Late Component Research Articles

Neurocomputational mechanisms underlying cross-modal associations and their influence on perceptual decisions

When exposed to complementary features of information across sensory modalities, our brains formulate cross-modal associations between features of stimuli presented separately to multiple modalities. For example, auditory pitch-visual size associations map high-pitch tones with small-size visual objects, and low-pitch tones with large-size visual objects. Preferential, or congruent, cross-modal associations have been shown to affect behavioural performance, i.e. choice accuracy and reaction time (RT) across multisensory decision-making paradigms. However, the neural mechanisms underpinning such influences in perceptual decision formation remain unclear. Here, we sought to identify when perceptual improvements from associative congruency emerge in the brain during decision formation. In particular, we asked whether such improvements represent ‘early’ sensory processing benefits, or ‘late’ post-sensory changes in decision dynamics. Using a modified version of the Implicit Association Test (IAT), coupled with electroencephalography (EEG), we measured the neural activity underlying the effect of auditory stimulus-driven pitch-size associations on perceptual decision formation. Behavioural results showed that participants responded significantly faster during trials when auditory pitch was congruent, rather than incongruent, with its associative visual size counterpart. We used multivariate Linear Discriminant Analysis (LDA) to characterise the spatiotemporal dynamics of EEG activity underpinning IAT performance. We found an ‘Early’ component (∼100–110 ms post-stimulus onset) coinciding with the time of maximal discrimination of the auditory stimuli, and a ‘Late’ component (∼330–340 ms post-stimulus onset) underlying IAT performance. To characterise the functional role of these components in decision formation, we incorporated a neurally-informed Hierarchical Drift Diffusion Model (HDDM), revealing that the Late component decreases response caution, requiring less sensory evidence to be accumulated, whereas the Early component increased the duration of sensory-encoding processes for incongruent trials. Overall, our results provide a mechanistic insight into the contribution of ‘early’ sensory processing, as well as ‘late’ post-sensory neural representations of associative congruency to perceptual decision formation.

Electrophysiological response to visual symmetry: Effects of the number of symmetry axes

The symmetry axes of a stimulus are a critical determinant of visual perception. Although much is known about the effects of a single symmetry axis on perception, the effects of multiple symmetry axes are still poorly understood. Here, we investigated the influence of the number of symmetry axes on brain activity using event-related potentials (ERPs). Our results showed that altering the number of symmetry axes affects both the amplitude and the latency of ERPs. Specifically, the amplitude of ERP components increased as the number of symmetry axes increased, starting at the N1 (165–175 ms) component and lasting until the P2 (230–250 ms) component in the bilateral posterior areas and until the N2 (340 ms) component in the frontal-central areas. Importantly, the latency of ERP components was reduced when the number of symmetry axes increased, starting at the N1 in the right posterior area and lasting until the P2 component in the bilateral posterior areas. The temporal and spatial differences in these effects imply that activity related to symmetry axes gradually changes throughout the ventral visual streams in the human brain.

Mindfulness Meditation Improves Musical Aesthetic Emotion Processing in Young Adults.

This study explored the behavioral and neural correlates of mindfulness meditation improvement in musical aesthetic emotion processing (MAEP) in young adults, using the revised across-modal priming paradigm. Sixty-two participants were selected from 652 college students who assessed their mindfulness traits using the Mindful Attention Awareness Scale (MAAS). According to the 27% ratio of the high and low total scores, participants were divided into two subgroups: high trait group (n = 31) and low trait group (n = 31). Participants underwent facial recognition and emotional arousal tasks while listening to music, and simultaneously recorded event-related potentials (ERPs). The N400, P3, and late positive component (LPC) were investigated. The behavioral results showed that mindfulness meditation improved executive control abilities in emotional face processing and effectively regulated the emotional arousal of repeated listening to familiar music among young adults. These improvements were associated with positive changes in key neural signatures of facial recognition (smaller P3 and larger LPC effects) and emotional arousal (smaller N400 and larger LPC effects). Our results show that P3, N400, and LPC are important neural markers for the improvement of executive control and regulating emotional arousal in musical aesthetic emotion processing, providing new evidence for exploring attention training and emotional processing. We revised the affecting priming paradigm and E-prime 3.0 procedure to fulfill the simultaneous measurement of music listening and experimental tasks and provide a new experimental paradigm to simultaneously detect the behavioral and neural correlates of mindfulness-based musical aesthetic processing.

