RESUMO
Background: The typology of word order in Hindi (Subject-Object-Verb, SOV) differs from that of English (Subject-Verb-Object, SVO). Bilinguals whose two languages have conflicting word order provide a unique opportunity to understand how word order affects language processing. Earlier behavioural and event-related brain potential (ERP) studies with Spanish-Basque bilinguals showed longer reading times and more errors in the comprehension of OSV sentences than SOV sentences in Basque language, indicating that non-canonical word orders (OSV) were difficult to process than canonical word order (SOV). Purpose: This study was designed to explore how the difference in word order in Hindi and English languages affects N400 parameters in proficient Hindi-English bilinguals, using semantic congruity paradigm. Methods: Twenty-five proficient Hindi-English bilingual subjects were asked to silently read the congruent and incongruent sentences presented in one word at a time in both the languages. ERPs were recorded from midline frontal, central and parietal sites. Results: The mean amplitude of the N400 effect at the parietal sites in Hindi-English proficient bilinguals was larger for English than for Hindi but there was no significant difference in the N400 latencies. Conclusion: Hindi-English bilingual subjects processed SOV and SVO sentences with equal ease as evidenced by the N400 latencies. Higher amplitude of the N400 effect with English sentences indicate that placing 'Object' as the final word makes sentences more predictable than verb as the final word. Understanding the word order difference might help to unravel the neurophysiological mechanisms of language comprehension and may offer some insights in terms of functional advantage of a particular word order in bilinguals.
RESUMO
Nearly one third of the population diagnosed with major depressive disorder (MDD) fail to respond to two or more antidepressant drugs of adequate dose and duration. This necessitates identification of confounding psychological and physiological factors that could contribute to treatment resistant depression (TRD). The present longitudinal study investigated the influence of behavioural inhibition system (BIS) and behavioural approach system (BAS) in treatment resistance. Further, the association of depression severity with physiological factors contributing to arterial stiffness was also investigated. Baseline data was acquired from 101 middle-aged (36-56 years) patients on immediate diagnosis with MDD using DSM-V criteria. Follow ups were conducted at 06 months and 12 months during treatment. Psychological assessment battery at baseline and follow ups comprised of Hamilton depression rating (HAM-D) for depression severity, WHODAS-2 and BIS-BAS score. Atherosclerosis and central arterial stiffness were measured by intima-media thickness of internal carotid artery and brachial-ankle pulse wave velocity. Physiological factors influencing central vascular function viz., body-mass index, estimated glomerular filtration rate, HbA1c, central systolic and diastolic blood pressure, heart rate and tetrahydrobiopterin were also investigated. Our results show lower reward responsiveness (BAS-RR) and higher BIS scores in TRD patients along with differentially higher intima-media thickness of left internal carotid artery. Higher depression severity at all stages of the study was correlated with lower tetrahydrobiopterin and BAS-RR scores. We, therefore, suggest that vascular depression resulting due to increased intima-media thickness of left carotid artery and lower tetrahydrobiopterin could be contributing factors for treatment resistance in middle-aged MDD patients.