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Shigeru Kitazawa - One of the best experts on this subject based on the ideXlab platform.
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neural correlates of tactile Temporal Order judgment in humans an fmri study
Cerebral Cortex, 2013Co-Authors: Toshimitsu Takahashi, Makoto Wada, Kenji Kansaku, Satoshi Shibuya, Shigeru KitazawaAbstract:Little is known about the neuronal mechanisms underlying the Temporal Ordering of tactile signals. We examined the brain regions involved in judgments of the Temporal Order of successive taps delivered to both hands. Participants received identical stimuli while engaging in 2 different tasks: Judging the Temporal Order and judging the numerosity of points of tactile stimulation. Comparisons of the functional magnetic resonance imaging data obtained during the 2 tasks revealed regions that were more strongly activated with the judgments of the Temporal Order than with the judgments of numerosity under both arms-uncrossed and -crossed conditions: The bilateral premotor cortices, the bilateral middle frontal gyri, the bilateral inferior parietal cortices and supramarginal gyri, and the bilateral posterior part of the superior and middle Temporal gyri. Stronger activation was found in some of these areas that implicated for remapping tactile stimuli to spatial coordinates after the participants crossed their arms. The activation in the perisylvian areas overlapped with the human visual-motion-sensitive areas in the posterior part. Based on these results, we propose that the Temporal Order of tactile signals is determined by combining spatial representations of stimuli in the parietal and prefrontal cortices with representations of "motion" or "changes" in the multisensory perisylvian cortex.
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acquisition of multiple prior distributions in tactile Temporal Order judgment
Frontiers in Psychology, 2012Co-Authors: Yasuhito Nagai, Shigeru Kitazawa, Makoto Miyazaki, Mayu SuzukiAbstract:The Bayesian estimation theory proposes that the brain acquires the prior distribution of a task and integrates it with sensory signals to minimize the effect of sensory noise. Psychophysical studies have demonstrated that our brain actually implements Bayesian estimation in a variety of sensory-motor tasks. However, these studies only imposed one prior distribution on participants within a task period. In this study, we investigated the conditions that enable the acquisition of multiple prior distributions in Temporal Order judgment of two tactile stimuli across the hands. In Experiment 1, stimulation intervals were randomly selected from one of two prior distributions (biased to right hand earlier and biased to left hand earlier) in association with color cues (green and red, respectively). Although the acquisition of the two priors was not enabled by the color cues alone, it was significant when participants shifted their gaze (above or below) in response to the color cues. However, the acquisition of multiple priors was not significant when participants moved their mouths (opened or closed). In Experiment 2, the spatial cues (above and below) were used to identify which eye position or retinal cue position was crucial for the eye-movement-dependent acquisition of multiple priors in Experiment 1. The acquisition of the two priors was significant when participants moved their gaze to the cues (i.e., the cue positions on the retina were constant across the priors), as well as when participants did not shift their gazes (i.e., the cue positions on the retina changed according to the priors). Thus, both eye and retinal cue positions were effective in acquiring multiple priors. Based on previous neurophysiological reports, we discuss possible neural correlates that contribute to the acquisition of multiple priors.
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c fos expression during Temporal Order judgment in mice
PLOS ONE, 2010Co-Authors: Makoto Wada, Shigeru Kitazawa, Shunjiro Moizumi, Noriyuki HigoAbstract:The neuronal mechanisms for Ordering sensory signals in time still need to be clarified despite a long history of research. To address this issue, we recently developed a behavioral task of Temporal Order judgment in mice. In the present study, we examined the expression of c-Fos, a marker of neural activation, in mice just after they carried out the Temporal Order judgment task. The expression of c-Fos was examined in C57BL/6N mice (male, n = 5) that were trained to judge the Order of two air-puff stimuli delivered bilaterally to the right and left whiskers with stimulation intervals of 50–750 ms. The mice were rewarded with a food pellet when they responded by orienting their head toward the first stimulus (n = 2) or toward the second stimulus (n = 3) after a visual “go” signal. c-Fos-stained cell densities of these mice (test group) were compared with those of two control groups in coronal brain sections prepared at bregma −2, −1, 0, +1, and +2 mm by applying statistical parametric mapping to the c-Fos immuno-stained sections. The expression of c-Fos was significantly higher in the test group than in the other groups in the bilateral barrel fields of the primary somatosensory cortex, the left secondary somatosensory cortex, the dorsal part of the right secondary auditory cortex. Laminar analyses in the primary somatosensory cortex revealed that c-Fos expression in the test group was most evident in layers II and III, where callosal fibers project. The results suggest that Temporal Order judgment involves processing bilateral somatosensory signals through the supragranular layers of the primary sensory cortex and in the multimodal sensory areas, including marginal zone between the primary somatosensory cortex and the secondary sensory cortex.
