Causality Between the Amplitude and Frequency of Cardiac Oscillations

Using an information-theoretic approach, causality between the systolic amplitude in blood pressure and the frequency of the heart beat was analyzed. Blood pressure and ECG were noninvasively recorded in young, healthy subjects. Three successive measurements were performed: during spontaneous breathing and during paced respiration—at frequencies both higher and lower than that of spontaneous respiration. We demonstrate that the amplitude and frequency of the cardiac rhythm are synchronized for most of the time. The synchronization is stronger during paced respiration at a frequency lower than that of spontaneous breathing. Episodes where the cardiac frequency was driven by the systolic pressure were also detected during slow, paced respiration.     

The effects of Morinda citrifolia L. (noni) on the immune system: its molecular mechanisms of action

The aim of this study was to investigate the mechanisms involved in the immunomodulatory effects of Morinda citrifolia L. (noni) in vitro and in vivo in mice. In vitro, Tahitian Noni Juice (TNJ) and Noni fruit juice concentrates (NFJC) (1, 5mg/mL) potently activate cannabinoid 2 (CB2), but inhibit cannabinoid 1 (CB1) receptors in a concentration-dependant manner. In vivo, oral administration of TNJ ad libitum for 16 days decreased the production of IL-4, but increased the production of IFN-gamma. These results suggest that noni modulates the immune system via activating of the CB2 receptors, and suppressing of the IL-4, but increasing the production of IFN-gamma cytokines. It may also exert beneficial immunomodulation effects in conditions involving inadequate immune responses.     

Morinda citrifolia（Noni）：A literature review and recent advances in Noni research

Morinda citrifolia L(Noni) has been used in folk remedies by Polynesians for over 2000 years,and is reported to have a broad range of therapeutic effects,including antibacterial,antiviral,antifungal,antitumor,antihelmin,analgesic,hypotensive,anti-inflammatory,and immune enhancing effects.In order to reveal the nutritional and medicinal value of the Noni plant,and to summarize scientific evidence that supports the Polynesians‘ claim,a literature review and recent advances in Noni research is given below.     

Lipid--lipoprotein composition in hypercholesterolemic children and their parents.

In 13 hypercholesterolemic children, re-screened for serum cholesterol after a 1-year interval, hypercholesterolemia was confirmed in only 61.5% of the cases. A tentative explanation seems to be the statistical principle of regression towards the mean. The lipid--lipoprotein analysis showed that serum and LDL cholesterol concentrations in the 13 hypercholesterolemic children and their parents were significantly higher compared to controls (children and parents). At re-screening, hyper-LDL cholesterolemia was present in only 8 of the 13 children (61.5%); 4 cases exhibited hyper-HDL cholesterolemia (30.7%). The high prevalence of the parents repeating the lipoprotein abnormality and the electrophoretic pattern found in the propositi (children) confirms the familial aggregation of the hypercholesterolemic states (hyper-LDL and hyper-HDL cholesterolemia). In conclusion the results of our study stress the importance of determining the lipid--lipoprotein composition, rather then merely evaluating total serum cholesterol in order to make a correct diagnosis of the hypercholesterolemic state. It should also be emphasized that the lipoprotein disturbances and their familial aggregation may be detected early in childhood, suggesting that the familial screening for risk factors of atherosclerosis should be done at pediatric age.     

Effects of interventions on community awareness and treatment of hypertension: results of a WHO study

A WHO-coordinated study of the community control of hypertension in six countries (Cuba, Finland, France, Italy, Mongolia and Portugal) has shown that a comprehensive approach clearly improves the care of hypertensives in various populations. Hypertension control programmes were individually designed in each country and were implemented in defined communities. The intervention strategies varied between countries, the major components being: establishment of hypertension clinics and hypertension registers, involvement of health care personnel, and health education of the entire community. As a result of this programme, the blood pressure in the age group 30-59 years decreased on average by 3/2 mmHg among men and by 6/3.5 mmHg among women; the mean blood pressure level decreased twice as much in hypertensive subjects as in the entire population in the intervention areas of the study.     

Orthogonal neural codes for speech in the infant brain

Creating invariant representations from an everchanging speech signal is a major challenge for the human brain. Such an ability is particularly crucial for preverbal infants who must discover the phonological, lexical, and syntactic regularities of an extremely inconsistent signal in order to acquire language. Within the visual domain, an efficient neural solution to overcome variability consists in factorizing the input into a reduced set of orthogonal components. Here, we asked whether a similar decomposition strategy is used in early speech perception. Using a 256-channel electroencephalographic system, we recorded the neural responses of 3-mo-old infants to 120 natural consonant–vowel syllables with varying acoustic and phonetic profiles. Using multivariate pattern analyses, we show that syllables are factorized into distinct and orthogonal neural codes for consonants and vowels. Concerning consonants, we further demonstrate the existence of two stages of processing. A first phase is characterized by orthogonal and context-invariant neural codes for the dimensions of manner and place of articulation. Within the second stage, manner and place codes are integrated to recover the identity of the phoneme. We conclude that, despite the paucity of articulatory motor plans and speech production skills, pre-babbling infants are already equipped with a structured combinatorial code for speech analysis, which might account for the rapid pace of language acquisition during the first year.

