Increased Event-Related Potentials and Alpha-, Beta-, and Gamma-Activity Associated with Intentional Actions

Abstract

Objective: Internally guided actions are defined as being purposeful, self-generated and offering choices between alternatives. Intentional actions are essential to reach individual goals. In previous empirical studies, internally guided actions were predominantly related to functional responses in frontal and parietal areas. The aim of the present study was to distinguish event-related potentials and oscillatory responses of intentional actions and externally guided actions. In addition, we compared neurobiological findings of the decision which action to perform with those referring to the decision whether or not to perform an action.Methods: Twenty-eight subjects participated in adapted go/nogo paradigms, including a voluntary selection condition allowing participants to (1) freely decide whether to press the response button or (2) to decide whether they wanted to press the response button with the right index finger or the left index finger.Results: The reaction times were increased when participants freely decided whether and how they wanted to respond compared to the go condition. Intentional processes were associated with a fronto-centrally located N2 and P3 potential. N2 and P3 amplitudes were increased during intentional actions compared to instructed responses (go). In addition, increased activity in the alpha-, beta- and gamma-frequency range was shown during voluntary behavior rather than during externally guided responses.Conclusion: These results may indicate that an additional cognitive process is needed for intentional actions compared to instructed behavior. However, the neural responses were comparatively independent of the kind of decision that was made (1) decision which action to perform; (2) decision whether or not to perform an action).Significance: The study demonstrates the importance of fronto-central alpha-, beta-, and gamma oscillations for voluntary behavior.

Mediation Analysis for Censored Survival Data Under an Accelerated Failure Time Model

“…Interestingly, they note that the product method appeared to remain unaffected by right censoring, while the difference method underestimated the indirect effect in their simulation studies. 16 The results of our paper will provide the theoretical underpinning for the conclusions drawn from simulation studies by Tein and MacKinnon 9 and Gelfand et al 16 . We supply formal justification for their conjecture that the difference method will often fail to provide a consistent estimator of the indirect effect under an accelerated failure time model even when the product method does.…”

“…They cautioned that the estimated direct and indirect effects for a Cox proportional hazards model are based on a rare disease assumption, while the accelerated failure time model does not require such an assumption. 15 In a more recent paper, Gelfand et al 16 encourage the use of accelerated failure time models over Cox proportional hazards models in mediation analysis. A commonly noted drawback of the accelerated failure time model is that the event times are assumed to follow a specific distribution, but Gelfand et al 16 argue that the breadth of distributions available can capture the variability in survival data, and the Weibull distribution can represent distributions commonly found in clinical research.…”

“…In doing so, researchers may estimate the indirect effect either by the product or difference method, as the results by Tein and MacKinnon 9 and VanderWeele 8 may inadvertently lead one to incorrectly assume that both estimators are valid. However, Gelfand et al 16 demonstrate in simulation studies that in the presence of right censoring the product and difference estimators are not necessarily equivalent under a Weibull accelerated failure time model. Interestingly, they note that the product method appeared to remain unaffected by right censoring, while the difference method underestimated the indirect effect in their simulation studies.…”

Cognitive Remediation and Bias Modification Strategies in Mood and Anxiety Disorders

“…One study compared a working memory intervention incorporating verbal and visuospatial training versus a group CBT intervention in adolescents aged 11-14 with high anxiety and low attentional control. Overall, both groups showed improvements in anxiety symptoms, increased inhibitory control, and reduced attentional biases to threat at post-treatment with the working memory group demonstrating superior performance to the CBT group on working memory tasks[90]. The authors cite these findings as evidence that working memory training has similar advantages to traditional CBT[90].…”

“…Overall, both groups showed improvements in anxiety symptoms, increased inhibitory control, and reduced attentional biases to threat at post-treatment with the working memory group demonstrating superior performance to the CBT group on working memory tasks[90]. The authors cite these findings as evidence that working memory training has similar advantages to traditional CBT[90]. By contrast, Wanmaker et al[91] found that an adaptive working memory training was not beneficial in improving anxiety, depressive, and ruminative symptoms in anxious and depressed patients.…”