Carina Fernandes

Effects of inter-stimulus interval (ISI) duration on the N1 and P2 components of the auditory event-related potential

The N1 and P2 components of the event-related potential are relevant markers in the processing of auditory information, indicating the presence of several acoustic phenomena, such as pure tones or speech sounds. In addition, the expression of these components seems to be sensitive to diverse experimental variations. The main purpose of the present investigation was to explore the role of inter-stimulus interval (ISI) on the N1 and P2 responses, considering two widely used experimental paradigms: a single tone task (1000 Hz sound repeated in a fixed rhythm) and an auditory oddball (80% of the stimuli were equal to the sound used in the single tone and the remaining were a 1500 Hz tone). Both tasks had four different conditions, and each one tested a fixed value of ISI (600, 1000, 3000, or 6000 ms). A sample of 22 participants performed these tasks, while an EEG was recorded, in order to examine the maximum amplitude of the N1 and P2 components. Analysis of the stimuli in the single tone task and the frequent tones in the oddball task revealed a similar outcome for both tasks and for both components: N1 and P2 amplitudes were enhanced in conditions with longer ISIs regardless of task. This response pattern emphasizes the dependence of both the N1 and P2 components on the ISI, especially in a scenario of repetitive and regular stimulation. The absence of task effects suggests that the ISI effect reported may depend on refractory mechanisms rather than being due to habituation effects.

Detrimental role of prolonged sleep deprivation on adult neurogenesis

Adult mammalian brains continuously generate new neurons, a phenomenon called adult neurogenesis. Both environmental stimuli and endogenous factors are important regulators of adult neurogenesis. Sleep has an important role in normal brain physiology and its disturbance causes very stressful conditions, which disrupt normal brain physiology. Recently, an influence of sleep in adult neurogenesis has been established, mainly based on sleep deprivation studies. This review provides an overview on how rhythms and sleep cycles regulate hippocampal and subventricular zone neurogenesis, discussing some potential underlying mechanisms. In addition, our review highlights some interacting points between sleep and adult neurogenesis in brain function, such as learning, memory, and mood states, and provides some insights on the effects of antidepressants and hypnotic drugs on adult neurogenesis.

Antisocial behaviour and psychopathy: uncovering the externalizing link in the P3 modulation

HIGHLIGHTSP3 amplitude is reduced in antisocial behaviour.P3 blunted amplitude is mainly predicted by impulsive‐antisocial psychopathic traits in cognitive tasks.P3 enhanced amplitude is mainly predicted by interpersonal‐affective facets in cognitive tasks.P3 reduced amplitude is mainly predicted by interpersonal‐affective facets in emotional‐affective tasks.P3 amplitude as a neurobiological marker of externalizing dimensions of psychopathology. ABSTRACT In 2009, Gao and Raines meta‐analysis analysed P3 modulation over the antisocial spectrum. However, some questions remained open regarding the P3 modulation patterns across impulsive and violent manifestations of antisocial behaviour, phenotypic components of psychopathy, and P3 components. A systematic review of 36 studies was conducted (N = 3514) to extend previous results and to address these unresolved questions. A clear link between decreased P3 amplitude and antisocial behaviour was found. In psychopathy, dimensional approaches become more informative than taxonomic models. Distinct etiological pathways of psychopathy were evidenced in cognitive tasks: impulsive‐antisocial psychopathic traits mainly predicted blunted P3 amplitude, while interpersonal‐affective psychopathic traits explained enhanced P3 amplitude. Supporting the low fear hypothesis, the interpersonal‐affective traits were associated with reduced P3 amplitude in emotional‐affective learning tasks. From the accumulated knowledge we propose a framework of P3 amplitude modulation that uncovers the externalizing link between psychopathy and antisocial behaviour. However, the main hypotheses are exploratory and call for more data before stablishing robust conclusions.

