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Validation of the parent-report pandemic anxiety scale (PAS-P) in the context of COVID-19
To be able to develop effective policy and targeted support for children and young people, it is vital to develop and validate measures that enable us to understand what aspects of pandemics are associated with anxiety and stress across a wide age range. We examined the psychometric properties of the Pandemic Anxiety Scale– Parent-report (PAS-P), which measures levels of child and adolescent pandemic-related anxieties. Factor structure, reliability, and convergent and discriminant validity of the PAS-P was assessed in a convenience sample of parents/carers (N = 8410) over at three time points in 2020 when COVID-19 case rates and restrictions varied. Factor structure was identified via two exploratory factor analyses (EFAs; n = 5601 and n = 1005) and then tested using confirmatory factor analysis (CFA; n = 800), measurement invariance tests, and a longitudinal CFA (n = 1651). Two factors structure for disease and consequence anxiety were observed across both EFAs and were found to have good fit in the CFAs. The PAS-P demonstrated good internal consistency and discriminant validity, as well as partial scalar invariance in latent construct measurement across child age, gender, and time. The PAS-P is a robust parent-report measure of two distinct forms of pandemic-related anxiety, suitable for reporting on children and adolescents aged 4-16 years. Although the scale has been validated in the context of the COVID-19 pandemic, it is not limited to this specific pandemic and, with minor wording modifications, may be a reliable tool in other health epidemic contexts.
Evaluating the effect of pupil diameter change on AOSLO image quality without pupil dilation
We performed imaging with an adaptive optics scanning laser ophthalmoscope (AOSLO) with a full-field intensity-modulated stimulus and no pupil dilation, and analysed how changes in pupil diameter affect AOSLO image quality.
Distractor effects in decision making are related to the individual's style of integrating choice attributes.
Humans make irrational decisions in the presence of irrelevant distractor options. There is little consensus on whether decision making is facilitated or impaired by the presence of a highly rewarding distractor, or whether the distractor effect operates at the level of options' component attributes rather than at the level of their overall value. To reconcile different claims, we argue that it is important to consider the diversity of people's styles of decision making and whether choice attributes are combined in an additive or multiplicative way. Employing a multi-laboratory dataset investigating the same experimental paradigm, we demonstrated that people used a mix of both approaches and the extent to which approach was used varied across individuals. Critically, we identified that this variability was correlated with the distractor effect during decision making. Individuals who tended to use a multiplicative approach to compute value, showed a positive distractor effect. In contrast, a negative distractor effect (divisive normalisation) was prominent in individuals tending towards an additive approach. Findings suggest that the distractor effect is related to how value is constructed, which in turn may be influenced by task and subject specificities. This concurs with recent behavioural and neuroscience findings that multiple distractor effects co-exist.
Layer-specific entrainment of γ-band neural activity by the α rhythm in monkey visual cortex.
Although the mammalian neocortex has a clear laminar organization, layer-specific neuronal computations remain to be uncovered. Several studies suggest that gamma band activity in primary visual cortex (V1) is produced in granular and superficial layers and is associated with the processing of visual input. Oscillatory alpha band activity in deeper layers has been proposed to modulate neuronal excitability associated with changes in arousal and cognitive factors. To investigate the layer-specific interplay between these two phenomena, we characterized the coupling between alpha and gamma band activity of the local field potential in V1 of the awake macaque. Using multicontact laminar electrodes to measure spontaneous signals simultaneously from all layers of V1, we found a robust coupling between alpha phase in the deeper layers and gamma amplitude in granular and superficial layers. Moreover, the power in the two frequency bands was anticorrelated. Taken together, these findings demonstrate robust interlaminar cross-frequency coupling in the visual cortex, supporting the view that neuronal activity in the alpha frequency range phasically modulates processing in the cortical microcircuit in a top-down manner.
Local entrainment of α oscillations by visual stimuli causes cyclic modulation of perception.
