An event-related fMRI Study of exogenous facilitation and inhibition of return in the auditory modality

Does the construction retrieval account apply to cross‐modal inhibition of return in semantic context?

The traditional attentional reorienting hypothesis is insufficient to explain spatial and nonspatial inhibition of return (IOR). Therefore, a construction retrieval account that includes the influence of top-down attentional sets has been proposed and can explain both spatial and nonspatial IOR. However, it remains unknown whether the construction retrieval account can be applied to non-surface features of stimuli, as well as whether its construction and retrieval mechanisms are supra-modal. The present study manipulated semantic feature congruency and spatial location congruency between the prime and the target in cross-modal audio-visual and visual-audio experimental conditions, respectively, by orthogonally combining spatial and nonspatial IOR paradigms. Our results showed that there was an interaction between semantic feature congruency and spatial location congruency controlled by the attentional sets, and that this interaction was consistent in cross-modal audio-visual and visual-audio conditions. These results suggest that the construction retrieval account can be applied to abstract semantic features and that its construction and retrieval mechanisms are supra-modal. The present study extends the application scope of the construction retrieval account and promotes the interpretation of IOR under a unified theoretical framework.

Correlates of Auditory Decision-Making in Prefrontal, Auditory, and Basal Lateral Amygdala Cortical Areas

Spatial selective listening and auditory choice underlie important processes including attending to a speaker at a cocktail party and knowing how (or whether) to respond. To examine task encoding and the relative timing of potential neural substrates underlying these behaviors, we developed a spatial selective detection paradigm for monkeys, and recorded activity in primary auditory cortex (AC), dorsolateral prefrontal cortex (dlPFC), and the basolateral amygdala (BLA). A comparison of neural responses among these three areas showed that, as expected, AC encoded the side of the cue and target characteristics before dlPFC and BLA. Interestingly, AC also encoded the choice of the monkey before dlPFC and around the time of BLA. Generally, BLA showed weak responses to all task features except the choice. Decoding analyses suggested that errors followed from a failure to encode the target stimulus in both AC and dlPFC, but again, these differences arose earlier in AC. The similarities between AC and dlPFC responses were abolished during passive sensory stimulation with identical trial conditions, suggesting that the robust sensory encoding in dlPFC is contextually gated. Thus, counter to a strictly PFC-driven decision process, in this spatial selective listening task AC neural activity represents the sensory and decision information before dlPFC. Unlike in the visual domain, in this auditory task, the BLA does not appear to be robustly involved in selective spatial processing.SIGNIFICANCE STATEMENT We examined neural correlates of an auditory spatial selective listening task by recording single-neuron activity in behaving monkeys from the amygdala, dorsolateral prefrontal cortex, and auditory cortex. We found that auditory cortex coded spatial cues and choice-related activity before dorsolateral prefrontal cortex or the amygdala. Auditory cortex also had robust delay period activity. Therefore, we found that auditory cortex could support the neural computations that underlie the behavioral processes in the task.

Basic auditory processing in the children with autistic features

This study aimed inhibition mechanisms of auditory processing in the group with autistic features. Thirty-two children (autistic group = 16, typically developing [TD] group = 16) received neuropsychological tests, IQ test and experimental tasks. Both groups showed similar performances except the processing speed index. The results showed that the group with autistic features had less inhibition of return (IOR) than the TD group. However, we did not get a statistically significant group difference in the auditory Go-NoGo task. These results might be attributed to a ceiling effect due to an adjustment failure of a difficulty level instead of showing that the group with autistic features would have intact inhibitory or pitch discriminative function problems. In conclusion, this study showed that the group with autistic features could have an inhibitory processing difficulty in both auditory and visual IOR tasks even when their general cognitive functions are relatively intact. This study presented a possibility that the group with autistic features might have a basic inhibitory function problem, but these findings should be investigated in the further study with enough samples. In addition, we are going to revise the auditory Go-NoGo task and verify the feasibility as a tool to detect ASD in an early stage in the following study.