Changes of attention-related brain activity over 6 months after acute organophosphate pesticide poisoning: a prospective follow-up study

Context Ingestion of organophosphate (OP) pesticides is a common method of self-harm in developing countries. Apart from acute cholinergic effects, limited evidence implicates OP poisoning in long-term neurocognitive deficits. However, prospective neurophysiological evidence of long-term deficits is scarce in humans. We aimed to determine long-term cognitive changes of acute OP pesticide self-poisoning in a prospective follow-up study, using event-related potentials (ERPs), an electroencephalographic index of cognitive functioning. Methods We recruited 203 patients (147 men) hospitalised with OP pesticide ingestion (OP group; all had significant erythrocyte cholinesterase inhibition) and 50 patients (23 men) with paracetamol overdose (control group) as a means of self-harm. We recorded their ERPs and behavioural performance in a selective attention task at three post-exposure time points: on discharge from hospital (around 14 days post-ingestion), 6 weeks and 6 months post-ingestion. We compared the reaction time and ERP components of the two groups at each time point, adjusting for sex, age, education and comorbid depression in multiple regression models. Results OP group had significantly slower reaction times than the control group on discharge and at 6 weeks, but not at 6 months. On discharge, the OP group also showed significantly prolonged latency of the parietal P3b component, signifying delayed attentional processing. P3b amplitudes were also significantly smaller in the OP group on discharge and at 6 months. Within the OP group, greater clinical severity of poisoning was associated with smaller P3b amplitudes. Early pre-attentive cortical processing (as indexed by N1 ERP component) showed no significant intergroup differences. Conclusions Acute OP pesticide poisoning was associated with impaired behavioural and neurophysiological indices of selective attention. These deficits outlast the cholinergic phase of intoxication. The neurobehavioral impairment disappears over months, but neurophysiological deficits seem to last even after 6 months. This impairment could potentially compromise the performance and safety of patients for months following clinical recovery.

Evaluation of visual-induced motion sickness from head-mounted display using heartbeat evoked potential: a cognitive load-focused approach

Based on sensory conflict theory, motion sickness is strongly related to the information processing capacity or resources of the brain to cope with the multi-sensory stimuli experienced by watching virtual reality (VR) content. The purpose of this research was to develop a method of measuring motion sickness using the heart-evoked potential (HEP) phenomenon and propose new indicators for evaluating motion sickness. Twenty-eight undergraduate volunteers of both genders (14 females) participated in this study by watching VR content on both 2D and head-mounted devices (HMD) for 15 min. The responses of HEP measures such as alpha power, latency, and amplitude of first and second HEP components were compared using paired t-tests and ANCOVA. This study confirmed that motion sickness leads to a decline in cognitive processing, as demonstrated by increasing in alpha power of HEP. Also, the proposed indicators such as latency and amplitude of the HEP waveform showed significant differences during the experience of motion sickness and exhibited high correlations with alpha power measures. Latencies of the first HEP component, in particular, are recommended as better quantitative evaluators of motion sickness than other measures, following the multitrait-multimethod matrix. The proposed model for motion sickness was implemented in a support vector machine with a radial basis function kernel, and validated on twenty new participants. The accuracy, F1 score, precision, recall, and area under the curve (AUC) of the motion-sickness classification results were 0.875, 0.865, 0.941, 0.8, and 0.962, respectively.

Evaluating frontoparietal network topography for diagnostic markers of Alzheimer’s disease

