Challenging the hypothesis of oriented connectivity in West Africa: Containerization and changes in intra-regional connectivity

Ebola virus disease (EVD) is a complex zoonosis that is highly virulent in humans. The largest recorded outbreak of EVD is ongoing in West Africa, outside of its previously reported and predicted niche. We assembled location data on all recorded zoonotic transmission to humans and Ebola virus infection in bats and primates (1976–2014). Using species distribution models, these occurrence data were paired with environmental covariates to predict a zoonotic transmission niche covering 22 countries across Central and West Africa. Vegetation, elevation, temperature, evapotranspiration, and suspected reservoir bat distributions define this relationship. At-risk areas are inhabited by 22 million people; however, the rarity of human outbreaks emphasises the very low probability of transmission to humans. Increasing population sizes and international connectivity by air since the first detection of EVD in 1976 suggest that the dynamics of human-to-human secondary transmission in contemporary outbreaks will be very different to those of the past.DOI: http://dx.doi.org/10.7554/eLife.04395.001

Over the last 40 years, the question of the “African exception” has regularly come to the forefront in the discussion of fertility trends. In the 1980s, there was uncertainty about when fertility decline would commence throughout the region: while fertility was declining at a steady pace in Latin America and Asia, decline was evident in only a minority of sub-Saharan countries and, indeed, some countries showed fertility increase. As of the 1990s there was evidence of fertility decline in most countries of sub-Saharan Africa, and it appeared that sub-Saharan Africa was following the historical pattern of the other major regions. With a slow pace of fertility decline, or even stagnation at relatively high levels in various countries (Bongaarts 2008), the question of Africa's exceptionality has resurfaced. The fertility level in sub-Saharan Africa is the world's highest (5.1 children per woman versus 2.2 in Latin America and Asia in 2010–15; United Nations 2015a) (see Table 1). Compared with the experience of other world regions, sub-Saharan Africa stands apart not only in terms of fertility levels, but also with regard to a flatter age pattern due to longer birth intervals, the persistence of high ideal family size, and a low level of contraceptive use (Bongaarts and Casterline 2013). Sub-Saharan Africa also deviates from standard international patterns in terms of nuptiality. The traditional nuptiality regime has been defined by a particular combination of features, both for first marriage (early marriage for girls, a large age gap between spouses, almost universal marriage for both sexes) and for later conjugal life (polygamy, prompt and widespread remarriage for widowed and divorced women of childbearing age) (Lesthaeghe et al. 1989; United Nations 1988, 1990; van de Walle 1968). This dominant pattern existed with geographical differences, however, and also exceptions (especially Southern African countries). It has also been affected by significant changes over recent decades, especially through the increase in women's age at first union (Antoine 2006; Garenne 2004; Hertrich 2007; Lloyd 2005; Mensch, Grant, and Blanc 2006; Mensch, Singh, and Casterline 2005; Ortega 2014; Shapiro and Gebreselassie 2014; Westoff 2003), a narrowing gap between male and female age at marriage, and recent evidence of polygyny decline in Western Africa (Antoine and Marcoux 2014; Hertrich 2006). Despite these trends, sub-Saharan Africa still stands out in international comparisons both for the youngest age at first union for women and the largest age difference between spouses at first union (see Table 1). In 2010, the median age at first union was 21.2 years for women in sub-Saharan Africa, 1.4 years earlier than in Asia, and much earlier than in other parts of the world (25 to 28 years). Except in Southern Africa, the pattern is even earlier (20.3–20.5) at subregional levels, but it has an equivalent counterpart in the subregion of South Asia. The difference in age at union between males and females also remains significantly higher in Africa (5.5 years on average) than in the rest of the world, where the regional average is around 3 years or less. To what extent are these sub-Saharan fertility and nuptiality patterns bound up with each other? Are nuptiality changes part of the fertility transition? Is fertility decline possible in a context of early marriage? Is there empirical evidence of changes in age at marriage before or at the onset of the fertility transition? In this chapter I adopt a comparative approach to examining long-term trends in female age at marriage and fertility in sub-Saharan Africa, with a focus on continental countries having at least 1 million inhabitants. My database on nuptiality includes over 360 censuses and national surveys conducted in these 39 countries since the 1960s. I analyze the association between changes in age at first union and the onset of fertility transition, examining whether there is a typical pattern of association followed by most countries in the region. Questions about nuptiality changes in connection to the fertility transition are present in the classical literature on the demographic transition. The issue is of particular interest in sub-Saharan Africa, where the traditional marriage regime strongly supports high fertility. The idea that nuptiality change is part of the demographic transition was conceptualized