101
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Sigalovsky IS, Melcher JR. Effects of sound level on fMRI activation in human brainstem, thalamic and cortical centers. Hear Res 2006; 215:67-76. [PMID: 16644153 PMCID: PMC1794213 DOI: 10.1016/j.heares.2006.03.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 02/27/2006] [Accepted: 03/07/2006] [Indexed: 10/24/2022]
Abstract
The dependence of fMRI activation on sound level was examined throughout the auditory pathway of normal human listeners using continuous broadband noise, a stimulus widely used in neuroscientific investigations of auditory processing, but largely neglected in neuro-imaging. Several specialized techniques were combined here for the first time to enhance detection of brainstem activation, mitigate scanner noise, and recover temporal resolution lost by the mitigation technique. The main finding was increased activation with increasing level in cochlear nucleus, superior olive, inferior colliculus, medial geniculate body and auditory cortical areas. We suggest that these increases reflect monotonically increasing activity in a preponderance of individual auditory neurons responsive to broadband noise. While the time-course of activation changed with level, the change was subtle and only significant in a part of the cortex. To our knowledge, these are the first fMRI data showing the effects of sound level in subcortical centers or for a non-tonal, non-speech stimulus at any stage of the pathway. The present results add to the body of parametric data in normal human listeners and are fundamental to the design of any fMRI experiment employing continuous noise.
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Affiliation(s)
- Irina S Sigalovsky
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA.
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102
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Voisin J, Bidet-Caulet A, Bertrand O, Fonlupt P. Listening in silence activates auditory areas: a functional magnetic resonance imaging study. J Neurosci 2006; 26:273-8. [PMID: 16399697 PMCID: PMC6674327 DOI: 10.1523/jneurosci.2967-05.2006] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Directing attention to some acoustic features of a sound has been shown repeatedly to modulate the stimulus-induced neural responses. On the contrary, little is known about the neurophysiological impact of auditory attention when the auditory scene remains empty. We performed an experiment in which subjects had to detect a sound emerging from silence (the sound was detectable after different durations of silence). Two frontal activations (right dorsolateral prefrontal and inferior frontal) were found, regardless of the side where sound was searched for, consistent with the well established role of these regions in attentional control. The main result was that the superior temporal cortex showed activations contralateral to the side where sound was expected to be present. The area extended from the vicinity of Heschl's gyrus to the surrounding areas (planum temporale/anterior lateral areas). The effect consisted of both an increase in the response to a sound delivered after attention was directed to detect its emergence and a baseline shift during the silent period. Thus, in absence of any acoustic stimulus, the search for an auditory input was found to activate the auditory cortex.
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Affiliation(s)
- Julien Voisin
- Institut National de la Santé et de la Recherche Médicale, Unité 280, Institut Fédératif des Neurosciences de Lyon, Université Claude Bernard Lyon 1, F-69000, Lyon, France
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103
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Devlin JT, Sillery EL, Hall DA, Hobden P, Behrens TEJ, Nunes RG, Clare S, Matthews PM, Moore DR, Johansen-Berg H. Reliable identification of the auditory thalamus using multi-modal structural analyses. Neuroimage 2006; 30:1112-20. [PMID: 16473021 PMCID: PMC1458525 DOI: 10.1016/j.neuroimage.2005.11.025] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 10/21/2005] [Accepted: 11/10/2005] [Indexed: 11/28/2022] Open
Abstract
The medial geniculate body (MGB) of the thalamus is a key component of the auditory system. It is involved in relaying and transforming auditory information to the cortex and in top-down modulation of processing in the midbrain, brainstem, and ear. Functional imaging investigations of this region in humans, however, have been limited by the difficulty of distinguishing MGB from other thalamic nuclei. Here, we introduce two methods for reliably delineating MGB anatomically in individuals based on conventional and diffusion MRI data. The first uses high-resolution proton density weighted scanning optimized for subcortical grey-white contrast. The second uses diffusion-weighted imaging and probabilistic tractography to automatically segment the medial and lateral geniculate nuclei from surrounding structures based on their distinctive patterns of connectivity to the rest of the brain. Both methods produce highly replicable results that are consistent with published atlases. Importantly, both methods rely on commonly available imaging sequences and standard hardware, a significant advantage over previously described approaches. In addition to providing useful approaches for identifying the MGB and LGN in vivo, our study offers further validation of diffusion tractography for the parcellation of grey matter regions on the basis of their connectivity patterns.
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Affiliation(s)
- J T Devlin
- Centre for Functional Magnetic Resonance Imaging of the Brain, Department of Clinical Neurology, John Radcliff Hospital, University of Oxford, Headley Way, Headington, Oxford OX3 9DU, UK.
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104
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Lehmann C, Herdener M, Esposito F, Hubl D, di Salle F, Scheffler K, Bach DR, Federspiel A, Kretz R, Dierks T, Seifritz E. Differential patterns of multisensory interactions in core and belt areas of human auditory cortex. Neuroimage 2006; 31:294-300. [PMID: 16473022 DOI: 10.1016/j.neuroimage.2005.12.038] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 11/23/2005] [Accepted: 12/07/2005] [Indexed: 10/25/2022] Open
Abstract
The auditory cortex is anatomically segregated into a central core and a peripheral belt region, which exhibit differences in preference to bandpassed noise and in temporal patterns of response to acoustic stimuli. While it has been shown that visual stimuli can modify response magnitude in auditory cortex, little is known about differential patterns of multisensory interactions in core and belt. Here, we used functional magnetic resonance imaging and examined the influence of a short visual stimulus presented prior to acoustic stimulation on the spatial pattern of blood oxygen level-dependent signal response in auditory cortex. Consistent with crossmodal inhibition, the light produced a suppression of signal response in a cortical region corresponding to the core. In the surrounding areas corresponding to the belt regions, however, we found an inverse modulation with an increasing signal in centrifugal direction. Our data suggest that crossmodal effects are differentially modulated according to the hierarchical core-belt organization of auditory cortex.