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Temporal Order judgment in the brain
Brain and nerve, 2008Co-Authors: Shigeru KitazawaAbstract:It is generally accepted that the brain can resolve the Order of two stimuli that are separated in time by 20-50 ms, irrespective of their sensory modalities. This may support a traditional view that there is a single common decision mechanism of Temporal Order that compares arrival times of sensory signals of any modalities. However, the traditional view has been challenged recently in two ways. Firstly, it has been shown that human judgment of the Temporal Order is liable to change depending on our prior experiences, and in a modality specific manner. A constant tone-light pair presented repeatedly is judged as occurring simultaneously (lag adaptation), whereas opposite perceptual changes occur in judging the Order of tactile stimuli delivered one to each hand. The latter change conforms to a Bayesian integration theory. Secondly, subjective Temporal Order has been shown to be inverted in some special conditions. Crossing the arms caused inverting of the Temporal Order of two tactile stimuli that were separated in time by 100-200 ms. The Temporal Order of visual and tactile stimuli separated by 50 ms was inverted when they were delivered just prior to the onset of a saccade. These recent results suggest that the mechanism of Temporal Order judgment is not so simple as previously hypothesized but would involve multiple processes whose results are later integrated to reconstruct a subjective Order of events in time.
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bayesian calibration of simultaneity in tactile Temporal Order judgment
Nature Neuroscience, 2006Co-Authors: Makoto Miyazaki, Shigeru Kitazawa, Shinya Yamamoto, Sunao UchidaAbstract:Human judgment of the Temporal Order of two sensory signals is liable to change depending on our prior experiences. Previous studies have reported that signals presented at short intervals but in the same Order as the most frequently repeated signal are perceived as occurring simultaneously. Here we report opposite perceptual changes that conform to a Bayesian integration theory in judging the Order of two stimuli delivered one to each hand.
Harvey Babkoff - One of the best experts on this subject based on the ideXlab platform.
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The effect of stimulus frequency, spectrum, duration, and location on Temporal Order judgment thresholds: distribution analysis
Psychological Research, 2017Co-Authors: Leah Fostick, Adi Lifshitz-ben-basat, Harvey BabkoffAbstract:The present study aimed to examine whether the judgments of Temporal Order are made by the same “central processor” regardless of the characteristics of the sound stimuli. The influence of stimulus parameters (e.g., frequency, spectrum, duration, location) on auditory Temporal Order judgment (TOJ) thresholds was tested in seven groups with a total of 192 participants received two-tone sequences of different: frequencies (3 groups); spectrum widths, via a pure tone and a Gaussian noise burst (1 group); durations (2 groups); or locations, via asynchronous presentation to each ear (1 group). No difference in the mean rankings of TOJ thresholds was found for frequency, spectrum, and location parameters. TOJ thresholds for the duration condition, however, were significantly longer than for any of the other conditions. Notably, the threshold distributions for all the parameters (frequency, spectrum, duration, location) differed in shape. These findings raise the question as to whether we can rely upon the mean or median threshold as truly representative of TOJ threshold data. Furthermore, the data suggest that Temporal Order judgments for the different stimulus parameters are processed differently. The differences observed when analyzing the data with central tendency measures, as compared to analyzing the threshold distributions, may explain some of the mixed results reported in the literature on the mechanisms involved in Temporal processing of different parameters. Stimulus parameters influence TOJ threshold distributions and response patterns, and may provide additional cues, beyond the standard Temporal cue inherent in the TOJ procedure, by which participants may judge the Order of the stimuli.
