Absence seizures are 5-10 s episodes of impaired consciousness accompanied by 3-4 Hz generalized spike-and-wave discharge on electroencephalography (EEG). The time course of functional magnetic resonance imaging (fMRI) changes in absence seizures in relation to EEG and behavior is not known. We acquired simultaneous EEG-fMRI in 88 typical childhood absence seizures from nine pediatric patients. We investigated behavior concurrently using a continuous performance task or simpler repetitive tapping task. EEG timefrequency analysis revealed abrupt onset and end of 3-4 Hz spike-wave discharges with a mean duration of 6.6 s. Behavioral analysis also showed rapid onset and end of deficits associated with electrographic seizure start and end. In contrast, we observed small early fMRI increases in the orbital/medial frontal and medial/lateral parietal cortex Ͼ5 s before seizure onset, followed by profound fMRI decreases continuing Ͼ20 s after seizure end. This time course differed markedly from the hemodynamic response function (HRF) model used in conventional fMRI analysis, consisting of large increases beginning after electrical event onset, followed by small fMRI decreases. Other regions, such as the lateral frontal cortex, showed more balanced fMRI increases followed by approximately equal decreases. The thalamus showed delayed increases after seizure onset followed by small decreases, most closely resembling the HRF model. These findings reveal a complex and long-lasting sequence of fMRI changes in absence seizures, which are not detectable by conventional HRF modeling in many regions. These results may be important mechanistically for seizure initiation and termination and may also contribute to changes in EEG and behavior.

Based on the authors’ long-term field research on low-skilled labor migration from China and Indonesia, this article establishes that more than ever labor migration is intensively mediated. Migration infrastructure – the systematically interlinked technologies, institutions, and actors that facilitate and condition mobility – serves as a concept to unpack the process of mediation. Migration can be more clearly conceptualized through a focus on infrastructure rather than on state policies, the labor market, or migrant social networks alone. The article also points to a trend of “infrastructural involution,” in which the interplay between different dimensions of migration infrastructure make it self-perpetuating and self-serving, and impedes rather than enhances people's migratory capability. This explains why labor migration has become both more accessible and more cumbersome in many parts of Asia since the late 1990s. The notion of migration infrastructure calls for research that is less fixated on migration as behavior or migrants as the primary subject, and more concerned with broader societal transformations.

Since the early 1980s, reduced migration control by the state and increasing economic liberalization in China have led to the movement of millions of peasants to the cities, creating various types of new “urban spaces” and “non-state spaces.” This influx has fundamentally changed the social, spatial and economic landscapes of the Chinese city, making the urban scene much more varied, lively and dynamic, but less safe and orderly than that of the Maoist era. Aside from the resulting expansion of city population, the Chinese city is also taking on some of the features common to other Third World cities, including the formation of migrant communities in both the cities and suburbs. In 1990, in the built-up areas of eight of China's largest cities, the “floating population” accounted for between 11.1 to 27.5 per cent of the total de facto urban population. At the same time, the urban population has also become much more diverse as peasants from different provinces group spontaneously in spatially distinct enclaves, producing a new urban mosaic that did not exist in Maoist China. Whereas some of enclaves are formed by non-Han minority groups, such as the two “Xinjiang villages” in Beijing where the Uygurs (more commonly but unofficially, “Uighurs”) from Xinjiang have congregated, most of them are formed by Han-Chinese. The Han peasant enclaves, however, are far from uniform in social structure, economic activity, population size or physical appearance.

This special issue takes the migrant broker as a starting point for investigating contemporary regimes of transnational migration across Asia. The articles, which span large parts of Asia-including China, Indonesia, Laos, Malaysia, Singapore, South Korea, Thailand, Vietnam, as well as New Zealand-show that marriage migration, student migration and various forms of unskilled labour migration, including predominantly male plantation and construction work and female domestic, entertainment and sex work, are all mediated by brokers. Although much is known about why migrants leave home and what happens to them upon arrival, considerably less is known about the forms of infrastructure that condition their mobility. A focus on brokers is one productive way of opening this "black box" of migration research. The articles in this issue are thus not primarily concerned with the experiences of migrants or in mapping migrant networks per se, but rather in considering how mobility is made possible and organized by brokers, most notably in the process of recruitment and documentation. Drawing from this evidence, we argue that in contrast to the social network approach, a focus on the migrant broker offers 1

