Validity and reliability of electroencephalographic frontal alpha asymmetry and frontal midline theta as biomarkers for depression

Electroencephalographic (EEG) frontal alpha asymmetry (FAA) and frontal midline (FM) theta have been suggested as biomarkers for depression and anxiety, but have mostly been assessed in small and non‐clinical studies. In a clinical sample of 79 adults with depression (ICD‐10: F32), resting EEG and scales of depression (MADRS) and anxiety (HADS‐A) were measured at intake and after 3 months. FAA and FM theta values were referenced to a normative population database. Internal consistency, test‐retest reliability, and correlations with psychiatric tests were examined. Reliability was sufficient. However, FAA and FM theta values were close to the general population, and correlations with psychiatric tests were mostly small and non‐significant, with the exception of FAA on F7–F8 z‐scores and HADS‐A. We conclude that the validity of FAA and FM theta and therefore their potential as biomarkers for depression and anxiety remain unclear.     

The relationship between outcome prediction and cognitive fatigue: A convergence of paradigms

Cognitive fatigue is common after strenuous cognitive effort. A large body of literature has implicated a network of brain areas in fatigue, including the basal ganglia and cortical areas including ventro-medal prefrontal cortex and anterior cingulate cortex (ACC). Furthermore, the ACC has been shown to be involved in processes such as error and conflict monitoring, outcome prediction, and effort processing. Thus, the ACC appears to be one common denominator between clinical work on fatigue and research on outcome prediction and effort. In the present study, we examined whether the same region of the ACC is activated during the processing of errors and fatigue. Cognitive fatigue was induced by having subjects perform a difficult working memory task, during which they rated on-task fatigue. Activation associated with error processing was determined by using error trials on the working memory task. After localizing the region engaged in error processing, we evaluated whether there was a relationship between BOLD activation of that region and on-task fatigue scores. The results showed that as subjects became more fatigued, they responded with longer latencies and increased accuracy for the more difficult task. Moreover, the ACC areas that were activated by error processing were also associated with fatigue. These results suggest that cognitive fatigue may be related to changes in effort and reward. We speculate that as the brain detects these changes, cognitive fatigue is generated as a way for the brain to signal itself that the effort required for the task no longer merits the rewards received for performing it.     

Are there control processes,and (if so) can they be studied?

Generally, so-called control processes are thought to be necessary when we must perform one out of several competing actions. Some examples include performance of a less well-practiced action instead of a well-practiced one (prepotency); learning a new action (novelty); and rapidly switching from one action to another (task-switching). While it certainly is difficult to perform the desired action in these circumstances, it is less clear that a separate set of processes (e.g., control processes) are necessary to explain the observed behavior. Another way to approach the study of control processes is to investigate physiological dependent measures (e.g., electrophysiological or neuroimaging measures). Although these offer another avenue of inquiry into control processes, they have yet to furnish unambiguous evidence that control processes exist. While this might suggest that there are no control processes, it is also possible that our methods are insufficiently sensitive to measure control processes. We have investigated this latter possibility using tasks that are neuroanatomically distinct, though within the same modality (vision). This approach did not yield evidence for a separable set of control processes. However, recent works using a task-switching paradigm in which subjects switch between a visual and an auditory task suggest that switching both task and modality may be importantly different than switching task within a given modality. This may represent a way forward in the study of control processes.     

Facing the Pariah of Science: The Frankenstein Myth as a Social and Ethical Reference for Scientists

Science and Engineering Ethics - Since its first publication in 1818, Mary Shelley’s Frankenstein; or, The Modern Prometheus has transcended genres and cultures to become a foundational myth...     

毛泽东、陈伯达和"马克思主义中国化"(1936-1938)

导言1938年毛泽东倡导的“马克思主义中国化”依然是中国共产党意识形态史上最有吸引力的话题之一。奇怪的是,虽然这个概念在大量的中国共产主义运动研究中受到过短暂的关注,但几乎没有被置于细致入微的历史和理论分析。①大致而言,这个概念包含两个相互独立又密切相关的维度。