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Affiliation(s)
- Christoph Lehmann
- University Hospital of Clinical Psychiatry, University of Bern, 3000 Bern, Switzerland.
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105
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Hawley ML, Melcher JR, Fullerton BC. Effects of sound bandwidth on fMRI activation in human auditory brainstem nuclei. Hear Res 2006; 204:101-10. [PMID: 15925195 PMCID: PMC1855158 DOI: 10.1016/j.heares.2005.01.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2004] [Accepted: 01/11/2005] [Indexed: 11/20/2022]
Abstract
Few neuro-imaging studies of the auditory system have examined the dependence of brain activation on sound bandwidth, a fundamental stimulus parameter, and none have examined bandwidth dependencies in the brainstem. The present study examined the effect of bandwidth on human brainstem activation using fMRI, an indicator of population neural activity. The studied stimuli (broadband, two-, one-, and third-octave continuous noise) activated three brainstem centers: cochlear nucleus, superior olivary complex, and inferior colliculus. Activation could be confidently attributed to these nuclei because it was appropriately punctate (given the small size of the imaged nuclei) and appropriately located (as determined from histological atlases). Activation in all three imaged centers increased monotonically with increasing bandwidth when either stimulus spectrum level or energy was held constant. Supplementary experiments indicated that the measured bandwidth dependencies were not contaminated by the extraneous sounds produced by the scanner. Increases in fMRI activation with increasing bandwidth would be expected from populations of neurons having a single best frequency and only excitatory responses to sound, but not necessarily from lower auditory system neurons with their often more complex responses. Our results provide basic information for designing auditory neuro-imaging studies that need to control for, or manipulate sound bandwidth.
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Affiliation(s)
- Monica L Hawley
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA
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106
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Rinne T, Pekkola J, Degerman A, Autti T, Jääskeläinen IP, Sams M, Alho K. Modulation of auditory cortex activation by sound presentation rate and attention. Hum Brain Mapp 2005; 26:94-9. [PMID: 15852467 PMCID: PMC6871736 DOI: 10.1002/hbm.20123] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We studied the effects of sound presentation rate and attention on auditory supratemporal cortex (STC) activation in 12 healthy adults using functional magnetic resonance imaging (fMRI) at 3 T. The sounds (200 ms in duration) were presented at steady rates of 0.5, 1, 1.5, 2.5, or 4 Hz while subjects either had to focus their attention to the sounds or ignore the sounds and attend to visual stimuli presented with a mean rate of 1 Hz. Consistent with previous observations, we found that both increase in stimulation rate and attention to sounds enhanced activity in STC bilaterally. Further, we observed larger attention effects with higher stimulation rates. This interaction of attention and presentation rate has not been reported previously. In conclusion, our results show both rate-dependent and attention-related modulations of STC indicating that both factors should be controlled, or at least addressed, in fMRI studies of auditory processing.
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Affiliation(s)
- Teemu Rinne
- Department of Psychology, University of Helsinki, Finland.
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107
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Haller S, Bartsch AJ, Radue EW, Klarhöfer M, Seifritz E, Scheffler K. Effect of fMRI acoustic noise on non-auditory working memory task: comparison between continuous and pulsed sound emitting EPI. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2005; 18:263-71. [PMID: 16320092 DOI: 10.1007/s10334-005-0010-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Accepted: 09/30/2005] [Indexed: 11/24/2022]
Abstract
Conventional blood oxygenation level-dependent (BOLD) based functional magnetic resonance imaging (fMRI) is accompanied by substantial acoustic gradient noise. This noise can influence the performance as well as neuronal activations. Conventional fMRI typically has a pulsed noise component, which is a particularly efficient auditory stimulus. We investigated whether the elimination of this pulsed noise component in a recent modification of continuous-sound fMRI modifies neuronal activations in a cognitively demanding non-auditory working memory task. Sixteen normal subjects performed a letter variant n-back task. Brain activity and psychomotor performance was examined during fMRI with continuous-sound fMRI and conventional fMRI. We found greater BOLD responses in bilateral medial frontal gyrus, left middle frontal gyrus, left middle temporal gyrus, left hippocampus, right superior frontal gyrus, right precuneus and right cingulate gyrus with continuous-sound compared to conventional fMRI. Conversely, BOLD responses were greater in bilateral cingulate gyrus, left middle and superior frontal gyrus and right lingual gyrus with conventional compared to continuous-sound fMRI. There were no differences in psychomotor performance between both scanning protocols. Although behavioral performance was not affected, acoustic gradient noise interferes with neuronal activations in non-auditory cognitive tasks and represents a putative systematic confound.
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Affiliation(s)
- Sven Haller
- Institute of Neuroradiology, Department of Medical Radiology, University Hospital Basel, Petersgraben 4, CH-4031 Basel, Switzerland.
