Brain activity during divided and selective attention to auditory and visual sentence comprehension tasks

A Review of Auditory Attention: Neural Mechanisms, Theories, and Affective Disorders

Attention is a fundamental aspect of human cognitive function and is crucial for essential activities such as learning, social interaction, and routine tasks. Notably, Auditory attention involves complex interactions and collaboration among multiple brain networks. Recognizing the impairment of auditory attention, comprehending its underlying mechanisms, and identifying the activated brain regions essential for the development of treatments and interventions for individuals facing auditory attention deficits, emphasizes the significance of investigating these matters. In the current study, we conducted a review by searching for the full text of 53 articles published related to auditory attention, mechanisms, and networks in databases like Science Direct, Google Scholar, ProQuest, and PubMed using the keywords Attention, Auditory Attention, Auditory Attention Impairment, theories of attention were investigated in the years 2000 to 2023 And focused on articles that provided discussions within this research domain. The studies have demonstrated that auditory attention exceeds being an acoustic attribute and assumes a fundamental role in complex acoustic environments, information processing, and even speech comprehension. In the context of this study, we have conducted a review and summary of the proposed theories related to attention and the brain networks involved in different forms of auditory attention. In conclusion, the integration of auditory attention assessments, behavioral observations, and an understanding of the neural mechanisms and brain regions implicated in auditory attention proves to be an effective approach for the diagnosis and treatment of attention-related disorders.

Developmental dyslexia susceptibility genes DNAAF4, DCDC2, and NRSN1 are associated with brain function in fluently reading adolescents and young adults

Reading skills and developmental dyslexia, characterized by difficulties in developing reading skills, have been associated with brain anomalies within the language network. Genetic factors contribute to developmental dyslexia risk, but the mechanisms by which these genes influence reading skills remain unclear. In this preregistered study (https://osf.io/7sehx), we explored if developmental dyslexia susceptibility genes DNAAF4, DCDC2, NRSN1, and KIAA0319 are associated with brain function in fluently reading adolescents and young adults. Functional MRI and task performance data were collected during tasks involving written and spoken sentence processing, and DNA sequence variants of developmental dyslexia susceptibility genes previously associated with brain structure anomalies were genotyped. The results revealed that variation in DNAAF4, DCDC2, and NRSN1 is associated with brain activity in key language regions: the left inferior frontal gyrus, middle temporal gyrus, and intraparietal sulcus. Furthermore, NRSN1 was associated with task performance, but KIAA0319 did not yield any significant associations. Our findings suggest that individuals with a genetic predisposition to developmental dyslexia may partly employ compensatory neural and behavioral mechanisms to maintain typical task performance. Our study highlights the relevance of these developmental dyslexia susceptibility genes in language-related brain function, even in individuals without developmental dyslexia, providing valuable insights into the genetic factors influencing language processing.

Cathodal HD-tDCS and attention: A study on patients with intractable left lateral frontal lobe epilepsy

OBJECTIVE

Defects in the attentional network in patients with epilepsy are influenced by factors such as the location of epileptic foci. Examining the impact of cathodal high-definition transcranial direct current stimulation (HD-tDCS) on attention components could provide insights into potential attention-related side effects of tDCS. This study aimed to investigate the effect of cathodal HD-tDCS on interictal epileptiform discharges (IEDs), auditory/visual (A/V) attention components, and reaction time (RT) in patients with intractable focal left lateral frontal lobe epilepsy (LFLE).

METHODS

To control for variations in individual epilepsy syndrome, 12 adult participants diagnosed with drug-resistant left LFLE with focal cortical IEDs on C3 underwent repeated measurements at pretest, posttest, and follow-up steps. 4 × 1 ring electrodes (cathode on C3 and four anodes on F3, P3, T3, and Cz) delivered 2 mA DC for 20 min per session for 10 consecutive days. The integrated visual and auditory continuous performance test (IVA+) assessed the A/V attention components and RT. One-way repeated-measure ANOVA was used.