in the 1960s. In Kingsley Davis's “theory of change and response” (1963), the restriction of nuptiality (through increases in age at marriage and/or in permanent celibacy) is, like emigration or limitation of marital fertility, one of the “multiphasic responses” to the sustained natural increase generated by mortality decline. Postponement of marriage is not a deliberate effort to reduce fertility; but, along with migration, it has often been a first collective response to demographic pressure, as it is easier to adopt than a restriction on marital fertility (United Nations 1990). Ansley Coale (1967, 1974) subsequently distinguished two steps in the fertility transition: first a “Malthusian transition” in which general fertility is lowered by the restriction of marriages; and, second, a “neo-Malthusian transition” in which a decrease in marital fertility resulted from the deliberate choice of couples to limit the number of their children. This two-step approach was later adopted by Jean-Claude Chesnais (1986) in his extensive work on demographic transition. Based on his assessment of the countries where fertility declined before the 1980s (i.e. excluding sub-Saharan Africa) and despite exceptions in Latin America, he concluded that nuptiality transition could be considered as a first step in the fertility transition across a large part of the world: “In all countries where there is appropriate statistical information, control of marriages preceded birth control by couples” (ibid., p. 381). More broadly, the robustness of this theory relies on a two-stage process where nuptiality change is a prelude to deliberate birth control; it acts as a regulator of general fertility but can occur before the sustained fertility decline that fixes the onset of fertility transition.1 The pronatalist nature of the traditional African nuptiality system has been widely documented2 and can be summarized by two aspects. First, it maximizes the span of a woman's reproductive life that is assigned to reproduction. Unlike pre-transitional Europe, where late marriage and permanent celibacy restricted the potential of fertility, in sub-Saharan Africa the traditional fertility-inhibiting factors operate mainly within marriage by means of the postpartum infecundability that results from long breastfeeding and postpartum abstinence (Page and Lesthaeghe 1981). A woman's life course is structured by marriage and reproduction: she is married at a young age; and if the marriage ends (through divorce or widowhood), she quickly remarries—at least while she is still of childbearing age. In the 1980s, the proportion of reproductive time spent out of union was usually below 20 percent (United Nations 1986), with an average of around 15 percent (Bongaarts, Frank, and Lesthaeghe 1984) and values below 10 percent in various Western African populations. Polygyny3 is one of the keys to the smooth running of this system, as it makes the marriage market more flexible. Indeed, in case of marital disruption, a woman can remarry rapidly without waiting for a single partner to become available (Locoh 2006; Hertrich 2006). The second aspect of the association between the nuptiality and high-fertility regimes is related to the organization of the conjugal unit and of gender relations. Institutional arrangements converge to limit the conjugal unit to its reproductive tasks and to impede conjugal intimacy and autonomous decision-making. The traditional marriage system largely contributes to building weak relationships between spouses and, therefore, to hindering the elaboration of common and independent fertility decisions (Caldwell 1982; Lesthaeghe 1980; Lesthaeghe et al. 1989; Mason 1993; National Research Council 1993; Ryder 1983). In addition large age gaps between spouses creates a distance between them as a result of the generational and cultural gap between the partners and reinforces the subordinate position of the wife. Polygyny and the high risk of marital disruption are other causes of a frail conjugal bond, because they create uncertainty and a climate of distrust between spouses (Antoine 2006; Hertrich and Locoh 1999). The weakness of the conjugal bond is seen as enhancing fertility through different paths. First, couples have little incentive to question normative behaviors when there is little privacy and opportunity for discussion between spouses. Husbands and wives usually have separate budgets and therefore little opportunity to discuss the full costs of childrearing (all the more so given that the costs of children are often spread across a larger family network). Second, the frailty of conjugal bonds provides women a powerful rationale for high fertility. In rural patrilineal societies, where women have limited access to land and economic assets, having children is a critical means to securing access to household resources and to consolidating their status in relation to husbands, in-laws, and possible co-wives. According to a recent study (Lambert and Rossi 2016), high fertility remains a strategy for women in the face of uncertainties and family rivalries in Senegal. According to these considerations, it makes sense to anticipate that fertility transition requires—or at least would be facilitated by—a loosening of traditional marriage patterns. Depending on the analytical approach, one can expect changes in nuptiality and fertility trends to be either simultaneous or sequential. The first case (simultaneity) refers to a direct, mechanical effect of nuptiality on fertility. It is conceptualized through the framework of the proximate determinants of fertility. At the population