Dissociation of prepotent response inhibition and interference control in problematic internet use: evidence from the Go/No-Go and Flanker tasks.

BACKGROUND: Problematic Internet Use (PIU), characterized by failures to control the overuse of internet, is associated with a range of functional impairments. However, there is limited research on the specific impact of PIU on inhibitory control functions, particularly in terms of differentiating between prepotent response inhibition and interference control. Therefore, the main objective of this study is to investigate these two components of inhibitory control in individuals with PIU. METHODS: Thirty participants who met the PIU criteria and 30 control participants were included in the present study. All participants completed the Go/No-Go and Flanker tasks, in which internet-related images and words were used as task stimuli. RESULTS: In the Go/No-Go task, all participants exhibited poorer performance in inhibiting internet-related stimuli compared to internet-unrelated stimuli, during the No-Go trials. In the Flanker task, results revealed a three-way interaction of Group, Stimulus type and Congruency. Specifically, in the incongruent condition, participants with PIU exhibited slower responses for internet-unrelated targets compared to internet-related targets, whereas no similar effect was observed among individuals with low internet use. CONCLUSIONS: The findings suggest that difficulties in controlling the interference effect of internet-related information represent a key dysfunction in inhibitory control of PIU.

Structural basis of agonist selectivity for different nAChR subtypes: insights from crystal structures, mutation experiments and molecular simulations.

Nicotinic acetylcholine receptors (nAChRs) are members of ligand gated ion channels (LGICs) which transduce chemical signal into electrical signal in neuron and neuromuscular junction. They are pentamerics which contain an extra-cellular domain (also known as ligand binding domain or LBD), a trans-membrane domain and a cytoplasmic domain (intra-cellular domain). Agonist binding to the extra-cellular domain invokes positive ion flux as well as action potential in neurons, muscle cells and endocrine cells whereas antagonist binding inhibits ion flux. There are various endogenous or exogenous compounds which behave as agonists or antagonists targeting nAChRs. During the last decades, the whole structure of muscle type nAChR as well as the crystal structures of acetylcholine-binding proteins (AChBPs) which are homologues of the nAChRs extra-cellular domain has been obtained. These structures, together with other studies including mutation experiments and molecular simulations, provide insights into both of the nAChR architecture and its agonist binding cavity. Our review gives detailed accounts of the recent progresses in order to gain insights into agonist selectivity for different nAChR subtypes.