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auditory spectral versus spatial Temporal Order judgment threshold distribution analysis
Journal of Experimental Psychology: Human Perception and Performance, 2017Co-Authors: Leah Fostick, Harvey BabkoffAbstract:Some researchers suggested that one central mechanism is responsible for Temporal Order judgments (TOJ), within and across sensory channels. This suggestion is supported by findings of similar TOJ thresholds in same modality and cross-modality TOJ tasks. In the present study, we challenge this idea by analyzing and comparing the threshold distributions of the spectral and spatial TOJ tasks. In spectral TOJ, the tones differ in their frequency ("high" and "low") and are delivered either binaurally or monaurally. In spatial (or dichotic) TOJ, the two tones are identical but are presented asynchronously to the two ears and thus differ with respect to which ear received the first tone and which ear received the second tone ("left"/"left"). Although both tasks are regarded as measures of auditory Temporal processing, a review of data published in the literature suggests that they trigger different patterns of response. The aim of the current study was to systematically examine spectral and spatial TOJ threshold distributions across a large number of studies. Data are based on 388 participants in 13 spectral TOJ experiments, and 222 participants in 9 spatial TOJ experiments. None of the spatial TOJ distributions deviated significantly from the Gaussian; while all of the spectral TOJ threshold distributions were skewed to the right, with more than half of the participants accurately judging Temporal Order at very short interstimulus intervals (ISI). The data do not support the hypothesis that 1 central mechanism is responsible for all Temporal Order judgments. We suggest that different perceptual strategies are employed when performing spectral TOJ than when performing spatial TOJ. We posit that the spectral TOJ paradigm may provide the opportunity for two-tone masking or Temporal integration, which is sensitive to the Order of the tones and thus provides perceptual cues that may be used to judge Temporal Order. This possibility should be considered when interpreting spectral TOJ data, especially in the context of comparing different populations. (PsycINFO Database Record
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the role of tone duration in dichotic Temporal Order judgment
Attention Perception & Psychophysics, 2013Co-Authors: Harvey Babkoff, Leah FostickAbstract:Over the past two decades, a number of studies have been based on the dichotic Temporal Order judgment (TOJ) paradigm, to compare auditory Temporal processing in various subpopulations to that of young, normal controls. The reported estimates of dichotic TOJ thresholds, expressed as the interstimulus intervals (ISIs) for 75 % accuracy among the controls, have varied. In the present study, we examined the influence of tone duration, within the 10- to 40-msec range, on dichotic TOJ accuracy and threshold. The results indicated that increases in either ISI or tone duration increased dichotic TOJ accuracy similarly, implying that changes in tone duration may affect dichotic TOJs simply by adding to the delay between onset of the tone at the lead ear and onset of the tone at the lag ear. The dichotic TOJ thresholds from three published studies that had used tones as stimuli and the dichotic thresholds from the present study all fell within 0.5 standard deviations from the theoretical line of a 10-msec reduction in threshold for every 10-msec increase in tone duration. When the dichotic TOJ threshold data from the present study and from the published studies were converted to stimulus onset asynchronies (SOAs) and plotted as a function of tone duration, they fell very close to or on a zero-slope line, indicating that when ISI and duration are summed to yield an SOA, dichotic TOJ thresholds are invariant to tone duration within the range of 10–40 msec.