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108
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Hall DA, Barrett DJK, Akeroyd MA, Summerfield AQ. Cortical Representations of Temporal Structure in Sound. J Neurophysiol 2005; 94:3181-91. [PMID: 16014796 DOI: 10.1152/jn.00271.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pitch and spatial width are two sound attributes that can be coded by temporal acoustic structure. In this study, periodicity pitch was created by temporal iteration in a regular-interval noise, whereas spatial width was determined by the degree of interaural correlation. Previous results suggest that nonprimary auditory cortex, particularly lateral Heschl's gyrus (HG), plays an important role in the analysis of both acoustic properties. It has been argued that this role might reflect a common computational process. One proposed candidate is that of integrating the temporal pattern information across frequency channels. This paper reports the results of a systematic test for whether different classes of temporal structure do indeed engage a common neural architecture in the human auditory cortex by presenting both classes of sound stimuli to a single group of listeners. Activations related to the pitch and spatial width of the sound were partly co-localized in two distinct cortical regions: close to lateral HG and in planum temporale (PT). Lateral HG was more responsive to temporal pitch than to spatial width. This difference plus the variability across listeners for spatial width dispute the claim that the activity in lateral HG reflects a common neural computational step that encodes the temporal patterns associated with pitch and spatial width. Rather, the activity patterns are consistent with a role for lateral HG in perceptual analysis as opposed to temporal acoustic structure. In PT, the superadditive relationship between pitch and spatial width is also consistent with the concept that the auditory cortex plays an important role in integrating different classes of sound information to form auditory objects.
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Affiliation(s)
- Deborah A Hall
- MRC Institute of Hearing Research, University Park, Nottingham, NG7 2RD, UK.
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109
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Seifritz E, Di Salle F, Esposito F, Herdener M, Neuhoff JG, Scheffler K. Enhancing BOLD response in the auditory system by neurophysiologically tuned fMRI sequence. Neuroimage 2005; 29:1013-22. [PMID: 16253522 DOI: 10.1016/j.neuroimage.2005.08.029] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 07/22/2005] [Accepted: 08/23/2005] [Indexed: 11/22/2022] Open
Abstract
Auditory neuroscience has not tapped fMRI's full potential because of acoustic scanner noise emitted by the gradient switches of conventional echoplanar fMRI sequences. The scanner noise is pulsed, and auditory cortex is particularly sensitive to pulsed sounds. Current fMRI approaches to avoid stimulus-noise interactions are temporally inefficient. Since the sustained BOLD response to pulsed sounds decreases with repetition rate and becomes minimal with unpulsed sounds, we developed an fMRI sequence emitting continuous rather than pulsed gradient sound by implementing a novel quasi-continuous gradient switch pattern. Compared to conventional fMRI, continuous-sound fMRI reduced auditory cortex BOLD baseline and increased BOLD amplitude with graded sound stimuli, short sound events, and sounds as complex as orchestra music with preserved temporal resolution. Response in subcortical auditory nuclei was enhanced, but not the response to light in visual cortex. Finally, tonotopic mapping using continuous-sound fMRI demonstrates that enhanced functional signal-to-noise in BOLD response translates into improved spatial separability of specific sound representations.
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Affiliation(s)
- Erich Seifritz
- University Hospital of Clinical Psychiatry, University of Bern, 3000 Bern, Switzerland.
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110
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Schönwiesner M, Rübsamen R, von Cramon DY. Hemispheric asymmetry for spectral and temporal processing in the human antero-lateral auditory belt cortex. Eur J Neurosci 2005; 22:1521-8. [PMID: 16190905 DOI: 10.1111/j.1460-9568.2005.04315.x] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The present study investigates the acoustic basis of the hemispheric asymmetry for the processing of speech and music. Experiments on this question ideally involve stimuli that are perceptually unrelated to speech and music, but contain acoustic characteristics of both. Stimuli in previous studies were derived from speech samples or tonal sequences. Here we introduce a new class of noise-like sound stimuli with no resemblance of speech or music that permit independent parametric variation of spectral and temporal acoustic complexity. Using these stimuli in a functional MRI experiment, we test the hypothesis of a hemispheric asymmetry for the processing of spectral and temporal sound structure by seeking cortical areas in which the blood oxygen level dependent (BOLD) signal covaries with the number of simultaneous spectral components (spectral complexity) or the temporal modulation rate (temporal complexity) of the stimuli. BOLD-responses from the left and right Heschl's gyrus (HG) and part of the right superior temporal gyrus covaried with the spectral parameter, whereas covariation analysis for the temporal parameter highlighted an area on the left superior temporal gyrus. The portion of superior temporal gyrus in which asymmetrical responses are apparent corresponds to the antero-lateral auditory belt cortex, which has been implicated with spectral integration in animal studies. Our results support a similar function of the anterior auditory belt in humans. The findings indicate that asymmetrical processing of complex sounds in the cerebral hemispheres does not depend on semantic, but rather on acoustic stimulus characteristics.
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111
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Van Meir V, Boumans T, De Groof G, Van Audekerke J, Smolders A, Scheunders P, Sijbers J, Verhoye M, Balthazart J, Van der Linden A. Spatiotemporal properties of the BOLD response in the songbirds' auditory circuit during a variety of listening tasks. Neuroimage 2005; 25:1242-55. [PMID: 15850742 DOI: 10.1016/j.neuroimage.2004.12.058] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 11/19/2004] [Accepted: 12/05/2004] [Indexed: 11/23/2022] Open
Abstract
Auditory fMRI in humans has recently received increasing attention from cognitive neuroscientists as a tool to understand mental processing of learned acoustic sequences and analyzing speech recognition and development of musical skills. The present study introduces this tool in a well-documented animal model for vocal learning, the songbird, and provides fundamental insight in the main technical issues associated with auditory fMRI in these songbirds. Stimulation protocols with various listening tasks lead to appropriate activation of successive relays in the songbirds' auditory pathway. The elicited BOLD response is also region and stimulus specific, and its temporal aspects provide accurate measures of the changes in brain physiology induced by the acoustic stimuli. Extensive repetition of an identical stimulus does not lead to habituation of the response in the primary or secondary telencephalic auditory regions of anesthetized subjects. The BOLD signal intensity changes during a stimulation and subsequent rest period have a very specific time course which shows a remarkable resemblance to auditory evoked BOLD responses commonly observed in human subjects. This observation indicates that auditory fMRI in the songbird may establish a link between auditory related neuro-imaging studies done in humans and the large body of neuro-ethological research on song learning and neuro-plasticity performed in songbirds.
