Integrated processing of spatial cues in human auditory cortex

Salminen, Nelli H.; Takanen, Marko; Santala, Olli; Lamminsalo, Jarkko; Altoè, Alessandro; Pulkki, Ville

doi:10.1016/j.heares.2015.06.006

Cited by 27 publications

(25 citation statements)

References 50 publications

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“…As mentioned in the Introduction, previous evoked-potential studies of ILD-ITD cue integration in human AC suggest partly integrated processing of the two cues, at least for matched changes in ILD/ITD cues (28,29). The current results support this view, in that regions of ITD and ILD sensitivity physically overlapped, and that patterns of voxel activity were consistent enough between the two cues to enable successful machine learning classification of one cue by the other.…”

Section: Spatial Listening Effects On the Cortical Topography Of Binasupporting

confidence: 85%

“…Evidence for integrated ITD and ILD processing includes results of EEG (28) and magnetoencephelography (MEG) (29) studies. Importantly, several studies reported mixed results (25,29), and one is led to conclude that the representations are neither fully integrated nor fully independent. One possibility is that multiple AC regions exhibit different patterns of sensitivity to ITD and ILD but that Significance Individuals determine horizontal sound location based on precise calculations of sound level and sound timing differences at the two ears.…”

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confidence: 99%

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Evidence for cue-independent spatial representation in the human auditory cortex during active listening

Higgins

McLaughlin

Rinne

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Few auditory functions are as important or as universal as the capacity for auditory spatial awareness (e.g., sound localization). That ability relies on sensitivity to acoustical cues-particularly interaural time and level differences (ITD and ILD)-that correlate with sound-source locations. Under nonspatial listening conditions, cortical sensitivity to ITD and ILD takes the form of broad contralaterally dominated response functions. It is unknown, however, whether that sensitivity reflects representations of the specific physical cues or a higher-order representation of auditory space (i.e., integrated cue processing), nor is it known whether responses to spatial cues are modulated by active spatial listening. To investigate, sensitivity to parametrically varied ITD or ILD cues was measured using fMRI during spatial and nonspatial listening tasks. Task type varied across blocks where targets were presented in one of three dimensions: auditory location, pitch, or visual brightness. Task effects were localized primarily to lateral posterior superior temporal gyrus (pSTG) and modulated binaural-cue response functions differently in the two hemispheres. Active spatial listening (location tasks) enhanced both contralateral and ipsilateral responses in the right hemisphere but maintained or enhanced contralateral dominance in the left hemisphere. Two observations suggest integrated processing of ITD and ILD. First, overlapping regions in medial pSTG exhibited significant sensitivity to both cues. Second, successful classification of multivoxel patterns was observed for both cue types and-criticallyfor cross-cue classification. Together, these results suggest a higherorder representation of auditory space in the human auditory cortex that at least partly integrates the specific underlying cues.auditory space | binaural cues | human auditory cortex | fMRI | sound localization A cross species, one of the most important functions of hearing is the capacity to localize and orient to sound sources throughout 360°of extrapersonal space. This function relies on the neural processing of a variety of acoustical cues, but particularly on interaural time (ITD) and level differences (ILD) that convey sound-source directions in the horizontal dimension (azimuth). The acoustical basis of these cues is well understood: sound arrives earlier and with greater intensity at the ear nearest the source. The magnitudes of both cues depend systematically on azimuth angle, sound frequency, and head size/shape. Acoustic reflections from surfaces of the outer ear and of the listening room further alter these cues in a frequency-and cuespecific manner.In the absence of echoes and reverberation, ITD and ILD cues vary more or less in parallel (i.e., redundantly) and human listeners appear to use the cues interchangeably. However, ITD is the psychophysically dominant cue for localization when sounds contain energy below ∼1.5 kHz (1-3). For higher-frequency sounds, ILD tends to dominate, although ITD carried by fluctuations in the sound envelope a...

