Spatial Selective Attention Research Articles

Searching for auditory targets in external space and in working memory: Electrophysiological mechanisms underlying perceptual and retroactive spatial attention

Attention can be shifted within internal representations maintained in working memory. These retroactive processes are particularly inherent to the processing of auditory information that is especially transient over time and thus, requires us to continuously maintain, attend to, and integrate information in working memory. Using EEG recordings, the present study investigated the neurophysiological mechanisms underlying selective spatial attention in a retroactive as opposed to a perceptual auditory search task. Two kinds of sound stimuli were employed: a horizontal sound array consisting of two natural sounds presented simultaneously in the left and right hemispace and a central single target sound. The target sound was provided either after (retroactive search) or before the presentation of the sound array (perceptual search). In both search conditions, participants completed a sound localization and a sound detection task, indicating the position (left or right) or the presence versus absence (yes or no) of a particular target sound. Analyses revealed a lateralization of alpha power oscillations (8–12 Hz) over parieto-occipital scalp in both perceptual and retroactive sound localization tasks, but not in respective sound detection tasks, suggesting auditory alpha lateralization to be restricted to spatially-specific task demands. The observed asymmetric modulations of alpha power in sound localization are consistent with analogous findings from the visual domain, supporting the supramodal role of alpha oscillations in the deployment of spatial attention. Hence, we conclude that auditory alpha lateralization is a higher-order attention mechanism that operates in perceptual and mnemonic space reflecting the access to a spatially-specific, supramodal response template.

Spatial selective attention and asynchrony of cognitive systems in adult dyslexic readers: an ERPs and behavioral study.

The aim of this study was to gain additional knowledge about the asynchrony phenomenon in developmental dyslexia, especially when spatial selective attention is manipulated. Adults with developmental dyslexia and non-impaired readers underwent two experimental tasks, one including alphabetic stimuli (pre-lexical consonant-vowel syllables) and the other containing non-alphabetic stimuli (pictures and sounds of animals). Participants were instructed to attend to the right or left hemifields and to respond to all stimuli on that hemifield. Behavioral parameters and event-related potentials were recorded. The main finding was that the dyslexic readers demonstrated asynchrony between the auditory and visual modalities when alphabetic stimuli were presented on the right hemifield. These results suggest that intact reading is linked to a synchronized auditory and visual speed of processing even when spatial selective attention is manipulated. The findings of the current study are discussed in terms of asynchrony between modalities as a neurocognitive marker in developmental dyslexia.

Impaired Neurobehavioural Performance in Untreated Obstructive Sleep Apnea Patients Using a Novel Standardised Test Battery

Objective/BackgroundAlthough polysomnography (PSG) is the gold-standard measure for assessing disease severity in obstructive sleep apnea (OSA), it has limited value in identifying individuals experiencing significant neurobehavioural dysfunction. This study used a brief and novel computerised test battery to examine neurobehavioural function in adults with and without OSA.Patients/Methods204 patients with untreated OSA [age 49.3 (12.5) years; body mass index, [BMI] 33.6 (8.0) kg/m2; Epworth sleepiness scale 12 (4.9)/24; apnea hypopnea index 33.6 (25.8)/h] and 50 non-OSA participants [age 39.2 (14.0) years; BMI 25.8 (4.2) kg/m2, ESS 3.6 (2.3)/24]. All participants completed a computerised neurobehavioural battery during the daytime in the sleep clinic. The OSA group subsequently underwent an overnight PSG. The 30 min test battery assessed cognitive domains of visual spatial scanning and selective attention (Letter Cancellation Test), executive function (Stroop task) and working memory (2- and 3-Back tasks), and a validated sustained attention task (psychomotor vigilance task, PVT). Group differences in performance were compared. Associations between disease severity and performance were examined in the OSA group.ResultsAfter controlling for age, gender and education, OSA patients demonstrated impaired performance on the Stroop-Text, 2 and 3-Back tasks, and the PVT compared with the non-OSA group. OSA patients had worse performance on the LCT with fewer average hits albeit with better accuracy. Some OSA polysomnographic disease severity measures were weakly correlated with performance.ConclusionsThis brief test battery may provide a sensitive, standardised method of assessing daytime dysfunction in OSA.

