Fixation Cross Research Articles

Can I see it in the eyes? An investigation of freezing-like motion patterns in response to avoidable threat.

Freezing is one of the most extensively studied defensive behaviors in rodents. Both reduced body and gaze movements during anticipation of threat also occur in humans and have been discussed as translational indicators of freezing but their relationship remains unclear. We thus set out to elucidate body and eye movements and concomitant autonomic dynamics in anticipation of avoidable threat. Specifically, 50 participants viewed naturalistic pictures that were preceded by a colored fixation cross, signaling them whether to expect an inevitable (shock), no (safety), or a potential shock (flight) that could be avoided by a quick button press. Body sway, eye movements, the heart rate and skin conductance were recorded. We replicated previously described reductions in body sway, gaze dispersion, and the heart rate, and a skin conductance increase in flight trials. Stronger reductions in gaze but not in body sway predicted faster motor reactions on a trial-wise basis, highlighting their functional role in action preparation. We failed to find a trait-like relationship between body and gaze movements across participants, but their temporal profiles were positively related within individuals, suggesting that both metrics partly reflect the same construct. However, future research is desirable to assess these response patterns in naturalistic environments. A more ethological examination of different movement dynamics upon threat would not only warrant better comparability between rodent and human research but also help determine whether and how eye-tracking could be implemented as a proxy for fear-related movements in restricted brain imaging environments.

The emergence of the EEG dominant rhythm across the first year of life.

The spectral composition of EEG provides important information on the function of the developing brain. For example, the frequency of the dominant rhythm, a salient features of EEG data, increases from infancy to adulthood. Changes of the dominant rhythm during infancy are yet to be fully characterized, in terms of their developmental trajectory and spectral characteristics. In this study, the development of dominant rhythm frequency was examined during a novel sustained attention task across 6-month-old (n= 39), 9-month-old (n= 30), and 12-month-old (n= 28) infants. During this task, computer-generated objects and faces floated down a computer screen for 10s after a 5-second fixation cross. The peak frequency in the range between 5 and 9Hz was calculated using center of gravity (CoG) and examined in response to faces and objects. Results indicated that peak frequency increased from 6 to 9 to 12months of age in face and object conditions. We replicated the same result for the baseline. There was high reliability between the CoGs in the face, object, and baseline conditions across all channels. The developmental increase in CoG was more reliable than measures of mode frequency across different conditions. These findings suggest that CoG is a robust index of brain development across infancy.

Functional Magnetic Resonance Imaging Activation During Unscripted Discourse in People With Poststroke Aphasia.

The purpose of this project was to determine the feasibility of employing a functional magnetic resonance imaging (fMRI) task that captured activation associated with overt, unscripted (or free) discourse of people with aphasia (PWA), using a continuous scan paradigm. Seven participants (six females, ages 48-70 years) with chronic poststroke aphasia underwent two fMRI scanning sessions that included a discourse fMRI paradigm that consisted of five 1-min picture description tasks, using personally relevant photographs, interspersed with two 30-s control periods where participants looked at a fixation cross. Audio during the continuous fMRI scan was collected and marked with speaking times and coded for correct information units. Activation maps from the fMRI data were generated for the contrast between speaking and control conditions. In order to show the effects of the multi-echo data analysis, we compared it to a single-echo analysis by using only the middle echo (echo time of 30 ms). Through the implementation of the free discourse fMRI task, we were able to elicit activation that included bilateral regions in the planum polare, central opercular cortex, precentral gyrus, superior temporal gyrus, middle temporal gyrus, superior temporal gyrus, Crus I of the cerebellum, as well as bilateral occipital regions. We describe a new tool for assessing discourse recovery in PWA. By demonstrating the feasibility of a natural language paradigm in patients with chronic, poststroke aphasia, we open a new area for future research.

Distinct patterns of spatial attentional modulation of steady-state visual evoked magnetic fields (SSVEFs) in subdivisions of the human early visual cortex.