Prestimulus oscillatory neural activity in the visual cortex has large consequences for perception and can be influenced by top-down control from higher-order brain regions. Making a causal claim about the mechanistic role of oscillatory activity requires that oscillations be directly manipulated independently of cognitive instructions. There are indications that a direct manipulation, or entrainment, of visual alpha activity is possible through visual stimulation. However, three important questions remain: (1) Can the entrained alpha activity be endogenously maintained in the absence of continuous stimulation?; (2) Does entrainment of alpha activity reflect a global or a local process?; and (3) Does the entrained alpha activity influence perception? To address these questions, we presented human subjects with rhythmic stimuli in one visual hemifield, and arhythmic stimuli in the other. After rhythmic entrainment, we found a periodic pattern in detection performance of near-threshold targets specific to the entrained hemifield. Using magnetoencephalograhy to measure ongoing brain activity, we observed strong alpha activity contralateral to the rhythmic stimulation outlasting the stimulation by several cycles. This entrained alpha activity was produced locally in early visual cortex, as revealed by source analysis. Importantly, stronger alpha entrainment predicted a stronger phasic modulation of detection performance in the entrained hemifield. These findings argue for a cortically focal entrainment of ongoing alpha oscillations by visual stimulation, with concomitant consequences for perception. Our results support the notion that oscillatory brain activity in the alpha band provides a causal mechanism for the temporal organization of visual perception.
Real-time MEG neurofeedback training of posterior alpha activity modulates subsequent visual detection performance.
It has been demonstrated that alpha activity is lateralized when attention is directed to the left or right visual hemifield. We investigated whether real-time neurofeedback training of the alpha lateralization enhances participants' ability to modulate posterior alpha lateralization and causes subsequent short-term changes in visual detection performance. The experiment consisted of three phases: (i) pre-training assessment, (ii) neurofeedback phase and (iii) post-training assessment. In the pre- and post-training phases we measured the threshold to covertly detect a cued faint Gabor stimulus presented in the left or right hemifield. During magnetoencephalography (MEG) neurofeedback, two face stimuli superimposed with noise were presented bilaterally. Participants were cued to attend to one of the hemifields. The transparency of the superimposed noise and thus the visibility of the stimuli were varied according to the momentary degree of hemispheric alpha lateralization. In a double-blind procedure half of the participants were provided with sham feedback. We found that hemispheric alpha lateralization increased with the neurofeedback training; this was mainly driven by an ipsilateral alpha increase. Surprisingly, comparing pre- to post-training, detection performance decreased for a Gabor stimulus presented in the hemifield that was un-attended during neurofeedback. This effect was not observed in the sham group. Thus, neurofeedback training alters alpha lateralization, which in turn decreases performances in the untrained hemifield. Our findings suggest that alpha oscillations play a causal role for the allocation of attention. Furthermore, our neurofeedback protocol serves to reduce the detection of unattended visual information and could therefore be of potential use for training to reduce distractibility in attention deficit patients, but also highlights that neurofeedback paradigms can have negative impact on behavioral performance and should be applied with caution.
Region-specific modulations in oscillatory alpha activity serve to facilitate processing in the visual and auditory modalities.
There have been a number of studies suggesting that oscillatory alpha activity (~10 Hz) plays a pivotal role in attention by gating information flow to relevant sensory regions. The vast majority of these studies have looked at shifts of attention in the spatial domain and only in a single modality (often visual or sensorimotor). In the current magnetoencephalography (MEG) study, we investigated the role of alpha activity in the suppression of a distracting modality stream. We used a cross-modal attention task where visual cues indicated whether participants had to judge a visual orientation or discriminate the auditory pitch of an upcoming target. The visual and auditory targets were presented either simultaneously or alone, allowing us to behaviorally gauge the "cost" of having a distractor present in each modality. We found that the preparation for visual discrimination (relative to pitch discrimination) resulted in a decrease of alpha power (9-11 Hz) in the early visual cortex, with a concomitant increase in alpha/beta power (14-16 Hz) in the supramarginal gyrus, a region suggested to play a vital role in short-term storage of pitch information (Gaab et al., 2003). On a trial-by-trial basis, alpha power over the visual areas was significantly correlated with increased visual discrimination times, whereas alpha power over the precuneus and right superior temporal gyrus was correlated with increased auditory discrimination times. However, these correlations were only significant when the targets were paired with distractors. Our work adds to increasing evidence that the top-down (i.e. attentional) modulation of alpha activity is a mechanism by which stimulus processing can be gated within the cortex. Here, we find that this phenomenon is not restricted to the domain of spatial attention and can be generalized to other sensory modalities than vision.
Metacognitive awareness of covert somatosensory attention corresponds to contralateral alpha power.