Sensorineural hearing loss degrades behavioral and physiological measures of human spatial selective auditory attention

Listeners with sensorineural hearing loss often have trouble understanding speech amid other voices. While poor spatial hearing is often implicated, direct evidence is weak; moreover, studies suggest that reduced audibility and degraded spectrotemporal coding may explain such problems. We hypothesized that poor spatial acuity leads to difficulty deploying selective attention, which normally filters out distracting sounds. In listeners with normal hearing, selective attention causes changes in the neural responses evoked by competing sounds, which can be used to quantify the effectiveness of attentional control. Here, we used behavior and electroencephalography to explore whether control of selective auditory attention is degraded in hearing-impaired (HI) listeners. Normal-hearing (NH) and HI listeners identified a simple melody presented simultaneously with two competing melodies, each simulated from different lateral angles. We quantified performance and attentional modulation of cortical responses evoked by these competing streams. Compared with NH listeners, HI listeners had poorer sensitivity to spatial cues, performed more poorly on the selective attention task, and showed less robust attentional modulation of cortical responses. Moreover, across NH and HI individuals, these measures were correlated. While both groups showed cortical suppression of distracting streams, this modulation was weaker in HI listeners, especially when attending to a target at midline, surrounded by competing streams. These findings suggest that hearing loss interferes with the ability to filter out sound sources based on location, contributing to communication difficulties in social situations. These findings also have implications for technologies aiming to use neural signals to guide hearing aid processing.

Ipsilesional deficit of selective attention in left homonymous hemianopia and left unilateral spatial neglect

AimsPatients with homonymous hemianopia may present a subtle ipsilesional deficit, recently referred to as ‘sightblindness’ in addition to the contralesional visual field defect. We recently demonstrated that this deficit could be worse in right brain-damaged patients with left hemianopia than in left brain-damaged patients with right hemianopia, confirming right hemisphere dominance for visuo-spatial and attentional capacities. In the present study we investigate whether this ipsilesional deficit could be attentional in nature and to what extent it is comparable in right brain-damaged (RBD) patients with left hemianopia and in RBD patients with left neglect. The study was also conducted in RBD patients with neither left hemianopia nor left neglect signs in order to test if a right hemisphere lesion per se could be responsible for subtle ipsilesional attentional deficit. To reach this aim, we tested selective attentional capacities in both visual fields of 10 right brain-damaged patients with left neglect (LN), 8 right brain-damaged patients with left homonymous hemianopia (LHH), 8 right brain-damaged patients with no signs of left neglect or left hemianopia (RBD controls), and 17 healthy age-matched participants (Normal controls). MethodA lateralized letter-detection task was used to test if right-brain damaged patients with LN or LH may present a deficit of selective attention in their right, ipsilesional visual field, in comparison to Normal and RBD controls. Participants were asked to detect a target letter in either a single large stimulus (low attentional load) or a small stimulus surrounded by flankers (high attentional load). Stimuli were displayed either in the left or in the right visual field. Accuracy and reaction times were recorded. ResultsResults on accuracy showed that both LN and LH patients exhibited lower correct responses than Normal controls in their ipsilesional right visual field, suggesting an attentional deficit in their ipsilesional, supposed healthy visual field. More specifically, LH patients exhibited a specific deficit for processing single large stimuli, but not for processing flanked stimuli, relative to normal controls. LN patients exhibited lower correct responses for processing all types of stimulus than normal controls, but also than right brain damaged controls, in both visual fields suggesting a non-lateralized deficit not only due to the right hemisphere lesion. Furthermore, this deficit is more pronounced for flanked small stimuli, requiring higher attentional load. ConclusionsThe present results bring further evidence that patients with left homonymous hemianopia or left unilateral neglect both present a weaker but significant ipsilesional deficit in addition to their well-known massive contralesional deficit. The presence of a specific attentional deficit in the right ipsilesional visual field of left hemianopic and left neglect patients is discussed regarding the hypothesis of hemispheric specialization for selective spatial attention and may have clinical implications for both conditions.