In recent years, steady-state visual evoked potentials (SSVEPs) became an increasingly valuable tool to investigate neural dynamics of competitive attentional interactions and brain-computer interfaces. This is due to their good signal-to-noise ratio, allowing for single-trial analysis, and their ongoing oscillating nature that enables to analyze temporal dynamics of facilitation and suppression. Given the popularity of SSVEPs, it is surprising that only a few studies looked at the cortical sources of these responses. This is in particular the case when searching for studies that assessed the cortical sources of attentional SSVEP amplitude modulations. To address this issue, we used a typical spatial attention task and recorded neuromagnetic fields (MEG) while presenting frequency-tagged stimuli in the left and right visual fields, respectively. Importantly, we controlled for attentional deployment in a baseline period before the shifting cue. Subjects either attended to a central fixation cross or to two peripheral stimuli simultaneously. Results clearly showed that signal sources and attention effects were restricted to the early visual cortex: V1, V2, hMT+, precuneus, occipital-parietal, and inferior-temporal cortex. When subjects attended to central fixation first, shifting attention to one of the peripheral stimuli resulted in a significant activation increase for the to-be-attended stimulus with no activation decrease for the to-be-ignored stimulus in hMT+ and inferio-temporal cortex, but significant SSVEF decreases from V1 to occipito-parietal cortex. When attention was first deployed to both rings, shifting attention away from one ring basically resulted in a significant activation decrease in all areas for the then-to-be-ignored stimulus.

Event-Related Desynchronization of MEG Alpha-Band Oscillations during Simultaneous Presentation of Audio and Visual Stimuli in Children with Autism Spectrum Disorder.

Alpha-band (8-12 Hz) event-related desynchronization (ERD) or a decrease in alpha power in electro- and magnetoencephalography (EEG and MEG) reflects the involvement of a neural tissue in information processing. It is known that most children with autism spectrum disorder (ASD) have difficulties in information processing, and, thus, investigation of alpha oscillations is of particular interest in this population. Previous studies have demonstrated alterations in this neural activity in individuals with ASD; however, little is known about alpha ERD during simultaneous presentation of auditory and visual stimuli in children with and without ASD. As alpha oscillations are intimately related to attention, and attention deficit is one of the common co-occurring conditions of ASD, we predict that children with ASD can have altered alpha ERD in one of the sensory domains. In the present study, we used MEG to investigate alpha ERD in groups of 20 children with ASD and 20 age-matched typically developing controls. Simple amplitude-modulated tones were presented together with a fixation cross appearing on the screen. The results showed that children with ASD had a bilateral reduction in alpha-band ERD in the auditory but not visual cortex. Moreover, alterations in the auditory cortex were associated with a higher presence of autistic traits measured in behavioral assessment.

Early sensory gain control is dominated by obligatory and global feature-based attention in top-down shifts of combined spatial and feature-based attention.

What are the dynamics of global feature-based and spatial attention, when deployed together? In an attentional shifting experiment, flanked by three control experiments, we investigated neural temporal dynamics of combined attentional shifts. For this purpose, orange- and blue-frequency-tagged spatially overlapping Random Dot Kinematograms were presented in the left and right visual hemifield to elicit continuous steady-state-visual-evoked-potentials. After being initially engaged in a fixation cross task, participants were at some point in time cued to shift attention to one of the Random Dot Kinematograms, to detect and respond to brief coherent motion events, while ignoring all such events in other Random Dot Kinematograms. The analysis of steady-state visual-evoked potentials allowed us to map time courses and dynamics of early sensory-gain modulations by attention. This revealed a time-invariant amplification of the to-be attended color both at the attended and the unattended side, followed by suppression for the to-be-ignored color at attended and unattended sides. Across all experiments, global and obligatory feature-based selection dominated early sensory gain modulations, whereas spatial attention played a minor modulatory role. However, analyses of behavior and neural markers such as alpha-band activity and event-related potentials to target- and distractor-event processing, revealed clear modulations by spatial attention.