AbstractBackgroundA group of mild, untreated AD patients (n = 63) and a control group of healthy age‐matched individuals (n = 73) were compared on amplitudes and latencies of the N4 and P6 ERP.MethodSecondary EEG and behavioral data used for the present study was collected on participants while taking the Alzheimer’s Disease Evoked Potential Test (ADEPT) (Kilborn et al., 2009).ResultWe found a statistically‐significant difference in groups by N4 amplitude [F(1)=32.18, p < 0.001] and N4 latency [F(1)=31.41, p < 0.001], though linear models showed no interaction between these factors. A Tukey HSD post‐hoc test revealed significant pairwise differences between patients and controls (‐0.96 in N4 amplitude and 7.44 in N4 latency). We also found a statistically‐significant difference in groups by P6 amplitude [F(1)=11.12 p < 0.001] and P6 latency [F(1)=11.06, p < 0.001], and linear models showed no interaction between these factors. A Tukey HSD post‐hoc test revealed significant pairwise differences between patients and controls (‐1.13 in P6 amplitude and 7.70 in P6 latency).ConclusionOur results reveal a distinct N4/P6 ERP amplitude attenuation and subsequent component latency increase of mild untreated AD patients during cross‐modal memory tasks, while systematically showing statistically significant group effects in N4/P6 amplitudes and latencies of controls and patients making old/new recognition judgments. Our findings go further to provide evidence that N4 ERP anomalies are potentially more effective than those of their P6 counterpart for use as possible candidate AD biomarkers. Using EEG scalp topography, we visually demonstrate how and approximately where healthy control participants demonstrate neural cohesion through FPN shifting during cross‐modal tasks whereas the AD patients do not.

Development of children's performance and ERP components in the equiprobable Go/NoGo task

Since the equiprobable Go/NoGo task lacks the dominant Go imperative of the usual Go/NoGo (with more Go than NoGo stimuli), it is generally regarded as involving little inhibition. However, children have relative difficulty with this task, and have a large frontal NoGo N2. We previously found that this ‘child N2’ does play an inhibitory role, with larger frontal N2b associated with fewer commission errors. Here we investigated age-related developmental differences in the N2b and other components in the equiprobable Go/NoGo task. Two groups of eighteen Younger children (aged 8.0 to 10.3 years) and eighteen Older children (aged 10.4 to 12.8 years), matched on sex, were presented with three stimulus blocks each containing 100 Go and 100 NoGo tone stimuli in random order. Four temporal PCAs, each with unrestricted VARIMAX rotation, separately quantified the Go and NoGo ERPs of each group, and similar components were extracted from each set. Most identified components were differentially enhanced to either Go or NoGo, as in adults, supporting a previously-proposed differential sequential processing schema. The Older group had Go component latencies that were systematically reduced by some 7.4% from the Younger group, and they displayed faster RT and fewer omission and commission errors. Between subjects in the Older group, larger frontocentral NoGo N2b was associated with fewer commission errors. Hence the NoGo N2b in this paradigm can be interpreted as an individual marker of inhibition in older, but not young, children.

Striatal BOLD and midfrontal theta power express motivation for action

Action selection is biased by the valence of anticipated outcomes. To assess mechanisms by which these motivational biases are expressed and controlled, we measured simultaneous EEG-fMRI during a motivational Go/NoGo learning task (N = 36), leveraging the temporal resolution of EEG and subcortical access of fMRI. VmPFC BOLD encoded cue valence, importantly predicting trial-by-trial valence-driven response speed differences and EEG theta power around cue onset. In contrast, striatal BOLD encoded selection of active Go responses and correlated with theta power around response time. Within trials, theta power ramped in the fashion of an evidence accumulation signal for the value of making a “Go” response, capturing the faster responding to reward cues. Our findings reveal a dual nature of midfrontal theta power, with early components reflecting the vmPFC contribution to motivational biases, and late components reflecting their striatal translation into behavior, in line with influential recent “value of work” theories of striatal processing.

Geochronology and geochemistry of Cretaceous–Eocene granites, Tengchong Block (SW China): Petrogenesis and implications for Mesozoic-Cenozoic tectonic evolution of Eastern Tethys

The Early Cretaceous–Early Eocene granitoids in the Tengchong Block record the evolutionary history of the Mesozoic-Cenozoic tectono-magmatic evolution of Eastern Tethys. (a) The Early Cretaceous granitoids with relatively low (87Sr/86Sr)i ratios of 0.7090–0.7169 and εNd(t) values of −9.8 to −7.8 display metaluminous, calc-alkaline dominated by I-type granite affinity and hybrid mantle–crust geochemical signatures. They may have been derived from melting of the subducted Meso-Tethyan Bangong-Nujiang oceanic crust with terrigenous sediments in an arc-continent collisional setting. (b) The Late Cretaceous–Paleocene granitoids with relatively high (87Sr/86Sr)i ratios of 0.7109–0.7627, and εNd(t) values of −12.1 to −7.9 exhibit metaluminous to peraluminous, calc-alkaline dominated by S-type granite affinity and hybrid Lower–Upper crust geochemical signatures, which may be originated from partial melting of the Meso-Proterozoic continental crust in the collision setting between the Tengchong Block and Baoshan Block. (c) The Early Eocene granitoids have metaluminous, calc-alkaline I-type and S-type granites dual affinity, with relatively high (87Sr/86Sr)i ratios of 0.711–0.736, εNd(t) values of −9.4 to −4.7, showing crust-mantle mixing geochemical signatures. They may have been originated from partial melting of the late Meso-Proterozoic upper crustal components mixed with some upper mantle material during the ascent process of mantle magma caused by the subduction of the Neo-Tethyan Putao–Myitkyian oceanic crust, and collision between the Western Burma Block and the Tengchong Block. It is these multi-stage subductions and collisions that caused the spatial and temporal distribution of the granitic rocks in the Tengchong Block.