Effects of vision, listener head movement, and target location on spatial selective auditory attention

Listeners can use spatial selective auditory attention (SSAA) to focus on one talker in a complex acoustic scene. We have reported [Macpherson & Ellis, ASA Salt Lake, 2016] that listeners’ ability to attend to a frontal target in the presence of spatially separated distractors is decreased in a head-movement condition, suggesting that listeners cannot rapidly update the focus of their SSAA to compensate fully for head motion. Participants reported anecdotally that being able to see the target loudspeaker seemed beneficial in directing SSAA. Here, we assessed the benefit of access to a visual reference frame in a similar task. Under lighted and dark conditions, on each trial, listeners either fixated toward 0 azimuth or oscillated their heads at ~0.5 Hz with an amplitude of ~±40 degrees while five different simultaneous equal-intensity sequences of four spoken digits were presented as target (at azimuths from 0 to 90 degrees) and four distractors (at azimuths ±22.5 and ±45 degrees relative to the central target). Listeners verbally reported the target sequence heard. Performance declined under head motion and with increasing target eccentricity, but not additionally in dark conditions, suggesting that a visual reference frame was not beneficial in directing SSAA in our task.Listeners can use spatial selective auditory attention (SSAA) to focus on one talker in a complex acoustic scene. We have reported [Macpherson & Ellis, ASA Salt Lake, 2016] that listeners’ ability to attend to a frontal target in the presence of spatially separated distractors is decreased in a head-movement condition, suggesting that listeners cannot rapidly update the focus of their SSAA to compensate fully for head motion. Participants reported anecdotally that being able to see the target loudspeaker seemed beneficial in directing SSAA. Here, we assessed the benefit of access to a visual reference frame in a similar task. Under lighted and dark conditions, on each trial, listeners either fixated toward 0 azimuth or oscillated their heads at ~0.5 Hz with an amplitude of ~±40 degrees while five different simultaneous equal-intensity sequences of four spoken digits were presented as target (at azimuths from 0 to 90 degrees) and four distractors (at azimuths ±22.5 and ±45 degrees relative to the central t...

Did You Listen to the Beat? Auditory Steady-State Responses in the Human Electroencephalogram at 4 and 7Hz Modulation Rates Reflect Selective Attention.

The acoustic envelope of human speech correlates with the syllabic rate (4-8Hz) and carries important information for intelligibility, which is typically compromised in multi-talker, noisy environments. In order to better understand the dynamics of selective auditory attention to low frequency modulated sound sources, we conducted a two-stream auditory steady-state response (ASSR) selective attention electroencephalogram (EEG) study. The two streams consisted of 4 and 7Hz amplitude and frequency modulated sounds presented from the left and right side. One of two streams had to be attended while the other had to be ignored. The attended stream always contained a target, allowing for the behavioral confirmation of the attention manipulation. EEG ASSR power analysis revealed a significant increase in 7Hz power for the attend compared to the ignore conditions. There was no significant difference in 4Hz power when the 4Hz stream had to be attended compared to when it had to be ignored. This lack of 4Hz attention modulation could be explained by a distracting effect of a third frequency at 3Hz (beat frequency) perceivable when the 4 and 7Hz streams are presented simultaneously. Taken together our results show that low frequency modulations at syllabic rate are modulated by selective spatial attention. Whether attention effects act as enhancement of the attended stream or suppression of to be ignored stream may depend on how well auditory streams can be segregated.

