Neural substrates of behavioral inhibitory control during the two-choice oddball task:functional neuroimaging evidence

Background:Behavioral inhibitory control(BIC)depicts a cognitive function of inhibiting inappropriate dominant responses to meet the context requirement.Despite abundant research into neural substrates of BIC during the go/no-go and stop signal tasks,these tasks were consistently shown hard to isolate neural processes of response inhibition,which is of primary interest,from those of response generation.Therefore,it is necessary to explore neural substrates of BIC using the two-choice oddball(TCO)task,whose design of dual responses is thought to produce an inhibition effect free of the confounds of response generation.Objective:The current study aims at depicting neural substrates of performing behavioral inhibitory control in the two-choice oddball task,which designs dual responses to balance response generation.Also,neural substrates of performing BIC during this task are compared with those in the go/no-go task,which designs a motor response in a single condition.Methods:The present study integrated go/no-go(GNG)and TCO tasks into a new Three-Choice BIC paradigm,which consists of stan-dard(75%),deviant(12.5%),and no-go(12.5%)conditions simultaneously.Forty-eight college students participated in this experiment,which required them to respond to standard(frequent)and deviant stimuli by pressing different keys,while inhibiting motor response to no-go stimuli.Conjunction analysis and ROI(region of interest)analysis were adopted to identify the unique neural mechanisms that subserve the processes of BIC.Results:Both tasks are effective in assessing BIC function,reflected by the significantly lower accuracy of no-go compared to standard condition in GNG,and the significantly lower accuracy and longer reaction time of deviant compared to standard condition in TCO.However,there were no significant differences between deviant and no-go conditions in accuracy.Moreover,functional neuroimaging has demonstrated that the anterior cingulate cortex(ACC)activation was observed for no-go vs.standard contrast in the GNG task,but not in deviant vs.standard contrast in the TCO task,suggesting that ACC involvement is not a necessary component of BIC.Second,ROI analysis of areas that were co-activated in TCO and GNG showed co-activations in the right inferior frontal cortex(triangle and orbital),with the signals in the TCO task significantly higher than those in the GNG task.Conclusions:These findings show that the designed responses to both standard and deviant stimuli in the TCO task,compared to the GNG task,produced a more prominent prefrontal inhibitory processing and extinguished an unnecessary component of ACC activation during BIC.This implies that prefrontal involvement,but not that of ACC,is mandatory for the successful performance of inhibiting prepotent behaviors.

Double emulsion-pretreated microwell culture for the in vitro production of multicellular spheroids and their in situ analysis

Multicellular spheroids have served as a promising preclinical model for drug efficacy testing and disease modeling.Many microfluidic tech no logies,in eluding those based on water-oil-water double emulsions,have been introduced for the production of spheroids.However,sustained culture and the in situ characterization of the gen erated spheroids are currently unavailable for the double emulsion-based spheroid model.This study presents a streamlined workflow,termed the double emulsion-pretreated microwell culture(DEPMiC),incorporating the features of(1)effective initiation of uniform-sized multicellular spheroids by the pretreatment of double emulsions produced by microfluidics without the requirement of biomaterial scaffolds;(2)sustained maintenance and culture of the produced spheroids with facile removal of the oil confinement;and(3)in situ characterization of individual spheroids localized in microwells by a built-in analytical station.Characterized by microscopic observations and Raman spectroscopy,the DEPMiC cultivated spheroids accumulated elevated lipid ordering on the apical membran巳similar to that observed in their Matrigel counterparts.Made possible by the proposed tech no logical advancement,this study subsequently examined the drug responses of these in vitro-generated multicellular spheroids.The developed DEPMiC platform is expected to gen erate health benefits in personalized cancer treatment by offering a pre-animal tool to dissect heterogeneity from individual tumor spheroids.

Demarcating the membrane damage for the extraction of functional mitochondria

Defective mitochondria have been linked to several critical human diseases such as neurodegenerative disorders,cancers and cardiovascular disease.However,the detailed characterization of mitochondria has remained relatively unexplored,largely due to the lack of effective extraction methods that may sufficiently retain the functionality of mitochondria,particularly when limited amount of sample is considered.In this study,we explore the possibility of modulating hydrodynamic stress through a cross-junction geometry at microscale to selectively disrupt the cellular membrane while mitochondrial membrane is secured.The operational conditions are empirically optimized to effectively shred the cell membranes while keeping mitochondria intact for the model mammalian cell lines,namely human embryonic kidney cells,mouse muscle cells and neuroblastoma cells.Unsurprisingly,the disruption of cell membranes with higher elastic moduli(neuroblastoma)requires elevated stress.This study also presents a comparative analysis of total protein yield and concentrations of extracted functional mitochondria with two commercially available mitochondria extraction approaches,the Dounce Homogenizer and the Qproteome®Mitochondria Isolation Kit,in a range of cell concentrations.Our findings show that the proposed“microscale cell shredder”yields at least 40%more functional mitochondria than the two other approaches and is able to preserve the morphological integrity of extracted mitochondria,particularly at low cell concentrations(5–20×10^(4) cells/mL).Characterized by its capability of rapidly processing a limited quantity of samples(200μL),demarcating the membrane damage through the proposed microscale cell shredder represents a novel strategy to extract subcellular organelles from clinical samples.