RESULTS

The findings suggest a significant effect in reducing IEDs. The IVA+ results showed a significant improvement in auditory divided attention and visual selective and focused attention (p < 0.05). In the follow-up, these changes demonstrated lasting efficacy. A/V speed scales increased (p < 0.05), showing a significant decrease in reaction time.

CONCLUSIONS

Cathodal HD-tDCS significantly reduced IEDs and improved the components of auditory divided attention, visual focused attention, and visual selective attention, with a reduction in patient reaction time. A significant lasting, side-effect-free positive effect was observed for up to one month after the intervention.

The neural oscillations in delta- and theta-bands contribute to divided attention in audiovisual integration

One of key mechanisms implicated in multisensory processing is neural oscillations in distinct frequency band. Many studies explored the modulation of attention by recording the electroencephalography signals when subjects attended one modality, and ignored the other modality input. However, when attention is directed toward one modality, it may be not always possible to shut out completely inputs from a different modality. Since many situations require division of attention between audition and vision, it is imperative to investigate the neural mechanisms underlying processing of concurrent auditory and visual sensory streams. In the present study, we designed a task of audiovisual semantic discrimination, in which the subjects were asked to share attention to both auditory and visual stimuli. We explored the contribution of neural oscillations in lower-frequency to the modulation of divided attention on audiovisual integration. Our results implied that theta-band activity contributes to the early modulation of divided attention, and delta-band activity contributes to the late modulation of divided attention to audiovisual integration. Moreover, the fronto-central delta- and theta-bands activity is likely a marker of divided attention in audiovisual integration, and the neural oscillation on delta- and theta-bands is conducive to allocating attention resources to dual-tasking involving task-coordinating abilities.

Listening to two speakers: Capacity and tradeoffs in neural speech tracking during Selective and Distributed Attention

Speech comprehension is severely compromised when several people talk at once, due to limited perceptual and cognitive resources. In such circumstances, top-down attention mechanisms can actively prioritize processing of task-relevant speech. However, behavioral and neural evidence suggest that this selection is not exclusive, and the system may have sufficient capacity to process additional speech input as well. Here we used a data-driven approach to contrast two opposing hypotheses regarding the system's capacity to co-represent competing speech: Can the brain represent two speakers equally or is the system fundamentally limited, resulting in tradeoffs between them? Neural activity was measured using magnetoencephalography (MEG) as human participants heard concurrent speech narratives and engaged in two tasks: Selective Attention, where only one speaker was task-relevant and Distributed Attention, where both speakers were equally relevant. Analysis of neural speech-tracking revealed that both tasks engaged a similar network of brain regions involved in auditory processing, attentional control and speech processing. Interestingly, during both Selective and Distributed Attention the neural representation of competing speech showed a bias towards one speaker. This is in line with proposed 'bottlenecks' for co-representation of concurrent speech and suggests that good performance on distributed attention tasks may be achieved by toggling attention between speakers over time.

Neural correlates of the attention training technique as used in metacognitive therapy – A randomized sham-controlled fMRI study in healthy volunteers

Introduction

The Attention Training Technique (ATT) developed as part of metacognitive therapy is a psychotherapeutic treatment method used to enhance top-down attentional flexibility and control. This study investigated potential neurocognitive changes due to ATT and its underlying neural mechanisms using pre-to-post functional magnetic resonance imaging (fMRI).

Materials and methods

Fifty-four healthy participants were subjected to a randomized, sham-controlled attention training and evaluated using a neurocognitive test battery that partly took place in an fMRI environment. Participants received two doses ATT or sham ATT daily for 1 week. On day eight, all subjects completed the neurocognitive test battery again.

Results

After the training, the ATT group showed a significant improvement in reaction times regarding attentional disengagement compared to the sham ATT group. fMRI data showed decreased levels of activation in the anterior cingulate cortex (ACC) when comparing the ATT group to the sham ATT group during attentional disengagement post intervention. No ATT &gt; sham ATT effects were found regarding selective auditory attention, working memory performance and inhibitory control.