Reward magnitude enhances early attentional processing of auditory stimuli.

Reward associations are known to shape the brain's processing of visual stimuli, but relatively less is known about how reward associations impact the processing of auditory stimuli. We leveraged the high-temporal resolution of electroencephalography (EEG) and event-related potentials (ERPs) to investigate the influence of low- and high-magnitude stimulus-reward associations in an auditory oddball task. We associated fast, correct detection of certain auditory target stimuli with larger monetary rewards, and other auditory targets with smaller rewards. We found enhanced attentional processing of the more highly rewarded target stimuli, as evidenced by faster behavioral detection of those stimuli compared with lower-rewarded stimuli. Neurally, higher-reward associations enhanced the early sensory processing of auditory targets. Targets associated with higher-magnitude rewards had higher amplitude N1 and mismatch negativity (MMN) ERP components than targets associated with lower-magnitude rewards. Reward did not impact the latency of these early components. Higher-reward magnitude also decreased the latency and increased the amplitude of the longer-latency P3 component, suggesting that reward also can enhance the final processing stages of auditory target stimuli. These results provide insight into how the sensory and attentional neural processing of auditory stimuli is modulated by stimulus-reward associations and the magnitude of those associations, with higher-magnitude reward associations yielding enhanced auditory processingat both early and late stages compared with lower-magnitude reward associations.

Abstract 12140: SCN1B Expression Modulates Sodium Influx in Cardiomyocytes and Diastolic Function in the Adult Heart

Voltage-gated sodium channels (VGSCs) are macromolecular complexes composed of a number of proteins regulating channel biophysical properties. VGSCs generate Na + current (I Na ) in myocytes and play fundamental roles in excitability and impulse conduction in the heart. Moreover, VGSCs condition mechanical properties of the myocardium, a process that appears to involve the late component of I Na . Variants in the gene SCN1B , encoding the VGSC β1 and β1B subunits, result in inherited neurological disorders and cardiac arrhythmias. But the precise contributions of β1/β1B subunits and VGSC integrity to the overall function of the adult heart remain to be clarified. For this purpose, adult mice with cardiac-restricted, inducible deletion of Scn1b (conditional knock-out, cKO) were studied. Myocytes from cKO mice had decreased levels of Scn1b transcripts (-85%) and increased densities of fast- (+20%) and slow-inactivating (+140%) components of I Na , with respect to cells from corresponding control (Ctrl) animals. By echocardiography, left ventricular (LV) mass, chamber volume, and systolic function were preserved in both male and female cKO mice, with respect to sex- and age-matched Ctrl animals. However, by transmitral flow Doppler echocardiography, cKO mice presented reduced velocity of the passive filling wave (-~20%), attenuated ratio of the passive-to-active filling velocity waves (-~20%), and prolonged isovolumic relaxation time (+~16%). Moreover, by pressure-volume (PV) loop assessment, cKO mice had steeper slope of the LV end diastolic PV relation and prolonged LV relaxation tau, suggesting impairment of diastolic function. Importantly, inhibition of late I Na with GS967 (0.5 mg/kg body weight) normalized left ventricular filling pattern and isovolumic relaxation time in cKO mice, but had no consequences in Ctrl animals. At the cellular level, cKO myocytes presented delayed kinetics of Ca 2+ transients decay and cell shortening with respect to Ctrl myocytes. These defects were partly corrected by inhibition of the late I Na . Collectively, these results document that VGSC β1/β1B subunits modulate electrical and mechanical function of the heart by regulating, at least in part, Na + influx in cardiomyocytes.

