a single dose of testosterone in women causes a substantial increase in fair bargaining behaviour, thereby reducing bargaining conflicts and increasing the efficiency of social interactions. However, subjects who believed that they received testosterone-regardless of whether they actually received it or not-behaved much more unfairly than those who believed that they were treated with placebo. Thus, the folk hypothesis seems to generate a strong negative association between subjects’ beliefs and the fairness of their offers, even though testosterone administration actually causes a substantial increase in the frequency of fair bargaining offers in our experiment.
Testosterone’s ‘bad guy’ image is rooted in folklore, not fact.
New report shows how a decade of investment in science and technology has moved the world’s most populous nation into the front ranks on key global indicators.
The ability to self-optimize is one of the fundamental properties of living organ- isms. Adaptive self-optimization in the course of biological evolution is an obvi- ous phenomenon, although it occurs on a time scale of millions of years. On page 439 of this issue, Tero et al. (1) describe a model system where self-optimization of cell morphology in response to a chosen experimental situation can be directly observed and mathematically quantified as it occurs on a time scale of hours to a few days. These living cells display adap- tive behavior of the sort that may be desired for scalable, multicomponent networks that are supposed to function robustly in the absence of central control mechanisms. Self-organization, self-optimization, and self-repair as it naturally occurs in the slime mold Physarum polyceph- alum are capabilities that may be required for technological systems such as mobile commu- nication networks or networks of dynamically connected computational devices.
Transport networks are ubiquitous in both social and biological systems. Robust network performance involves a complex trade-off involving cost, transport efficiency, and fault tolerance. Biological networks have been honed by many cycles of evolutionary selection pressure and are likely to yield reasonable solutions to such combinatorial optimization problems. Furthermore, they develop without centralized control and may represent a readily scalable solution for growing networks in general. We show that the slime mold Physarum polycephalum forms networks with comparable efficiency, fault tolerance, and cost to those of real-world infrastructure networks–in this case, the Tokyo rail system. The core mechanisms needed for adaptive network formation can be captured in a biologically inspired mathematical model that may be useful to guide network construction in other domains.
Dynamic aspects of interactions between astrocytes, neurons and the vasculature have recently been in the neuroscience spotlight. It has emerged that not only neurons but also astrocytes are organized into networks. Whereas neuronal networks exchange information through electrical and chemical synapses, astrocytes are interconnected through gap junction channels that are regulated by extra- and intracellular signals and allow exchange of information. This intercellular communication between glia has implications for neuroglial and gliovascular interactions and hence has added another level of complexity to our understanding of brain function.
Sleep has been identified as a state that optimizes the consolidation of newly acquired information in memory, depending on the specific conditions of learning and the timing of sleep. Consolidation during sleep promotes both quantitative and qualitative changes of memory representations. Through specific patterns of neuromodulatory activity and electric field potential oscillations, slow-wave sleep (SWS) and rapid eye movement (REM) sleep support system consolidation and synaptic consolidation, respectively. During SWS, slow oscillations, spindles and ripples – at minimum cholinergic activity – coordinate the re-activation and redistribution of hippocampus-dependent memories to neocortical sites, whereas during REM sleep, local increases in plasticity-related immediate-early gene activity – at high cholinergic and theta activity – might favour the subsequent synaptic consolidation of memories in the cortex.
Rarely in the history of neuroscience has a single illustration been as influential as the cytoarchitectonic map of the human brain published by Korbinian Brodmann in his monograph from 1909. The map presents the segregation of the cerebral cortex into 43 areas, as visible in cell body-stained histological sections. More importantly, Brodmann provided a comparative neuroanatomical approach and discussed ontogenetic and pathological aspects as well as structural-functional correlations. One hundred years later, a large number of neuroscientists still use Brodmann’s map for localizing neuroimaging data obtained in the living human brain.