Discussion

These findings putatively indicate that ATT facilitates faster attention allocation and increased attentional flexibility in healthy subjects. The fMRI results suggest this ATT-dependent improvement is accompanied by reduced ACC activity, indicating a more flexible attentional state.

Different brain activation patterns in the prefrontal area between self-paced and high-speed driving tasks

The purpose of this study was to investigate the effects on prefrontal cortex brain activity when participants attempted to stop a car accurately at a stop line when driving at different speeds using functional near-infrared spectroscopy (fNIRS). Twenty healthy subjects with driving experience drove their own cars for a distance of 60 m five times each at their own pace or as fast as possible. The variation in the distance between the stop line and the car was not significantly different between the self-paced and high-speed tasks. However, oxygenated hemoglobin concentration in the prefrontal cortex was significantly higher in the high-speed task than in the self-paced task. These findings suggest that driving at high speed requires more divided attention than driving at self-paced speed, even though the participants were able to stop the car at the same distance from the target. This study shows the advantages and usefulness of fNIRS .

Brain Responses to Peer Feedback in Social Media Are Modulated by Valence in Late Adolescence

Previous studies have examined the neural correlates of receiving negative feedback from peers during virtual social interaction in young people. However, there is a lack of studies applying platforms adolescents use in daily life. In the present study, 92 late-adolescent participants performed a task that involved receiving positive and negative feedback to their opinions from peers in a Facebook-like platform, while brain activity was measured using functional magnetic resonance imaging (fMRI). Peer feedback was shown to activate clusters in the ventrolateral prefrontal cortex (VLPFC), medial prefrontal cortex (MPFC), superior temporal gyrus and sulcus (STG/STS), and occipital cortex (OC). Negative feedback was related to greater activity in the VLPFC, MPFC, and anterior insula than positive feedback, replicating previous findings on peer feedback and social rejection. Real-life habits of social media use did not correlate with brain responses to negative feedback.

Effect of Audiovisual Cross-Modal Conflict during Working Memory Tasks: A Near-Infrared Spectroscopy Study

Cognitive conflict effects are well characterized within unimodality. However, little is known about cross-modal conflicts and their neural bases. This study characterizes the two types of visual and auditory cross-modal conflicts through working memory tasks and brain activities. The participants consisted of 31 healthy, right-handed, young male adults. The Paced Auditory Serial Addition Test (PASAT) and the Paced Visual Serial Addition Test (PVSAT) were performed under distractor and no distractor conditions. Distractor conditions comprised two conditions in which either the PASAT or PVSAT was the target task, and the other was used as a distractor stimulus. Additionally, oxygenated hemoglobin (Oxy-Hb) concentration changes in the frontoparietal regions were measured during tasks. The results showed significantly lower PASAT performance under distractor conditions than under no distractor conditions, but not in the PVSAT. Oxy-Hb changes in the bilateral ventrolateral prefrontal cortex (VLPFC) and inferior parietal cortex (IPC) significantly increased in the PASAT with distractor compared with no distractor conditions, but not in the PVSAT. Furthermore, there were significant positive correlations between Δtask performance accuracy and ΔOxy-Hb in the bilateral IPC only in the PASAT. Visual cross-modal conflict significantly impairs auditory task performance, and bilateral VLPFC and IPC are key regions in inhibiting visual cross-modal distractors.

Attention to Speech: Mapping Distributed and Selective Attention Systems

When faced with situations where many people talk at once, individuals can employ different listening strategies to deal with the cacophony of speech sounds and to achieve different goals. In this fMRI study, we investigated how the pattern of neural activity is affected by the type of attention applied to speech in a simulated "cocktail party." Specifically, we compared brain activation patterns when listeners "attended selectively" to only one speaker and ignored all others, versus when they "distributed their attention" and followed several concurrent speakers. Conjunction analysis revealed a highly overlapping network of regions activated for both types of attention, including auditory association cortex (bilateral STG/STS) and frontoparietal regions related to speech processing and attention (bilateral IFG/insula, right MFG, left IPS). Activity within nodes of this network, though, was modulated by the type of attention required as well as the number of competing speakers. Auditory and speech-processing regions exhibited higher activity during distributed attention, whereas frontoparietal regions were activated more strongly during selective attention. These results suggest a common "attention to speech" network, which provides the computational infrastructure to deal effectively with multi-speaker input, but with sufficient flexibility to implement different prioritization strategies and to adapt to different listener goals.