level, other things being equal, a decline in the time spent in union (i.e., having a regular sexual life) will lower fertility. Modeling fertility by using a large body of international data has confirmed nuptiality as one of the four key proximate determinants of fertility (the three others being contraception, postpartum infertility, and abortion) (Bongaarts 1978, 1992). According to this outline, the inhibiting effect of delayed nuptiality increases, on average, in the first stage of fertility transition, but the impact of contraception becomes dominant and much stronger as the fertility transition progresses (Bongaarts 1992). In some regions, like North Africa in the 1970s and the 1980s, the postponement of marriage was a leading cause of fertility decline (Westoff 1992; Ouadah-Bedidi and Vallin 2000). In sub-Saharan Africa, the picture is more mixed. Data and studies are fragmentary concerning the impact of nuptiality on fertility at the outset of the transition. Country-level studies usually provide evidence of changes in the age at first union at the onset of fertility decline. For Eastern and Southern Africa, Harwood-Lejeune (2001) estimates that one-sixth to one-third of the fertility declines in the 1980s and early 1990s is explained by rising age at marriage. Two recent large-scale comparative studies (Garenne 2014; Shapiro and Gebreselassie 2014) conclude that delayed marriage in most countries in the region had a small impact on fertility decline when compared to the overwhelming contribution of contraception. However, these studies examine long periods of time (comparing the results from the most recent DHS to those from the first available one or to the estimates at the onset of fertility decline); therefore, the possible effect of nuptiality at the onset of fertility decline is difficult to capture and is probably underestimated because it is diluted over time and superseded by the impact of contraception. In the second approach, nuptiality changes first—that is, before and possibly as a precursor to fertility decline. This is a possible scenario if the mechanical inhibiting effect of delayed nuptiality on fertility is counterbalanced by other changes, for instance if there is an increase in marital fertility. Here, the possible link between nuptiality and fertility decline does not necessarily have to be understood in a deterministic way: a single factor (for instance, increases in level of education) may both raise the age at marriage and increase contraceptive uptake. The general assumption is that the delay between later marriage and fertility decline corresponds to a period of change in the context of reproduction, especially in terms of increased individual autonomy and, possibly, conjugal autonomy. This type of scenario (delayed age at marriage without simultaneous fertility decline) has been considered for Africa by Chojnacka (1993, 1995). The comparative analysis of long-term trends in age at marriage and fertility throughout sub-Saharan Africa presented below will provide the opportunity to examine the occurrence of both scenarios. The objective here is to describe historical trends in age at first union and fertility and to examine the temporal relationship between the two trends, especially during the period around the beginning of fertility decline. Tracing long-term demographic trends across sub-Saharan Africa is difficult. Although the availability of data has increased significantly since the 1980s, the situation was previously fragmentary. The quality of data and the comparability between sources are additional obstacles to obtaining consistent series. One usual solution is to limit the analysis to a single source (for instance, using retrospective data from one survey or several surveys from the same program, such as the DHS). By contrast, the approach used here seeks to take into account all available national censuses and surveys since 1950. The objective is to extend as far as possible the time span considered and to increase the robustness of the data by taking advantage of cross-validation between sources. The cost, however, is that the statistical series are disconnected from other kinds of indicators. For instance, while indicators on nuptiality and fertility from the DHS could be linked with indicators on contraception, education, etc. (since they are computed from the same databases), this is not possible with the present series because they are derived from different sources and further harmonized. For fertility I use TFR series from the UN World Population Prospects (WPP), which are provided in 5-year periods since 1950 (UN 2015a). These series, which have been constructed by taking into account multiple sources and varying methods of estimation (Alkema et al. 2011, 2012), are certainly the most reliable data on African fertility. Unlike in the case of fertility, there are no ready-to-use harmonized data series on nuptiality, and a specific database was constructed. The indicator used is the median age at first union for women.4 Both series are available at the national level only. Most of the analysis focuses on continental sub-Saharan Africa and countries with at least 1 million inhabitants in 2010, a total of 39 countries. To examine trends in age at marriage, I use statistical tables on marital status by sex and age from INED's pan-African database on nuptiality (Hertrich 2007; Hertrich and Lardoux 2014) (see Appendix5). For the 39 countries considered here, the database includes 362 national censuses and surveys carried out since 1950—9.3 per country on average. These data are extensive enough to trace