Attentional disengagement from negative natural sounds for high-anxious individuals

BACKGROUND AND OBJECTIVES

Previous studies have not consistently concluded whether high-anxious persons exhibit attentional bias towards negative natural auditory stimuli. The present study explores whether auditory negative stimuli could induce attentional bias to negative sounds in real life and investigates the exact nature of these biases using an emotional spatial cueing task.

DESIGN

Experimental study with a mixed factorial design.

METHOD

We created two groups according to the state-trait anxiety scale, namely high and low trait anxiety. Participants (N = 68 undergraduate students) were required to respond to an auditory target after receiving a negative (aversive sounds from natural life) or neutral auditory stimuli.

RESULTS

A 2 (Validity: valid/invalid)   × 2 (Cue Valence: negative/neutral) × 2 (Anxiety Group: LA/HA) repeated-measures ANOVA on reaction times revealed that participants with high trait anxiety exhibited slower reaction times in invalid trials following negative cues than following neutral cues. Higher levels of trait anxiety were associated with more difficult attentional disengagement from negative auditory information.

CONCLUSIONS

The results demonstrate that impaired attentional disengagement was one of the mechanisms by which high-anxious participants exhibited auditory attentional bias to natural negative information.

Bimodal-divided attention attenuates visually induced inhibition of return with audiovisual targets

Inhibition of return (IOR) refers to the slower response to a target appearing at a previously attended location in a cue-target paradigm. It has been greatly explored in the visual or auditory modality. This study investigates differences between the IOR of audiovisual targets and the IOR of visual targets under conditions of modality-specific selective attention (Experiment 1) and divided-modalities attention (Experiment 2). We employed an exogenous spatial cueing paradigm and manipulated the modalities of targets, including visual, auditory, or audiovisual modalities. The participants were asked to detect targets in visual modality or both visual and auditory modalities, which were presented on the same (cued) or opposite (uncued) side as the preceding visual peripheral cues. In Experiment 1, we found the comparable IOR with visual and audiovisual targets when participants were asked to selectively focus on visual modality. In Experiment 2, however, there was a smaller magnitude of IOR with audiovisual targets as compared with visual targets when paying attention to both visual and auditory modalities. We also observed a reduced multisensory response enhancement effect and race model inequality violation at cued locations relative to uncued locations. These results provide the first evidence of the IOR with audiovisual targets. Furthermore, IOR with audiovisual targets decreases when paying attention to both modalities. The interaction between exogenous spatial attention and audiovisual integration is discussed.

From Behavioral Facilitation to Inhibition: The Neuronal Correlates of the Orienting and Reorienting of Auditory Attention

Successful adaptive behavior relies on the ability to automatically (bottom-up) orient attention to different locations in the environment. This results in a biphasic pattern in which reaction times (RT) are faster for stimuli that occur in the same spatial location (valid) for the first few hundred milliseconds, which is termed facilitation. This is followed by faster RT for stimuli that appear in novel locations (invalid) after longer delays, termed inhibition of return. The neuronal areas and networks involved in the transition between states of facilitation and inhibition remain poorly understood, especially for auditory stimuli. Functional magnetic resonance imaging (fMRI) data were therefore collected in a large sample of healthy volunteers (N = 52) at four separate auditory stimulus onset asynchronies (SOAs; 200, 400, 600, and 800 ms). Behavioral results indicated that facilitation (valid RT < invalid RT) occurred at the 200 ms SOA, with inhibition of return (valid RT > invalid RT) present at the three longer SOAs. fMRI results showed several brain areas varying their activation as a function of SOA, including bilateral superior temporal gyrus, anterior thalamus, cuneus, dorsal anterior cingulate gyrus, and right ventrolateral prefrontal cortex (VLPFC)/anterior insula. Right VLPFC was active during a behavioral state of facilitation, and its activation (invalid – valid trials) further correlated with behavioral reorienting at the 200 ms delay. These results suggest that right VLPFC plays a critical role when auditory attention must be quickly deployed or redeployed, demanding heightened cognitive and inhibitory control. In contrast to previous work, the ventral and dorsal frontoparietal attention networks were both active during valid and invalid trials across SOAs. These results suggest that the dorsal and ventral networks may not be as specialized during bottom-up auditory orienting as has been previously reported during visual orienting.