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Section: Spatial Listening Effects On the Cortical Topography Of Binasupporting

confidence: 85%

mentioning

confidence: 99%

Evidence for cue-independent spatial representation in the human auditory cortex during active listening

Higgins

McLaughlin

Rinne

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…specialized for processing different spatial cues. Results from a more recent study show that auditory N1 396 modulation does not differ across spatial cue conditions, indicating integrated processing of sound 397 locations in auditory cortex regardless of cues (Salminen et al, 2015). In the current study, N1 398 modulation did not differ across the three spatialization conditions.…”

Section: Impoverished Spatial Cues Results In Less Neural Modulation Dcontrasting

confidence: 50%

Impoverished auditory cues fail to engage brain networks controlling spatial selective attention

Deng

Choi

Shinn‐Cunningham

et al. 2019

Preprint

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Spatial selective attention enables listeners to process a signal of interest in natural settings. However, most past studies on auditory spatial attention used impoverished spatial cues: presenting competing sounds to different ears, using only interaural differences in time (ITDs) and/or intensity (IIDs), or using non-individualized head-related transfer functions (HRTFs). Here we tested the hypothesis that impoverished spatial cues impair spatial auditory attention by only weakly engaging relevant cortical networks. Eighteen normal-hearing listeners reported the content of one of two competing syllable streams simulated at roughly +30 ° and −30° azimuth. The competing streams consisted of syllables from two different-sex talkers. Spatialization was based on natural spatial cues (individualized HRTFs), individualized IIDs, or generic ITDs. We measured behavioral performance as well as electroencephalographic markers of selective attention. Behaviorally, subjects recalled target streams most accurately with natural cues. Neurally, spatial attention significantly modulated early evoked sensory response magnitudes only for natural cues, not in conditions using only ITDs or IIDs. Consistent with this, parietal oscillatory power in the alpha band (8-14 Hz; associated with filtering out distracting events from unattended directions) showed significantly less attentional modulation with isolated spatial cues than with natural cues. Our findings support the hypothesis that spatial selective attention networks are only partially engaged by impoverished spatial auditory cues. These results not only suggest that studies using unnatural spatial cues underestimate the neural effects of spatial auditory attention, they also illustrate the importance of preserving natural spatial cues in assistive listening devices to support robust attentional control.

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“…A recent study with a different paradigm, employing changes of ITD/ILD and their combination after presentation of an adaptor, has provided evidence that points toward an integrated ITD/ILD code with the possibility of some residual independent coding (Edmonds and Krumbholz, 2014). Similarly, a recent magnetoencephalography (MEG) study has observed location-specific adaptation of the N1 response of auditory cortex across ITD/ILD cues (Salminen et al, 2015). The authors have interpreted this as an indication of integrated ITD/ILD processing, but given that adaptation effects in their study were larger within compared to across cues, they suggest that neural populations with separate selectivity are likely to exist in auditory cortex.…”

Section: Discussionmentioning

confidence: 90%

Auditory Mismatch Negativity in Response to Changes of Counter-Balanced Interaural Time and Level Differences

Altmann¹,

Ueda²,

Furukawa³

et al. 2017

Front. Neurosci.

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Interaural time differences (ITD) and interaural level differences (ILD) both signal horizontal sound source location. To achieve a unified percept of our acoustic environment, these two cues require integration. In the present study, we tested this integration of ITD and ILD with electroencephalography (EEG) by measuring the mismatch negativity (MMN). The MMN can arise in response to spatial changes and is at least partly generated in auditory cortex. In our study, we aimed at testing for an MMN in response to stimuli with counter-balanced ITD/ILD cues. To this end, we employed a roving oddball paradigm with alternating sound sequences in two types of blocks: (a) lateralized stimuli with congruently combined ITD/ILD cues and (b) midline stimuli created by counter-balanced, incongruently combined ITD/ILD cues. We observed a significant MMN peaking at about 112–128 ms after change onset for the congruent ITD/ILD cues, for both lower (0.5 kHz) and higher carrier frequency (4 kHz). More importantly, we also observed significant MMN peaking at about 129 ms for incongruently combined ITD/ILD cues, but this effect was only detectable in the lower frequency range (0.5 kHz). There were no significant differences of the MMN responses for the two types of cue combinations (congruent/incongruent). These results suggest that—at least in the lower frequency ranges (0.5 kHz)—ITD and ILD are processed independently at the level of the MMN in auditory cortex.

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Integrated processing of spatial cues in human auditory cortex

Cited by 27 publications

References 50 publications

Evidence for cue-independent spatial representation in the human auditory cortex during active listening

Evidence for cue-independent spatial representation in the human auditory cortex during active listening

Impoverished auditory cues fail to engage brain networks controlling spatial selective attention

Auditory Mismatch Negativity in Response to Changes of Counter-Balanced Interaural Time and Level Differences

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