long-term trends in age at marriage since at least the 1970s for 31 countries, and since the 1960s for 24 countries. For 31 countries, the trends can be followed up to at least 2010; for 3 countries the data end between 2001 and 2005. Period estimates of age at first union were calculated from these cross-sectional data on marital status by sex and age using the approach proposed by Hajnal (Hajnal 1953; United Nations 1984). The series of proportions of never-married individuals by age can be equated with that of a theoretical cohort and summarized by a standard indicator such as mean age or median age at first marriage. I use the median age at first union rather than the singulate mean age at marriage (SMAM), which is difficult to interpret when nuptiality is changing. In sub-Saharan Africa (with the exception of Southern Africa), where marriage is nearly universal, occurs at young ages for women, and is concentrated within a narrow age range, the median age at first union captures the current pattern of nuptiality, which is that of the young cohorts (aged 15–24 years) reaching the age at marriage at the time of the survey. Precise information on age at first marriage is difficult to obtain because people in many African countries do not have good knowledge of ages and dates, and also because African marriage is often a process (rather than an event) involving various ceremonies and stages, and this leads to varying interpretations of the timing of entry into union (van de Walle 1968; Meekers 1992; Hertrich and Locoh 1999; Antoine et al. 2009; Hertrich 2013). The issue is especially important when using retrospective data and this leads to a preference for cross-sectional indicators (Lesthaeghe 1989; van de Walle 1968, 1993). Yet, errors may also arise with period data—for instance, concerning the marital status of women who have uncertain or transitional marital status. There may also be errors of age reporting, depending on women's marital status (with age transfer toward younger ages for never-married women, and toward later ages for married women) (Pullum 2006). Such distortions may be further exacerbated by the design of the survey or census (criteria of eligibility, status of the respondent, more inclusive approach to conjugal union by surveys as compared to censuses, lower coverage of unmarried women by surveys, etc.). Systematic evaluation that estimates of median age at first union in sub-Saharan Africa to be underestimated by individual surveys when compared to census data (Hertrich and Lardoux To take into account these between census and survey trends in median age at marriage were for each country to obtain harmonized series (see series were computed by between the or survey For the related to periods with estimates were when in to an The data on fertility are given by period and the series of fertility were computed by between the were to one A countries have or trends in nuptiality. This is especially the case for the African and and, to a and For of I the trends in these countries but I them to be I to changes in age at first union to the onset of fertility transition, the of the onset of fertility transition is Two One is to that fertility transition has when and fertility decline is a common (Bongaarts and Casterline Casterline is to the onset of fertility at the the TFR a level 10 percent below its The other approach (Alkema et al. the of fertility to sustained fertility decline as the onset of fertility transition. I that these two the period when fertility decline The of TFR could be as the (the of or early of fertility decline. I the for the when the TFR is 10 percent below the As fertility decline is slow in many African countries, the time between the two is usually years on average (see Table and one that fertility transition is confirmed when TFR is 10 percent lower than the historical is the only country still in a The comparative work on trends in African nuptiality, on a of censuses and surveys, was carried out in the early 1980s by Lesthaeghe and by van de Walle It showed an increase in women's age at first union but on the of such trends. Over the last 20 years, a number of studies extensive and often limited to retrospective have provided additional evidence on the increase in women's age at marriage (Garenne 2004; Hertrich 2007; Lloyd 2005; Mensch, Grant, and Blanc 2006; Mensch, Singh, and Casterline 2005; Ortega 2014; Shapiro and Gebreselassie 2014; and 2004; Westoff My data the change in first marriage patterns across the The pattern of early female which was a of the sub-Saharan nuptiality system, has been 1 and the toward later age at marriage spread to the during the last In the an early marriage pattern was The median age was below in most countries, with the exception of Southern Africa, where late marriage was the and to a extent some countries from and Eastern In the part of the during the the age at first marriage for women to increase By only a minority of countries in Western Africa) still had a median age at first marriage Over the following decades, the increase spread to much of Western Africa, and the pattern was confirmed in other regions. In the the early marriage that had been dominant years before had The one exception by was The standard is a median age over years at the beginning of conjugal and the years in a large number of countries. in women's age at first union and total fertility, UN for fertility; database on African nuptiality for median age at first trends in women's median age at first by country database on African nuptiality. The delay in women's first union has been a the assumption