Functional neuroanatomy of spatial sound processing in Alzheimer's disease

Deficits of auditory scene analysis accompany Alzheimer's disease (AD). However, the functional neuroanatomy of spatial sound processing has not been defined in AD. We addressed this using a “sparse” fMRI virtual auditory spatial paradigm in 14 patients with typical AD in relation to 16 healthy age-matched individuals. Sound stimulus sequences discretely varied perceived spatial location and pitch of the sound source in a factorial design. AD was associated with loss of differentiated cortical profiles of auditory location and pitch processing at the prescribed threshold, and significant group differences were identified for processing auditory spatial variation in posterior cingulate cortex (controls > AD) and the interaction of pitch and spatial variation in posterior insula (AD > controls). These findings build on emerging evidence for altered brain mechanisms of auditory scene analysis and suggest complex dysfunction of network hubs governing the interface of internal milieu and external environment in AD. Auditory spatial processing may be a sensitive probe of this interface and contribute to characterization of brain network failure in AD and other neurodegenerative syndromes.

Electrophysiological correlates of cocktail-party listening

Detecting, localizing, and selectively attending to a particular sound source of interest in complex auditory scenes composed of multiple competing sources is a remarkable capacity of the human auditory system. The neural basis of this so-called "cocktail-party effect" has remained largely unknown. Here, we studied the cortical network engaged in solving the "cocktail-party" problem, using event-related potentials (ERPs) in combination with two tasks demanding horizontal localization of a naturalistic target sound presented either in silence or in the presence of multiple competing sound sources. Presentation of multiple sound sources, as compared to single sources, induced an increased P1 amplitude, a reduction in N1, and a strong N2 component, resulting in a pronounced negativity in the ERP difference waveform (N2d) around 260 ms after stimulus onset. About 100 ms later, the anterior contralateral N2 subcomponent (N2ac) occurred in the multiple-sources condition, as computed from the amplitude difference for targets in the left minus right hemispaces. Cortical source analyses of the ERP modulation, resulting from the contrast of multiple vs. single sources, generally revealed an initial enhancement of electrical activity in right temporo-parietal areas, including auditory cortex, by multiple sources (at P1) that is followed by a reduction, with the primary sources shifting from right inferior parietal lobule (at N1) to left dorso-frontal cortex (at N2d). Thus, cocktail-party listening, as compared to single-source localization, appears to be based on a complex chronology of successive electrical activities within a specific cortical network involved in spatial hearing in complex situations.

Tactile spatial negative priming occurs without feature mismatch

Negative priming (NP) refers to fact that people respond more slowly and make more errors when responding to target stimuli that were previously ignored. This phenomenon has also been observed when participants respond to the location, and not only to the identity, of the stimulus. Intriguingly, while roughly the same pattern of results has been observed in the visual, auditory, and tactile modalities when it comes to identity-based NP, the same does not hold true for spatial NP: In particular, feature mismatch seems to be the sole cause of auditory spatial NP, whereas response inhibition would appear to be the sole cause of spatial NP in vision. We conducted a novel tactile variant of the spatial NP task. We investigated whether spatial NP in the tactile modality exists, and further, we investigated whether the pattern of spatial NP in the tactile modality compares with what has been documented previously in vision or audition. Tactile spatial NP was observed, and it was independent of feature mismatch, thereby reflecting a comparable pattern as visual spatial NP. We discuss spatial selection with respect to possible modality-specific processes.

