Working memory (WM) impairment has been well characterized in normal ageing. Various studies have explored changes in either the regional activity or the interregional connectivity underlying the WM ageing process. We proposed that brain activity and connectivity would independently alter with ageing and affect WM performance. WM was assessed with a classical N-back task during functional magnetic resonance imaging in a community-based sample comprising 168 elderly subjects (aged 55 to 86 years old). Following the rationale of background functional connectivity, we assessed age-related alterations in brain activity and seed-based interregional connectivity independently. Analyses revealed age-related decrease in the activity of the inferior parietal lobule (IPL) and an increase in the activity of the ventral anterior cingulate cortex (ACC), and the local functional dysfunctions were accompanied by alterations in their connectivity to other cortical regions. Importantly, regional activity impairments in the IPL and ACC could mediate age-related effects on accuracy rate and reaction time, respectively, and those effects were further counterbalanced by enhancement of their background functional connectivity. We thus claimed that age-induced alterations in regional activity and interregional connectivity occurred independently and contributed to WM changes in ageing. Our findings presented the way brain activity and functional connectivity interact in the late adulthood, thus providing a new perspective for understanding WM and cognitive ageing.

Our sensory system is able to build a unified perception of the world, which although rich, is limited and inaccurate. Sometimes, features from different objects are erroneously combined. At the neural level, the role of the parietal cortex in feature integration is well-known (Humphreys, 2016; Shafritz et al., 2002). However, the brain dynamics underlying correct and incorrect feature integration are less clear. To explore the temporal dynamics of feature integration, we studied the modulation of different frequency bands in trials in which feature integration was correct or incorrect. Participants responded to the color of a shape target, surrounded by distractors. A calibration procedure ensured that accuracy was around 70% in each participant. To explore the role of expectancy in feature integration, we introduced an unexpected feature to the target in the last blocks of trials. Results demonstrated the contribution of several frequency bands to feature integration both pre- and post-stimulus. During the pre-stimulus period, alpha power was higher for illusions compared to hits. After stimulus onset, alpha, beta, and gamma-band power was reduced for hits compared to illusions. Moreover, gamma power was overall larger during the experiment for participants who were aware of the unexpected target presented during the last blocks of trials (as compared to unaware participants). These results demonstrate that feature integration is a complex process that can go wrong at different stages of information processing and is influenced by top-down expectancies.

Hypnotizability is a psychophysiological trait measured by scales and associated with several differences including interoceptive accuracy and the morpho-functional characteristics of interoception-related brain regions. The aim of the study was to assess whether the amplitude of the heartbeat evoked cortical potential (HEP), a correlate of interoceptive accuracy, differs in participants with low (lows) and high (highs) hypnotizability scores (assessed by the Stanford Hypnotic Susceptibility Scale, form A) before and after the induction of hypnosis. ECG and EEG were monitored in 16 highs and 15 lows during an experimental session including open eyes baseline (B), closed eyes relaxation (R), hypnotic induction (IND), neutral hypnosis (NH), post session baseline (Post). No significant difference was observed between groups and conditions in autonomic variables. The HEP amplitude was lower in highs than in lows at the right parietal site, likely due to hypnotizability-related differences in the functional connection between the right insula and parietal cortex. It increased in highs and decreased in lows across the session, possibly due to the highs’ preeminently internally directed attention and to the lows’ possible disengagement from the task. Since interoception is involved in several cognitive-emotional functions, its hypnotizability-related differences may contribute to the variability of experience and behavior in daily life.

A document by Emma Tinney. Click on the document to view its contents.

The tendency to ruminate (i.e., repetitive, self-referential, negative thoughts) is a maladaptive form of emotional regulation and represents a transdiagnostic vulnerability factor for stress-related psychopathology. Vagally-mediated heart rate variability (HRV), reflecting parasympathetic nervous system activity, is commonly used as a physiological marker of stress regulation. Past research has suggested a link between trait rumination and resting HRV at baseline; however, inconsistent results exist in healthy individuals. In this study, we investigated the association between the tendency to ruminate and resting HRV measured at baseline in a healthy population using a large cross-sectional dataset (N = 1189, 88% women; mean age = 21.55, ranging from 17 to 48 years old), which was obtained by combining samples of healthy individuals from different studies from our laboratory. The results showed no cross-sectional correlation between resting baseline HRV and trait rumination (confirmed by Bayesian analyses), even after controlling for important confounders such as gender, age, and depressive symptoms. Also, a nonlinear relationship was rejected. In summary, based on our results in a large sample of healthy individuals, baseline resting HRV is not a trait marker of the tendency to ruminate.

Heightened impulsivity and compulsivity are often found in association with both dysfunctional everyday behavior as well as with psychopathology. Impulsivity and compulsivity are also linked to alterations in behavioral response inhibition and its electrophysiological correlates. However, they are rarely examined jointly and their effect outside of clinical samples is still disputed. This study assesses the influence and interaction of impulsivity and compulsivity as measured by questionnaires on behavioral performance and event-related potentials (N2, P3a and P3b) in a visual Go/Nogo task. Data from 250 participants from the general population (49% female; age M = 25.16, SD = 5.07; education level: 94% high school or higher; self-reported lifetime diagnosis of any mental disorder: 12%) were collected. We used robust linear regression as well as regression tree analyses, a type of machine learning algorithm, to uncover potential non-linear effects. We did not find any significant relationship between the self-report measures and behavioral or neural inhibition effects in either type of analysis, with the exception of a linear effect of the premeditation scale of the UPPS on behavioral performance. The current sample size was large enough to uncover even small effects. We discuss potential explanations for this current null finding. One possibility is that inhibitory performance was unimpaired in the current sample and that associations between inhibitory performance and self-report measures might only be seen in samples with mental disorders.