On the relationship between rhythm-based temporal expectations and endogenous spatial attention in simple reaction-time tasks

IntroductionRecent evidence suggests that the temporal expectations afforded by a regular rhythmic structure operate independently from endogenous spatial attention in simple reaction-time tasks. The most common manipulation followed in previous studies consisted of presenting a target stimulus either “in-time” or “out-of-time” (earlier or later) with a preceding rhythm. However, contrary to the proposal of entrainment models predicting a behavioral advantage for in-time compared to both early and late targets, responses were still faster for late targets, according to the so-called “foreperiod effect”. This finding makes it difficult to fully disentangle the impact of rhythm and the benefits afforded by the passage of time on the relationship between rhythm-based temporal and endogenous spatial attention.MethodsTo shed more light on this issue, we combined a spatial orienting task with a rhythmic manipulation, in which two placeholders flanking the fixation cross flickered at either a regular or irregular pace. Spatial orienting to the target location was deployed by symbolic color cues that were displayed independently of the rhythm (independent cues) or were integrated with the temporal rhythmic cues (integrated cues). Crucially, for both independent and integrated cues, and for regular and irregular rhythms, the interval between the rhythm and the target (i.e., the foreperiod) was kept fixed in Experiments 1–3 to control for the foreperiod effect, while the effect of foreperiod was explored in Experiment 4.ResultsResults showed a more beneficial effect of rhythms with independent cues as compared to integrated cues. Additionally, the benefit of rhythms was slightly but significantly larger at valid, compared to invalid, spatial locations, regardless of the foreperiod.DiscussionOur results extend previous studies by showing that interactive effects of rhythms and endogenous spatial attention may emerge in low-demanding detection tasks.

Binocular see-through configuration and eye movement attenuate visual rivalry in peripheral wearable displays.

Visual confusion occurs when two dissimilar images are superimposed onto the same retinal location. In the context of wearable displays, it can be used to provide multiple sources of information to users on top of the real-world scene. While useful, visual confusion may cause visual rivalry that can suppress one of the sources. If two different images are projected to each eye (i.e., monocular displays), it provokes binocular rivalry wherein visual perception intermittently switches between the two images. When a semi-transparent image is superimposed (i.e., see-through displays), monocular rivalry results, causing perceptual alternations between the foreground and the background images. Here, we investigated how these rivalries influence the visibility of the peripheral target using three configurations of wearable displays (i.e., monocular opaque, monocular see-through, and binocular see-through) with three eye movement conditions (i.e., saccades, smooth pursuit, and central fixation). Using the HTC VIVE Eye Pro headset, subjects viewed a forward vection of a 3D corridor with a horizontally moving vertical grating at 10° above the center fixation. During each trial (~1 min), subjects followed a fixation cross that varied in location to induce eye movements and simultaneously reported whether the peripheral target was visible. Results showed that the binocular display had significantly higher target visibility than both monocular displays, and the monocular see-through display had the lowest target visibility. Target visibility was also higher when eye movements were executed, suggesting that the effects of rivalry are attenuated by eye movements and binocular see-through displays.

Evidence of target enhancement and distractor suppression in early visual areas

Although the mechanisms of target enhancement and distractor suppression have been investigated along the visual processing hierarchy, there remains some unknown as to the role of perceptual load on the competition between different task-related information as attention deployment is manipulated. We present an fMRI spatial cueing paradigm, in which 32 participants had to attend to either a left or a right hemifield location and to indicate the orientation of the target Gabor that was presented simultaneously to a noise patch distractor. Critically, the target could appear at either the cued, valid location or at the uncued, invalid location; in the latter, the noise patch distractor appeared at the cued location. Perceptual load was manipulated by the presence or absence of high-contrast Gabor patches close to the fixation cross, which acted as lateral masks. Behavioural results indicated that participants performed more efficiently in validly cued trials compared to invalidly cued trials and under low compared to high load. Enhancement effects for targets and suppression effects for noise patches were greater in early visual areas at high load, that is in the presence of lateral masks. These results are in line with the hypothesis that attention results in both target enhancement and distractor suppression, and that these effects are most marked under high perceptual load. Theoretical implications of these results for different models of attention are discussed.