Visuospatial Attention Allocation as an Indicator of Cognitive Deficit in Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Traumatic Brain Injury (TBI) is defined by changes in brain function resulting from external forces acting on the brain and is typically characterized by a host of physiological and functional changes such as cognitive deficits including attention problems. In the present study, we focused on the effect of TBI on the ability to allocate attention in vision (i.e., the use of endogenous and exogenous visual cues) by systematically reviewing previous literature on the topic. We conducted quantitative synthesis of 16 selected studies of visual attention following TBI, calculating 80 effect size estimates. The combined effect size was large (g = 0.79, p < 0.0001) with medium heterogeneity (I² = 68.39%). Subgroup analyses revealed an increase in deficit with moderate-to-severe and severe TBI as compared to mild TBI [F_{(2, 76)} = 24.14, p < 0.0001]. Task type was another key source of variability and subgroup analyses indicated that higher order attention processes were severely affected by TBI [F_{(2, 77)} = 5.66, p = 0.0051). Meta-regression analyses revealed significant improvement in visual attention deficit with time [p(mild) = 0.031, p(moderate-to-severe) = 0.002, p(severe) < 0.0001]. Taken together, these results demonstrate that visual attention is affected by TBI and that regular assessment of visual attention, using a systematic attention allocation task, may provide a useful clinical measure of cognitive impairment and change after TBI.

Convergence of Modality Invariance and Attention Selectivity in the Cortical Semantic Circuit

The human linguistic system is characterized by modality invariance and attention selectivity. Previous studies have examined these properties independently and reported perisylvian region involvement for both; however, their relationship and the linguistic information they harbor remain unknown. Participants were assessed by functional magnetic resonance imaging, while spoken narratives (auditory) and written texts (visual) were presented, either separately or simultaneously. Participants were asked to attend to one stimulus when both were presented. We extracted phonemic and semantic features from these auditory and visual modalities, to train multiple, voxel-wise encoding models. Cross-modal examinations of the trained models revealed that perisylvian regions were associated with modality-invariant semantic representations. Attentional selectivity was quantified by examining the modeling performance for attended and unattended conditions. We have determined that perisylvian regions exhibited attention selectivity. Both modality invariance and attention selectivity are both prominent in models that use semantic but not phonemic features. Modality invariance was significantly correlated with attention selectivity in some brain regions; however, we also identified cortical regions associated with only modality invariance or only attention selectivity. Thus, paying selective attention to a specific sensory input modality may regulate the semantic information that is partly processed in brain networks that are shared across modalities.

Orienting Attention to Short-Term Memory Representations via Sensory Modality and Semantic Category Retro-Cues

There is growing interest in characterizing the neural mechanisms underlying the interactions between attention and memory. Current theories posit that reflective attention to memory representations generally involves a fronto-parietal attentional control network. The present study aimed to test this idea by manipulating how a particular short-term memory (STM) representation is accessed, that is, based on its input sensory modality or semantic category, during functional magnetic resonance imaging (fMRI). Human participants performed a novel variant of the retro-cue paradigm, in which they were presented with both auditory and visual non-verbal stimuli followed by Modality, Semantic, or Uninformative retro-cues. Modality and, to a lesser extent, Semantic retro-cues facilitated response time relative to Uninformative retro-cues. The univariate and multivariate pattern analyses (MVPAs) of fMRI time-series revealed three key findings. First, the posterior parietal cortex (PPC), including portions of the intraparietal sulcus (IPS) and ventral angular gyrus (AG), had activation patterns that spatially overlapped for both modality-based and semantic-based reflective attention. Second, considering both the univariate and multivariate analyses, Semantic retro-cues were associated with a left-lateralized fronto-parietal network. Finally, the experimental design enabled us to examine how dividing attention cross-modally within STM modulates the brain regions involved in reflective attention. This analysis revealed that univariate activation within bilateral portions of the PPC increased when participants simultaneously attended both auditory and visual memory representations. Therefore, prefrontal and parietal regions are flexibly recruited during reflective attention, depending on the representational feature used to selectively access STM representations.

