Obesity is one of the major health problems of the world, and one of the most common surgical treatments is the Roux-en-Y gastric bypass surgery. This can however lead to problems with postprandial ...hypoglycemia, but sometimes, the meal test does not render any signs of hypoglycemia. Here, 3 cases are presented with postprandial normoglycemic hypokalemia.
Graphical abstract
The incidence of nativelikeness in adult second language acquisition is a controversial issue in SLA research. Although some researchers claim that any learner, regardless of age of acquisition, can ...attain nativelike levels of second language (L2) proficiency, others hold that attainment of nativelike proficiency is, in principle, impossible. The discussion has traditionally been framed within the paradigm of a critical period for language acquisition and guided by the question of whether SLA is constrained by the maturation of the brain. The work presented in this article can be positioned among those studies that have focused exclusively on the apparent counterexamples to the critical period. We report on a large‐scale study of Spanish/Swedish bilinguals (n = 195) with differing ages of onset of acquisition (<1–47 years), all of whom identify themselves as potentially nativelike in their L2. Listening sessions with native‐speaker judges showed that only a small minority of those bilinguals who had started their L2 acquisition after age 12, but a majority of those with an age of onset below this age, were actually perceived as native speakers of Swedish. However, when a subset (n = 41) of those participants who did pass for native speakers was scrutinized in linguistic detail with a battery of 10 highly complex, cognitively demanding tasks and detailed measurements of linguistic performance, representation, and processing, none of the late learners performed within the native‐speaker range; in fact, the results revealed also that only a few of the early learners exhibited actual nativelike competence and behavior on all measures of L2 proficiency that were employed. Our primary interpretation of the results is that nativelike ultimate attainment of a second language is, in principle, never attained by adult learners and, furthermore, is much less common among child learners than has previously been assumed.
Results from a number of recent studies suggest that nativelike adult second language (L2) learners possess a high degree of language learning aptitude, the positive effects of which may have ...compensated for the negative effects of a critical period in these learners. According to the same studies, child learners seem to attain a nativelike command of the L2 regardless of high or low aptitude, which has led researchers to conclude that this factor plays no role in early acquisition. The present study investigates the L2 proficiency and language aptitude of 42 near-native L2 speakers of Swedish (i.e., individuals whom actual mother-tongue speakers of Swedish believe are native speakers). The results confirm previous research suggesting that a high degree of language aptitude is required if adult learners are to reach a L2 proficiency that is indistinguishable from that of native speakers. However, in contrast to previous studies, the present results also identify small yet significant aptitude effects in child SLA. Our findings lead us to the conclusions that the rare nativelike adult learners sometimes observed would all turn out to be exceptionally talented language learners with an unusual ability to compensate for maturational effects and, consequently, that their nativelikeness per se does not constitute a reason to reject the critical period hypothesis.
Aims/hypothesis
Results from animal models and some clinical work suggest a role for the central nervous system (CNS) in glucose regulation and type 2 diabetes pathogenesis by modulation of ...glucoregulatory hormones and the autonomic nervous system (ANS). The aim of this study was to characterise the neuroendocrine response to various glucose concentrations in overweight and insulin-resistant individuals compared with lean individuals.
Methods
Overweight/obese (HI,
n
= 15, BMI ≥27.0 kg/m
2
) and lean (LO,
n
= 15, BMI <27.0 kg/m
2
) individuals without diabetes underwent hyperinsulinaemic euglycaemic–hypoglycaemic clamps and hyperglycaemic clamps on two separate occasions with measurements of hormones, Edinburgh Hypoglycaemic Symptom Scale (ESS) score and heart rate variability (HRV). Statistical methods included groupwise comparisons with Mann–Whitney
U
tests, multilinear regressions and linear mixed models between neuroendocrine responses and continuous metabolic variables.
Results
During hypoglycaemic clamps, there was an elevated cortisol response in HI vs LO (median ΔAUC 12,383 vs 4793 nmol/l × min;
p
= 0.050) and a significantly elevated adrenocorticotropic hormone (ACTH) response in HI vs LO (median ΔAUC 437.3 vs 162.0 nmol/l × min;
p
= 0.021). When adjusting for clamp glucose levels, obesity (
p
= 0.033) and insulin resistance (
p
= 0.009) were associated with elevated glucagon levels. By contrast, parasympathetic activity was less suppressed in overweight individuals at the last stage of hypoglycaemia compared with euglycaemia (high-frequency power of HRV,
p
= 0.024).
M
value was the strongest predictor for the ACTH and P
HF
responses, independent of BMI and other variables. There was a BMI-independent association between the cortisol response and ESS score response (
p
= 0.024). During hyperglycaemic clamps, overweight individuals displayed less suppression of glucagon levels (median ΔAUC −63.4% vs −73.0%;
p
= 0.010) and more suppression of sympathetic relative to parasympathetic activity (low-frequency/high-frequency power,
p
= 0.011).
Conclusions/interpretation
This study supports the hypothesis that altered responses of insulin-antagonistic hormones and the ANS to glucose fluctuations occur in overweight and insulin-resistant individuals, and that these responses are probably partly mediated by the CNS. Their potential role in development of type 2 diabetes needs to be addressed in future research.