The effects of sequential attention shifts within visual working memory

Previous studies have shown conflicting data as to whether it is possible to sequentially shift spatial attention among visual working memory (VWM) representations. The present study investigated this issue by asynchronously presenting attentional cues during the retention interval of a change detection task. In particular, we focused on two types of sequential attention shifts: (1) orienting attention to one location, and then withdrawing attention from it, and (2) switching the focus of attention from one location to another. In Experiment 1, a withdrawal cue was presented after a spatial retro-cue to measure the effect of withdrawing attention. The withdrawal cue significantly reduced the cost of invalid spatial cues, but surprisingly, did not attenuate the benefit of valid spatial cues. This indicates that the withdrawal cue only triggered the activation of facilitative components but not inhibitory components of attention. In Experiment 2, two spatial retro-cues were presented successively to examine the effect of switching the focus of attention. We observed equivalent benefits of the first and second spatial cues, suggesting that participants were able to reorient attention from one location to another within VWM, and the reallocation of attention did not attenuate memory at the first-cued location. In Experiment 3, we found that reducing the validity of the preceding spatial cue did lead to a significant reduction in its benefit. However, performance was still better at first-cued locations than at uncued and neutral locations, indicating that the first cue benefit might have been preserved both partially under automatic control and partially under voluntary control. Our findings revealed new properties of dynamic attentional control in VWM maintenance.

Attention to memory: orienting attention to sound object representations

Despite a growing acceptance that attention and memory interact, and that attention can be focused on an active internal mental representation (i.e., reflective attention), there has been a paucity of work focusing on reflective attention to 'sound objects' (i.e., mental representations of actual sound sources in the environment). Further research on the dynamic interactions between auditory attention and memory, as well as its degree of neuroplasticity, is important for understanding how sound objects are represented, maintained, and accessed in the brain. This knowledge can then guide the development of training programs to help individuals with attention and memory problems. This review article focuses on attention to memory with an emphasis on behavioral and neuroimaging studies that have begun to explore the mechanisms that mediate reflective attentional orienting in vision and more recently, in audition. Reflective attention refers to situations in which attention is oriented toward internal representations rather than focused on external stimuli. We propose four general principles underlying attention to short-term memory. Furthermore, we suggest that mechanisms involved in orienting attention to visual object representations may also apply for orienting attention to sound object representations.

Rethinking the role of the rTPJ in attention and social cognition in light of the opposing domains hypothesis: findings from an ALE-based meta-analysis and resting-state functional connectivity

The right temporo-parietal junction (rTPJ) has been associated with two apparently disparate functional roles: in attention and in social cognition. According to one account, the rTPJ initiates a “circuit-breaking” signal that interrupts ongoing attentional processes, effectively reorienting attention. It is argued this primary function of the rTPJ has been extended beyond attention, through a process of evolutionarily cooption, to play a role in social cognition. We propose an alternative account, according to which the capacity for social cognition depends on a network which is both distinct from and in tension with brain areas involved in focused attention and target detection: the default mode network (DMN). Theory characterizing the rTPJ based on the area's purported role in reorienting may be falsely guided by the co-occurrence of two distinct effects in contiguous regions: activation of the supramarginal gyrus (SMG), associated with its functional role in target detection; and the transient release, during spatial reorienting, of suppression of the angular gyrus (AG) associated with focused attention. Findings based on meta-analysis and resting functional connectivity are presented which support this alternative account. We find distinct regions, possessing anti-correlated patterns of resting connectivity, associated with social reasoning (AG) and target detection (SMG) at the rTPJ. The locus for reorienting was spatially intermediate between the AG and SMG and showed a pattern of connectivity with similarities to social reasoning and target detection seeds. These findings highlight a general methodological concern for brain imaging. Given evidence that certain tasks not only activate some areas but also suppress activity in other areas, it is suggested that researchers need to distinguish two distinct putative mechanisms, either of which may produce an increase in activity in a brain area: functional engagement in the task vs. release of suppression.