A major, fundamental challenge for any brain is to build stable representations of a changing world. In particular regarding speech, the breadth of the human lexicon and its possibilities of morphemic composition are based on fine phonetic differences that undergo substantial acoustic restructuring depending on many contextual factors such as voice peculiarities, intonation, and coarticulation. Nonetheless, we effortlessly perceive “bog” and “dog” as steady and distinct words, no matter whether shouted by a little girl or whispered by an elderly man. The capacity to extract invariant neural representations from the extremely variable speech signal is essential for adults and even more crucial for infants, who must discover the organizing regularities of speech in order to acquire their native language. Yet, the neural underpinnings of such an ability remain underspecified.In the visual domain, recent findings, based on neuronal recordings during object (1) and face recognition (2), suggest that in order to deal with the large amount of incoming pictures, the brain factorizes the input into independent and orthogonal low-dimensional components, each coding for a different dimension of variation. For instance, faces may be decomposed into as little as 50 orthogonal dimensions, thus effecting a remarkable dimensional reduction (2). The components are thought to be subsequently recombined to yield unified percepts. Can such an account be applied to speech? Apart from any neural consideration, linguists have defined phonemes as bundles of a small set of orthogonal phonetic features, each corresponding to a binary code that summarizes an articulatory dimension and its acoustic correlates (3). For instance, the phonemes “b” and “d” from the example above share all parameters (+consonantal and −vocalic, +obstruent and −sonorant, +voiced, etc.) except for the place of articulation (+labial/−alveolar versus +alveolar/−labial). Given their linguistic characteristics (distinctive, minimal, and combinable), these features might correspond to the basic decomposition axes harnessed by the brain to reduce the high dimensionality of the speech input, thereby overcoming its variability.In the last years, high-resolution intracranial recordings on adults (4) and functional MRI (fMRI) adult data (5, 6) have provided evidence in line with this hypothesis: a partial neural specialization for phonetic features was observed during passive listening of speech. Here, we ask whether such a decomposition strategy is already present in early infancy.The first essential step for language acquisition consists in the identification of the native sound structure. Delineating the type of speech representations infants start with is thus crucial to elucidate how they can discover the phonetic repertoire and phonological grammar of their native tongue. A plethora of classical studies has demonstrated that infants come to the world with the perceptual abilities necessary to distinguish a variety of phonetic contrasts (refs. 7 to 9, among others). Moreover, both behavioral and neuroimaging researches have shown that, since birth, they spontaneously override the acoustic variability produced by changes in talker’s voice (10, 11), speaking rate (12, 13), and prosody (14). Interestingly, the type of perceptual constancy newborns exhibit corresponds precisely to that required to establish reliable links between speech sound differences and changes in meaning. Although remarkable, the early ability to detect minimal phonetic contrasts among syllables does not truly inform upon the nature of the underlying neural code: infants might either process utterances as integral wholes (e.g., in the form of broad spectro-temporal patterns organized around sonorous nuclei) or decompose them into smaller elements (e.g., phonemes or phonetic features).Behavioral investigations have shown that newborns and 2 mo olds fail at identifying a shared consonant in a group of syllables containing different vowels (15, 16). Furthermore, neonates proved capable of categorizing utterances using the number of their syllabic constituents but not the number of phonemes (17). Following these results, many authors have proposed the syllable as the primitive unit for speech processing. Computational modeling has corroborated the plausibility of this conclusion by showing that sonority-based syllable-like structures are indeed accessible, in conversational speech, by means of general auditory mechanisms (18). Currently, such kind of broad and holistic units is widely assumed to be the starting point for lexical learning when no linguistic knowledge is available.However, progress in neuroimaging has opened the way to new paradigms that, bypassing behavioral limitations, may uncover the existence of unexpectedly refined abilities early in development. Following the repetition of CV (consonant–vowel) syllables differing only in their vocalic component, electroencephalographic (EEG) recordings revealed that 3 mo olds could recognize the shared consonant and detect when it changed (19). They could even learn to associate each consonant to a visual shape independently of the vocalic surroundings (20). Such a finding, easily explicable in terms of sub-syllabic processing, prompts to reexamine the format of early speech representations.To this aim, we combined high-resolution EEG recordings with time-resolved multivariate pattern analysis. A total of 25 3-mo-old infants were exposed to 120 natural CV syllables presented in pseudorandom order during about 1 h. Syllables were chosen to independently vary the consonantal dimensions of manner (obstruent versus sonorant) and place of articulation (labial versus alveolar versus velar). Each consonant was coupled with two vowels (/i/ and /o/) and produced by a male and a female speaker in five distinct utterances to ensure acoustic and coarticulatory variability across tokens with the same phonetic profile (Fig. 1A). The dimensions of manner and place of articulation were chosen due to the highly contrasted levels of consistency characterizing their acoustic correlates: whereas manners are reflected in prominent spectro-temporal prototypes (21), the acoustic cues for place are more subtle (22) and complex (23), hence fundamentally dependent on the context of production (24). Such acoustical divergence was especially evident in the auditory similarity structure of our stimuli set, as illustrated in SI Appendix, Fig. S1.Open in a separate windowFig. 1.Experimental setup and average syllable-related potential. (A) Stimuli subconditions and their phonetic characteristics (f = female, m = male voice). (B) 256 channels super high-density net on a 3-mo-old infant: tight grids of custom electrodes are arranged over the auditory linguistic areas of the superior temporal lobe (see also SI Appendix, Fig. S2). (C) Grand average ERP: all conditions are pulled together.We used multivariate decoding analyses to investigate infant speech processing at three possible levels corresponding to holistic syllables, phonemes, and phonetic features.^* Linear classification algorithms are powerful tools in that they can combine multiple sources (here, EEG channels) to find the optimal combination of brain signals reflecting the variables of interest (25). Since any peculiarity in the data can be used to separate classes, showing that neural responses can be sorted according to certain labels, in itself, does not speak to the underlying encoding scheme. A key strategy in this regard consists in examining the pattern of generalization: how decoders trained in a particular context perform across variations that are expected to be nonpertinent for a given code (26). For instance, if infants extract speaker-invariant information, then decoders trained on the brain responses to syllables produced by the male voice are expected to generalize to the female voice (and vice versa). This logic was central to the purpose of the present study. We reasoned that, if consonants and vowels were processed separately, then a decoder trained in the context of, say, vowel “o,” should generalize to the context of the other vowel “i.” Conversely, such generalization should not be possible if each syllable was encoded by its own idiosyncratic neural code. At the subsyllabic level, we could ask whether a decoder trained to separate “bo” versus “do” is able to 1) correctly classify “mi” versus “ni,” thus revealing the presence a neural code for the places “labial” versus “alveolar” that is orthogonal to vowels and manners, or 2) generalize only to “bi” versus “di,” thus indicating an idiosyncratic and integrated neural code for the consonants “b” versus “d” without further decomposition into separable dimensions.In addition, by using time-resolved EEG signals, it is possible to train a distinct decoder at each time point to probe the presence of distinct patterns of generalization over time (27). By tracing the time course of generalizations and class confusability, we could ask whether and when particular pieces of information were recoded across stages of processing. A factorized encoding model, similar to that observed for faces (2), predicts an early projection of the signal into a small set of orthogonal dimensions followed by their integration into broader chunks (consonants/vowels or even entire syllables). The opposite decomposition process, progressing from holistic syllables to phonemes or/and features, is also imaginable.Decoding speech from noisy infant event-related potentials (ERPs) is a difficult task. To enable it, we recorded a large data set consisting of ∼3,100 trials/participant. Furthermore, we collected ERPs with a high-density custom net featuring an unusual number of 256 channels (Figs. 1B and SI Appendix, Fig. S2; see also Fig. 1C and Movie S1 for the grand average across all syllables and its sources). This intensive electrode coverage, combined with the thinness of infant skulls, should enhance the spatial resolution of our recordings and facilitate the discrimination of ERPs arising from spatially close neuronal clusters (28).     