of a decline in age at first marriage in countries had from retrospective data (Garenne this is not by the cross-sectional Indeed, the only in which data a decrease or are those with In terms of geographical Southern Africa stands both because late marriage was common years and because age at marriage to increase rapidly in most countries. Except for median age at first marriage in most countries years and in some it The nuptiality pattern in Southern Africa a combination of late marriage for both significant of people who small gender difference in ages at marriage, marital low and low levels of polygyny and The of this marriage system has been in large part to widespread (especially in which and and more affected arrangements and between and women's and and high are as additional factors and 1989; and 2009; and 2013). is no longer considered to be the normative context for and fertility. and childbearing marriage are in North Africa are levels and trends in age at first union to those in Southern Africa in this and Vallin 2013). a median age at marriage for women age has been in other continental sub-Saharan countries, there are of increases in age at first marriage in each region: and in Africa, in Eastern Africa, and most countries in the of in Western Africa For Eastern and Africa, the general picture is that of a slow but regular increase in age at marriage from the 1970s to the the increase has since with a median age of around years in most countries. to be the region with the most traditional of African nuptiality, Western Africa, however, does not from the general pattern of the postponement of women's first marriage is in all these countries, but with in timing and pace of can be distinguished in the of to with and long-term changes since the the Western to where the increase in age at marriage usually in the and the countries to with but trends. countries in Western Africa increased during the last In the 1960s and all countries in the region a pattern of early marriage while the of is larger years). The of cross-sectional indicators provides a first into the relationship between fertility and patterns of age at marriage. As for the recent there is a between them the higher the median age at first marriage in the the lower the As on the the is between Southern Africa marriage is especially late and fertility and the countries fertility remains over children per woman and women at earlier A result is that the at the country level was weak in the the late 1980s, than one of the was by the In other the in fertility levels during the period not with the in ages at marriage. However, at when the fertility transition in the 1990s with between countries, the becomes as if nuptiality when things to In this nuptiality to be the as its pattern more with the fertility level 10 years later than with the level of the same To further the relationship and temporal between changes in nuptiality and fertility, I will in two by examining nuptiality in the period of early fertility second, by the time to the years the transition. decline in most sub-Saharan countries taking an average of years for a 10 percent decrease in with regional means from years Africa) to more than 15 years Africa) (see Table The period when fertility decline is by changes in nuptiality, in the of early marriage patterns in the countries where it was still the of fertility transition (the historical of fertility to sustained a median age at first marriage below was still dominant in Eastern Africa percent of the and widespread in Western Africa percent of the At the onset of fertility decline TFR is 10 percent below the this pattern a minority in both percent in Eastern Africa, percent in Western Africa) and even common in and Southern Africa, where it was In most of sub-Saharan Africa percent of the the median age at marriage years at the onset of fertility transition. According to these an early marriage pattern with a sustained fertility on countries with consistent there is no empirical evidence of fertility transition in a context where the median age at marriage was below age at the time of the the and the onset of fertility decline, most countries percent of the sub-Saharan a postponement in women's age at first marriage. only in Africa, where the fertility transition later in a context in which age at marriage was to 20 In contrast, the in age at marriage was in Western Africa, where early marriage was the what is the picture before the fertility For countries, the time series on age at marriage at least years before the of fertility decline (i.e., it possible to examine the between nuptiality and fertility over a larger time for each of these countries, the in the

Non-rapid eye movement (NREM) sleep is characterised by reduced consciousness; thus, studying its neural characteristics acts as a useful indication of what is needed for conscious experience. The integrated information theory (Tononi, 2008) states that the ability of different thalamocortical regions to interact is crucial for consciousness, thereby motivating research concerning connectivity changes in the thalamocortical system that accompany changing consciousness levels. This review aims to discuss investigations of functional connectivity of resting-state and large-scale brain networks, applying correlational approaches to neuroimaging data as well as studies that used brain stimulation to investigate effective connectivity. Most findings suggest a reorganisation of functional brain networks where inter-region connectivity is reduced and intra-region connectivity is stronger in deep sleep than wakefulness.