Attention as the ‘glue’ for object integration in parietal extinction

Patients with unilateral, parietal brain damage frequently show visual extinction, which manifests in a failure to identify contralesional stimuli when presented simultaneously with other, ipsilesional stimuli (but full awareness for single stimulus presentations). Extinction reflects an impairment of spatial selective attention, leaving basic preattentive processing unaffected. For instance, access to bilaterally grouped objects is usually spared in extinction, suggesting that grouping occurs at a stage preceding (in the patients: abnormally biased) spatial-attentional selection. Here, we reinvestigated this notion by comparing (largely between participants, but also within a single-case participant) conditions with objects that varied in their dominant direction of grouping: from the attended to the non-attended hemifield (data from Conci et al., 2009) versus from the non-attended to the attended hemifield (new data). We observe complete absence of extinction when shape completion extended from the attended hemifield. By contrast, extinction was not diminished when object groupings propagate from the unattended hemifield. Moreover, we found the individual severity of the attentional impairment (assessed by a standard “inattention” test) to be directly related to the degree of completion in the unattended hemifield. This pattern indicates that grouping can overcome visual extinction only when object integration departs from the attended visual field, implying, contrary to many previous accounts, that attention is crucial for grouping to be initiated.

Predicting Eye Movements from Deep Neural Network Activity Decoded from fMRI Responses to Natural Scenes

Computational models of selective spatial attention can reliably predict eye movements to complex images. However, researchers lack a simple way to measure covert representations of spatial attention in the brain and their link to overt eye movement behavior, especially in response to natural scenes. Here, we predict eye movement patterns from spatial priority maps reconstructed from brain activity measured with functional magnetic resonance imaging (fMRI). First, we define a computational spatial attention model using a deep convolutional neural network (CNN) pretrained for scene categorization. Next, we decode CNN unit activity from fMRI activity and reconstruct spatial priority maps by applying our computational spatial attention model to decoded CNN activity. Finally, we predict eye movements in a subsequent behavioral experiment within and between individuals using reconstructed spatial priority maps. These results demonstrate that features represented in CNN unit activity can guide spatial attention and eye movements, providing a crucial link between CNN models, brain activity, and behavior.

Interplay of Gravicentric, Egocentric, and Visual Cues About the Vertical in the Control of Arm Movement Direction.

Our perception of the vertical corresponds to the weighted sum of gravicentric, egocentric, and visual cues. Here we evaluate the interplay of those cues not for the perceived but rather for the motor vertical. Participants were asked to flip an omnidirectional switch down while their egocentric vertical was dissociated from their visual-gravicentric vertical. Responses were directed mid-between the two verticals; specifically, the data suggest that the relative weight of congruent visual-gravicentric cues averages 0.62, and correspondingly, the relative weight of egocentric cues averages 0.38. We conclude that the interplay of visual-gravicentric cues with egocentric cues is similar for the motor and for the perceived vertical. Unexpectedly, we observed a consistent dependence of the motor vertical on hand position, possibly mediated by hand orientation or by spatial selective attention.

Dynamic modulation of the perceptual load on microsaccades during a selective spatial attention task

Selective spatial attention enhances task performance at restricted regions within the visual field. The magnitude of this effect depends on the level of attentional load, which determines the efficiency of distractor rejection. Mechanisms of attentional load include perceptual selection and/or cognitive control involving working memory. Recent studies have provided evidence that microsaccades are influenced by spatial attention. Therefore, microsaccade activities may be exploited to help understand the dynamic control of selective attention under different load levels. However, previous reports in humans on the effect of attentional load on microsaccades are inconsistent, and it is not clear to what extent these results and the dynamic changes of microsaccade activities are similar in monkeys. We trained monkeys to perform a color detection task in which the perceptual load was manipulated by task difficulty with limited involvement of working memory. Our results indicate that during the task with high perceptual load, the rate and amplitude of microsaccades immediately before the target color change were significantly suppressed. We also found that the occurrence of microsaccades before the monkeys’ detection response deteriorated their performance, especially in the hard task. We propose that the activity of microsaccades might be an efficacious indicator of the perceptual load.