Multi-spectral oscillatory dynamics serving directed and divided attention

Attention-related amplification of neural representations of external stimuli has been well documented in the visual domain, however, research concerning the oscillatory dynamics of such directed attention is relatively sparse in humans. Specifically, it is unknown which spectrally-specific neural responses are mainly impacted by the direction and division of attention, as well as whether the effects of attention on these oscillations are spatially disparate. In this study, we use magnetoencephalography and a visual-somatosensory oddball task to investigate the whole-brain oscillatory dynamics of directed (Experiment 1; N = 26) and divided (Experiment 2; N = 34) visual attention. Sensor-level data were transformed into the time-frequency domain and significant responses from baseline were imaged using a frequency-resolved beamformer. We found that multi-spectral cortical oscillations were stronger when attention was sustained in the visual space and that these effects exhibited informative spatial distributions that differed by frequency. More specifically, we found stronger frontal theta (4–8 Hz), frontal and occipital alpha (8–14 Hz), occipital beta (16–22 Hz), and frontal gamma (74–84 Hz) responses when visual attention was sustained than when it was directed away from the visual domain. Similarly, in the divided attention condition, we observed stronger fronto-parietal theta activity and temporo-parietal alpha and beta oscillations when visual attention was sustained toward the visual stimuli than divided between the visual and somatosensory domains. Investigating how attentional gain is implemented in the human brain is essential for better understanding how this process is degraded in disease, and may provide useful targets for future therapies.

The SwAD-Task – An Innovative Paradigm for Measuring Costs of Switching Between Different Attentional Demands

Task switching paradigms are frequently used to identify costs of switching between modalities, spatiality, attributes, rules, etc., but switching between different attentional demands has been somehow neglected. The present study introduces an innovative paradigm, that allows to test single attentional demands (such as selective and divided attention), and more importantly the process of switching between these demands. We examined the feasibility of the paradigm by focusing on the demands of selective and divided attention with a sample of 94 people (age: M = 21.44 years, SD = 2.68; 76 women). In addition, we tested correlations between the implemented single attentional demands and commonly used measures of selective and divided attention. Results show no general difference between individual assessments under single demand conditions. Reaction times under divided attention are significantly higher compared to selective attention. In the switching condition, reaction times in both demands increase with increased switching. Furthermore, switching costs significantly increase in selective but not in divided attention. Means of selective and divided attention in single and switching conditions significantly correlate with a commonly used measure of selective attention. Means of divided attention under single demand significantly correlate with performance in a commonly used dual-task paradigm. Summarizing the present findings, it can be stated that the introduced paradigm comprises a feasible way for quantifying the process of switching attention between different demands.

Classifying Attention Types with Thermal Imaging and Eye Tracking

Despite the importance of attention in user performance, current methods for attention classification do not allow to discriminate between different attention types. We propose a novel method that combines thermal imaging and eye tracking to unobtrusively classify four types of attention: sustained, alternating, selective, and divided. We collected a data set in which we stimulate these four attention types in a user study (N = 22) using combinations of audio and visual stimuli while measuring users' facial temperature and eye movement. Using a Logistic Regression on features extracted from both sensing technologies, we can classify the four attention types with high AUC scores up to 75.7% for the user independent-condition independent, 87% for the user-independent-condition dependent, and 77.4% for the user-dependent prediction. Our findings not only demonstrate the potential of thermal imaging and eye tracking for unobtrusive classification of different attention types but also pave the way for novel applications for attentive user interfaces and attention-aware computing.

