Testing the Asymmetric Inhibition Model: Frontal EEG Asymmetry Does Not Predict Inhibitory Control of Emotional Distractors

<p>Frontal electroencephalographic (EEG) asymmetry is a reliable marker of psychopathology vulnerability, yet the mechanisms underlying this relationship remain unclear. There is accumulating evidence that frontal asymmetry reflects individual differences in ability to use cognitive control to regulate emotional processing. This thesis provides the first test of the asymmetric inhibition model (Grimshaw & Carmel, 2014), which holds that frontal asymmetry reflects ability to engage valence-specific inhibitory control mechanisms supported by dorsolateral prefrontal cortex (dlPFC): left dlPFC inhibits negative distractors and right dlPFC inhibits positive distractors. Frontal asymmetry was tested as a predictor of ability to inhibit distracting emotional images. Frontal asymmetry was measured at rest and during emotional challenge, which is argued to provide a more powerful measure of individual differences (capability model; Coan, Allen, & McKnight, 2006). Emotional challenge was induced using a stressful serial subtraction task, verified to be effective in Study 1, followed by a silent speech preparation task, during which EEG was recorded. An irrelevant distractor paradigm measured ability to inhibit emotional distraction; participants identified a target letter within a central symbol array while attempting to inhibit positive, negative and neutral peripheral images (Study 2). Overall, positive and negative images were more distracting than neutral images. Critically, neither resting nor emotional challenge frontal asymmetry predicted distraction by positive, negative or neutral images, suggesting that frontal asymmetry does not reflect ability to inhibit irrelevant emotional distractors. Thus, the asymmetric inhibition model was not supported. This thesis provides the first direct test of the relationship between frontal EEG asymmetry and inhibitory control of emotion, paving the way for future explorations into this relationship. These findings add to a growing literature attempting to elucidate the cognitive mechanisms underlying frontal asymmetry in order to better understand the etiology of psychopathology.</p>

Testing the Asymmetric Inhibition Model: Frontal EEG Asymmetry Does Not Predict Inhibitory Control of Emotional Distractors

<p>Frontal electroencephalographic (EEG) asymmetry is a reliable marker of psychopathology vulnerability, yet the mechanisms underlying this relationship remain unclear. There is accumulating evidence that frontal asymmetry reflects individual differences in ability to use cognitive control to regulate emotional processing. This thesis provides the first test of the asymmetric inhibition model (Grimshaw & Carmel, 2014), which holds that frontal asymmetry reflects ability to engage valence-specific inhibitory control mechanisms supported by dorsolateral prefrontal cortex (dlPFC): left dlPFC inhibits negative distractors and right dlPFC inhibits positive distractors. Frontal asymmetry was tested as a predictor of ability to inhibit distracting emotional images. Frontal asymmetry was measured at rest and during emotional challenge, which is argued to provide a more powerful measure of individual differences (capability model; Coan, Allen, & McKnight, 2006). Emotional challenge was induced using a stressful serial subtraction task, verified to be effective in Study 1, followed by a silent speech preparation task, during which EEG was recorded. An irrelevant distractor paradigm measured ability to inhibit emotional distraction; participants identified a target letter within a central symbol array while attempting to inhibit positive, negative and neutral peripheral images (Study 2). Overall, positive and negative images were more distracting than neutral images. Critically, neither resting nor emotional challenge frontal asymmetry predicted distraction by positive, negative or neutral images, suggesting that frontal asymmetry does not reflect ability to inhibit irrelevant emotional distractors. Thus, the asymmetric inhibition model was not supported. This thesis provides the first direct test of the relationship between frontal EEG asymmetry and inhibitory control of emotion, paving the way for future explorations into this relationship. These findings add to a growing literature attempting to elucidate the cognitive mechanisms underlying frontal asymmetry in order to better understand the etiology of psychopathology.</p>

In vitro inhibitory effect of obtusofolin on the activity of CYP3A4, 2C9, and 2E1

Background Obtusofolin is the major active ingredient of Catsia tora L., which possesses the activity of improving eyesight and protecting the optic nerve. Investigation on the interaction of obtusofolin with cytochrome P450 enzymes (CYP450s) could provide a reference for the clinical application of obtusofolin. Methods The effect of obtusofolin on the activity of CYP450s was investigated in the presence of 100 μM obtusofolin in pooled human liver microsomes (HLMs) and fitted with the Lineweaver–Burk plots to characterize the specific inhibition model and kinetic parameters. Results Obtusofolin was found to significantly inhibited the activity of CYP3A4, 2C9, and 2E1. In the presence of 0, 2.5, 5, 10, 25, 50, and 100 μM obtusofolin, the inhibition of these CYP450s showed a dose-dependent manner with the IC50 values of 17.1 ± 0.25, 10.8 ± 0.13, and 15.5 ± 0.16 μM, respectively. The inhibition of CYP3A4 was best fitted with the non-competitive inhibition model with the Ki value of 8.82 μM. While the inhibition of CYP2C9 and 2E1 was competitive with the Ki values of 5.54 and 7.79 μM, respectively. After incubating for 0, 5, 10, 15, and 30 min, the inhibition of CYP3A4 was revealed to be time-dependent with the KI value of 4.87 μM− 1 and the Kinact value of 0.0515 min− 1. Conclusions The in vitro inhibitory effect of obtusofolin implying the potential drug-drug interaction between obtusofolin and corresponding substrates, which needs further in vivo validations.

Theoretical formulations and simulations of one-dimensional inhibition kinetics of ethanologenic microorganisms in batch fermenters

The utilization of bio-based technology for energy has piqued researchers' curiosity around the world. As a result, bioethanol fermentation has been a hot topic of research for many scientists since it uses less energy and chemicals, produces fewer harmful by-products and emissions, and has environmentally favorable applications. The modeling and simulations of one-dimensional product and substrate inhibitions for sorghum, maize, and cassava extracts are discussed in this paper. Because it provides an edge over other methodologies, mechanistic modeling techniques are used. Models of substrate and product inhibitions in one dimension (1-D) are constructed. These 1-D models are then confirmed using parameter estimates before being employed in the work's simulations. For each dynamic model constructed, model fitness coefficients (α) are calculated. For the product, the exponential inhibition model, sorghum extract data has the best model fitness coefficient (α = 0.4088), for product sudden stop inhibition model and cassava extract data gives the best model fitness coefficient ($$\alpha $$ α = 0.4417) for product exponential model. The projected yield increases for substrate exponential inhibition with sorghum extract data, substrate linear inhibition with maize extract data, and substrate linear inhibition with cassava extract data are 74%, 27%, and 25%, respectively. This unique framework has offered the industry a wide choice of kinetics models to choose from to alleviate inhibitions in fermentation systems and maximize yield and productivity in the bioethanol fermentation process. Article Highlights The modeling of inhibitions namely linear, sudden stop, and exponential in batch fermentation processes are presented in this article. Model fitness coefficient analysis showed the product as a primary inhibitor and substrate as a secondary inhibitor during the process The cassava and maize processes described linear inhibition model and sorghum fermentation showed exponential product inhibition model.