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Affiliation(s)
- Vincent Van Meir
- Bio-Imaging Laboratory, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
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112
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Krumbholz K, Schönwiesner M, Rübsamen R, Zilles K, Fink GR, von Cramon DY. Hierarchical processing of sound location and motion in the human brainstem and planum temporale. Eur J Neurosci 2005; 21:230-8. [PMID: 15654860 DOI: 10.1111/j.1460-9568.2004.03836.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Horizontal sound localization relies on the extraction of binaural acoustic cues by integration of the signals from the two ears at the level of the brainstem. The present experiment was aimed at detecting the sites of binaural integration in the human brainstem using functional magnetic resonance imaging and a binaural difference paradigm, in which the responses to binaural sounds were compared with the sum of the responses to the corresponding monaural sounds. The experiment also included a moving sound condition, which was contrasted against a spectrally and energetically matched stationary sound condition to assess which of the structures that are involved in general binaural processing are specifically specialized in motion processing. The binaural difference contrast revealed a substantial binaural response suppression in the inferior colliculus in the midbrain, the medial geniculate body in the thalamus and the primary auditory cortex. The effect appears to reflect an actual reduction of the underlying activity, probably brought about by binaural inhibition or refractoriness at the level of the superior olivary complex. Whereas all structures up to and including the primary auditory cortex were activated as strongly by the stationary as by the moving sounds, non-primary auditory fields in the planum temporale responded selectively to the moving sounds. These results suggest a hierarchical organization of auditory spatial processing in which the general analysis of binaural information begins as early as the brainstem, while the representation of dynamic binaural cues relies on non-primary auditory fields in the planum temporale.
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113
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Ross B, Herdman AT, Pantev C. Right Hemispheric Laterality of Human 40 Hz Auditory Steady-state Responses. Cereb Cortex 2005; 15:2029-39. [PMID: 15772375 DOI: 10.1093/cercor/bhi078] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Hemispheric asymmetries during auditory sensory processing were examined using whole-head magnetoencephalographic recordings of auditory evoked responses to monaurally and binaurally presented amplitude-modulated sounds. Laterality indices were calculated for the transient onset responses (P1m and N1m), the transient gamma-band response, the sustained field (SF) and the 40 Hz auditory steady-state response (ASSR). All response components showed laterality toward the hemisphere contralateral to the stimulated ear. In addition, the SF and ASSR showed right hemispheric (RH) dominance. Thus, laterality of sustained response components (SF and ASSR) was distinct from that of transient responses. ASSR and SF are sensitive to stimulus periodicity. Consequently, ASSR and SF likely reflect periodic stimulus attributes and might be relevant for pitch processing based on temporal stimulus regularities. In summary, the results of the present studies demonstrate that asymmetric organization in the cerebral auditory cortex is already established on the level of sensory processing.
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Affiliation(s)
- B Ross
- The Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Canada, and Institute for Biomagnetism and Biosignalanalysis, Münster University Hospital, Germany.
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114
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Boemio A, Fromm S, Braun A, Poeppel D. Hierarchical and asymmetric temporal sensitivity in human auditory cortices. Nat Neurosci 2005; 8:389-95. [PMID: 15723061 DOI: 10.1038/nn1409] [Citation(s) in RCA: 400] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Accepted: 01/25/2005] [Indexed: 11/09/2022]
Abstract
Lateralization of function in auditory cortex has remained a persistent puzzle. Previous studies using signals with differing spectrotemporal characteristics support a model in which the left hemisphere is more sensitive to temporal and the right more sensitive to spectral stimulus attributes. Here we use single-trial sparse-acquisition fMRI and a stimulus with parametrically varying segmental structure affecting primarily temporal properties. We show that both left and right auditory cortices are remarkably sensitive to temporal structure. Crucially, beyond bilateral sensitivity to timing information, we uncover two functionally significant interactions. First, local spectrotemporal signal structure is differentially processed in the superior temporal gyrus. Second, lateralized responses emerge in the higher-order superior temporal sulcus, where more slowly modulated signals preferentially drive the right hemisphere. The data support a model in which sounds are analyzed on two distinct timescales, 25-50 ms and 200-300 ms.