Neural correlates of sound localization in complex acoustic environments

Listening to and understanding people in a “cocktail-party situation” is a remarkable feature of the human auditory system. Here we investigated the neural correlates of the ability to localize a particular sound among others in an acoustically cluttered environment with healthy subjects. In a sound localization task, five different natural sounds were presented from five virtual spatial locations during functional magnetic resonance imaging (fMRI). Activity related to auditory stream segregation was revealed in posterior superior temporal gyrus bilaterally, anterior insula, supplementary motor area, and frontoparietal network. Moreover, the results indicated critical roles of left planum temporale in extracting the sound of interest among acoustical distracters and the precuneus in orienting spatial attention to the target sound. We hypothesized that the left-sided lateralization of the planum temporale activation is related to the higher specialization of the left hemisphere for analysis of spectrotemporal sound features. Furthermore, the precuneus − a brain area known to be involved in the computation of spatial coordinates across diverse frames of reference for reaching to objects − seems to be also a crucial area for accurately determining locations of auditory targets in an acoustically complex scene of multiple sound sources. The precuneus thus may not only be involved in visuo-motor processes, but may also subserve related functions in the auditory modality.

An event-related FMRI study of exogenous orienting across vision and audition

The orienting of attention to the spatial location of sensory stimuli in one modality based on sensory stimuli presented in another modality (i.e., cross-modal orienting) is a common mechanism for controlling attentional shifts. The neuronal mechanisms of top-down cross-modal orienting have been studied extensively. However, the neuronal substrates of bottom-up audio-visual cross-modal spatial orienting remain to be elucidated. Therefore, behavioral and event-related functional magnetic resonance imaging (FMRI) data were collected while healthy volunteers (N = 26) performed a spatial cross-modal localization task modeled after the Posner cuing paradigm. Behavioral results indicated that although both visual and auditory cues were effective in producing bottom-up shifts of cross-modal spatial attention, reorienting effects were greater for the visual cues condition. Statistically significant evidence of inhibition of return was not observed for either condition. Functional results also indicated that visual cues with auditory targets resulted in greater activation within ventral and dorsal frontoparietal attention networks, visual and auditory "where" streams, primary auditory cortex, and thalamus during reorienting across both short and long stimulus onset asynchronys. In contrast, no areas of unique activation were associated with reorienting following auditory cues with visual targets. In summary, current results question whether audio-visual cross-modal orienting is supramodal in nature, suggesting rather that the initial modality of cue presentation heavily influences both behavioral and functional results. In the context of localization tasks, reorienting effects accompanied by the activation of the frontoparietal reorienting network are more robust for visual cues with auditory targets than for auditory cues with visual targets.

An FMRI study of auditory orienting and inhibition of return in pediatric mild traumatic brain injury

Studies in adult mild traumatic brain injury (mTBI) have shown that two key measures of attention, spatial reorienting and inhibition of return (IOR), are impaired during the first few weeks of injury. However, it is currently unknown whether similar deficits exist following pediatric mTBI. The current study used functional magnetic resonance imaging (fMRI) to investigate the effects of semi-acute mTBI (<3 weeks post-injury) on auditory orienting in 14 pediatric mTBI patients (age 13.50±1.83 years; education: 6.86±1.88 years), and 14 healthy controls (age 13.29±2.09 years; education: 7.21±2.08 years), matched for age and years of education. The results indicated that patients with mTBI showed subtle (i.e., moderate effect sizes) but non-significant deficits on formal neuropsychological testing and during IOR. In contrast, functional imaging results indicated that patients with mTBI demonstrated significantly decreased activation within the bilateral posterior cingulate gyrus, thalamus, basal ganglia, midbrain nuclei, and cerebellum. The spatial topography of hypoactivation was very similar to our previous study in adults, suggesting that subcortical structures may be particularly affected by the initial biomechanical forces in mTBI. Current results also suggest that fMRI may be a more sensitive tool for identifying semi-acute effects of mTBI than the procedures currently used in clinical practice, such as neuropsychological testing and structural scans. fMRI findings could potentially serve as a biomarker for measuring the subtle injury caused by mTBI, and documenting the course of recovery.

