Background: Recent evidence suggests that transcranial direct current stimulation (tDCS) may interact with the dopaminergic system to affect cognitive flexibility. Objective/hypotheses: We examined whether putative reduction of dopamine levels through the acute phenylalanine/tyrosine depletion (APTD) procedure and excitatory anodal tDCS of the dorsolateral prefrontal cortex (dlPFC) are causally related to cognitive flexibility as measured by task switching and reversal learning. Method: A double-blind, sham-controlled, randomised trial was conducted to test the effects of combining anodal tDCS and depletion of catecholaminergic precursor tyrosine on cognitive flexibility. Results: Anodal tDCS and tyrosine depletion had a significant effect on task switching, but not reversal learning. Whilst perseverative errors were significantly improved by anodal tDCS, the APTD impaired reaction times. Importantly, the combination of APTD and anodal tDCS resulted in cognitive performance which did not statistically differ to that of the control condition. Conclusions: Our results suggest that the effects of tDCS on cognitive flexibility are modulated by dopaminergic tone.
This paper explores the experience of a section of the stateless Tibetan exile community in India as they face urban displacement in New Delhi and Himachal Pradesh. Drawing on a comparative analysis of the Tibetan settlements of Majnu Ka Tilla (MT) in New Delhi and McLeodganj, Dharamshala HP, we map the various pathways they energise in the face of eviction orders from local Indian municipal authorities. While both are highly dense communities of Tibetan exiles, their experience of negotiating urban displacement is dissimilar. This obtains due to different institutional and participatory mechanisms available to them as communities of stateless urban residents.
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