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Affiliation(s)
- Anthony Boemio
- Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
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115
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Harms MP, Guinan JJ, Sigalovsky IS, Melcher JR. Short-Term Sound Temporal Envelope Characteristics Determine Multisecond Time Patterns of Activity in Human Auditory Cortex as Shown by fMRI. J Neurophysiol 2005; 93:210-22. [PMID: 15306629 DOI: 10.1152/jn.00712.2004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) of human auditory cortex has demonstrated a striking range of temporal waveshapes in responses to sound. Prolonged (30 s) low-rate (2/s) noise burst trains elicit “sustained” responses, whereas high-rate (35/s) trains elicit “phasic” responses with peaks just after train onset and offset. As a step toward understanding the significance of these responses for auditory processing, the present fMRI study sought to resolve exactly which features of sound determine cortical response waveshape. The results indicate that sound temporal envelope characteristics, but not sound level or bandwidth, strongly influence response waveshapes, and thus the underlying time patterns of neural activity. The results show that sensitivity to sound temporal envelope holds in both primary and nonprimary cortical areas, but nonprimary areas show more pronounced phasic responses for some types of stimuli (higher-rate trains, continuous noise), indicating more prominent neural activity at sound onset and offset. It has been hypothesized that the neural activity underlying the onset and offset peaks reflects the beginning and end of auditory perceptual events. The present data support this idea because sound temporal envelope, the sound characteristic that most strongly influences whether fMRI responses are phasic, also strongly influences whether successive stimuli (e.g., the bursts of a train) are perceptually grouped into a single auditory event. Thus fMRI waveshape may provide a window onto neural activity patterns that reflect the segmentation of our auditory environment into distinct, meaningful events.
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Affiliation(s)
- Michael P Harms
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA.
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116
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Brechmann A, Scheich H. Hemispheric shifts of sound representation in auditory cortex with conceptual listening. ACTA ACUST UNITED AC 2004; 15:578-87. [PMID: 15319313 DOI: 10.1093/cercor/bhh159] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The weak field specificity and the heterogeneity of neuronal filters found in any given auditory cortex field does not substantiate the view that such fields are merely descriptive maps of sound features. But field mechanisms were previously shown to support behaviourally relevant classification of sounds. Here the prediction was tested in human auditory cortex (AC) that classification-tasks rather than the stimulus class per se determine which auditory cortex area is recruited. By presenting the same set of frequency-modulations we found that categorization of their pitch direction (rising versus falling) increased functional magnetic resonance imaging activation in right posterior AC compared with stimulus exposure and in contrast to left posterior AC dominance during categorization of their duration (short versus long). Thus, top-down influences appear to select not only auditory cortex areas but also the hemisphere for specific processing.
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Affiliation(s)
- André Brechmann
- Leibniz-Institute for Neurobiology, Brenneckestrasse 6, 39118 Magdeburg, Germany.
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117
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Reyes SA, Salvi RJ, Burkard RF, Coad ML, Wack DS, Galantowicz PJ, Lockwood AH. PET imaging of the 40 Hz auditory steady state response. Hear Res 2004; 194:73-80. [PMID: 15276678 DOI: 10.1016/j.heares.2004.04.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Accepted: 04/01/2004] [Indexed: 11/20/2022]
Abstract
The auditory steady state response (aSSR) is an oscillatory electrical potential recorded from the scalp induced by amplitude-modulated (AM) or click/tone burst stimuli. Its clinical utility has been limited by uncertainty regarding the specific areas of the brain involved in its generation. To identify the generators of the aSSR, 15O-water PET imaging was used to locate the regions of the brain activated by a steady 1 kHz pure tone, the same tone amplitude modulated (AM) at 40 Hz and the specific regions of the brain responsive to the AM component of the stimulus relative to the continuous tone. The continuous tone produced four clusters of activation. The boundaries of these activated clusters extended to include regions in left primary auditory cortex, right non-primary auditory cortex, left thalamus, and left cingulate. The AM tone produced three clusters of activation. The boundaries of these activated clusters extended to include primary auditory cortex bilaterally, left medial geniculate and right middle frontal gyrus. Two regions were specifically responsive to the AM component of the stimulus. These activated clusters extended to include the right anterior cingulate near frontal cortex and right auditory cortex. We conclude that cortical sites, including areas outside primary auditory cortex, are involved in generating the aSSR. There was an unexpected difference between morning and afternoon session scans that may reflect a pre- versus post-prandial state. These results support the hypothesis that a distributed resonating circuit mediates the generation of the aSSR.
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Affiliation(s)
- Samuel A Reyes
- Department of Communicative Disorders and Sciences, University at Buffalo, Buffalo, NY 14214, USA
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118
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Snyder JS, Large EW. Tempo dependence of middle- and long-latency auditory responses: power and phase modulation of the EEG at multiple time-scales. Clin Neurophysiol 2004; 115:1885-95. [PMID: 15261867 DOI: 10.1016/j.clinph.2004.03.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2004] [Indexed: 11/28/2022]
Abstract
OBJECTIVE We measured the influences of power and phase modulations of neuroelectric activity on auditory responses to pure-tone patterns with inter-onset intervals typical of music. METHODS Tones were presented to 8 subjects at 10 different tempos from 150 to 3125 ms and with random intervals. We quantified time-frequency (TF) power with respect to a pre-tone-onset baseline and the TF phase coherence across trials. Peak-to-peak event-related potential (ERP) amplitude values for the middle and long-latency auditory responses were obtained for comparison. RESULTS ERP amplitude, size of power modulation, and amount of phase coherence were larger at slower tempos for the long-latency response (LLR) but not for the middle-latency response (MLR). Multiple regression analysis indicated that for MLR and LLR, phase modulation was a better predictor of ERP amplitude than power modulation. CONCLUSIONS Phase modulation is a better predictor of ERP amplitude than power modulation for middle and long-latency auditory responses. SIGNIFICANCE Lack of diminution of the MLR at fast tempos indicates its usefulness for studying early cortical processing of music and speech patterns.
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Affiliation(s)
- Joel S Snyder
- Department of Psychology, Cornell University, Ithaca, NY, USA.