Auditory orienting and inhibition of return in schizophrenia: a functional magnetic resonance imaging study

Patients with schizophrenia (SP) exhibit deficits in both attentional reorienting and inhibition of return (IOR) during visual tasks. However, it is currently unknown whether these deficits are supramodal in nature and how these deficits relate to other domains of cognitive dysfunction. In addition, the neuronal correlates of this pathological orienting response have not been investigated in either the visual or auditory modality. Therefore, 30 SP and 30 healthy controls (HC) were evaluated with an extensive clinical protocol and functional magnetic resonance imaging (fMRI) during an auditory cuing paradigm. SP exhibited both increased costs and delayed IOR during auditory orienting, suggesting a prolonged interval for attentional disengagement from cued locations. Moreover, a delay in the development of IOR was associated with cognitive deficits on formal neuropsychological testing in the domains of attention/inhibition and working memory. Event-related fMRI showed the characteristic activation of a frontoparietal network (invalid trials>valid trials), but there were no differences in functional activation between patients and HC during either attentional reorienting or IOR. Current results suggest that orienting deficits are supramodal in nature in SP, and are related to higher-order cognitive deficits that directly interfere with day-to-day functioning.

Evoked and intrinsic asymmetries during auditory attention: implications for the contralateral and neglect models of functioning

Unlike the visual system, a direct mapping of extrapersonal space does not exist within human auditory cortex (AC). Thus, models (contralateral bias vs. neglect) of how auditory spatial attention is allocated remain debated, as does the role of hemispheric asymmetries. To further examine these questions, 27 participants completed an exogenous auditory orienting task while undergoing functional magnetic resonance imaging. Resting-state data were also collected to characterize intrinsic activity within the AC. Current results provide the first evidence of hemispheric specialization in the "where" (right secondary AC) auditory processing stream during both evoked (orienting task) and intrinsic (resting-state data) activity, suggesting that spontaneous and evoked activity may be synchronized by similar cortical hierarchies. Strong evidence for a contralateral bias model was observed during rapid deployment stages (facilitation) of auditory attention in bilateral AC. However, contralateral bias increased for left and decreased for right AC (neglect model) after longer stimulus onset asynchronies (inhibition of return), suggesting a role for higher-order cortical structures in modulating AC functioning. Prime candidates for attentional modulation include the frontoparietal network, which demonstrated right hemisphere lateralization across multiple attentional states.

A cerebellar thalamic cortical circuit for error-related cognitive control

Error detection and behavioral adjustment are core components of cognitive control. Numerous studies have focused on the anterior cingulate cortex (ACC) as a critical locus of this executive function. Our previous work showed greater activation in the dorsal ACC and subcortical structures during error detection, and activation in the ventrolateral prefrontal cortex (VLPFC) during post-error slowing (PES) in a stop signal task (SST). However, the extent of error-related cortical or subcortical activation across subjects was not correlated with VLPFC activity during PES. So then, what causes VLPFC activation during PES? To address this question, we employed Granger causality mapping (GCM) and identified regions that Granger caused VLPFC activation in 54 adults performing the SST during fMRI. These brain regions, including the supplementary motor area (SMA), cerebellum, a pontine region, and medial thalamus, represent potential targets responding to errors in a way that could influence VLPFC activation. In confirmation of this hypothesis, the error-related activity of these regions correlated with VLPFC activation during PES, with the cerebellum showing the strongest association. The finding that cerebellar activation Granger causes prefrontal activity during behavioral adjustment supports a cerebellar function in cognitive control. Furthermore, multivariate GCA described the "flow of information" across these brain regions. Through connectivity with the thalamus and SMA, the cerebellum mediates error and post-error processing in accord with known anatomical projections. Taken together, these new findings highlight the role of the cerebello-thalamo-cortical pathway in an executive function that has heretofore largely been ascribed to the anterior cingulate-prefrontal cortical circuit.