No abstract

Impaired consciousness requires altered cortical function. This can occur either directly from disorders that impair widespread bilateral regions of the cortex or indirectly through effects on subcortical arousal systems. It has therefore long been puzzling why focal temporal lobe seizures so often impair consciousness. Early work suggested that altered consciousness may occur with bilateral or dominant temporal lobe seizure involvement. However, other bilateral temporal lobe disorders do not impair consciousness. More recent work supports a 'network inhibition hypothesis' in which temporal lobe seizures disrupt brainstem-diencephalic arousal systems, leading indirectly to depressed cortical function and impaired consciousness. Indeed, prior studies show subcortical involvement in temporal lobe seizures and bilateral frontoparietal slow wave activity on intracranial electroencephalography. However, the relationships between frontoparietal slow waves and impaired consciousness and between cortical slowing and fast seizure activity have not been directly investigated. We analysed intracranial electroencephalography recordings during 63 partial seizures in 26 patients with surgically confirmed mesial temporal lobe epilepsy. Behavioural responsiveness was determined based on blinded review of video during seizures and classified as impaired (complex-partial seizures) or unimpaired (simple-partial seizures). We observed significantly increased delta-range 1-2 Hz slow wave activity in the bilateral frontal and parietal neocortices during complex-partial compared with simple-partial seizures. In addition, we confirmed prior work suggesting that propagation of unilateral mesial temporal fast seizure activity to the bilateral temporal lobes was significantly greater in complex-partial than in simple-partial seizures. Interestingly, we found that the signal power of frontoparietal slow wave activity was significantly correlated with the temporal lobe fast seizure activity in each hemisphere. Finally, we observed that complex-partial seizures were somewhat more common with onset in the language-dominant temporal lobe. These findings provide direct evidence for cortical dysfunction in the form of bilateral frontoparietal slow waves associated with impaired consciousness in temporal lobe seizures. We hypothesize that bilateral temporal lobe seizures may exert a powerful inhibitory effect on subcortical arousal systems. Further investigations will be needed to fully determine the role of cortical-subcortical networks in ictal neocortical dysfunction and may reveal treatments to prevent this important negative consequence of temporal lobe epilepsy.

Purpose-Absence seizures cause transient impairment of consciousness. Typical absence seizures occur in children, and are accompanied by 3-4 Hz spike-wave discharges (SWD) on EEG. Prior EEG-fMRI studies of SWD have shown a network of cortical and subcortical changes during these electrical events. However, fMRI during typical childhood absence seizures with confirmed impaired consciousness has not been previously investigated.Methods-We performed EEG-fMRI with simultaneous behavioral testing in 37 children with typical childhood absence epilepsy. Attentional vigilance was evaluated by a continuous performance task (CPT), and simpler motor performance was evaluated by a repetitive tapping task (RTT).Results-SWD episodes were obtained during fMRI scanning from 9 patients among the 37 studied. fMRI signal increases during SWD were observed in the thalamus, frontal cortex, primary visual, auditory, somatosensory, and motor cortex, and fMRI decreases were seen in the lateral and medial parietal cortex, cingulate gyrus, and basal ganglia. Omission error rate (missed targets) with SWD during fMRI was 81% on CPT and 39% on RTT. For those seizure epochs during which CPT performance was impaired, fMRI changes were seen in cortical and subcortical structures typically involved in SWD, while minimal changes were observed for the few epochs during which performance was spared.Discussion-These findings suggest that typical absence seizures involve a network of corticalsubcortical areas necessary for normal attention and primary information processing. Identification

The cumulative effect of repetitive subconcussive collisions on the structural and functional integrity of the brain remains largely unknown. Athletes in collision sports, like football, experience a large number of impacts across a single season of play. The majority of these impacts, however, are generally overlooked, and their long-term consequences remain poorly understood. This study sought to examine the effects of repetitive collisions across a single competitive season in NCAA Football Bowl Subdivision athletes using advanced neuroimaging approaches. Players were evaluated before and after the season using multiple MRI sequences, including T1-weighted imaging, diffusion tensor imaging (DTI), arterial spin labeling (ASL), resting-state functional MRI (rs-fMRI), and susceptibility weighted imaging (SWI). While no significant differences were found between pre- and post-season for DTI metrics or cortical volumes, seed-based analysis of rs-fMRI revealed significant (p < 0.05) changes in functional connections to right isthmus of the cingulate cortex (ICC), left ICC, and left hippocampus. ASL data revealed significant (p < 0.05) increases in global cerebral blood flow (CBF), with a specific regional increase in right postcentral gyrus. SWI data revealed that 44% of the players exhibited outlier rates (p < 0.05) of regional decreases in SWI signal. Of key interest, athletes in whom changes in rs-fMRI, CBF and SWI were observed were more likely to have experienced high G impacts on a daily basis. These findings are indicative of potential pathophysiological changes in brain integrity arising from only a single season of participation in the NCAA Football Bowl Subdivision, even in the absence of clinical symptoms or a diagnosis of concussion. Whether these changes reflect compensatory adaptation to cumulative head impacts or more lasting alteration of brain integrity remains to be further explored.