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119
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Deike S, Gaschler-Markefski B, Brechmann A, Scheich H. Auditory stream segregation relying on timbre involves left auditory cortex. Neuroreport 2004; 15:1511-4. [PMID: 15194885 DOI: 10.1097/01.wnr.0000132919.12990.34] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
An important aspect of auditory scene analysis is sequential grouping of sounds that are similar to one another in preference to sounds that follow one another. This grouping problem is captured by stream segregation tasks with alternating distinct sounds. We examined human auditory cortex activity with low noise fMRI in a stream segregation experiment relying on timbre differences of alternating harmonic tones (organ-like and trumpet-like). We found that stream segregation performance in comparison to monitoring a non-separable control stream increased activation exclusively in left auditory cortex and particularly in posterior areas. Our results suggest that left auditory cortex is selectively involved in this complex sequential task although the available cue for sequential grouping was timbre, usually attributed to right hemisphere analysis.
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Affiliation(s)
- Susann Deike
- Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany.
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120
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Okada T, Honda M, Okamoto J, Sadato N. Activation of the primary and association auditory cortex by the transition of sound intensity: a new method for functional examination of the auditory cortex in humans. Neurosci Lett 2004; 359:119-23. [PMID: 15050725 DOI: 10.1016/j.neulet.2004.02.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2003] [Revised: 01/26/2004] [Accepted: 02/05/2004] [Indexed: 11/17/2022]
Abstract
During functional MRI image acquisition, the scanning equipment generates substantial auditory noise, the effects of which are usually ignored. To investigate the neural activity in response to the transition of noise, we measured cerebral responses to short silent periods (1 and 5 s) during which the slice readout gradients were switched off. In all 15 normal volunteers, the 1 s silence bilaterally activated the primary and association auditory cortex. Subtraction of the response to the 1 s silent period from that to the 5 s silent period revealed the activation related to the onset (transition of sound from OFF to ON) event, indicating that the 1 s response is offset (transition of sound from ON to OFF) related. The complex response of the auditory cortex to the transition of the noise should be considered in designing functional MRI with auditory tasks.
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Affiliation(s)
- Tomohisa Okada
- National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, 444-8585, Japan
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121
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Scott SK, Wise RJS. The functional neuroanatomy of prelexical processing in speech perception. Cognition 2004; 92:13-45. [PMID: 15037125 DOI: 10.1016/j.cognition.2002.12.002] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2001] [Revised: 07/11/2002] [Accepted: 12/10/2002] [Indexed: 10/26/2022]
Abstract
In this paper we attempt to relate the prelexical processing of speech, with particular emphasis on functional neuroimaging studies, to the study of auditory perceptual systems by disciplines in the speech and hearing sciences. The elaboration of the sound-to-meaning pathways in the human brain enables their integration into models of the human language system and the definition of potential auditory processing differences between the two cerebral hemispheres. Further, it facilitates comparison with recent developments in the study of the anatomy of non-human primate auditory cortex, which has very precisely revealed architectonically distinct regions, connectivity, and functional specialization.
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Affiliation(s)
- Sophie K Scott
- MRC Clinical Sciences Centre, Cyclotron Unit, Hammersmith Hospital, London W12 0NN, UK.
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122
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Abstract
Amplitude modulation (AM) is a temporal feature of most natural acoustic signals. A long psychophysical tradition has shown that AM is important in a variety of perceptual tasks, over a range of time scales. Technical possibilities in stimulus synthesis have reinvigorated this field and brought the modulation dimension back into focus. We address the question whether specialized neural mechanisms exist to extract AM information, and thus whether consideration of the modulation domain is essential in understanding the neural architecture of the auditory system. The available evidence suggests that this is the case. Peripheral neural structures not only transmit envelope information in the form of neural activity synchronized to the modulation waveform but are often tuned so that they only respond over a limited range of modulation frequencies. Ascending the auditory neuraxis, AM tuning persists but increasingly takes the form of tuning in average firing rate, rather than synchronization, to modulation frequency. There is a decrease in the highest modulation frequencies that influence the neural response, either in average rate or synchronization, as one records at higher and higher levels along the neuraxis. In parallel, there is an increasing tolerance of modulation tuning for other stimulus parameters such as sound pressure level, modulation depth, and type of carrier. At several anatomical levels, consideration of modulation response properties assists the prediction of neural responses to complex natural stimuli. Finally, some evidence exists for a topographic ordering of neurons according to modulation tuning. The picture that emerges is that temporal modulations are a critical stimulus attribute that assists us in the detection, discrimination, identification, parsing, and localization of acoustic sources and that this wide-ranging role is reflected in dedicated physiological properties at different anatomical levels.
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Affiliation(s)
- P X Joris
- Laboratory of Auditory Neurophysiology, K.U. Leuven, Campus Gasthuisberg, B-3000 Leuven, Belgium.
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123
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Hart HC, Palmer AR, Hall DA. Different areas of human non-primary auditory cortex are activated by sounds with spatial and nonspatial properties. Hum Brain Mapp 2004; 21:178-90. [PMID: 14755837 PMCID: PMC6872110 DOI: 10.1002/hbm.10156] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
In humans, neuroimaging studies have identified the planum temporale to be particularly responsive to both spatial and nonspatial attributes of sound. However, a functional segregation of the planum temporale along these acoustic dimensions has not been firmly established. We evaluated this scheme in a factorial design using modulated sounds that generated a percept of motion (spatial) or frequency modulation (nonspatial). In addition, these sounds were presented in the context of a motion detection and a frequency-modulation detection task to investigate the cortical effects of directing attention to different perceptual attributes of the sound. Motion produced stronger activation in the medial part of the planum temporale and frequency-modulation produced stronger activation in the lateral part of the planum temporale, as well as an additional non-primary area lateral to Heschl's gyrus. These separate subregions are consistent with the notion of divergent processing streams for spatial and nonspatial auditory information. Activation in the superior parietal cortex, putatively involved in the spatial pathway, was dependent on the task of motion detection and not simply on the presence of acoustic cues for motion. This finding suggests that the listening task is an important determinant of how the processing stream is engaged.