Graphical abstract
Ever since Claude Bernards discovery in the mid 19th-century that a lesion in the floor of the third ventricle in dogs led to altered systemic glucose levels, a role of the CNS in whole-body glucose ...regulation has been acknowledged. However, this finding was later overshadowed by the isolation of pancreatic hormones in the 20th century. Since then, the understanding of glucose homeostasis and pathology has primarily evolved around peripheral mechanism. Due to scientific advances over these last few decades, however, increasing attention has been given to the possibility of the brain as a key player in glucose regulation and the pathogenesis of metabolic disorders such as type 2 diabetes. Studies of animals have enabled detailed neuroanatomical mapping of CNS structures involved in glucose regulation and key neuronal circuits and intracellular pathways have been identified. Furthermore, the development of neuroimaging techniques has provided methods to measure changes of activity in specific CNS regions upon diverse metabolic challenges in humans. In this narrative review, we discuss the available evidence on the topic. We conclude that there is much evidence in favor of active CNS involvement in glucose homeostasis but the relative importance of central vs. peripheral mechanisms remains to be elucidated. An increased understanding of this field may lead to new CNS-focusing pharmacologic strategies in the treatment of type 2 diabetes.
Research has consistently shown there is a negative correlation between age of onset (AO) of acquisition and ultimate attainment (UA) of either pronunciation or grammar in a second language (L2). A ...few studies have indeed reported nativelike behavior in some postpuberty learners with respect to either phonetics/phonology or morphosyntax, a result that has sometimes been taken as evidence against the critical period hypothesis (CPH). However, in the few studies that have employed a wide range of linguistic tests and tasks, adult learners have not exhibited nativelike L2 proficiency across the board of measures, which, according to some, suggests that the hypothesis still holds. The present study investigated the relationship between AO and UA and the incidence of nativelikeness when measures of phonetic and grammatical intuition are combined. An additional aim was to investigate whether children and adults develop the L2 through fundamentally different brain mechanisms—namely, whether children acquire the language (more) implicitly as an interdependent whole, whereas adults learn it (more) explicitly as independent parts of a whole.
This study aimed to characterize how the dysregulation of counter-regulatory hormones contribute to diabetes by investigating the association between insulin sensitivity and the glucose- and ...insulin-dependent secretion of glucagon, ACTH and cortisol in non-diabetic individuals using a population model analysis. Data, from hyperinsulinemic-hypoglycemic clamps, were pooled for analysis, including 52 individuals with a wide range of insulin resistance (reflected by glucose infusion rate 20-60 min; GIR20-60min). Glucagon secretion was suppressed by glucose and, to a lesser extent, insulin. The GIR20-60min and BMI were identified as predictors of the insulin effect on glucagon. At normoglycemia (5 mmol/L), a 90% suppression of glucagon was achieved at insulin concentrations 16.3 μU/mL and 43.4 μU/mL in individuals belonging to the highest and lowest quantiles of insulin sensitivity, respectively. Insulin resistance of glucagon secretion explained the elevated fasting glucagon for individuals with a low GIR20-60min. ACTH secretion was suppressed by glucose and not affected by insulin. The GIR20-60min was superior to other measures as a predictor of glucose-dependent ACTH secretion, with 90% suppression of ACTH secretion by glucose at 3.1 and 3.5 mmol/L for insulin-sensitive and insulin-resistant individuals, respectively. This difference may appear small but shifts the suppression range into normoglycemia for individuals with insulin resistance, thus, leading to earlier and greater ACTH/cortisol response when glucose falls. Based on modeling of pooled glucose-clamp data, insulin resistance was associated with generally elevated glucagon and a potentiated cortisol-axis response to hypoglycemia, and over time both hormonal pathways may therefore contribute to dysglycemia and possibly type 2 diabetes.
On the basis of their review of studies, Mayberry and Kluender (2017) propose that the human language learning ability becomes severely compromised if it is not developed in tandem with brain ...development in early childhood, but that it functions more or less flawlessly, even in adulthood, if language acquisition had at one time proceeded according to the maturational timetable. Mayberry and Kluender therefore suggest that the critical period hypothesis (CPH) for language is unambiguously tied to the timing of L1 acquisition, but that its relevance to L2 acquisition is less clear, the implication being that the well-documented AoA effects in the SLA literature are due to non-maturational (i.e., psychological, experiential, cross-linguistic, etc.) causes.
Abstract
In most event-related potential (ERP) studies on the second language (L2) processing, the native speaker (L1) control group’s grand average ERP pattern serves as the ‘gold standard’ that the ...L2 group has to reach to be labeled ‘native-like’. This relies on the assumption that the grand average is representative of all or most individuals in a group. Recent research, however, has shown that there can be considerable systematic qualitative variability between individuals even in coherent L1 samples, especially in studies on morphosyntactic processing. We discuss how these qualitative individual differences can undermine previous findings from the gold standard paradigm, and critically assess the main ERP components used as markers for nativelike grammatical processing, namely the left-anterior negativity and the P600. We argue that qualitative variation reflects the dynamics characteristic of nativelike grammatical processing and propose a model for experimental designs that can capture these processing dynamics and, thereby, has the potential to provide a more fine-grained understanding of nativelike attainment in an L2.
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