Computerized Progressive Attention Training (CPAT) vs. Active Control in Adults with ADHD

Higher education students with ADHD cope with various academic obstacles such as difficulty to sustain attention while studying and deficient ability to focus attention effectively on academic tasks. Shalev et al. (Child Neuropsychology, 13(4), 382–388, 2007) have developed a computerized progressive attentional training (CPAT) program for children with ADHD, which is composed of four sets of structured tasks designed to uniquely activate various attentional functions: sustained-, selective-spatial, orienting-, and executive-attention. The goal of the present study was to evaluate the effect of the CPAT vs. an active control training program on improving attention functioning among high functioning adults with ADHD. Thirty participants, randomly assigned either to the CPAT or to the active control (computer games; CG) groups, completed 16 1-h training sessions across 8 weeks. Attention functioning was assessed using both objective and subjective tools three times: before the intervention (pre-test), after the intervention (post-test), and at follow-up (2–3 months later). Participants in the CPAT group exhibited significantly greater improvements in selective-spatial attention and in executive attention tasks (that were different than the attention training tasks) compared to participants in the CG group, and these gains were maintained at follow-up. These results provide strong evidence for near transfer effects of the CPAT. In addition, modest improvement in sustained attention was recorded in both training groups. However, analyses of the self-reported ADHD symptoms across the three points of assessment showed no change in either group. Future studies with larger samples should replicate and elaborate the present findings in order to assess whether the near transfer effects of the CPAT program could be translated to everyday functioning in high functioning adults with ADHD.

Spatial attention modulates visual gamma oscillations across the human ventral stream

Oscillatory synchronization in the gamma frequency range has been proposed as a neuronal mechanism to prioritize processing of relevant stimuli over competing ones. Recent studies in animals found that selective spatial attention enhanced gamma-band synchronization in high-order visual areas (V4) and increased the gamma peak frequency in V1. The existence of such mechanisms in the human visual system is yet to be fully demonstrated. In this study, we used MEG, in combination with an optimised stimulus design, to record visual gamma oscillations from human early visual cortex, while participants performed a visuospatial attention cueing task. First, we reconstructed virtual sensors in V1/V2, where gamma oscillations were strongly induced by visual stimulation alone. Second, following the results of a statistical comparison between conditions of attention, we reconstructed cortical activity also in inferior occipital-temporal regions (V4). The results indicated that gamma amplitude was modulated by spatial attention across the cortical hierarchy, both in the early visual cortex and in higher-order regions of the ventral visual pathway. In contrast, we found no evidence for an increase in the gamma peak frequency in V1/V2 with attention. The gamma response tended to peak earlier in V1/V2 than in V4 by approximately 70 ms, consistent with a feed-forward role of gamma-band activity in propagating sensory representations across the visual cortical hierarchy. Together, these findings suggest that differences in experimental design or methodology can account for the inconsistencies in previous animal and human studies. Furthermore, our results are in line with the hypothesis of enhanced gamma-band synchronization as an attentional mechanism in the human visual cortex.

Consumption of Iron-Biofortified Beans Positively Affects Cognitive Performance in 18- to 27-Year-Old Rwandan Female College Students in an 18-Week Randomized Controlled Efficacy Trial

Background: Evidence shows that iron deficiency in adulthood may affect cognitive performance, possibly by disrupting neurotransmitter regulation or brain energy metabolism. Women of reproductive age (WRA) are among those who are most vulnerable to iron deficiency; however, they have been largely ignored in the literature relating iron status to cognition.Objective: Our aim was to determine the efficacy of iron-biofortified beans in improving cognition in WRA compared with control beans.Methods: A double-blind, randomized intervention study was conducted in 150 women aged 18–27 y with low iron status (ferritin <20 μg/L). Women were randomly assigned to consume iron-biofortified beans (86.1 ppm iron) or control beans (50.1 ppm iron) daily for 18 wk. Iron status was assessed based on hemoglobin, ferritin, transferrin receptor, and body iron values and on cognitive performance on 5 computerized tasks at baseline and endline.Results: Groups did not differ on any variables at baseline. Per protocol analyses revealed that consumption of the biofortified beans resulted in a 17% larger improvement in the speed of spatial selective attention; a nearly 7-fold larger improvement in the speed, a 68% greater improvement in the efficiency, and a >2-fold greater improvement in the specificity of memory retrieval; and a >2-fold larger improvement in the speed and a >3-fold larger improvement in the efficiency of memory search—all of which are relative to consumption of the control beans (P < 0.01 for all comparisons).Conclusions: Cognitive performance is sensitive to iron status, and consumption of iron-biofortified beans for 18 wk improved cognitive performance, especially the efficiency of search and the speed of retrieval on memory tasks, in young adult women. This trial was registered at clinicaltrials.gov as NCT01594359.