Evaluation of visual food stimuli paradigms on healthy adolescents for future use in fMRI studies in anorexia nervosa

BackgroundMostly, visual food stimuli paradigms for functional Magnetic Resonance Imaging are used in studies of eating disorders. However, the optimal contrasts and presentation modes are still under discussion. Therefore, we aimed to create and analyse a visual stimulation paradigm with defined contrast.MethodsIn this prospective study, a block-design fMRI paradigm with conditions of randomly altering blocks of high- and low-calorie food images and images of fixation cross was established. Food pictures were rated in advance by a group of patients diagnosed with anorexia nervosa to address the dedicated perception of patients with eating disorders. To optimize the scanning procedure and fMRI contrasts we have analysed neural activity differences between high-calorie stimuli versus baseline (H vs. X), low-calorie stimuli versus baseline (L vs. X) and high- versus low-calorie stimuli (H vs. L).ResultsBy employing the developed paradigm, we were able to obtain results comparable to other studies and analysed them with different contrasts. Implementation of the contrast H versus X led to increased blood-oxygen-level-dependent signal (BOLD) mainly in unspecific areas, such as the visual cortex, the Broca´s area, bilaterally in the premotor cortex and the supplementary motor area, but also in thalami, insulae, the right dorsolateral prefrontal cortex, the left amygdala, the left putamen (p < .05). When applying the contrast L versus X, an enhancement of the BOLD signal was detected similarly within the visual area, the right temporal pole, the right precentral gyrus, Broca´s area, left insula, left hippocampus, the left parahippocampal gyrus, bilaterally premotor cortex and thalami (p < .05). Comparison of brain reactions regarding visual stimuli (high- versus low-calorie food), assumed to be more relevant in eating disorders, resulted in bilateral enhancement of the BOLD signal in primary, secondary and associative visual cortex (including fusiform gyri), as well as angular gyri (p < .05).ConclusionsA carefully designed paradigm, based on the subject’s characteristics, can increase the reliability of the fMRI study, and may reveal specific brain activations elicited by this custom-built stimuli. However, a putative disadvantage of implementing the contrast of high- versus low-calorie stimuli might be the omission of some interesting outcomes due to lower statistical power.Trial registration NCT02980120.

Clinical outcomes of closed, displaced phalangeal neck fractures in children with different types of kirschner wire fixation: A retrospective observational study.

Inappropriate treatment of Closed displaced phalangeal neck fractures (CDPNF) in children usually leads to poor outcomes.This study was to evaluate the clinical outcomes of closed/open reduction, age, and different types of fracture and Kirschner wire (K-wire) fixation in the treatment of CDPNF. Participants: Sixty patients (male, 46 and female,14; right-handed, 35 and left-handed, 25; mean age, 7.9-years-old [range, 1.0-14.5 years]) who had CDPNF were included. Preoperative x-rays showed that the fractures were displaced and exhibited obvious deformities. Interventions: First, reduction (four cases of open reduction and 56 cases of closed reduction) was performed followed by percutaneous K-wire fixation (cross fixation, 24 cases; longitudinal and slanting fixation, 17 cases; homolateral fixation, four cases; and single longitudinal fixation, 15 cases,) and immobilized by cast. x-ray examination following removal of the K-wires showed that the fractures were healed; the criteria for fracture healing were callus formation and the absence of fracture lines. Clinical outcome and radiographs between groups were compared. According to the visual analogue scale, the pain scores were excellent. According to the Al-Qattan Grade system(AGS),all the patients presented with closed, type II phalangeal neck fractures,the results were excellent in 36 cases (36/60, 60%), good in 15 cases (15/60, 25%), fair in 5 cases (5/60, 8.3%) and poor in 4 cases (4/60, 6.7%). There were significant differences in different fracture type groups (P = 0.013*), operation age groups (P = 0.025*) and open/closed reduction groups (P = 0.042*). There was no significant difference in K-wire fixation type groups (P > 0.05). Patients with open reduction, the more serious fracture type, the older at the operation, were more likely to have poor AGS result. Different K-wire fixation types for CDPNF in children had the same satisfactory results.