Studies on metacognition have shown that participants can report on their performance on a wide range of perceptual, memory and behavioral tasks. We know little, however, about the ability to report on one's attentional focus. The degree and direction of somatosensory attention can, however, be readily discerned through suppression of alpha band frequencies in EEG/MEG produced by the somatosensory cortex. Such top-down attentional modulations of cortical excitability have been shown to result in better discrimination performance and decreased response times. In this study we asked whether the degree of attentional focus is also accessible for subjective report, and whether such evaluations correspond to the amount of somatosensory alpha activity. In response to auditory cues participants maintained somatosensory attention to either their left or right hand for intervals varying randomly between 5 and 32 seconds, while their brain activity was recorded with MEG. Trials were terminated by a probe sound, to which they reported their level of attention on the cued hand right before probe-onset. Using a beamformer approach, we quantified the alpha activity in left and right somatosensory regions, one second before the probe. Alpha activity from contra- and ipsilateral somatosensory cortices for high versus low attention trials were compared. As predicted, the contralateral somatosensory alpha depression correlated with higher reported attentional focus. Finally, alpha activity two to three seconds before the probe-onset was correlated with attentional focus. We conclude that somatosensory attention is indeed accessible to metacognitive awareness.
Good practice for conducting and reporting MEG research.
Magnetoencephalographic (MEG) recordings are a rich source of information about the neural dynamics underlying cognitive processes in the brain, with excellent temporal and good spatial resolution. In recent years there have been considerable advances in MEG hardware developments and methods. Sophisticated analysis techniques are now routinely applied and continuously improved, leading to fascinating insights into the intricate dynamics of neural processes. However, the rapidly increasing level of complexity of the different steps in a MEG study make it difficult for novices, and sometimes even for experts, to stay aware of possible limitations and caveats. Furthermore, the complexity of MEG data acquisition and data analysis requires special attention when describing MEG studies in publications, in order to facilitate interpretation and reproduction of the results. This manuscript aims at making recommendations for a number of important data acquisition and data analysis steps and suggests details that should be specified in manuscripts reporting MEG studies. These recommendations will hopefully serve as guidelines that help to strengthen the position of the MEG research community within the field of neuroscience, and may foster discussion in order to further enhance the quality and impact of MEG research.
Selective inhibition of distracting input.
We review a series of studies exploring distractor suppression. It is often assumed that preparatory distractor suppression is controlled via top-down mechanisms of attention akin to those that prepare brain areas for target enhancement. Here, we consider two alternative mechanisms: secondary inhibition and expectation suppression within a predictive coding framework. We draw on behavioural studies, evidence from neuroimaging and some animal studies. We conclude that there is very limited evidence for selective top-down control of preparatory inhibition. By contrast, we argue that distractor suppression often relies secondary inhibition of non-target items (relatively non-selective inhibition) and on statistical regularities of the environment, learned through direct experience.
Beta and gamma synchronous oscillations in neural network activity in mice-induced by food deprivation.
Food deprivation is known to trigger hunger sensation and motivation to eat for energy replenishing. However, brain mechanisms associated with hunger and neural circuitries that mediate hunger driven responses remained to be investigated. To understand neural signaling of hunger, local field potentials (LFPs) in the lateral hypothalamus (LHa), nucleus accumbens (NAc), dorsal hippocampus (HP) and olfactory bulb (OB) and their interconnectivities were studied in freely moving adult male Albino mice during 18-20 h food deprivation and fed periods. Raw LFP signals were recorded and analyzed for mean values of spectral frequency power and coherence values. One-way repeated measures ANOVA revealed significant increases in spectral powers of beta and gamma frequency ranges induced by food deprivation in the LHa, HP, NAc but not OB. No change of spectral power in these brain regions was induced by food feeding. The analyses of coherent activity between brain regions also deliniated some distributed neural network activities correlated with hunger. In particular, coherent function indicated the increased beta and gamma phase synchrony between the pairs of LHa-HP and NAc-OB regions, and decreased gamma synchrony between the pairs of LHa-NAc and NAc-HP induced by food deprivation. It was found that plasma glucose level, locomotor count, travelled distance and time spent on moving were not altered by food deprivation. These results suggest that changes in LFP hallmarks in these brain regions were associated with hunger driven by negative energy balance.
The relationship between oscillatory EEG activity and the laminar-specific BOLD signal.