The growing uses of deep brain stimulation for various basal ganglia (BG) abnormalities have reinforced the need to better understand its functional circuitry and organization. Here we focus on cortico-basal-ganglia pathways to test the “parallel, segregated” versus “funneling, integrated” theories. Using manganese-enhanced MRI (MEMRI) together with principal component spatiotemporal analysis, we previously described two patterns of caudomedial striatum efferent connectivity to the substantia nigra pars reticulata (SNr) that were hypothesized to represent the coexistence of integrated and segregated processes. These patterns corresponded to a direct mono-synaptic projection to the dorsolateral core of the SN and to a di-synaptic projection covering the entire nucleus. In the current study, MEMRI of the rostrolateral striatum was carried out to test whether this coexistence remains in the mirror pathway, by measuring rostrolateral striatum efferent connectivity that is known to connect to the ventromedial SNr. Only one spatiotemporal pattern of manganese accumulation, corresponding to projections from the striatum, was observed. It corresponds to a mono-synaptic projection to the ventromedial SNr covering SNr laminas, but no manganese was observed at the dorsolateral SNr core. Together with our previous findings, this suggests functional asymmetry along the SNr which is consistent with the known anatomical organization of dendrite and axonal 3D arborization. Consequently, the polarized connectivity along the dorsolateral-ventromedial axis implies that funneling and integration occur in the core (dorsolateral SNr) to the lamina (ventromedial SNr) direction, whereas in the other direction, and within other parts of the SNr, segregation predominates.
Functional neuroimaging has evolved into an indispensable tool for noninvasively investigating brain function. A recent development of such methodology is the creation of connectivity models for brain regions and related networks, efforts that have been inhibited by notable limitations. We present a new method for ascertaining functional connectivity of specific brain structures using metaanalytic connectivity modeling (MACM), along with validation of our method using a nonhuman primate database. Drawing from decades of neuroimaging research and spanning multiple behavioral domains, the method overcomes many weaknesses of conventional connectivity analyses and provides a simple, automated alternative to developing accurate and robust models of anatomically-defined human functional connectivity. Applying MACM to the amygdala, a small structure of the brain with a complex network of connections, we found high coherence with anatomical studies in nonhuman primates as well as human-based theoretical models of emotive-cognitive integration, providing evidence for this novel method’s utility.
Independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) time-series reveals distinct coactivation patterns in the resting brain representing spatially coherent spontaneous fluctuations of the fMRI signal. Among these patterns, the so-called default-mode network (DMN) has been attributed to the ongoing mental activity of the brain during wakeful resting state. Studies suggest that many neuropsychiatric diseases disconnect brain areas belonging to the DMN. The potential use of the DMN as functional imaging marker for individuals at risk for these diseases, however, requires that the components of the DMN are reproducible over time in healthy individuals. In this study, we assessed the reproducibility of the DMN components within and between imaging sessions in 18 healthy young subjects (mean age, 27.5 years) who were scanned three times with two resting state scans during each session at 3.0T field strength. Statistical analysis of fMRI time-series was done using ICA implemented with BrainVoyager QX. At all three sessions the essential components of the DMN could be identified in each individual. Spatial extent of DMN activity and size of overlap within and between sessions were most reproducible for the anterior and posterior cingulate gyrus. The degree of reproducibility of the DMN agrees with the degree of reproducibility found with motor paradigms. We conclude that DMN coactivation patterns are reproducible in healthy young subjects. Therefore, these data can serve as basis to further explore the effects of aging and neuropsychiatric diseases on the DMN of the brain.
In many situations, decision makers need to negotiate between the competing demands of response speed and response accuracy, a dilemma generally known as the speed-accuracy tradeoff (SAT). Despite the ubiquity of SAT, the question of how neural decision circuits implement SAT has received little attention up until a year ago. We review recent studies that show SAT is modulated in association and pre-motor areas rather than in sensory or primary motor areas. Furthermore, the studies suggest that emphasis on response speed increases the baseline firing rate of cortical integrator neurons. We also review current theories on how and where in the brain the SAT is controlled, and we end by proposing research directions that could distinguish between these theories.
19) Schauer. Neuroscience, Lie-Detection, and the Law: Contrary to the prevailing view, the suitability of brain-based lie-detection for courtroom or forensic use should be determined according to legal and not scientific standards. Trends Cogn Sci (2010) pp.
