No abstract

Toxoplasma gondii (T. gondii) seropositivity may be associated with decreased memory in older adults. To further investigate the association between T. gondii seropositivity and memory in non-demented older adults, we obtained serum samples from 114 non-demented older adults evaluated by the Alzheimer’s Disease and Research Center at Washington University in St. Louis Missouri, USA. We determined T. gondii seropositivity and anti-T. gondii IgG antibody titer and examined associations with memory function while controlling for socioeconomic status, education level, age, and apolipoprotein E4 status. There were few associations between T. gondii seropositivity or anti-T. gondii IgG antibodies and memory, although there was some support suggesting an interaction between anti-T. gondii and sex. In the seropositive-only sample, there was an inverse relationship between anti-T. gondii titer and performance on the selective reminding test. Overall, we found little evidence of an association between impaired memory function and T. gondii seropositivity and anti-T gondii IgG antibodies in this sample of non-demented older adults.

The impact of individual differences on performance monitoring and psychopathology is a question of active debate. Personality traits associated with psychopathology may be related to poor internal performance monitoring (as measured by the error-related negativity [ERN]) but intact external performance monitoring (as measured by the reward positivity [RewP]), suggesting that there are underlying neural differences between internal and external performance monitoring processes. We tested the relationships between individual difference measures of perfectionism, locus of control, and ERN, error-positivity (Pe), and RewP component difference amplitude in a healthy undergraduate sample. A total of 128 participants (69 female, M(SD)age = 20.6(2.0) years) completed two tasks: a modified version of the Eriksen Flanker and a doors gambling task along with the Frost Multidimensional Perfectionism scale, the Rotter Locus of Control scale, and the Levenson Multidimensional Locus of Control scale to quantify perfectionism and locus of control traits, respectively. Linear regressions adjusting for age and gender showed that neither ΔERN nor ΔRewP amplitude were significantly moderated by perfectionism or locus of control scores. Findings suggest that, in psychiatrically-healthy individuals, there is not a strong link between perfectionism, locus of control, and ERN or RewP amplitude. Future research on individual difference measures in people with psychopathology may provide further insight into how these personality traits affect performance monitoring.

Psychological stress is increasingly associated with alterations in performance and affect. Yet, the relationship between experimentally induced psychological stress and neural indices of performance monitoring and error processing, as well as response inhibition, are unclear. Using scalp-recorded event-related potentials (ERPs), we tested the relationship between experimental stress, using the Trier Social Stress Test (TSST), and the error-related negativity (ERN), error positivity (Pe), and N2 ERP components. A final sample of 71 undergraduate students were randomly assigned to go through the TSST (n = 36; 18 female) or a brief mindfulness relaxation exercise (n = 35; 16 female) immediately followed by a go/no-go task while electroencephalogram (EEG) data were collected. Salivary cortisol, heart rate, and blood pressure confirmed increased physiological stress in the TSST group relative to control. Reaction times, accuracy, and post-error slowing did not differ by stress group. Two-group (TSST, control) by 2-trial type (correct, incorrect for ERN/Pe; go correct, no-go correct for N2) repeated measures ANOVAs for the ERN, Pe, and N2 showed the expected main effects of trial type; neither the ERN nor the N2 ERP components showed interactions with the stress manipulation. In contrast, the Pe component showed a significant Group by Trial interaction, with reduced Pe amplitude following the stress condition relative to control. Pe amplitude did not, however, correlate with cortisol reactivity. Findings suggest a reduction in Pe amplitude following experimental stress that may be associated with reduced error awareness or attention to errors following the TSST. Given the variability in the extant literature on the relationship between experimentally induced stress and neurophysiological reflections of performance monitoring, we provide another point of data and conclude that better understanding of moderating variables is needed followed by high-powered replication studies to get at the nuance that is not yet understood in the relationship between induced stress and performance monitoring/response inhibition processes.

Error-monitoring, an individual's ability to detect an incorrect response and subsequently adjust to improve future behavior, is an essential skill to achieve successful goal-directed behavior (Mohamed, Börger, Geuze, & van der Meere, 2019; Rabbitt & Rodgers, 1977). Individual differences in error-monitoring may be related to personality traits and transdiagnostic psychopathology symptoms, such as worry, negative affect, impulsivity, and conscientiousness (Hill, Samuel, & Foti, 2016; Moser, Moran, & Jendrusina, 2012). Error-monitoring processes are also altered in individuals