The Effect of Task Interruption on Working Memory Performance.

This study used electroencephalography to explore the behavioral and electrophysiological effects of task interruption on performance. Task interruption is known to harm work performance, especially on working memory-related tasks. However, most studies pay little attention to cognitive processes by exploring brain activity and ignore the cumulative effect of sequential interruptions. Thirty-four healthy participants performed a spatial 2-back in three conditions: (1) interruptions with simple math questions, (2) suspensions with prolonged fixation cross, and (3) a pure 2-back. The measured outcomes comprise performance data, ERP amplitudes, EEG power, and subjective workload. Work performance decreased in the resumption trials, and cumulative interruptions had a more destructive effect on performance. EEG results showed that the P2 and P3 amplitudes induced by the 2-back task significantly increased after interruptions; theta and alpha power increased after interruptions. The P3 amplitude and alpha power induced by interruptions were significantly higher than that induced by suspensions. Behavioral data revealed the disruptive effect of interruptions on postinterruption performance and the cumulative effect of interruptions on accuracy. Changes in ERP amplitudes and EEG power indicate the mechanisms of attention reallocation and working memory during interruptions. Larger P3 amplitudes and alpha power after interruptions than after suspensions suggested the inhibition of irrelevant information. These results may support the memory for goals model and improve the understanding of the effects of interruption on working memory. Focusing upon the mechanisms at play during the interruption process can support interruption management to ensure work safety and efficiency.

Moving visual world experiments online? A web-based replication of Dijkgraaf, Hartsuiker, and Duyck (2017) using PCIbex and WebGazer.js.

The visual world paradigm is one of the most influential paradigms to study real-time language processing. The present study tested whether visual world studies can be moved online, using PCIbex software (Zehr & Schwarz, 2018) and the WebGazer.js algorithm (Papoutsaki et al., 2016) to collect eye-movement data. Experiment 1 was a fixation task in which the participants looked at a fixation cross in multiple positions on the computer screen. Experiment 2 was a web-based replication of a visual world experiment by Dijkgraaf et al. (2017). Firstly, both experiments revealed that the spatial accuracy of the data allowed us to distinguish looks across the four quadrants of the computer screen. This suggest that the spatial resolution of WebGazer.js is fine-grained enough for most visual world experiments (which typically involve a two-by-two quadrant-based set-up of the visual display). Secondly, both experiments revealed a delay of roughly 300 ms in the time course of the eye movements, possibly caused by the internal processing speed of the browser or WebGazer.js. This delay can be problematic in studying questions that require a fine-grained temporal resolution and requires further investigation.

The impact of emotional context on neural substrates of respiratory sensory gating.

Psychological challenges have been found to impact respiratory symptom perception in healthy individuals as well as in patients with various neurological disorders. Human respiratory sensory gating is an objective measure to examine respiratory sensory information processing of repetitive respiratory mechanical stimuli in the central nervous system. With this electrophysiological method, patients with higher anxiety levels showed reduced respiratory sensory gating function in the cortex, and increased symptom perception. In addition, positive emotional contexts were found to increase the respiratory sensory gating function using RREPs. However, neural substrates related to emotional impacts on respiratory sensory gating remain still unclear. In the present study, we examined the emotion processing of respiratory sensory gating using functional magnetic resonance imaging. We hypothesized that positive compared with neutral stimuli would result in reduced brain activations in cortical areas with the paired occlusion paradigm. Thirty-five healthy adults participated in this event-designed fMRI experiment. Paired inspiratory occlusions (two transient occlusions with a 500 ms inter-stimulus-interval are delivered during one inspiration) were provided using an external trigger outside of the scanner. At least 40 paired inspiratory occlusions were collected for each trial. The experiment contained three runs during which participants underwent 12 min for the paired inspiratory occlusion paradigm while watching a fixation cross (the control condition), neutral and positive emotional picture series. The order of emotional picture series was randomized across the participants. Our results revealed an overall trend of reduction of brain activity from the neutral (minus fixation) condition, to the pleasant (minus fixation) condition. For bilateral thalamus and primary visual cortices, there was no significant difference in neural activation between the two contrasts of pleasant (ContrastP-F) and neutral condition (ContrastN-F). The activation of the mid-cingulate and the orbitofrontal cortex was lower in ContrastP-F compared to ContrastN-F. In conclusion, our results suggest that emotional context, especially positive valence, modulates neural correlates in middle cingulate cortex and orbitofrontal cortex in terms of respiratory sensory gating. Future studies are recommended to test emotional impacts on respiratory sensations in patients with neurological disorders.