Brain Response and Reaction Time in Natural and Comfort Conditions, with Energy-Saving Potential in an Office Environment

Psychological adaptation to ambient temperatures is fascinating and critical, both theoretically and practically, for energy efficiency in temperate climates. In this study, we investigated and compared the brain response (event-related potentials with a late positive component and latency ~300 milliseconds; labeled “P300” in the present study) and reaction times of Indonesian participants (n = 11), as tropical natives living in Japan, and Japanese participants (n = 9) in natural (i.e., hot during the summer and cold during the winter) and comfort conditions (with cooling and heating). Thermal comfort under contrasting conditions was studied using both instruments and subjective ratings. P300 potential and reaction time were measured before and after a Uchida–Kraepelin (U–K) test (30 summation lines). The results showed that P300 potential and latency did not change between the pre- and post-U–K test among conditions in any of the groups. Furthermore, Indonesian participants showed lower P300 potential (hot conditions) and slower P300 latency (hot and cooling conditions) than Japanese participants. We also found that the reaction time of the Indonesian group significantly differed between the pre- and post-U–K test in an air-conditioned environment, with either cooling or heating. In this study, Indonesian participants demonstrated a resistance to P300 and worse reaction times during work in a thermally unfamiliar season, specifically indicated by the indifferent performances among contrasting environmental conditions. Indonesian participants also showed similar thermal and comfort sensations to Japanese participants among the conditions. In the winter, when the Indonesian neutral temperature is higher than Japanese’s, the energy consumption may increase.

Mycobacterium tuberculosis canonical virulence factors interfere with a late component of the TLR2 response.

For many intracellular pathogens, the phagosome is the site of events and interactions that shape infection outcome. Phagosomal membrane damage, in particular, is proposed to benefit invading pathogens. To define the innate immune consequences of this damage, we profiled macrophage transcriptional responses to wild-type Mycobacterium tuberculosis (Mtb) and mutants that fail to damage the phagosomal membrane. We identified a set of genes with enhanced expression in response to the mutants. These genes represented a late component of the TLR2-dependent transcriptional response to Mtb, distinct from an earlier component that included Tnf. Expression of the later component was inherent to TLR2 activation, dependent upon endosomal uptake, and enhanced by phagosome acidification. Canonical Mtb virulence factors that contribute to phagosomal membrane damage blunted phagosome acidification and undermined the endosome-specific response. Profiling cell survival and bacterial growth in macrophages demonstrated that the attenuation of these mutants is partially dependent upon TLR2. Further, TLR2 contributed to the attenuated phenotype of one of these mutants in a murine model of infection. These results demonstrate two distinct components of the TLR2 response and identify a component dependent upon endosomal uptake as a point where pathogenic bacteria interfere with the generation of effective inflammation. This interference promotes tuberculosis (TB) pathogenesis in both macrophage and murine infection models.

Is there a change in P300 evoked potential after 6 months in cochlear implant users?

ObjectiveThere are few studies on long-latency auditory evoked potential (P300) in people with hearing loss who use a cochlear implant. Central auditory system evaluation with behavioral and electrophysiological tests is believed to help understand the neuroplasticity mechanisms involved in auditory functioning after cochlear implant surgery. This study investigated the electrophysiological processing of cortical level acoustic signals in a group of 21 adult individuals with postlingual bilateral severe-to-profound hearing loss who were submitted to cochlear implant surgery. MethodsData were collected in three phases: pre-cochlear implant surgery, at cochlear implant activation, and 6 months after surgery. P300 measures were also registered during all phases. Tone-burst and speech stimuli were used to elicit P300 and were presented in free field. ResultsMean P3 component latency with tone-burst and speech stimuli were 352.9 and 321.9 ms in the pre-cochlear implant phase, 364.9 and 368.7 ms in the activation phase, 336.2 and 343.6 ms 6 months after the surgery. The P3 component mean latency values using tone-burst at activation were significantly different from those 6 months after cochlear implant. They were also significantly different using speech, between pre-cochlear implant and activation phases. Lower P3 component latency occurred 6 months after cochlear implant activation with tone-burst and pre-cochlear implant with speech stimulus. There was a weak correlation between mean P3 component latency with speech stimulus and time of hearing loss. There was no difference in amplitude between phases or in the comparison with the other variables. ConclusionThere were changes in P3 component latency during the period assessed, for both speech and pure-tone stimuli, with increased latency in the activation phase and similar lower results in the two other phases, Pre-CI and 6 months after CI use. Mean amplitude measures did not vary in the three phases.