The possibility of using neuroimaging to detect deception in legal settings has generated widespread resistance. Many neuroscientists insist the research is flawed science, containing weaknesses of reliability (the degree of accuracy), external validity (do laboratory results predict real-world outcomes), and construct validity (do studies test what they purport to test). These flaws are real, but although using neural lie-detection in non-experimental legal settings is premature, the critics are mistaken in believing that scientific standards should determine when these methods are ready for legal use. Law’s goals differ from science’s, and the legal suitability of neural lie-detection depends on legal standards and not those determining what good science is.
A free-energy principle has been proposed recently that accounts for action, perception and learning. This Review looks at some key brain theories in the biological (for example, neural Darwinism) and physical (for example, information theory and optimal control theory) sciences from the free-energy perspective. Crucially, one key theme runs through each of these theories – optimization. Furthermore, if we look closely at what is optimized, the same quantity keeps emerging, namely value (expected reward, expected utility) or its complement, surprise (prediction error, expected cost). This is the quantity that is optimized under the free-energy principle, which suggests that several global brain theories might be unified within a free-energy framework.
This article reviews a free-energy formulation that advances Helmholtz’s agenda to find principles of brain function based on conservation laws and neuronal energy. It rests on advances in statistical physics, theoretical biology and machine learning to explain a remarkable range of facts about brain structure and function. We could have just scratched the surface of what this formulation offers; for example, it is becoming clear that the Bayesian brain is just one facet of the free-energy principle and that perception is an inevitable consequence of active exchange with the environment. Furthermore, one can see easily how constructs like memory, attention, value, reinforcement and salience might disclose their simple relationships within this framework.
In Friston’s recent article , the structure of an agent’s world is taken to be represented by a ‘conditional density’, a probabilistic mapping from ‘causes’ to sensory stimu- lation. Friston argues that the brain can arrive at an approximation of this mapping by minimizing ‘free energy’, which is a function of sensory stimulation and brain states. A generative model of causal structure in the environment is then obtained, on which basis the agent is able to infer the ‘causes of sensory samples’ . What is unclear is how this mechanism would function when sensory samples are ambiguous. In general, there are multiple interpretations for the causes of any sensory data, and these cannot be resolved on the basis of inspecting the data alone .
Chris Thornton poses some simple but key questions about the free-energy principle reviewed in. These puzzles have simple and clear answer.
Behavioral analyses are a natural choice for understanding the wide-ranging behavioral consequences of racial stereotyping and prejudice. However, studies using neuroimaging and electrophysiological research have recently considered the neural mechanisms that underlie racial categorization and the activation and application of racial stereotypes and prejudice, revealing exciting new insights. Work that we review here points to the importance of neural structures previously associated with face processing, semantic knowledge activation, evaluation and self-regulatory behavioral control, enabling specification of a neural model of race processing. We show how research on the neural correlates of race can serve to link otherwise disparate lines of evidence on the neural underpinnings of a broad array of social-cognitive phenomena; we also consider the implications for effecting change in race relations.
Cognitive neurosciencists have recently begun to study self-consiousness and intersubjectivity but have not yet taken into account adequately the influence of culture on these phenomena. Here, we argue against the naïve inclusion of ‘culture’ as an additional independent factor that can be empirically addressed adequately merely by considering mother tongue or nationality. Instead, we propose that culture needs to be considered as a dynamical system of individuals; that culture is in continous dialectic interaction and exchange with the individuals that constitute it; and that cultural classifications feed back into social practices and identity processes, hence exhibiting a ‘looping effect’. These proposals have important implications for the development of cultural neuroscience.
It was suggested over 20 years ago that the supplementary motor cortex is involved in self-generated behaviour. Since then, there have been many studies using electrophysiology and brain imaging of the role of the supplementary motor cortex and anterior cingulate cortex. In the light of the findings, the proposal that these regions are crucial for self-generated action has recently been challenged. Here, we review the recent literature and argue that the proposal survives the findings. We further argue that it can be generalised to cover reflection on mental states. Finally, we suggest that the pattern of anatomical connections is consistent with the proposal that the medial frontal cortex is crucially involved in self-generated action and self-reflection.