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different response patterns between auditory spectral and spatial Temporal Order judgment toj
Experimental Psychology, 2013Co-Authors: Leah Fostick, Harvey BabkoffAbstract:Temporal Order judgment (TOJ) thresholds have been widely reported as valid estimates of the Temporal disparity necessary for correctly identifying the Order of two stimuli. Data for two auditory TOJ paradigms are often reported in the literature: (1) spatially-based TOJ in which the Order of presentation of the same stimulus to the right and left ear differs; and (2) spectrally-based TOJ in which the Order of two stimuli differing in frequency is presented to one ear or to both ears simultaneously. Since the thresholds reported using the two paradigms differ, the aim of the current study was to compare their response patterns. The results from three different experiments showed that: (1) while almost none of the participants were able to perform the spatial TOJ task when ISI = 5 ms, with the spectral task, 50% reached an accuracy level of 75% when ISI = 5 ms; (2) Temporal separation was only a partial predictor for performance in the spectral task, while it fully predicted performance in the spatial task; and (3) training improved performance markedly in the spectral TOJ task, but had no effect on spatial TOJ. These results suggest that the two paradigms may reflect different perceptual mechanisms.
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reaction time rt as a dependent variable for spatial Temporal Order judgment toj
Proceedings of Fechner Day, 2011Co-Authors: Leah Fostick, Harvey BabkoffAbstract:We have reported previously that the speed of response (1/RT) of spatial Temporal Order judgments (TOJ) increases in parallel with the increases in accuracy as a function of increasing inter-stimulus interval (ISI). In the current study we expand the study of parallel changes in RT with accuracy to include the effect of stimulus frequency and stimulus onset asynchrony (SOA). The RT-accuracy parallelism is also found when comparing spatial TOJ to spectral TOJ, when measured either by constant stimuli or by an adaptive staircase procedure. The parallelism between RT and accuracy becomes even more interesting when we compared a population of adult dyslexic readers, showing ISI*group interaction (i.e., the difference between groups only becomes apparent as ISI = 30 msec or longer) when measured by accuracy, but shows parallel performance when measured by RT, with dyslexic readers yielding longer RTs across all ISIs.
Leah Fostick - One of the best experts on this subject based on the ideXlab platform.
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The effect of stimulus frequency, spectrum, duration, and location on Temporal Order judgment thresholds: distribution analysis
Psychological Research, 2017Co-Authors: Leah Fostick, Adi Lifshitz-ben-basat, Harvey BabkoffAbstract:The present study aimed to examine whether the judgments of Temporal Order are made by the same “central processor” regardless of the characteristics of the sound stimuli. The influence of stimulus parameters (e.g., frequency, spectrum, duration, location) on auditory Temporal Order judgment (TOJ) thresholds was tested in seven groups with a total of 192 participants received two-tone sequences of different: frequencies (3 groups); spectrum widths, via a pure tone and a Gaussian noise burst (1 group); durations (2 groups); or locations, via asynchronous presentation to each ear (1 group). No difference in the mean rankings of TOJ thresholds was found for frequency, spectrum, and location parameters. TOJ thresholds for the duration condition, however, were significantly longer than for any of the other conditions. Notably, the threshold distributions for all the parameters (frequency, spectrum, duration, location) differed in shape. These findings raise the question as to whether we can rely upon the mean or median threshold as truly representative of TOJ threshold data. Furthermore, the data suggest that Temporal Order judgments for the different stimulus parameters are processed differently. The differences observed when analyzing the data with central tendency measures, as compared to analyzing the threshold distributions, may explain some of the mixed results reported in the literature on the mechanisms involved in Temporal processing of different parameters. Stimulus parameters influence TOJ threshold distributions and response patterns, and may provide additional cues, beyond the standard Temporal cue inherent in the TOJ procedure, by which participants may judge the Order of the stimuli.
