Grip type and task goal modify reach-to-grasp performance in post-stroke hemiparesis

This study investigated whether grip type and/or task goal influenced reaching and grasping performance in post-stroke hemiparesis. Sixteen adults with post-stroke hemiparesis and twelve healthy adults reached to and grasped a cylindrical object using one of two grip types (3-finger or palmar) to achieve one of two task goals (hold or lift). Performance of the stroke group was characteristic of hemiparetic limb movement during reach-to-grasp, with more curved handpaths and slower velocities compared to the control group. These effects were present regardless of grip type or task goal. Other measures of reaching (reach time and reach velocity at object contact) and grasping (peak thumb-index finger aperture during the reach and peak grip force during the grasp) were differentially affected by grip type, task goal, or both, despite the presence of hemiparesis, providing new evidence that changes in motor patterns after stroke may occur to compensate for stroke-related motor impairment

Conscientiousness predicts greater recovery from negative emotion

Greater levels of conscientiousness have been associated with lower levels of negative affect. We focus on one mechanism through which conscientiousness may decrease negative affect: effective emotion regulation, as reflected by greater recovery from negative stimuli. In 273 adults who were 35 - 85 years old, we collected self-report measures of personality including conscientiousness and its self-control facet, followed on average 2 years later by psychophysiological measures of emotional reactivity and recovery. Among middle-aged adults (35 - 65 years old), the measures of conscientiousness and self-control predicted greater recovery from, but not reactivity to, negative emotional stimuli. The effect of conscientiousness and self-control on recovery was not driven by other personality variables or by greater task adherence on the part of high conscientiousness individuals. In addition, the effect was specific to negative emotional stimuli and did not hold for neutral or positive emotional stimuli

Chapter 26: the temporal dynamics of emotional responding: implications for well-being and health from the MIDUS

In this chapter findings are reviewed from the MIDUS Neuroscience Project that underscore the value in examining the temporal dynamics of responses to brief emotional provocation for understanding linkages among emotions and factors contributing to health and well-being across the MIDUS study. This rich dataset has allowed the exploration of associations between individual differences in the affective chronometry of negative and positive emotional responses in vulnerable vs. resilient profiles. Findings from functional magnetic resonance imaging (fMRI) as well as electromyographic recordings (EMG) of the facial muscles to objectively measure emotional responses demonstrate that the temporal dynamics of emotional responses to affective stimuli are associated with aging, personality, psychopathology, stress exposure, biomarkers, and well-being. Overall, these findings suggest that variation in health and well-being are differentially predicted by specific temporal parameters of the emotional response, such as the magnitude of the immediate response to the presence of a stimulus (i.e., reactivity), residual activity and its duration after stimulus offset (i.e., recovery), as well as the change in response – or habituation - across repeated presentations of similarly-valenced stimuli. Besides the seemingly obvious import of recovering quickly from negative or unpleasant provocations, the chronometry of positive emotional responses appears to be particularly vital for determining how emotional processes may take a physiological toll or promote resiliency in the face of stress and disease. By examining such temporal dynamics in response to affective stimuli in MIDUS, a better understanding of the brain-behavior associations underlying emotion, and how emotions “get under the skin” to impact well-being and health across the lifespan is gained

Periodic and aperiodic contributions to theta‐beta ratios across adulthood

The ratio of fronto-central theta (4–7 Hz) to beta oscillations (13–30 Hz), known as the theta-beta ratio, is negatively correlated with attentional control, reinforcement learning, executive function, and age. Although theta-beta ratios have been found to decrease with age in adolescents and young adults, theta has been found to increase with age in older adults. Moreover, age-related decrease in individual alpha peak frequency and flattening of the 1/f aperiodic component may artifactually inflate the association between theta-beta ratio and age. These factors lead to an incomplete understanding of how theta-beta ratio varies across the lifespan and the extent to which variation is due to a conflation of aperiodic and periodic activity. We conducted a partially preregistered analysis examining the cross-sectional associations between age and resting canonical fronto-central theta-beta ratio, individual alpha peak frequency, and aperiodic component (n = 268; age 36–84, M = 55.8, SD = 11.0). Age was negatively associated with theta-beta ratios, individual peak alpha frequencies, and the aperiodic exponent. The correlation between theta-beta ratios and age remained after controlling for individual peak alpha frequencies, but was nonsignificant when controlling for the aperiodic exponent. Aperiodic exponent fully mediated the relationship between theta-beta ratio and age, although beta remained significantly associated with age after controlling for theta, individual peak alpha, and aperiodic exponent. Results replicate previous observations and show age-related decreases in theta-beta ratios are not due to age-related decrease in individual peak alpha frequencies but primarily explained by flattening of the aperiodic component with age

Aging is associated with positive responding to neutral information but reduced recovery from negative information

Studies on aging and emotion suggest an increase in reported positive affect, a processing bias of positive over negative information, as well as increasingly adaptive regulation in response to negative events with advancing age. These findings imply that older individuals evaluate information differently, resulting in lowered reactivity to, and/or faster recovery from, negative information, while maintaining more positive responding to positive information. We examined this hypothesis in an ongoing study on Midlife in the US (MIDUS II) where emotional reactivity and recovery were assessed in a large number of respondents (N = 159) from a wide age range (36–84 years). We recorded eye-blink startle magnitudes and corrugator activity during and after the presentation of positive, neutral and negative pictures. The most robust age effect was found in response to neutral stimuli, where increasing age is associated with a decreased corrugator and eyeblink startle response to neutral stimuli. These data suggest that an age-related positivity effect does not essentially alter the response to emotion-laden information, but is reflected in a more positive interpretation of affectively ambiguous information. Furthermore, older women showed reduced corrugator recovery from negative pictures relative to the younger women and men, suggesting that an age-related prioritization of well-being is not necessarily reflected in adaptive regulation of negative affect