Obesity,Type II diabetes and the Ala54Thr polymorphism of fatty acid binding protein 2 in the Tongan population

Genetic variation of fatty acid binding protein 2 (FABP2) may contribute to the high prevalence of obesity and Type II diabetes in Tonga. To explore this we assessed the frequency of the FABP2 Ala54Thr polymorphism, obesity, and Type II diabetes in Tongans and possible inter-relationships. We investigated 1022 Tongan subjects, 433 men and 589 women aged 15-85 years, to identify possible associations between the FABP2 Ala54Thr polymorphism, obesity, Type II diabetes, BMI, glucose tolerance and standard lipid variables. The prevalence of the polymorphism was compared with that reported for other ethnic populations (studies from: Japanese, Finnish, African American, Native Canadian and Inuit, Swedish, Guadeloupe Indians, European males, and Caucasian populations). We found that 84% of the Tongan men and 93% of the Tongan women were overweight or obese (BMI> or =25kg/m2). The mean BMI+/-SD was not significantly different among those who were and were not carrying the Thr allele (males: Ala/Ala 30.4+/-5.4 and Thr carriers 29.8+/-5.1; females: Ala/Ala 33.8+/-6.4 and Thr carriers 33.6+/-5.1). The genotype frequencies were 76.2% Ala/Ala, 22.8% Ala/Thr, and 1.0% Thr/Thr. The Alal/Ala frequency is higher than the prevalences reported for all populations studied. The Thr allele was significantly associated with lower total cholesterol and LDL cholesterol in both sexes and in women also with lower HDL cholesterol. We conclude that there is a high prevalence of the FABP2 Ala54Thr polymorphism in Tongans. The polymorphism may be involved in lipid metabolism as the Thr allele is associated with low total and LDL cholesterol levels in this population.