Dynamics of brain activation during learning of syllable-symbol paired associations

Initial stages of reading acquisition require the learning of letter and speech sound combinations. While the long-term effects of audio-visual learning are rather well studied, relatively little is known about the short-term learning effects at the brain level. Here we examined the cortical dynamics of short-term learning using magnetoencephalography (MEG) and electroencephalography (EEG) in two experiments that respectively addressed active and passive learning of the association between shown symbols and heard syllables. In experiment 1, learning was based on feedback provided after each trial. The learning of the audio-visual associations was contrasted with items for which the feedback was meaningless. In experiment 2, learning was based on statistical learning through passive exposure to audio-visual stimuli that were consistently presented with each other and contrasted with audio-visual stimuli that were randomly paired with each other. After 5-10 min of training and exposure, learning-related changes emerged in neural activation around 200 and 350 ms in the two experiments. The MEG results showed activity changes at 350 ms in caudal middle frontal cortex and posterior superior temporal sulcus, and at 500 ms in temporo-occipital cortex. Changes in brain activity coincided with a decrease in reaction times and an increase in accuracy scores. Changes in EEG activity were observed starting at the auditory P2 response followed by later changes after 300 ms. The results show that the short-term learning effects emerge rapidly (manifesting in later stages of audio-visual integration processes) and that these effects are modulated by selective attention processes.

Cognitive control in the prefrontal cortex: A central or distributed executive?

Cognitive control is the foundation for attaining goals by flexible adaptation of action to changing environmental demands. It has been hypothesized to be critically dependent upon the prefrontal cortex (PFC). In this mini-review, evidence for domain-general versus domain-specific cognitive control is examined, with a particular focus on attention and memory. The reviewed studies examined different levels of cognitive control in relation to performance and patterns of brain activity, and a few included direct comparisons of cognitive-control modulations across cognitive domains. Within domains, increased demands on cognitive control consistently translated into increased PFC activity, but limited overlap in recruited PFC regions was observed between domains. It is concluded that the PFC supports multiple cognitive-control systems that collectively may be conceived of as a distributed executive.

Neural activity patterns between different executive tasks are more similar in adulthood than in adolescence

BACKGROUND

Adolescence is a time of ongoing neural maturation and cognitive development, especially regarding executive functions. In the current study, age-related differences in the neural correlates of different executive functions were tracked by comparing three age groups consisting of adolescents and young adults.

METHODS

Brain activity was measured with functional magnetic resonance imaging (fMRI) from 167 human participants (13- to 14-year-old middle adolescents, 16- to 17-year-old late adolescents and 20- to 24-year-old young adults; 80 female, 87 male) while they performed attention and working memory tasks. The tasks were designed to tap into four putative sub-processes of executive function: division of attention, inhibition of distractors, working memory, and attention switching.

RESULTS

Behaviorally, our results demonstrated superior task performance in older participants across all task types. When brain activity was examined, young adult participants demonstrated a greater degree of overlap between brain regions recruited by the different executive tasks than adolescent participants. Similarly, functional connectivity between frontoparietal cortical regions was less task specific in the young adult participants than in adolescent participants.

CONCLUSIONS

Together, these results demonstrate that the similarity between different executive processes in terms of both neural recruitment and functional connectivity increases with age from middle adolescence to early adulthood, possibly contributing to age-related behavioral improvements in executive functioning. These developmental changes in brain recruitment may reflect a more homogenous morphological organization between process-specific neural networks, increased reliance on a more domain-general network involved in executive processing, or developmental changes in cognitive strategy.

Neurophysiological correlates of the attention training technique: A component study

In the current study, we investigate the neuronal correlates of the Attention Training Technique (ATT), a psychotherapeutic intervention used in metacognitive therapy to enhance flexible cognitive control and ameliorate rumination.

