Error-related brain potentials are differentially related to awareness of response errors: evidence from an antisaccade task

The error negativity (Ne/ERN) and error positivity (Pe) are two components of the event-related brain potential (ERP) that are associated with action monitoring and error detection. To investigate the relation between error processing and conscious self-monitoring of behavior, the present experiment examined whether an Ne and Pe are observed after response errors of which participants are unaware. Ne and Pe measures, behavioral accuracy, and trial-to-trial subjective accuracy judgments were obtained from participants performing an antisaccade task, which elicits many unperceived, incorrect reflex-like saccades. Consistent with previous research, subjectively unperceived saccade errors were almost always immediately corrected, and were associated with faster correction times and smaller saccade sizes than perceived errors. Importantly, irrespective of whether the participant was aware of the error or not, erroneous saccades were followed by a sizable Ne. In contrast, the Pe was much more pronounced for perceived than for unperceived errors. Unperceived errors were characterized by the absence of posterror slowing. These and other results are consistent with the view that the Ne and Pe reflect the activity of two separate error monitoring processes, of which only the later process, reflected by the Pe, is associated with conscious error recognition and remedial action.     

Between a hygiene rock and a hygienic hard place: Avoiding SARS-CoV-2 while needing environmental exposures for immunity

Suboptimal understanding of concepts related to hygiene by the general public, clinicians and researchers is a persistent problem in health and medicine. Although hygiene is necessary to slow or prevent deadly pandemics of infectious disease such as coronavirus disease 2019 (COVID-19), hygiene can have unwanted effects. In particular, some aspects of hygiene cause a loss of biodiversity from the human body, characterized by the almost complete removal of intestinal worms (helminths) and protists. Research spanning more than half a century documents that this loss of biodiversity results in an increased propensity for autoimmune disease, allergic disorders, probably neuropsychiatric problems and adverse reactions to infectious agents. The differences in immune function between communities with and communities without helminths have become so pronounced that the reduced lethality of severe acute respiratory syndrome coronavirus 2 in low-income countries compared to high-income countries was predicted early in the COVID-19 pandemic. This prediction, based on the maladaptive immune responses observed in many cases of COVID-19 in high-income countries, is now supported by emerging data from low-income countries. Herein, hygiene is subdivided into components involving personal choice versus components instituted by community wide systems such as sewage treatment facilities and water treatment plants. The different effects of personal hygiene and systems hygiene are described, and appropriate measures to alleviate the adverse effects of hygiene without losing the benefits of hygiene are discussed. Finally, text boxes are provided to function as stand-alone, public-domain handouts with the goal of informing the public about hygiene and suggesting solutions for biomedical researchers and policy makers.Lay Summary: Hygiene related to sewer systems and other technology can have adverse effects on immune function, and is distinct from personal hygiene practices such as hand washing and social distancing. Dealing with the drawbacks of hygiene must be undertaken without compromising the protection from infectious disease imposed by hygiene.     

High-altitude pulmonary edema

Lay summary: High Altitude Pulmonary Edema (HAPE) is a potentially fatal disease of altitude, in which the lungs can become filled with fluid. In this article we explore the mechanisms causing this condition and how it can be viewed as a condition of a mismatch between current environment and evolutionary experience.     

Error-related processing during a period of extended wakefulness

The nature of error detection as manifested by the error-related negativity was examined in both a Sternberg memory search task and a visual search task. Both tasks were performed in conditions with consistent or varied stimulus-response mapping and loads of three or six letters. After subjects were trained extensively in all conditions, they performed the tasks throughout the night without sleeping. The data suggest that the effectiveness of error detection decreases over time because of a decrease in the quality of perceptual processing. Error detection also suffers when performance requires more search-related resources. In both cases, the representation of the correct response is compromised. These results indicate that error detection depends on the same perceptual and cognitive processes that are required for correct performance.     