Dynamic Visual Acuity Test To Denote Visuomotor Changes In Adolescents Participating In High Impact Sports

Repetitive head impacts (RHI), independent of concussion, can have a negative influence on the visual system but data are sparse in adolescent contact athletes. PURPOSE: Evaluate the effect of repetitive head impacts influence on adolescent football players oculomotor and vision throughout the mid-point of a single contact season using a dynamic visual acuity (DVA) task. METHODS:4 NIAA Varsity and JV football high school players (all males) with ≤20/20 static visual acuity with or without corrective lenses participated in this study. Student-athletes were evaluated prior (PRE) to the start of the season and in the middle (MID) of the season. The football players all wore instrumented mouthguards to track head impacts during each practice and game. Every participant completed 120 randomized trials of smooth pursuit (SPEM) (30°/s) and saccadic (90°/s) eye movements at (PRE) and (MID) of the season. All participants eye movements were tracked by (500 Hz; Eyelink SR research, Ottawa, CN) while their heads were stable in a chin rest 150 cm away from a 26° monitor. Participants were tasked to determine the orientation of Landolt-C’s openings (left, right, up, down) that moved across the monitor (horizontally left to fight) using a keypad. Depending on the correct/incorrect responses during the smooth pursuit and saccadic trials, the size of the C’s would either increase or decrease in size (2-up, 1-down staircase). Between each trial, a retinal flush image was presented for 2 ms before the appearance of a fixation cross. Smoot pursuit eye movement (SPEM) gain, and vision alongside saccadic peak velocity were evaluated at each time point. RESULTS: No significant difference was noted at PRE (1.09 ± 0.04) to MID (1.07 ± 0.08; p = 0.33, Cohen’s d = 0.32) for SPEM gain and for saccadic peak velocity (PRE = 386.70 ± 36.94 m/s, MID = 397.20 ± 2.12 m/s; p = 0.935, Cohen’s d = 0.33). Similarly, no difference was noted for SPEM Vision at PRE (20/32) and MID (20/32; p = 0.71) and for saccades (PRE = 20/40, MID = 20/40; p = 0.935). Participants had ≤20/20 static visual acuity at both time points. CONCLUSIONS: Oculomotor control and vision do not decline in the presence of RHI from the beginning to the middle of a contact football season in adolescents. Additional data are needed given the strength of the effect size.

Simultaneous and alternate combinations of action-observation and motor imagery involve a common lower-level sensorimotor process

Combining the motor simulation techniques of action observation and motor imagery (AOMI) is known to enhance motor performance more than when these techniques are presented in isolation. The present study examined the involvement of lower-level sensorimotor processes for the improvement in a dart-throwing task using AOMI. Novice participants (n = 70) were assessed on their dart-throwing both before and after a six-week AOMI training intervention that was contingent upon the random allocation of groups. Participants were randomly allocated into groups involving AOMI, where they observed either a congruent action, incongruent action or fixation cross (control), while simultaneously or alternately imagining the dart-throwing task. Dart-throwing performance was significantly more improved for the simultaneous- and alternate-congruent groups compared to the simultaneous-fixation and control groups. There was no indication of improvement by any of the other groups. This improvement appeared to coincide with lower EMG activity at the agonist and antagonist muscles, which would indicate greater movement efficiency. The findings suggest that AOMI involves a common lower-level sensorimotor process, which can lead to motor facilitation or interference, dependent upon whether the simulation techniques are congruent or incongruent with each other, respectively. What's more, this feature does not appear to differ as a function of the structure of delivery (i.e., simultaneous vs. alternate).