Age differences in neural correlates of feedback processing after economic decisions under risk

This study examines age-related differences in behavioral responses to risk and in the neurophysiological correlates of feedback processing. Our sample was composed of younger, middle-aged, and older adults, who were asked to decide between 2 risky options, in the gain and loss domains, during an EEG recording. Results evidenced group-related differences in early and later stages of feedback processing, indexed by differences in the feedback-related negativity (FRN) and P3 amplitudes. Specifically, in the loss domain, younger adults showed higher FRN amplitudes after non-losses than after losses, whereas middle-aged and older adults had similar FRN amplitudes after both. In the gain domain, younger and middle-aged adults had higher P3 amplitudes after gains than after non-gains, whereas older adults had similar P3 amplitudes after both. Behaviorally, older adults had higher rates of risky decisions than younger adults in the loss domain, a result that was correlated with poorer performance in memory and executive functions. Our results suggest age-related differences in the outcome-related expectations, as well as in the affective relevance attributed to the outcomes, which may underlie the group differences found in risk-aversion.

Emotion identification and aging: Behavioral and neural age-related changes

OBJECTIVE Aging is known to alter the processing of facial expressions of emotion (FEE), however the impact of this alteration is less clear. Additionally, there is little information about the temporal dynamics of the neural processing of facial affect. METHODS We examined behavioral and neural age-related changes in the identification of FEE using event-related potentials. Furthermore, we analyze the relationship between behavioral/neural responses and neuropsychological functioning. To this purpose, 30 younger adults, 29 middle-aged adults and 26 older adults identified FEE. RESULTS The behavioral results showed a similar performance between groups. The neural results showed no significant differences between groups for the P100 component and an increased N170 amplitude in the older group. Furthermore, a pattern of asymmetric activation was evident in the N170 component. Results also suggest deficits in facial feature decoding abilities, reflected by a reduced N250 amplitude in older adults. Neuropsychological functioning predicts P100 modulation, but does not seem to influence emotion identification ability. CONCLUSIONS The findings suggest the existence of a compensatory function that would explain the age-equivalent performance in emotion identification. SIGNIFICANCE The study may help future research addressing behavioral and neural processes involved on processing of FEE in neurodegenerative conditions.

The effect of aging on the (mis)perception of intentionality - an ERP study

ABSTRACT Despite the accumulated knowledge on moral decision-making in the early stages of development, empirical evidence is still limited in the old-aged adults. The current study contributes to unveil the neural correlates of judgments of moral transgressions as a function of aging, by examining the temporal dynamics of neural activation elicited by intentional and accidental harmful actions in three groups of healthy participants: young adults (18–35), adults (40–55), and older adults (60–75). Older adults were slower and less accurate in rating intentionality, compared to the younger groups. In ERP analysis, the older group showed increased P2 amplitude, which was predicted by poorer performance on neuropsychological tests. Reduced amplitudes were found on critical ERP components to moral cognition (N2 and LPP), namely while processing intentional harmful scenarios. Older adults seem to allocate more attentional resources (P2) to the task, probably to compensate the age-related decline in executive functioning, while younger groups show a pronounced negativity while detecting harm (N2) and increased neural activation to encode the intentions behind the acts (LPP).

Effects of age on the identification of emotions in facial expressions: a meta-analysis

Background Emotion identification is a fundamental component of social cognition. Although it is well established that a general cognitive decline occurs with advancing age, the effects of age on emotion identification is still unclear. A meta-analysis by Ruffman and colleagues (2008) explored this issue, but much research has been published since then, reporting inconsistent findings. Methods To examine age differences in the identification of facial expressions of emotion, we conducted a meta-analysis of 24 empirical studies (N = 1,033 older adults, N = 1,135 younger adults) published after 2008. Additionally, a meta-regression analysis was conducted to identify potential moderators. Results Results show that older adults less accurately identify facial expressions of anger, sadness, fear, surprise, and happiness compared to younger adults, strengthening the results obtained by Ruffman et al. (2008). However, meta-regression analyses indicate that effect sizes are moderated by sample characteristics and stimulus features. Importantly, the estimated effect size for the identification of fear and disgust increased for larger differences in the number of years of formal education between the two groups. Discussion We discuss several factors that might explain the age-related differences in emotion identification and suggest how brain changes may account for the observed pattern. Furthermore, moderator effects are interpreted and discussed.

Age-related changes in frontal, striatal, and medial temporal activity during expected value evaluation

A growing number of studies have indicated that aging alters decision-making processes, but the knowledge about the trajectory and causes of these changes are still limited ([Samanez-Larkin and Knutson, 2015][1]). A recent meta-analysis revealed that age-related differences in decision-making vary