Proactive or reactive? Neural oscillatory insight into the leader-follower dynamics of early infant-caregiver interaction

We know that infants’ ability to coordinate attention with others towards the end of the first year is fundamental to language acquisition and social cognition (Carpenter et al., 1998). Yet, we understand little about the neural and cognitive mechanisms driving infant attention in shared interaction: do infants play a proactive role in creating episodes of joint attention? Recording EEG from 12-month-old infants whilst they engaged in table-top play with their caregiver, we examined the ostensive signals and neural activity preceding and following infant- vs. adult-led joint attention. Contrary to traditional theories of socio-communicative development (Tomasello et al., 2007), infant-led joint attention episodes appeared largely reactive: they were not associated with increased theta power, a neural marker of endogenously driven attention, or ostensive signals before the initiation. Infants were, however, sensitive to whether their initiations were responded to. When caregivers joined their attentional focus, infants showed increased alpha suppression, a pattern of neural activity associated with predictive processing. Our results suggest that at 10-12 months, infants are not yet proactive in creating joint attention. They do, however, anticipate behavioural contingency, a potentially foundational mechanism for the emergence of intentional communication (Smith & Breazeal, 2007).

Emotion Regulation Choice in Internet Addiction: Less Reappraisal, Lower Frontal Alpha Asymmetry

Individuals with internet addiction (IA) show difficulties in emotion regulation. However, they could effectively employ emotion regulation strategies when instructed. We speculate that this discrepancy might be caused by maladaptive emotion regulation choices. Recent studies indicated that decreased activity of the left frontal cortex could be a neural marker of reappraisal use. To address this problem, individuals with IA ( n = 17, IA group) and healthy individuals ( n = 23, healthy control [HC] group) were required to choose an emotion regulation strategy between reappraisal and distraction to regulate their emotions varying in emotional intensity and valence. We also compared the resting state frontal alpha asymmetry (FAA) of these 2 groups. The results replicated more choices of reappraisal in low- versus high-intensity emotional contexts across groups. More importantly, the IA group chose reappraisal less frequently compared with the HC group, irrespective of emotional intensity. Furthermore, we found individuals with IA have lower FAA than healthy controls, and FAA shows a positive correlation with the use of reappraisal. These findings suggest that IA alters individuals’ patterns of emotion regulation choice and impairs frontal activities, causing difficulties in emotion regulation.

Tracking transitional probabilities and segmenting auditory sequences are dissociable processes in adults and neonates

Since speech is a continuous stream with no systematic boundaries between words, how do pre-verbal infants manage to discover words? A proposed solution is that they might use the transitional probability between adjacent syllables, which drops at word boundaries. Here, we tested the limits of this mechanism by increasing the size of the word-unit to 4 syllables, and its automaticity by testing asleep neonates. Using markers of statistical learning in neonates' EEG, compared to adult' behavioral performances in the same task, we confirmed that statistical learning is automatic enough to be efficient even in sleeping neonates. But we also revealed that : 1) Successfully tracking transition probabilities in a sequence is not sufficient to segment it 2) Prosodic cues, as subtle as subliminal pauses, enable to recover segmenting capacities 3) Adults' and neonates' capacities are remarkably similar despite the difference of maturation and expertise. Finally, we observed that learning increased the similarity of neural responses across infants, providing a new neural marker to monitor learning. Thus, from birth, infants are equipped with adult-like tools, allowing to extract small coherent word-like units within auditory streams, based on the combination of statistical analyses and prosodic cues.

Neural attentional-filter mechanisms of listening success in middle-aged and older individuals

Successful listening crucially depends on intact attentional filters that separate relevant from irrelevant information. Research into their neurobiological implementation has focused on two potential auditory filter strategies: the lateralization of alpha power and selective neural speech tracking. However, the functional interplay of the two neural filter strategies and their potency to index listening success in an ageing population remains unclear. Using electroencephalography and a dual-talker task in a representative sample of listeners (N = 155; age=39–80 years), we here demonstrate an often-missed link from single-trial behavioural outcomes back to trial-by-trial changes in neural attentional filtering. First, we observe preserved attentional–cue-driven modulation of both neural filters across chronological age and hearing levels. Second, neural filter states vary independently of one another, demonstrating complementary neurobiological solutions of spatial selective attention. Stronger neural speech tracking but not alpha lateralization boosts trial-to-trial behavioural performance. Our results highlight the translational potential of neural speech tracking as an individualized neural marker of adaptive listening behaviour.

Increased PACAP- and DβH-Positive Hepatic Nerve Fibers after Bisphenol A Exposure

Bisphenol A (BPA) is an endocrine-disrupting compound (EDC) that can be found nearly everywhere in our polluted world. BPA has been correlated with pathophysiologies that include psychological disorders, especially in children. This study used juvenile porcine models to investigate the effects of BPA on the liver of developing vertebrates in order to determine the effects of BPA on innervated hepatic samples with the use of double-labeled immunofluorescence. This study specifically investigated the sympathetic nervous system (SNS) colocalized with a specific neural marker (PACAP) that has previously been correlated with specific pathophysiologies in the literature. In the liver, it was observed that there were significantly increased nerve fibers in the SNS colocalized with the neural marker PACAP after exposure to BPA at concentrations considered to be “safe” with the same or more profound effects at higher exposure levels. The implications of childhood exposure to BPA are then discussed with regard to several correlation studies that have linked BPA exposure to behavioral/psychological disorders. It is possible that BPA exposure in childhood may upregulate the SNS and PACAP levels, thereby contributing to the correlations in the literature.

Reduced cortico-muscular beta coupling in Parkinsons disease predicts motor impairment

Long range communication through the motor system is thought to be facilitated by phase coupling between neural activity in the 15-30 Hz beta range. During periods of sustained muscle contraction (grip), such coupling is manifest between motor cortex and the contralateral forearm muscles, measured as the cortico-muscular coherence (CMC). We examined alterations in CMC in individuals with Parkinsons disease (PD), while equating grip strength between individuals with PD (off their medication) and healthy control participants. We show a marked reduction in beta CMC in the PD group, even though the grip strength was comparable between the two groups. Moreover, the reduced CMC was related to motor symptoms, so that individuals with lower CMC also displayed worse motor symptoms. These findings highlight the CMC as a simple, effective, and clinically relevant neural marker of PD pathology, with the potential to aid monitoring of disease progression and the efficacy of novel treatments for PD.

Towards a view from within: On the scientific study of consciousness and the contribution of Francisco Varela

The contents of consciousness are complex and dynamic, presenting in most perceptual and cognitive functions. The study of consciousness and subjective experience has been central to philosophy for centuries. However, despite its relevance for understanding cognition and behaviour, the empirical study of consciousness is relatively new, embroiled by the seemingly opposing subjective and objective sources of data. Francisco Varela (1946 – 2001) pioneered the empirical study of consciousness by developing novel and rich approaches in a non-reductive and comprehensive manner. In this article, we review the main conceptual distinctions, properties, problems, and theories of consciousness, and highlight the main contributions of Varela and his associates: the development of neurophenomenology as a methodological framework that builds a bridge between subjective and objective sources of data, and the discovery of gamma-band phase synchronisation as a neural marker of perceptual awareness.