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Affiliation(s)
- Heledd C. Hart
- MRC Institute of Hearing Research, University Park, Nottingham, United Kingdom
| | - Alan R. Palmer
- MRC Institute of Hearing Research, University Park, Nottingham, United Kingdom
| | - Deborah A. Hall
- MRC Institute of Hearing Research, University Park, Nottingham, United Kingdom
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124
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Abstract
Structural asymmetries in the supratemporal plane of the human brain are often cited as the anatomical basis for the lateralization of language predominantly to the left hemisphere. However, similar asymmetries are found for structures mediating earlier events in the auditory processing stream, suggesting that functional lateralization may occur even at the level of primary auditory cortex. We tested this hypothesis using functional magnetic resonance imaging to evaluate human auditory cortex responses to monaurally presented tones. Relative to silence, tones presented separately to either ear produced greater activation in left than right Heschl's gyrus, the location of primary auditory cortex. This functional lateralization for primary auditory cortex is distinct from the contralateral dominance reported for other mammals, including nonhuman primates, and may have contributed to the evolution of a unique role for the left hemisphere in language processing.
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125
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Budd TW, Hall DA, Gonçalves MS, Akeroyd MA, Foster JR, Palmer AR, Head K, Summerfield AQ. Binaural specialisation in human auditory cortex: an fMRI investigation of interaural correlation sensitivity. Neuroimage 2004; 20:1783-94. [PMID: 14642488 DOI: 10.1016/j.neuroimage.2003.07.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
A listener's sensitivity to the interaural correlation (IAC) of sound plays an important role in several phenomena in binaural hearing. Although IAC has been examined humans, little is known about the neural basis of sensitivity to IAC in humans. The present study employed functional magnetic resonance imaging to measure blood oxygen level-dependent (BOLD) activity in auditory brainstem and cortical structures in human listeners during presentation of band-pass noise stimuli between which IAC was varied systematically. The stimuli evoked significant bilateral activation in the inferior colliculus, medial geniculate body, and auditory cortex. There was a significant positive relationship between BOLD activity and IAC which was confined to a distinct subregion of primary auditory cortex located bilaterally at the lateral extent of Heschl's gyrus. Comparison with published anatomical data indicated that this area may also be cytoarchitecturally distinct. Larger differences in activation were found between levels of IAC near unity than between levels near zero. This response pattern is qualitatively compatible with previous measures of psychophysical and neurophysiological sensitivity to IAC. extensively in neurophysiological studies in animals and in psychophysical studies in
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Affiliation(s)
- T W Budd
- MRC Institute of Hearing Research, University Park, Nottingham NG7 2RD, UK.
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126
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Harms MP, Melcher JR. Detection and quantification of a wide range of fMRI temporal responses using a physiologically-motivated basis set. Hum Brain Mapp 2004; 20:168-83. [PMID: 14601143 PMCID: PMC1866291 DOI: 10.1002/hbm.10136] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The temporal dynamics of fMRI responses can span a broad range, indicating a rich underlying physiology, but also posing a significant challenge for detection. For instance, in human auditory cortex, prolonged sound stimuli ( approximately 30 sec) can evoke responses ranging from sustained to highly phasic (i.e., characterized by prominent peaks just after sound onset and offset). In the present study, we developed a method capable of detecting a wide variety of responses, while simultaneously extracting information about individual response components, which may have different neurophysiological underpinnings. Specifically, we implemented the general linear model using a novel set of basis functions chosen to reflect temporal features of cortical fMRI responses. This physiologically-motivated basis set (the "OSORU" basis set) was tested against (1) the commonly employed "sustained-only" basis "set" (i.e., a single smoothed "boxcar" function), and (2) a sinusoidal basis set, which is capable of detecting a broad range of responses, but lacks a direct relationship to individual response components. On data that included many different temporal responses, the OSORU basis set performed far better overall than the sustained-only set, and as well or better than the sinusoidal basis set. The OSORU basis set also proved effective in exploring brain physiology. As an example, we demonstrate that the OSORU basis functions can be used to spatially map the relative amount of transient vs. sustained activity within auditory cortex. The OSORU basis set provides a powerful means for response detection and quantification that should be broadly applicable to any brain system and to both human and non-human species.
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Affiliation(s)
- Michael P Harms
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston and Harvard-MIT Division of Health Sciences and Technology, Hearing Bioscience and Technology Program, Cambridge, Massachusetts, USA.
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127
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Okada T, Nakai T. Silent fMRI acquisition methods for large acoustic noise during scan. Magn Reson Med Sci 2003; 2:181-7. [PMID: 16222112 DOI: 10.2463/mrms.2.181] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) is now the method of choice for studying neural correlates of various tasks in normal subjects as well as patients. This method, however, is inevitably coupled with the acoustic noise produced during the image acquisition process. This is a problem not only in auditory experiments but also in other cognitive tasks in general. The problems caused by such noise are modulation of auditory activation, impaired perception of auditory stimuli, and deterioration of task performance possibly due to stress from the abnormal circumstances. While both hardware and software solutions have been reported, several methods are introduced here that focus on software solutions that can be implemented in scanners already installed. Their advantages and disadvantages differ depending on the kinds of tasks involved, i.e. whether block design or event-related design, and they are discussed with a view to better utilization.