Electrophysiological recordings in animals have indicated that visual cortex γ-band oscillatory activity is predominantly observed in superficial cortical layers, whereas α- and β-band activity is stronger in deep layers. These rhythms, as well as the different cortical layers, have also been closely related to feedforward and feedback streams of information. Recently, it has become possible to measure laminar activity in humans with high-resolution functional MRI (fMRI). In this study, we investigated whether these different frequency bands show a differential relation with the laminar-resolved blood-oxygen level-dependent (BOLD) signal by combining data from simultaneously recorded EEG and fMRI from the early visual cortex. Our visual attention paradigm allowed us to investigate how variations in strength over trials and variations in the attention effect over subjects relate to each other in both modalities. We demonstrate that γ-band EEG power correlates positively with the superficial layers' BOLD signal and that β-power is negatively correlated to deep layer BOLD and α-power to both deep and superficial layer BOLD. These results provide a neurophysiological basis for human laminar fMRI and link human EEG and high-resolution fMRI to systems-level neuroscience in animals.
Accumulation of evidence during sequential decision making: the importance of top-down factors.
In the last decade, great progress has been made in characterizing the accumulation of neural information during simple unitary perceptual decisions. However, much less is known about how sequentially presented evidence is integrated over time for successful decision making. The aim of this study was to study the mechanisms of sequential decision making in humans. In a magnetoencephalography (MEG) study, we presented healthy volunteers with sequences of centrally presented arrows. Sequence length varied between one and five arrows, and the accumulated directions of the arrows informed the subject about which hand to use for a button press at the end of the sequence (e.g., LRLRR should result in a right-hand press). Mathematical modeling suggested that nonlinear accumulation was the rational strategy for performing this task in the presence of no or little noise, whereas quasilinear accumulation was optimal in the presence of substantial noise. MEG recordings showed a correlate of evidence integration over parietal and central cortex that was inversely related to the amount of accumulated evidence (i.e., when more evidence was accumulated, neural activity for new stimuli was attenuated). This modulation of activity likely reflects a top-down influence on sensory processing, effectively constraining the influence of sensory information on the decision variable over time. The results indicate that, when making decisions on the basis of sequential information, the human nervous system integrates evidence in a nonlinear manner, using the amount of previously accumulated information to constrain the accumulation of additional evidence.
Shift from hippocampal to neocortical centered retrieval network with consolidation.
The standard model of system-level consolidation posits that the hippocampus is part of a retrieval network for recent memories. According to this theory, the memories are gradually transferred to neocortical circuits with consolidation, where the connections within this circuit grow stronger and reorganized so that redundant and/or contextual details may be lost. Thus, remote memories are based on neocortical networks and can be retrieved independently of the hippocampus. To test this model, we measured regional brain activity and connectivity during retrieval with functional magnetic resonance imaging. Subjects were trained on two sets of face-location association and were tested with two different delays, 15 min and 24 h including a whole night of sleep. We hypothesized that memory traces of the locations associated with specific faces will be linked through the hippocampus for the retrieval of recently learned association, but with consolidation, the activity and the functional connectivity between the neocortical areas will increase. We show that posterior hippocampal activity related to high-confidence retrieval decreased and neocortical activity increased with consolidation. Moreover, the connectivity between the hippocampus and the neocortical regions decreased and in turn, cortico-cortical connectivity between the representational areas increased. The results provide mechanistic support for a two-level process of the declarative memory system, involving initial representation of new associations in a network including the hippocampus and subsequent consolidation into a predominantly neocortical network.
Theta and gamma oscillations predict encoding and retrieval of declarative memory.
Although studies in animals and patients have demonstrated that brain oscillations play a role in declarative memory encoding and retrieval, little has been done to investigate the temporal dynamics and sources of brain activity in healthy human subjects performing such tasks. In a magnetoencephalography study using pictorial stimuli, we have now identified oscillatory activity in the gamma (60-90 Hz) and theta (4.5-8.5 Hz) band during declarative memory operations in healthy participants. Both theta and gamma activity was stronger for the later remembered compared with the later forgotten items (the "subsequent memory effect"). In the retrieval session, theta and gamma activity was stronger for recognized items compared with correctly rejected new items (the "old/new effect"). The gamma activity was also stronger for recognized compared with forgotten old items (the "recognition effect"). The effects in the theta band were observed over right parietotemporal areas, whereas the sources of the effects in the gamma band were identified in Brodmann area 18/19. We propose that the theta activity is directly engaged in mnemonic operations. The increase in neuronal synchronization in the gamma band in occipital areas may result in a stronger drive to subsequent areas, thus facilitating both memory encoding and retrieval. Alternatively, the gamma synchronization might reflect representations being reinforced by top-down activity from higher-level memory areas. Our results provide additional insight on human declarative memory operations and oscillatory brain activity that complements previous electrophysiological and brain imaging studies.