This paper focuses on a conundrum that has dominated the literature on pastoral mobility and institutions in dryland regions of the world, where livestock production is the main livelihood system. High spatiotemporal variability of rainfall and forage resources are seen to require flexible rules and porous social boundaries to facilitate pastoral mobility—characteristics that run counter to conventional views of the requirements for effective common property institutions. We seek to explore this paradox by investigating the spatiotemporal variability of forage availability (using satellite derived vegetation indices as a proxy for green forage) in four transhumance zones (“transhumance sheds”) in Mali, West Africa. For each transhumance shed, three characteristics with important institutional implications are evaluated over an eleven-year period between 2000 and 2010: the inter-annual variability of forage phenology, seasonal changes in connectivity of green forage patches, and the degree to which key forage locations exist in the form of consistently early green-up and/or late senescence. Periods of vegetation green-up and senescence, which determine the timing of transhumant livestock movements, are found to be sufficiently regular from year to year to be governed by conventional institutions. Seasonal changes in the north-south connectivity of green patches are sufficiently rapid for customary systems of sharing of pasture information to be effective (rather than more technologically sophisticated systems of pasture information). Moreover, transhumance sheds contain key pastoral forage sites, which because of their consistently early greening or late senescence, are strong candidates for territorial protection from alternative land uses such as agriculture. These findings support local herders’ views of transhumance as composed of regular patterns of herd movements along prescribed corridors between key pastoral sites. The seasonal regularity of key pastoral resources has been obscured by an overemphasis on environmental unpredictability that characterizes dryland systems at certain spatial and temporal scales. This paper suggests that policies directed at improving pastoral resource governance must focus instead on securing pastoralists’ access rights to movement corridors, specific pastures and water points.

This study investigates intra-regional connectivity and regional hemispheric asymmetry under two vigilance states: alertness and vigilance decrement. The vigilance states were induced on nine healthy subjects while performing 30 min in-congruent Stroop color-word task (I-SCWT). We measured brain activity using Electroencephalography (EEG) signals with 64-channels. We quantified the regional network connectivity using the phase-locking value (PLV) with graph theory analysis (GTA) and Support Vector Machines (SVM). Results showed that the vigilance decrement state was associated with impaired information processing within the frontal and central regions in delta and theta frequency bands. Meanwhile, the hemispheric asymmetry results showed that the laterality shifted to the right-temporal in delta, right-central, parietal, and left frontal in theta, right-frontal and left-central, temporal and parietal in alpha, and right-parietal and left temporal in beta frequency bands. These findings represent the first demonstration of intra-regional connectivity and hemispheric asymmetry changes as a function of cognitive vigilance states. The overall results showed that vigilance decrement is region and frequency band-specific. Our SVM model achieved the highest classification accuracy of 99.73% in differentiating between the two vigilance states based on the frontal and central connectivity networks measures.

As a process, containerization in Africa is still on-going. In the last decades, a number of new port projects have emerged in parallel with the reorganization of services by shipping companies. To reflect these changes, this paper studies several questions on the geographic differentiation of maritime connectivities across the continent as well as on the longitudinal trends in maritime connectivities in relation to evolving economic, trade and logistical contexts. To this end, we propose a synthetic visualization of the country-level containerized links using the Liner Shipping Bilateral Connectivity Indicator (LSBCI). The resulting graph, obtained through Multidimensional Scaling (MDS), shows that West Africa and East Africa appear as relatively separated subsystems, mediated by several countries in the Northern and the Southern parts of Africa. Between 2006 and 2016, West Africa, initially tied to Europe and America, is increasingly tied to Asia. Our results show major improvements in the maritime connectivity of Morocco, Djibouti and several West African ports. Conversely, most of mainland East African countries stagnate or decline. Connectivities have not converged across the continent. In some cases changes in maritime connectivity mostly result from variations in vessel size. We explore a method to identify these situations.