PB 7 The role of Rolandic alpha-activity on processing of subliminal and supraliminal somatosensory stimulation during selective spatial attention

Research questions We investigated, whether attentional modulation of somatosensory evoked potentials (SEPs) are mediated by variations in the rolandic alpha-rhythm. Furthermore, we asked whether the attention effect is limited to consciously perceivable (i.e. supraliminal) stimuli, or also applies to imperceptible (i.e. subliminal) stimulation. Methods To address these questions, we recorded EEG in healthy volunteers (n = 40) undergoing supraliminal and subliminal finger nerve stimulation at the left or right index finger and identified both oscillatory activity and SEPs. Participants performed the following detection task: Spatial attention should be directed either to the left or the right index finger and participants indicated perception of stimuli only at the attended finger. Results Detection rates for supraliminal stimulation was 71%, when attention was on the left and 74%, when it was on the right finger, respectively (detection rates for subliminal stimulation ∼ 0%). In the EEG, selective spatial attention increased SEP-amplitudes (in a time window 50–60 ms after stimulation; P1) both to supraliminal and subliminal stimulation. Mu-rhythm amplitudes directly preceding stimulation showed a negative quadratic relationship to P1-amplitudes under attention, which reversed, when the stimulated finger was not attended. I.e. the same mu-rhythm amplitude was associated with the highest P1-amplitudes during attention and smallest P1-amplitudes during lack of attention. Conclusion The modulation of the mu-rhythm obviously seems to support the behavioral goal: ‘detect’ stimuli at the cued while ‘ignoring’ the other index finger. To summarize, our results show, that – firstly – selective spatial attention enhances central processing of supraliminal as well as subliminal stimulation and – secondly – they underline the importance of mu-rhythm activity in mediating the effect of attention on stimulus processing.

Selective attention within the foveola.

Efficient control of attentional resources and high-acuity vision are both fundamental for survival. Shifts in visual attention are known to covertly enhance processing at locations away from the center of gaze, where visual resolution is low. It is unknown, however, whether selective spatial attention operates where the observer already looks, i.e., within the high-acuity foveola, the small, yet disproportionally important rod-free region of the retina. Using new methods for precisely controlling retinal stimulation, here we show that covert attention flexibly improves and speeds-up both detection and discrimination at loci only a fraction of a degree apart within the foveola. These findings reveal a surprisingly precise control of attention and its involvement in fine spatial vision. They show that the commonly studied covert shifts of attention away from the fovea are the expression of a global mechanism that exerts its action across the entire visual field.

Two different mechanisms support selective attention at different phases of training.

Selective attention supports the prioritized processing of relevant sensory information to facilitate goal-directed behavior. Studies in human subjects demonstrate that attentional gain of cortical responses can sufficiently account for attention-related improvements in behavior. On the other hand, studies using highly trained nonhuman primates suggest that reductions in neural noise can better explain attentional facilitation of behavior. Given the importance of selective information processing in nearly all domains of cognition, we sought to reconcile these competing accounts by testing the hypothesis that extensive behavioral training alters the neural mechanisms that support selective attention. We tested this hypothesis using electroencephalography (EEG) to measure stimulus-evoked visual responses from human subjects while they performed a selective spatial attention task over the course of ~1 month. Early in training, spatial attention led to an increase in the gain of stimulus-evoked visual responses. Gain was apparent within ~100 ms of stimulus onset, and a quantitative model based on signal detection theory (SDT) successfully linked the magnitude of this gain modulation to attention-related improvements in behavior. However, after extensive training, this early attentional gain was eliminated even though there were still substantial attention-related improvements in behavior. Accordingly, the SDT-based model required noise reduction to account for the link between the stimulus-evoked visual responses and attentional modulations of behavior. These findings suggest that training can lead to fundamental changes in the way attention alters the early cortical responses that support selective information processing. Moreover, these data facilitate the translation of results across different species and across experimental procedures that employ different behavioral training regimes.