Auditory orienting and inhibition of return in mild traumatic brain injury: a FMRI study

The semiacute phase of mild traumatic brain injury (mTBI) is associated with deficits in the cognitive domains of attention, memory, and executive function, which previous work suggests may be related to a specific deficit in disengaging attentional focus. However, to date, there have only been a few studies that have employed dynamic imaging techniques to investigate the potential neurological basis of these cognitive deficits during the semiacute stage of injury. Therefore, event-related functional magnetic resonance imaging was used to investigate the neurological correlates of attentional dysfunction in a clinically homogeneous sample of 16 patients with mTBI during the semiacute phase of injury (<3 weeks). Behaviorally, patients with mTBI exhibited deficits in disengaging and reorienting auditory attention following invalid cues as well as a failure to inhibit attentional allocation to a cued spatial location compared to a group of matched controls. Accordingly, patients with mTBI also exhibited hypoactivation within thalamus, striatum, midbrain nuclei, and cerebellum across all trials as well as hypoactivation in the right posterior parietal cortex, presupplementary motor area, bilateral frontal eye fields, and right ventrolateral prefrontal cortex during attentional disengagement. Finally, the hemodynamic response within several regions of the attentional network predicted response times better for controls than for patients with mTBI. These objective neurological findings represent a potential biomarker for the behavioral deficits in spatial attention that characterize the initial recovery phase of mTBI.

Interactions between Voluntary and Stimulus-driven Spatial Attention Mechanisms across Sensory Modalities

In everyday life, the allocation of spatial attention typically entails the interplay between voluntary (endogenous) and stimulus-driven (exogenous) attention. Furthermore, stimuli in different sensory modalities can jointly influence the direction of spatial attention, due to the existence of cross-sensory links in attentional control. Using fMRI, we examined the physiological basis of these interactions. We induced exogenous shifts of auditory spatial attention while participants engaged in an endogenous visuospatial cueing task. Participants discriminated visual targets in the left or right hemifield. A central visual cue preceded the visual targets, predicting the target location on 75% of the trials (endogenous visual attention). In the interval between the endogenous cue and the visual target, task-irrelevant nonpredictive auditory stimuli were briefly presented either in the left or right hemifield (exogenous auditory attention). Consistent with previous unisensory visual studies, activation of the ventral fronto-parietal attentional network was observed when the visual targets were presented at the uncued side (endogenous invalid trials, requiring visuospatial reorienting), as compared with validly cued targets. Critically, we found that the side of the task-irrelevant auditory stimulus modulated these activations, reducing spatial reorienting effects when the auditory stimulus was presented on the same side as the upcoming (invalid) visual target. These results demonstrate that multisensory mechanisms of attentional control can integrate endogenous and exogenous spatial information, jointly determining attentional orienting toward the most relevant spatial location.

Neuronal modulation of auditory attention by informative and uninformative spatial cues

Sounds provide important information about the spatial environment, including the location of approaching objects. Attention to sounds can be directed through automatic or more controlled processes, which have been well studied in the visual modality. However, little is known about the neural underpinnings of attentional control mechanisms for auditory signals. We studied healthy adults who underwent event-related FMRI while performing a task that manipulated automatic and more controlled auditory orienting by varying the probability that cues correctly predicted target location. Specifically, we examined the effects of uninformative (50% validity ratio) and informative (75% validity ratio) auditory cues on reaction time (RT) and neuronal functioning. The stimulus-onset asynchrony (SOA) between the cue and the target was either 100 or 800 ms. At the 100 ms SOA, RT was faster for valid than invalid trials for both cue types, and frontoparietal activation was greater for invalid than valid trials. At the 800 ms SOA, RT and functional activation depended on whether cues were informative or uninformative, and whether cues correctly or incorrectly predicted the target location. Contrary to our prediction, activation in a frontoparietal network was greater for uninformative than informative cues across several different comparisons and at both SOAs. This finding contrasts with similar research of visual orienting, and suggests that the auditory modality may be more biased toward automatic shifts of attention following uninformative cues.