Functional connectivity is linked to several degenerative brain diseases prevalent in our aging society. Electrical stimulation is used for the clinical treatment and rehabilitation of patients with many cognitive disorders. In this study, the effects of high‐definition transcranial direct current stimulation (HD‐tDCS) on resting‐state brain networks in the human prefrontal cortex were investigated by using functional near‐infrared spectroscopy (fNIRS). The intrahemispheric as well as interhemispheric connectivity changes induced by 1 mA HD‐tDCS were examined in 15 healthy subjects. Pearson correlation coefficient‐based correlation matrices were generated from filtered time series oxyhemoglobin (ΔHbO) signals and converted into binary matrices. Common graph theory metrics were computed to evaluate the network changes. Systematic interhemispheric, intrahemispheric, and intraregional connectivity analyses demonstrated that the stimulation positively affected the resting‐state connectivity in the prefrontal cortex. The poststimulation connectivity was increased throughout the prefrontal region, while focal HD‐tDCS effects induced an increased rate of connectivity in the stimulated hemisphere. The graph theory metrics clearly distinguished the prestimulation and poststimulation networks for a range of thresholds. The results of this study suggest that HD‐tDCS can be used to increase functional connectivity in the prefrontal cortex. The increase in functional connectivity can be explored clinically for neurorehabilitation of patients with degenerative brain diseases.

The original mission of Black Studies is producing consciousness transforming knowledge, and teaching for social change in close connection with Black communities, not mimicking other disciplines in producing esoteric knowledge for establishment legitimacy in the academy. Two principal pillars for Black Studies curriculum theorizing and praxis have been: (a) knowledge making as (and for) consciousness transformation and (b) social change for (and as) Diaspora literacy knowledge making also refers to the ability to “read” various cultural signs as continuities in African-descended people’s experience. As a foundation for collective cultural agency, Heritage knowledge or group memory, refers to a repository or heritable legacy that makes a feeling of belonging, peoplehood, and communal solidarity as an outcome of education possible. Vèvè A. Clark, scholar of African and Caribbean literature, African American dance histories, and African diaspora theatre, coined the concept of Diaspora literacy in a 1984 paper analyzing allegory in Guadeloupean writer Maryse Condé’s novel, Hérémakhonon, which situated an Afro-Caribbean women’s identity quest in postcolonial West Africa. Clark later revised and expanded the concept to denote a narrator’s or reader’s ability to understand and/or interpret the multilayered meanings of stories, words, and other folk sayings within any given African diaspora community. Heritage knowledge takes the unjust system out of the center and puts the Africanity of group memory, the Black perspective, which is the cultural foundation that generates people’s collective cultural agency, at the center. While Heritage knowledge is a cultural birthright of every human being, the experience of Blackness as “ontological lack” obstructs and denies African people’s humanity and agency. These conceptual tools and revolutionary African-centered pedagogy provide opportunities for consciousness transforming education for Black liberation. Such theoretical concepts and praxis in Black Studies are neglected in curriculum theorizing discourse and praxis. This is so even though curriculum is viewed as racial text and reconceptualists focus on autobiography, subjectivity, identity, transformation, and more to define curriculum as a process (currere) not an object of study. Likewise, curriculum theorizing has yet to become an identifiable subfield within the transdiscipline of Black or Africana Studies, notwithstanding decades of institutionalizing curricula in higher education since the 1980s, including a National Council of Black Studies curriculum framework. Because African-descended people’s continent of origin and history, as well as Black children, their families, and teachers have been maligned in society, the radical introduction of African content in Afrocentric curriculum and pedagogy is needed to change the quality of education and to create new understanding of the racial politics of knowledge for all students and teachers. Revolutionary African-centered pedagogy aims to undo “twisted thinking” about Africa; challenge the oppressive educational system’s vision; defend students from self-hatred, and support agency for those who have been marginalized by hegemonic concepts, themes, and curricular ideas. The aim of examining relevant theoretical, epistemological, curriculum, and pedagogical developments in Black Studies and Black education scholarship is to clarify the meaning, significance, and implications of (a) African diaspora/s as a concept in education, political discourse, and method in Black Studies; (b) what deciphering Africanity in Diaspora literacy consciousness and Heritage knowledge reveals about the importance of the Black (Studies) perspective; and (c) revolutionary African-centered pedagogy as a philosophy and method of teaching for consciousness transformation.