Resting EEG periodic and aperiodic components predict cognitive decline over 10 years

Measures of intrinsic brain function at rest show promise as predictors of cognitive decline in humans, including EEG metrics such as individual alpha peak frequency (IAPF) and the aperiodic exponent, reflecting the strongest frequency of alpha oscillations and the relative balance of excitatory:inhibitory neural activity, respectively. Both IAPF and the aperiodic exponent decrease with age and have been associated with worse executive function and working memory. However, few studies have jointly examined their associations with cognitive function, and none have examined their association with longitudinal cognitive decline rather than cross-sectional impairment. In a preregistered secondary analysis of data from the longitudinal Midlife in the United States (MIDUS) study, we tested whether IAPF and aperiodic exponent measured at rest predict cognitive function (N = 235; age at EEG recording M = 55.10, SD = 10.71) over 10 years. The IAPF and the aperiodic exponent interacted to predict decline in overall cognitive ability, even after controlling for age, sex, education, and lag between data collection timepoints. Post-hoc tests showed that “mismatched” IAPF and aperiodic exponents (e.g., higher exponent with lower IAPF) predicted greater cognitive decline compared to “matching” IAPF and aperiodic exponents (e.g., higher exponent with higher IAPF; lower IAPF with lower aperiodic exponent). These effects were largely driven by measures of executive function. Our findings provide the first evidence that IAPF and the aperiodic exponent are joint predictors of cognitive decline from midlife into old age and thus may offer a useful clinical tool for predicting cognitive risk in aging

Linking amygdala persistence to real-world emotional experience and psychological well-being.

Neural dynamics in response to affective stimuli are linked to momentary emotional experiences. The amygdala, in particular, is involved in subjective emotional experience and assigning value to neutral stimuli. Because amygdala activity persistence following aversive events varies across individuals, some may more readily evaluate subsequent neutral stimuli than others. This may lead to more frequent and long-lasting momentary emotional experiences, which may also be linked to self-evaluative measures of psychological well-being (PWB). Despite extant links between daily affect and PWB, few studies have directly explored the links between amygdala persistence, daily affective experience, and PWB. To that end, we examined data from 52 human adults (67% female) in the Midlife in the United States (MIDUS) study who completed measures of PWB, daily affect, and functional MRI (fMRI). During fMRI, participants viewed affective images followed by a neutral facial expression, permitting quantification of individual differences in the similarity of amygdala representations of affective stimuli and neutral facial expressions that follow. Using representational similarity analysis (RSA), neural persistence to aversive stimuli was operationalized as similarity between the amygdala activation patterns while encoding negative images and the neutral facial expressions shown afterward. Individuals demonstrating less persistent activation patterns in the left amygdala to aversive stimuli reported more frequent positive and less frequent negative affect (NA) in daily life. Further, daily positive affect (PA) served as an indirect link between left amygdala persistence and PWB. These results clarify important connections between individual differences in brain function, daily experiences of affect, and well-being

Aging is associated with a prefrontal lateral-medial shift during picture-induced negative affect

The capacity to adaptively respond to negative emotion is in part dependent upon lateral areas of the prefrontal cortex (PFC). Lateral PFC areas are particularly susceptible to age-related atrophy, which affects executive function (EF). We used structural and functional magnetic resonance imaging (MRI) to test the hypothesis that older age is associated with greater medial PFC engagement during processing of negative information, and that this engagement is dependent upon the integrity of grey matter structure in lateral PFC as well as EF. Participants (n = 64, 38–79 years) viewed negative and neutral scenes while in the scanner, and completed cognitive tests as part of a larger study. Grey matter probability (GMP) was computed to index grey matter integrity. FMRI data demonstrated less activity in the left ventrolateral PFC (VLPFC) and greater ventromedial PFC (VMPFC) activity with increasing age during negative-picture viewing. Age did not correlate with amygdala responding. GMP in VLPFC and EF were negatively associated with VMPFC activity. We conclude that this change from lateral to medial PFC engagement in response to picture-induced negative affect reflects decreased reliance on executive function-related processes, possibly associated with reduced grey matter in lateral PFC, with advancing age to maintain emotional functioning

Purpose in life as a resilience factor for brain health: diffusion MRI findings from the Midlife in the U.S. study

IntroductionA greater sense of purpose in life is associated with several health benefits relevant for active aging, but the mechanisms remain unclear. We evaluated if purpose in life was associated with indices of brain health.MethodsWe examined data from the Midlife in the United States (MIDUS) Neuroscience Project. Diffusion weighted magnetic resonance imaging data (n=138; mean age 65.2 years, age range 48-95; 80 females; 37 black, indigenous, and people of color) were used to estimate microstructural indices of brain health such as axonal density, and axonal orientation. The seven-item purpose in life scale was used. Permutation analysis of linear models was used to examine associations between purpose in life scores and the diffusion metrics in white matter and in the bilateral hippocampus, adjusting for age, sex, education, and race.Results and discussionGreater sense of purpose in life was associated with brain microstructural features consistent with better brain health. Positive associations were found in both white matter and the right hippocampus, where multiple convergent associations were detected. The hippocampus is a brain structure involved in learning and memory that is vulnerable to stress but retains the capacity to grow and adapt through old age. Our findings suggest pathways through which an enhanced sense of purpose in life may contribute to better brain health and promote healthy aging. Since purpose in life is known to decline with age, interventions and policy changes that facilitate a greater sense of purpose may extend and improve the brain health of individuals and thus improve public health