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auditory spectral versus spatial Temporal Order judgment threshold distribution analysis
Journal of Experimental Psychology: Human Perception and Performance, 2017Co-Authors: Leah Fostick, Harvey BabkoffAbstract:Some researchers suggested that one central mechanism is responsible for Temporal Order judgments (TOJ), within and across sensory channels. This suggestion is supported by findings of similar TOJ thresholds in same modality and cross-modality TOJ tasks. In the present study, we challenge this idea by analyzing and comparing the threshold distributions of the spectral and spatial TOJ tasks. In spectral TOJ, the tones differ in their frequency ("high" and "low") and are delivered either binaurally or monaurally. In spatial (or dichotic) TOJ, the two tones are identical but are presented asynchronously to the two ears and thus differ with respect to which ear received the first tone and which ear received the second tone ("left"/"left"). Although both tasks are regarded as measures of auditory Temporal processing, a review of data published in the literature suggests that they trigger different patterns of response. The aim of the current study was to systematically examine spectral and spatial TOJ threshold distributions across a large number of studies. Data are based on 388 participants in 13 spectral TOJ experiments, and 222 participants in 9 spatial TOJ experiments. None of the spatial TOJ distributions deviated significantly from the Gaussian; while all of the spectral TOJ threshold distributions were skewed to the right, with more than half of the participants accurately judging Temporal Order at very short interstimulus intervals (ISI). The data do not support the hypothesis that 1 central mechanism is responsible for all Temporal Order judgments. We suggest that different perceptual strategies are employed when performing spectral TOJ than when performing spatial TOJ. We posit that the spectral TOJ paradigm may provide the opportunity for two-tone masking or Temporal integration, which is sensitive to the Order of the tones and thus provides perceptual cues that may be used to judge Temporal Order. This possibility should be considered when interpreting spectral TOJ data, especially in the context of comparing different populations. (PsycINFO Database Record
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the role of tone duration in dichotic Temporal Order judgment
Attention Perception & Psychophysics, 2013Co-Authors: Harvey Babkoff, Leah FostickAbstract:Over the past two decades, a number of studies have been based on the dichotic Temporal Order judgment (TOJ) paradigm, to compare auditory Temporal processing in various subpopulations to that of young, normal controls. The reported estimates of dichotic TOJ thresholds, expressed as the interstimulus intervals (ISIs) for 75 % accuracy among the controls, have varied. In the present study, we examined the influence of tone duration, within the 10- to 40-msec range, on dichotic TOJ accuracy and threshold. The results indicated that increases in either ISI or tone duration increased dichotic TOJ accuracy similarly, implying that changes in tone duration may affect dichotic TOJs simply by adding to the delay between onset of the tone at the lead ear and onset of the tone at the lag ear. The dichotic TOJ thresholds from three published studies that had used tones as stimuli and the dichotic thresholds from the present study all fell within 0.5 standard deviations from the theoretical line of a 10-msec reduction in threshold for every 10-msec increase in tone duration. When the dichotic TOJ threshold data from the present study and from the published studies were converted to stimulus onset asynchronies (SOAs) and plotted as a function of tone duration, they fell very close to or on a zero-slope line, indicating that when ISI and duration are summed to yield an SOA, dichotic TOJ thresholds are invariant to tone duration within the range of 10–40 msec.
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different response patterns between auditory spectral and spatial Temporal Order judgment toj
Experimental Psychology, 2013Co-Authors: Leah Fostick, Harvey BabkoffAbstract:Temporal Order judgment (TOJ) thresholds have been widely reported as valid estimates of the Temporal disparity necessary for correctly identifying the Order of two stimuli. Data for two auditory TOJ paradigms are often reported in the literature: (1) spatially-based TOJ in which the Order of presentation of the same stimulus to the right and left ear differs; and (2) spectrally-based TOJ in which the Order of two stimuli differing in frequency is presented to one ear or to both ears simultaneously. Since the thresholds reported using the two paradigms differ, the aim of the current study was to compare their response patterns. The results from three different experiments showed that: (1) while almost none of the participants were able to perform the spatial TOJ task when ISI = 5 ms, with the spectral task, 50% reached an accuracy level of 75% when ISI = 5 ms; (2) Temporal separation was only a partial predictor for performance in the spectral task, while it fully predicted performance in the spatial task; and (3) training improved performance markedly in the spectral TOJ task, but had no effect on spatial TOJ. These results suggest that the two paradigms may reflect different perceptual mechanisms.