Enhanced limbic/impaired cortical-loop connection onto the hippocampus of NHE rats: Application of resting-state functional connectivity in a preclinical ADHD model

Due to a hyperfunctioning mesocorticolimbic system, Naples-High-Excitability (NHE) rats have been proposed to model for the meso-cortical variant of attention deficit/hyperactivity disorder (ADHD). Compared to Naples Random-Bred (NRB) controls, NHE rats show hyperactivity, impaired non-selective attention (Aspide et al., 1998), and impaired selective spatial attention (Ruocco et al., 2009a, 2014). Alteration in limbic functions has been proposed; however, resulting unbalance among forebrain areas has not been assessed yet. By resting-state functional Magnetic-Resonance Imaging (fMRI) in vivo, we investigated the connectivity of neuronal networks belonging to limbic vs. cortical loops in NHE and NRB rats (n=10 each). Notably, resting-state fMRI was applied using a multi-slice sagittal, gradient-echo sequence. Voxel-wise connectivity maps at rest, based on temporal correlation among fMRI time-series, were computed by seeding the hippocampus (Hip), nucleus accumbens (NAcc), dorsal striatum (dStr), amygdala (Amy) and dorsal/medial prefrontal cortex (PFC), both hemispheres. To summarize patterns of altered connection, clearly directional connectivity was evident within the cortical loop: bilaterally and specularly, from orbital and dorsal PFCs through dStr and hence towards Hip. Such network communication was reduced in NHE rats (also, with less mesencephalic/pontine innervation). Conversely, enhanced network activity emerged within the limbic loop of NHE rats: from left PFC, both through the NAcc and directly, to the Hip (all of which received greater ventral tegmental innervation, likely dopamine). Together with tuned-down cortical loop, this potentiated limbic loop may serve a major role in controlling ADHD-like behavioral symptoms in NHE rats.

Prolonged Interruption of Cognitive Control of Conflict Processing Over Human Faces by Task-Irrelevant Emotion Expression.

As documented by Darwin 150 years ago, emotion expressed in human faces readily draws our attention and promotes sympathetic emotional reactions. How do such reactions to the expression of emotion affect our goal-directed actions? Despite the substantial advance made in the neural mechanisms of both cognitive control and emotional processing, it is not yet known well how these two systems interact. Here, we studied how emotion expressed in human faces influences cognitive control of conflict processing, spatial selective attention and inhibitory control in particular, using the Eriksen flanker paradigm. In this task, participants viewed displays of a central target face flanked by peripheral faces and were asked to judge the gender of the target face; task-irrelevant emotion expressions were embedded in the target face, the flanking faces, or both. We also monitored how emotion expression affects gender judgment performance while varying the relative timing between the target and flanker faces. As previously reported, we found robust gender congruency effects, namely slower responses to the target faces whose gender was incongruent with that of the flanker faces, when the flankers preceded the target by 0.1 s. When the flankers further advanced the target by 0.3 s, however, the congruency effect vanished in most of the viewing conditions, except for when emotion was expressed only in the flanking faces or when congruent emotion was expressed in the target and flanking faces. These results suggest that emotional saliency can prolong a substantial degree of conflict by diverting bottom-up attention away from the target, and that inhibitory control on task-irrelevant information from flanking stimuli is deterred by the emotional congruency between target and flanking stimuli.

Differential effects of fearful faces under spatial attended and unattended conditions: evidence from an event-related potential study.

We examined the influence of spatial selective attention on the processing of emotional faces (happy neutral, and fear) using behavioral as well as event-related potential recordings. Emotional stimuli were rapidly presented randomly to the right or the left visual field while participants attended to one visual field at a time, detecting smaller stimuli that were shown in the attended field. Behavioral results showed decreased accuracy for the fearful faces compared with neutral and happy faces. Event-related potential data showed that compared with the neutral and happy faces, fearful faces appearing in the right visual field elicited enhanced contralateral P1 amplitudes in the unattended condition, whereas fearful faces appearing in the left visual field elicited decreased contralateral N170 activity in the attended condition. These findings provide evidence for differential emotional processing under spatial attended and unattended conditions.