Action planning modulates the representation of object features in human fronto-parietal and occipital cortex.

The visual cortex has been extensively studied to investigate its role in object recognition but to a lesser degree to determine how action planning influences the representation of objects' features. We used functional MRI and pattern classification methods to determine if during action planning, object features (orientation and location) could be decoded in an action‐dependent way. Sixteen human participants used their right dominant hand to perform movements (Align or Open reach) towards one of two 3D‐real oriented objects that were simultaneously presented and placed on either side of a fixation cross. While both movements required aiming towards target location, Align but not Open reach movements required participants to precisely adjust hand orientation. Therefore, we hypothesized that if the representation of object features is modulated by the upcoming action, pre‐movement activity pattern would allow more accurate dissociation between object features in Align than Open reach tasks. We found such dissociation in the anterior and posterior parietal cortex, as well as in the dorsal premotor cortex, suggesting that visuomotor processing is modulated by the upcoming task. The early visual cortex showed significant decoding accuracy for the dissociation between object features in the Align but not Open reach task. However, there was no significant difference between the decoding accuracy in the two tasks. These results demonstrate that movement‐specific preparatory signals modulate object representation in the frontal and parietal cortex, and to a lesser extent in the early visual cortex, likely through feedback functional connections.

Gray's Impulsivity Is Differentially Associated With Amygdala-Insula Functional Connectivity in Adolescents, Depending on ADHD Risk Status

AimsAttention-Deficit/Hyperactivity Disorder (ADHD) is associated with alterations in both reinforcement sensitivity and affective processing but the nature of the associations of these characteristics is yet to be examined. We hypothesized that individual differences in the sensitivity of the Behavioral Approach System (BAS) would exhibit differential relations with affective network connectivity – involved in emotional regulation and salience monitoring – in youth at-risk for, relative to youth not at-risk for, ADHD.MethodsAdolescents (n = 125; Mage=16.24 years, SD = 1.09 years; 61.6% boys) were recruited as part of The Budapest Longitudinal Study of ADHD and Externalizing Disorders. Forty-nine were classified as at-risk for ADHD (Mage=16.15 years; SD = 1.21 years; 77.6% boys), defined as exhibiting ≥4 parent-rated symptoms of either domain on the ADHD Rating Scale-5. Participants completed a 10-minute resting-state functional Magnetic Resonance Imaging session, during which they were asked to focus their attention on a fixation cross, as well as various self-report assessments, including the Reinforcement Sensitivity Theory of Personality Questionnaire (RST-PQ).ResultsFunctional Network Connectivity analyses indicated an interaction effect between the RST-PQ BAS impulsivity subscale and at-risk status on functional connectivity between four affective network region-pairs (ps &lt; .05, False Discovery Rate [FDR] corrected) within a cluster based on functional similarity (p = .014, FDR-corrected). Follow-up OLS linear regressions showed higher impulsivity scores predicted stronger functional connectivity between the (1) left amygdala-right insula (F(6, 117) = 3.298, p = .005, adjusted R2=.101), (2) left amygdala-left insula (F(6, 117) = 2.2, p = .048, adjusted R2=.055), (3) right amygdala-right insula (F(6, 117) = 3.833, p = .002, adjusted R2=.121), and (4) right amygdala-left insula (F(6, 117) = 3.064, p = .008, adjusted R2=.092) in at-risk youth, whereas an inverse relationship was apparent in not at-risk youth.There was no main effect of group status on BAS impulsivity scores (t(122)=−1.167, p = .246) or on functional connectivity ((1) t(122) = .383, p = .702; (2) t(122) = .195, p = .846; (3) t(122)=−.107, p = .915; (4) t(122)=−.206, p = .837).ConclusionThe amygdala-insula connection has been shown to be involved in trait impulsivity, however, available ADHD-focused studies targeted emotional functioning. To our knowledge, we are the first to demonstrate that Gray's impulsivity – reflecting trait reward sensitivity – is predictive of amygdala-insula functional connectivity at rest and that this relation differs given ADHD risk. Results have conceptual and practical implications (e.g., early identification) as the role of the amygdala-insula connection in reward sensitivity appears especially relevant for a developmental phase and a diagnostic group linked to increased risk taking.