Electrophysiological indices of acute effects of ethanol on involuntary attention shifting

Dose-related effects of ethanol (placebo, 0.30, and 0.60 g/kg) on behavioral and event-related brain potential (ERP) indices of involuntary attention shifting of audition were investigated. ERPs were recorded from 11 healthy social drinkers during a forced-choice reaction-time (RT) task. Subjects were presented with 100 and 200 ms tones (P = 0.50 for each) with a constant inter-stimulus interval (ISI) of 1 s. The task was to press either of two buttons, depending on the tone duration. The majority of the tones (“standards”) were of 700 Hz (P = 0.82). Occasionally, however, the frequency of the tones changed, deviating either slightly (750 Hz), moderately (900 Hz), or widely (1200 Hz; P = 0.06 for each) from the standard frequency. In accordance with previous findings, the task-irrelevant frequency deviations prolonged the RT. This RT prolongation was attenuated by alcohol with the 0.3 g/kg dose, thus suggesting less distraction by irrelevant stimulus deviations under the influence of ethanol. Furthermore, the P3a, reflecting involuntary attention shifting, was suppressed by alcohol even with the 0.3 g/kg dose. These findings demonstrate a detrimental effect of alcohol on involuntary attention shifting, evident with doses considerably smaller than previously described, and still juridically acceptable in road traffic in most countries. Received: 19 December 1997/Final version: 26 May 1998     

Acute noise stress impairs feedback processing

We examined the impact of acute noise stress on the feedback-related negativity (FRN) and whether this effect depended on stressor predictability. Participants performed a gambling task in a silence and a noise condition with either predictable or unpredictable noise. FRN amplitude was measured in three ways, either neglecting (mean amplitude) or correcting for overlap with other components (base-to-peak; mean amplitude minus average mean amplitude of surrounding peaks). Notably, results differed between measures. Valence and magnitude both affected the FRN. These effects were additive on the mean amplitude and base-to-peak measures, but interactive on the mean amplitude corrected for both peaks measure. Acute noise stress specifically modulated valence and magnitude effects on the FRN, although evidence differed between measures as to whether valence and/or magnitude were processed differently. These findings indicate that acute stress impairs cognitive control by the anterior cingulate cortex. Stressor predictability added little to the explanation of effects.     

Negative bias in expression-related mismatch negativity(MMN) in remitted late-life depression: An event-related potential study

Negative bias in cognition is closely associated with susceptibility to recurrent episodes of depression. Given the high recurrence rate of depression, previous studies have focused on the attentive level in late-life depression (LLD), but depression relapse is difficult to detect as a lower chief complaint in elderly people. Facial expression mismatch negativity (EMMN) is a tool that can measure cognitive bias in pre-attentive processing. In this study, we sought to explore the cognitive bias in pre-attentive emotional information processing in LLD. Thirty patients with remitted LLD and 30 non-depressed, age- and gender-matched normal controls (NC) were enrolled in this study. Automatic emotional processing was elicited by using an expression-related oddball paradigm in all participants. There were no significant differences in N170 amplitude and latency between remitted LLD and NC. Compared with NC subjects, patients with remitted LLD demonstrated an attenuated mean amplitude of positive and negative EMMN, whereas the mean amplitude of negative EMMN in remitted LLD was much larger than that of positive EMMN. Our findings suggest that although basic processing of facial expressions is intact in remitted LLD, automatic processing of facial expressions in remitted LLD is impaired with a negative bias in cognition. Further investigation of the contributions of negative bias in EMMN to susceptibility to recurrence of LLD is warranted.     

Transcranial direct current stimulation of prefrontal cortex: An auditory event-related potential and proton magnetic resonance spectroscopy study

Transcranial direct current stimulation (tDCS) is a non-invasive intervention altering neural plasticity by modulating neuronal excitability of pre- and postsynaptic neuron populations, which has been shown to improve depression symptoms and cognition. We investigated the effects of a single session of 20 min of 2 mA left-prefrontal anodal versus sham stimulation on auditory event-related potentials (ERPs) in 11 male and 5 female healthy subjects (mean age of 28.6 [SD 6.2] years) by employing a randomized single-blind crossover design. Stimulation effects on cortical glutamate (Glu) and glutamine (Glx) levels were subsequently measured in 12 of the 16 healthy subjects in a 3 T proton magnetic resonance spectroscopy scan. tDCS was associated with a significant increase of N1 amplitudes while smaller P3b amplitudes correlated with higher cortical Glu and Glx levels in the stimulated brain area when performing an auditory go/no-go discrimination task. tDCS did not change mismatch negativity, nor task performance or cortical Glu/Glx levels which, together with N1 amplitudes, depended on stimulation order (“sham” versus “active”). Increased N1 amplitudes are consistent with higher levels of cortical excitability following prefrontal anodal tDCS. The failure to replicate Glu/Glx changes with tDCS may have been masked by between-session carry-over effects while ceiling effects may have masked tDCS effects on task performance.