We adapted the ATT in a neuroscientific attention paradigm in order to investigate the effects of its components: selective attention, attention switching and divided attention in comparison to a control task. Functional near-infrared spectroscopy was used to measure changes in blood oxygenation of fronto-lateral and parietal cortical areas. Furthermore, subjects rated their task performance, effort and attention drifts in each task condition.

We observed increased blood oxygenation in the right inferior frontal gyrus, right dorsolateral prefrontal cortex and superior parietal lobule during the ATT conditions in comparison to the control condition. Additionally, subjective effort was associated with blood oxygenation in the right inferior prefrontal cortex.

Our results are consistent with the theoretical underpinnings of the ATT suggesting that the ATT's mechanism of change lies in the training of areas of the cognitive control network and dorsal attention network. Aberrant functioning of both networks has been shown to be related to depression and rumination.

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The neurophysiological underpinnings of the Attention Training Technique (ATT) were investigated in an experimental design.

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The ATT requires activation of brain areas in the cognitive control network (CCN) and dorsal attention network (DAN).

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We observed increased blood oxygenation in the right IFG, dlPFC and superior parietal lobule during the ATT.

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Subjective effort during the ATT was associated with blood oxygenation in the IFG.

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The ATT might influence depressive rumination through the training of the CCN and DAN.

Auditory-Motor Control of Vocal Production during Divided Attention: Behavioral and ERP Correlates

When people hear unexpected perturbations in auditory feedback, they produce rapid compensatory adjustments of their vocal behavior. Recent evidence has shown enhanced vocal compensations and cortical event-related potentials (ERPs) in response to attended pitch feedback perturbations, suggesting that this reflex-like behavior is influenced by selective attention. Less is known, however, about auditory-motor integration for voice control during divided attention. The present cross-modal study investigated the behavioral and ERP correlates of auditory feedback control of vocal pitch production during divided attention. During the production of sustained vowels, 32 young adults were instructed to simultaneously attend to both pitch feedback perturbations they heard and flashing red lights they saw. The presentation rate of the visual stimuli was varied to produce a low, intermediate, and high attentional load. The behavioral results showed that the low-load condition elicited significantly smaller vocal compensations for pitch perturbations than the intermediate-load and high-load conditions. As well, the cortical processing of vocal pitch feedback was also modulated as a function of divided attention. When compared to the low-load and intermediate-load conditions, the high-load condition elicited significantly larger N1 responses and smaller P2 responses to pitch perturbations. These findings provide the first neurobehavioral evidence that divided attention can modulate auditory feedback control of vocal pitch production.

Theta and Alpha Oscillations in Attentional Interaction during Distracted Driving

Performing multiple tasks simultaneously usually affects the behavioral performance as compared with executing the single task. Moreover, processing multiple tasks simultaneously often involve more cognitive demands. Two visual tasks, lane-keeping task and mental calculation, were utilized to assess the brain dynamics through 32-channel electroencephalogram (EEG) recorded from 14 participants. A 400-ms stimulus onset asynchrony (SOA) factor was used to induce distinct levels of attentional requirements. In the dual-task conditions, the deteriorated behavior reflected the divided attention and the overlapping brain resources used. The frontal, parietal and occipital components were decomposed by independent component analysis (ICA) algorithm. The event- and response-related theta and alpha oscillations in selected brain regions were investigated first. The increased theta oscillation in frontal component and decreased alpha oscillations in parietal and occipital components reflect the cognitive demands and attentional requirements as executing the designed tasks. Furthermore, time-varying interactive over-additive (O-Add), additive (Add) and under-additive (U-Add) activations were explored and summarized through the comparison between the summation of the elicited spectral perturbations in two single-task conditions and the spectral perturbations in the dual task. Add and U-Add activations were observed while executing the dual tasks. U-Add theta and alpha activations dominated the posterior region in dual-task situations. Our results show that both deteriorated behaviors and interactive brain activations should be comprehensively considered for evaluating workload or attentional interaction precisely.