Paleomagnetism of the Carboniferous–Permian Myall blocks, Tamworth Belt, southern New England Orogen: Permian counterclockwise rotations and Triassic clockwise rotation

This paleomagnetic study on the Myall blocks of the southern New England Orogen complements studies on four other Tamworth Belt blocks aiming to unravel evolution of the Tamworth Belt and the Manning Orocline in particular. Focus is on ignimbritic successions that have partly interlinked stratigraphies across the five blocks and can retain primary magnetisations despite prevalent overprinting. This makes the Tamworth Belt prospective to oroclinal testing by comparing poles and pole paths for individual blocks across its curved structure. Paleomagnetic, rock magnetic and magnetic fabric results are detailed from an upper lower Carboniferous to lower Permian succession, sampled across forearc basin and arc sites (64) of the western Myall Block and forearc basin sites (16) of the eastern Myall Block. Predominantly thermal demagnetisations show a widely present low-temperature component, attributed to late Oligocene weathering, intermediate-temperature primary and overprint components confined to the Nerong Volcanics, and high-temperature primary and overprint components. Overprinting proved more prevalent in the Myall blocks than in other Tamworth Belt blocks, with five phases dated from mid-Carboniferous to mid-Triassic. Comparison of primary and overprint poles against Carboniferous, Permian and Triassic reference paths shows counterclockwise rotations ranging from 20–45° for the western Myall Block forearc basin, to 30° to 90° west to east across the southwestern Myall Block arc complex, to 85–110° for the eastern Myall Block forearc basin, occurring from the latest Carboniferous–early Permian Tablelands phase probably to the mid- to late Permian initial pulse of the Hunter-Bowen phase. The southwestern Myall Block also shows a mid-Triassic, or later, clockwise rotation ranging west to east from 50° to 110°. KEY POINTS Paleomagnetism of upper lower Carboniferous to lower Permian successions of the Myall blocks constrains evolution of the Manning Orocline. The Myall blocks are heavily affected by overprints, with five phases dated from mid-Carboniferous to mid-Triassic. Primary and overprint magnetisations show various counterclockwise and clockwise rotations of the western, eastern and southwestern parts of the Myall blocks. Counterclockwise rotations occurred from latest Carboniferous–earliest Permian probably to mid- to late Permian and clockwise rotation during or after mid-Triassic.

Astrocytes and retrograde degeneration of nigrostriatal dopaminergic neurons in Parkinson\u2019s disease: removing axonal debris

ObjectiveThe dopaminergic nigrostriatal neurons (DA cells) in healthy people present a slow degeneration with aging, which produces cellular debris throughout life. About 2%–5% of people present rapid cell degeneration of more than 50% of DA cells, which produces Parkinson’s disease (PD). Neuroinflammation accelerates the cell degeneration and may be critical for the transition between the slow physiological and the rapid pathological degeneration of DA cells, particularly when it activates microglial cells of the medial forebrain bundle near dopaminergic axons. As synaptic debris produced by DA cell degeneration may trigger the parkinsonian neuroinflammation, this study investigated the removal of axonal debris produced by retrograde degeneration of DA cells, paying particular attention to the relative roles of astrocytes and microglia.MethodsRats and mice were injected in the lateral ventricles with 6-hydroxydopamine, inducing a degeneration of dopaminergic synapses in the striatum which was not accompanied by non-selective tissue damage, microgliosis or neuroinflammation. The possible retrograde degeneration of dopaminergic axons, and the production and metabolization of DA-cell debris were studied with immunohistochemical methods and analyzed in confocal and electron microscopy images.ResultsThe selective degeneration of dopaminergic synapses in the striatum was followed by a retrograde degeneration of dopaminergic axons whose debris was found within spheroids of the medial forebrain bundle. These spheroids retained mitochondria and most (e.g., tyrosine hydroxylase, the dopamine transporter protein, and amyloid precursor protein) but not all (e.g., α-synuclein) proteins of the degenerating dopaminergic axons. Spheroids showed initial (autophagosomes) but not late (lysosomes) components of autophagy (incomplete autophagy). These spheroids were penetrated by astrocytic processes of the medial forebrain bundle, which provided the lysosomes needed to continue the degradation of dopaminergic debris. Finally, dopaminergic proteins were observed in the cell somata of astrocytes. No microgliosis or microglial phagocytosis of debris was observed in the medial forebrain bundle during the retrograde degeneration of dopaminergic axons.ConclusionsThe present data suggest a physiological role of astrocytic phagocytosis of axonal debris for the medial forebrain bundle astrocytes, which may prevent the activation of microglia and the spread of retrograde axonal degeneration in PD.