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Affiliation(s)
- Tomohisa Okada
- Institute for Biomedical Research and Innovation, 2-2 Minatojima Minamimachi, Chuo-ku, Kobe 650-0047, Japan
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128
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Seifritz E, Di Salle F, Esposito F, Bilecen D, Neuhoff JG, Scheffler K. Sustained blood oxygenation and volume response to repetition rate-modulated sound in human auditory cortex. Neuroimage 2003; 20:1365-70. [PMID: 14568505 DOI: 10.1016/s1053-8119(03)00421-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2003] [Revised: 07/01/2003] [Accepted: 07/11/2003] [Indexed: 11/21/2022] Open
Abstract
The blood oxygen level-dependent (BOLD) signal time course in the auditory cortex is characterized by two components, an initial transient peak and a subsequent sustained plateau with smaller amplitude. Because the T(2)(*) signal detected by functional magnetic resonance imaging (fMRI) depends on at least two counteracting factors, blood oxygenation and volume, we examined whether the reduction in the sustained BOLD signal results from decreased levels of oxygenation or from increased levels of blood volume. We used conventional fMRI to quantify the BOLD signal and fMRI in combination with superparamagnetic contrast agent to quantify blood volume and employed repetition rate-modulated sounds in a silent background to manipulate the response amplitude in the auditory cortex. In the BOLD signal, the initial peak reached 3.3% with pulsed sound and 1.9% with continuous sound, whereas the sustained BOLD signal fell to 2.2% with pulsed sound and to 0.5% with continuous sound, respectively. The repetition rate-dependent reduction in the sustained BOLD amplitude was accompanied by concordant changes in sustained blood volume levels, which, compared to silence, increased by approximately 30% with pulsed and by approximately 10% with continuous sound. Thus, our data suggest that the reduced amplitude of the sustained BOLD signal reflects stimulus-dependent modulation of blood oxygenation rather than blood volume-related effects.
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Affiliation(s)
- Erich Seifritz
- Department of Psychiatry, University of Basel, 4025, Basel, Switzerland.
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129
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d'Avossa G, Shulman GL, Corbetta M. Identification of cerebral networks by classification of the shape of BOLD responses. J Neurophysiol 2003; 90:360-71. [PMID: 12660356 DOI: 10.1152/jn.01040.2002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Changes in regional blood oxygen level dependent (BOLD) signals in response to brief visual stimuli can exhibit a variety of time-courses. To demonstrate the anatomical distribution of BOLD response shapes during a match to sample task, a formal analysis of their time-courses is presented. An event-related design was used to estimate regional BOLD responses evoked by a cue word, which instructed the subject to attend to the motion or color of an upcoming target, and those evoked by a briefly presented moving target consisting of colored dots. Regional BOLD time-courses were adequately represented by the linear combination of three orthogonal waveforms. BOLD response shapes were then classified using a fuzzy clustering scheme. Three classes (sustained, phasic, and negative) best characterized cue responses. Four classes (sustained, sustained-phasic, phasic, and bi-phasic) best characterized target responses. In certain regions, the shape of the BOLD responses was modulated by the instruction to attend to the target's motion or color. A left frontal and a posterior parietal region showed sustained activity when motion was cued and transient activity when color was cued. A right thalamic and a left lateral occipital region showed sustained activity when color was cued and transient activity when motion was cued. Following the target several regions showed more sustained activity during motion than color trials. In summary, the effect of the task variable was focal following the cue and widespread following the target. We conclude that the temporal patterns of neural activity affected the shape of the BOLD signal.
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Affiliation(s)
- Giovanni d'Avossa
- Department of Neurology and Neurological Surgery, Alzheimer's Disease Research Center, Washington University, St. Louis, Missouri 63110, USA.
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130
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Current awareness in NMR in biomedicine. NMR IN BIOMEDICINE 2003; 16:56-65. [PMID: 12619641 DOI: 10.1002/nbm.799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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131
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Hall DA, Gonçalves MS, Smith S, Jezzard P, Haggard MP, Kornak J. A method for determining venous contribution to BOLD contrast sensory activation. Magn Reson Imaging 2002; 20:695-706. [PMID: 12591565 DOI: 10.1016/s0730-725x(02)00607-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
While BOLD contrast reflects hemodynamic changes within capillaries serving neural tissue, it also has a venous component. Studies that have determined the relation of large blood vessels to the activation map indicate that veins are the source of the largest response, and the most delayed in time. It would be informative if the location of these large veins could be extracted from the properties of the functional responses, since vessels are not visible in BOLD contrast images. The present study describes a method for investigating whether measures taken from the functional response can reliably predict vein location, or at least be useful in down-weighting the venous contribution to the activation response, and illustrates this method using data from one subject. We combined fMRI at 3 Tesla with high-resolution anatomic imaging and MR venography to test whether the intrinsic properties of activation time courses corresponded to tissue type. Measures were taken from a gamma fit to the functional response. Mean magnitude showed a significant effect of tissue type (p < 0.001) where CSF > veins approximately gray matter > white matter. Mean delays displayed the same ranking across tissue types (p < 0.001), except that veins > gray matter. However, measures for all tissue types were distributed across an overlapping range. A logistic regression model correctly discriminated 72% of the veins from gray matter in the absence of independent information of macroscopic vessels (ROC = 0.72). While tissue classification was not perfect for this subject, weighting the T contrast by the predicted probabilities materially reduced the venous component to the activation map.
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Affiliation(s)
- Deborah A Hall
- MRC Institute of Hearing Research, University Park, Nottingham, UK NG7 2RD.
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