From separate items to an integrated unit in visual working memory: Similarity chunking vs. configural grouping

It is unclear whether sequentially presented items can be grouped into an ensemble by similarity chunking without the aid of the configural cue (e.g., Kanizsa figure). The current study systematically explored this issue by gradually weakening the configural cue until it was completely removed. The results showed that sequentially presented Pac-Men could be integrated into a Kanizsa figure for better memory only when they were successively presented in adjacent locations. When Pac-Men were presented at non-adjacent or unpredictable locations, they could be chunked by their orientation similarity (they all faced toward the fixation cross) to improve memory performance. Importantly, such orientation similarity alone was sufficient to evoke memory benefit, even when successively presented Pac-Men could not form a Kanizsa object structure. This memory benefit cannot simply be attributed to the statistic regularity or mental transformation based on the egocentric reference frame. However, the configural cue alone could not produce a memory benefit if these Pac-Men did not face toward the fixation cross. All of these results indicate that the memory benefit of sequentially presented items could occur by similarity chunking without the aid of the configural cue. The memory benefit based on the configural grouping was fragile when items were sequentially presented.

Neural correlates of working memory and compensation at different stages of cognitive impairment in Parkinson’s disease

Working memory (WM) impairment is one of the most frequent cognitive deficits in Parkinson's disease (PD). However, it is not known how neural activity is altered and compensatory responses eventually fail during progression. We aimed to elucidate neural correlates of WM and compensatory mechanisms in PD. Eighteen cognitively normal PD patients (PD-CogNL), 16 with PD with mild cognitive impairment (PD-MCI), 11 with PD with dementia (PDD), and 17 healthy controls (HCs) were evaluated. Subjects performed an n-back task. Functional MRI data were analyzed by event-related analysis for correct responses. Brain activations were evaluated by comparing them to fixation cross or 0-back task, and correlated with n-back task performance. When compared to fixation cross, PD-CogNL patients had more activation in WM areas than HCs for both the 2- and 3-back tasks. PD-MCI and PDD patients had more activation in WM areas than HCs for the 0- and 1-back task. 2-back task performance was correlated with brain activations (vs. 0-back task) in the bilateral dorsolateral prefrontal cortex and frontal eye field (FEF) and left rostral prefrontal cortex, caudate nucleus, inferior/superior parietal lobule (IPL/SPL), and anterior insular cortex as well as anterior cingulate cortex. 3-back task performance was correlated with brain activations (vs. 0-back task) in the left FEF, right caudate nucleus, and bilateral IPL/SPL. Additional activations on top of the 0-back task, rather than fixation cross, are the neural correlates of WM. Our results suggest PD patients have two types of compensatory mechanisms: (1) Hyperactivation for different WM load tasks depending on their cognitive status. PD-CogNL have hyperactivation for moderate and heavy working memory load tasks while maintaining normal working memory performance. In contrast, PD-MCI and PDD have hyperactivation for control task and light working memory load task, leaving less neural resources to further activate for more demanding tasks and resulting in impaired working memory performance. (2) Bilateral recruitment of WM-related areas, in particular the DLPFC, FEF, IPL/SPL and caudate nucleus, to improve WM performance.