Using precise word timing information improves decoding accuracy in a multiband-accelerated multimodal reading experiment

The blood-oxygen-level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments is generally regarded as sluggish and poorly suited for probing neural function at the rapid timescales involved in sentence comprehension. However, recent studies have shown the value of acquiring data with very short repetition times (TRs), not merely in terms of improvements in contrast to noise ratio (CNR) through averaging, but also in terms of additional fine-grained temporal information. Using multiband-accelerated fMRI, we achieved whole-brain scans at 3-mm resolution with a TR of just 500 ms at both 3T and 7T field strengths. By taking advantage of word timing information, we found that word decoding accuracy across two separate sets of scan sessions improved significantly, with better overall performance at 7T than at 3T. The effect of TR was also investigated; we found that substantial word timing information can be extracted using fast TRs, with diminishing benefits beyond TRs of 1000 ms.

Brain activity associated with selective attention, divided attention and distraction

Top-down controlled selective or divided attention to sounds and visual objects, as well as bottom-up triggered attention to auditory and visual distractors, has been widely investigated. However, no study has systematically compared brain activations related to all these types of attention. To this end, we used functional magnetic resonance imaging (fMRI) to measure brain activity in participants performing a tone pitch or a foveal grating orientation discrimination task, or both, distracted by novel sounds not sharing frequencies with the tones or by extrafoveal visual textures. To force focusing of attention to tones or gratings, or both, task difficulty was kept constantly high with an adaptive staircase method. A whole brain analysis of variance (ANOVA) revealed fronto-parietal attention networks for both selective auditory and visual attention. A subsequent conjunction analysis indicated partial overlaps of these networks. However, like some previous studies, the present results also suggest segregation of prefrontal areas involved in the control of auditory and visual attention. The ANOVA also suggested, and another conjunction analysis confirmed, an additional activity enhancement in the left middle frontal gyrus related to divided attention supporting the role of this area in top-down integration of dual task performance. Distractors expectedly disrupted task performance. However, contrary to our expectations, activations specifically related to the distractors were found only in the auditory and visual cortices. This suggests gating of the distractors from further processing perhaps due to strictly focused attention in the current demanding discrimination tasks.

Media multitasking is associated with distractibility and increased prefrontal activity in adolescents and young adults

The current generation of young people indulges in more media multitasking behavior (e.g., instant messaging while watching videos) in their everyday lives than older generations. Concerns have been raised about how this might affect their attentional functioning, as previous studies have indicated that extensive media multitasking in everyday life may be associated with decreased attentional control. In the current study, 149 adolescents and young adults (aged 13-24years) performed speech-listening and reading tasks that required maintaining attention in the presence of distractor stimuli in the other modality or dividing attention between two concurrent tasks. Brain activity during task performance was measured using functional magnetic resonance imaging (fMRI). We studied the relationship between self-reported daily media multitasking (MMT), task performance and brain activity during task performance. The results showed that in the presence of distractor stimuli, a higher MMT score was associated with worse performance and increased brain activity in right prefrontal regions. The level of performance during divided attention did not depend on MMT. This suggests that daily media multitasking is associated with behavioral distractibility and increased recruitment of brain areas involved in attentional and inhibitory control, and that media multitasking in everyday life does not translate to performance benefits in multitasking in laboratory settings.

Neural bases of accented speech perception

The recognition of unfamiliar regional and foreign accents represents a challenging task for the speech perception system (Floccia et al., 2006; Adank et al., 2009). Despite the frequency with which we encounter such accents, the neural mechanisms supporting successful perception of accented speech are poorly understood. Nonetheless, candidate neural substrates involved in processing speech in challenging listening conditions, including accented speech, are beginning to be identified. This review will outline neural bases associated with perception of accented speech in the light of current models of speech perception, and compare these data to brain areas associated with processing other speech distortions. We will subsequently evaluate competing models of speech processing with regards to neural processing of accented speech. See Cristia et al. (2012) for an in-depth overview of behavioral aspects of accent processing.