Spatiotemporal Characteristics of Event-Related Potentials Triggered by Unexpected Events during Simulated Driving and Influence of Vigilance.

We investigated the spatiotemporal characteristics of brain activity due to sudden events during monotonous driving and how it changes with vigilance level. Two types of sudden events, emergency stop and car drifting, were presented using driving simulator, and event-related potentials (ERPs) were measured. From the ERPs of both types of events, an early component representing sensory information processing and a late component were observed. The early component was expected to represent sensory information processing, which corresponded to visual and somatosensory/vestibular information processing for the sudden stop and lane departure tasks, respectively. The late components showed spatiotemporal characteristics of the well-known P300 component for both types of events. Common characteristic brain activities occurred in response to sudden events, regardless of the type. The modulation of brain activity due to the vigilance level also shared common characteristics between the two types. We expect that our results will contribute to the development of an effective means to assist drivers’ reactions to ambulatory situations.

Attentional bias towards high and low caloric food on repeated visual food stimuli: An ERP study.

Food variety influences appetitive behaviour, motivation to eat and energy intake. Research found that repeated exposure to varied food images increases the motivation towards food in adults and children. This study investigates the effects of repetition on the modulation of early and late components of event-related potentials (ERPs) when participants passively viewed the same food and non-food images repeatedly. The motivational attention to food and non-food images were assessed in frontal, centroparietal, parietooccipital and occipitotemporal areas of the brain. Participants showed increased late positive potential (late ERP component) to high caloric image in the occipitotemporal region compared to low caloric and non-food images. Similar effects could be seen in the early ERP component in the frontal region, but with reversed polarity. Data suggest that both the early and late ERP components show greater ERP amplitude when viewing high caloric images than low caloric and non-food images. Despite repeated exposure to same image, high caloric food continued to show sustained attention compared to low caloric and non-food image.

Fusing multimodal neuroimaging data with a variational autoencoder.

Neuroimaging studies often collect multimodal data. These modalities contain both shared and mutually exclusive information about the brain. This work aims to find a scalable and interpretable method to fuse the information of multiple neuroimaging modalities into a lower-dimensional latent space using a variational autoencoder (VAE). To assess whether the encoder-decoder pair retains meaningful information, this work evaluates the representations using a schizophrenia classification task. The linear classifier, trained on the representations obtained through dimensionality reduction, achieves an area under the curve of the receiver operating characteristic (ROC-AUC) of 0.8609. Thus, training on a multimodal dataset with functional brain networks and a structural magnetic resonance imaging (sMRI) scan, leads to dimensionality reduction that retains meaningful information. The proposed dimensionality reduction outperforms both early and late fusion principal component analysis on the classification task.Clinical relevance - This work examines the interplay between neuroimaging modalities and their relation to mental disorders. This allows for more complex and rigorous analysis of multimodal neuroimaging data throughout clinical settings.

Metaphorical representation modulates the weight-embodiment effect: Evidence from behavioral- and event-related-potential-based experiments

In this study, the representation of sensation experiences was manipulated to investigate the effect of cognition on the embodiment process. Participants used two computer mouse devices (one heavy and one light) to categorize currency words in terms of value. The default “weight-importance” association (Experiment 1) and a manipulated “weight-encumbrance” association (Experiment 2) were applied to examine the modulation effect of metaphorical representation on weight embodiment. In the traditional association, a larger late positive component (LPC) and faster RTs were found when participants responded to high-value currency words with the heavy mouse and to low-value currency words with the light mouse (congruent condition) when compared to the reversed (incongruent) stimuli-response condition. In the manipulated association, a larger LPC around the central-parietal areas was found in the incongruent condition than in the congruent condition. These results suggest that the metaphorical representation of weight modulates the weight-embodiment effect.