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reaction time rt as a dependent variable for spatial Temporal Order judgment toj
Proceedings of Fechner Day, 2011Co-Authors: Leah Fostick, Harvey BabkoffAbstract:We have reported previously that the speed of response (1/RT) of spatial Temporal Order judgments (TOJ) increases in parallel with the increases in accuracy as a function of increasing inter-stimulus interval (ISI). In the current study we expand the study of parallel changes in RT with accuracy to include the effect of stimulus frequency and stimulus onset asynchrony (SOA). The RT-accuracy parallelism is also found when comparing spatial TOJ to spectral TOJ, when measured either by constant stimuli or by an adaptive staircase procedure. The parallelism between RT and accuracy becomes even more interesting when we compared a population of adult dyslexic readers, showing ISI*group interaction (i.e., the difference between groups only becomes apparent as ISI = 30 msec or longer) when measured by accuracy, but shows parallel performance when measured by RT, with dyslexic readers yielding longer RTs across all ISIs.
Lucas Spierer - One of the best experts on this subject based on the ideXlab platform.
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pre stimulus beta oscillations within left posterior sylvian regions impact auditory Temporal Order judgment accuracy
International Journal of Psychophysiology, 2011Co-Authors: Fosco Bernasconi, Micah M Murray, Aurelie L Manuel, Lucas SpiererAbstract:Both neural and behavioral responses to stimuli are influenced by the state of the brain immediately preceding their presentation, notably by pre-stimulus oscillatory activity. Using frequency analysis of high-density electroencephalogram coupled with source estimations, the present study investigated the role of pre-stimulus oscillatory activity in auditory spatial Temporal Order judgments (TOJ). Oscillations within the beta range (i.e. 18-23 Hz) were significantly stronger before accurate than inaccurate TOJ trials. Distributed source estimations identified bilateral posterior sylvian regions as the principal contributors to pre-stimulus beta oscillations. Activity within the left posterior sylvian region was significantly stronger before accurate than inaccurate TOJ trials. We discuss our results in terms of a modulation of sensory gating mechanisms mediated by beta activity.
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interhemispheric coupling between the posterior sylvian regions impacts successful auditory Temporal Order judgment
Neuropsychologia, 2010Co-Authors: Fosco Bernasconi, Jeremy Grivel, Micah M Murray, Lucas SpiererAbstract:Abstract Accurate perception of the Temporal Order of sensory events is a prerequisite in numerous functions ranging from language comprehension to motor coordination. We investigated the spatio-Temporal brain dynamics of auditory Temporal Order judgment (aTOJ) using electrical neuroimaging analyses of auditory evoked potentials (AEPs) recorded while participants completed a near-threshold task requiring spatial discrimination of left–right and right–left sound sequences. AEPs to sound pairs modulated topographically as a function of aTOJ accuracy over the 39–77 ms post-stimulus period, indicating the engagement of distinct configurations of brain networks during early auditory processing stages. Source estimations revealed that accurate and inaccurate performance were linked to bilateral posterior sylvian regions activity (PSR). However, activity within left, but not right, PSR predicted behavioral performance suggesting that left PSR activity during early encoding phases of pairs of auditory spatial stimuli appears critical for the perception of their Order of occurrence. Correlation analyses of source estimations further revealed that activity between left and right PSR was significantly correlated in the inaccurate but not accurate condition, indicating that aTOJ accuracy depends on the functional decoupling between homotopic PSR areas. These results support a model of Temporal Order processing wherein behaviorally relevant Temporal information – i.e. a Temporal ‘stamp’ – is extracted within the early stages of cortical processes within left PSR but critically modulated by inputs from right PSR. We discuss our results with regard to current models of Temporal of Temporal Order processing, namely gating and latency mechanisms.
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plastic brain mechanisms for attaining auditory Temporal Order judgment proficiency
NeuroImage, 2010Co-Authors: Fosco Bernasconi, Jeremy Grivel, Micah M Murray, Lucas SpiererAbstract:Abstract Accurate perception of the Order of occurrence of sensory information is critical for the building up of coherent representations of the external world from ongoing flows of sensory inputs. While some psychophysical evidence reports that performance on Temporal perception can improve, the underlying neural mechanisms remain unresolved. Using electrical neuroimaging analyses of auditory evoked potentials (AEPs), we identified the brain dynamics and mechanism supporting improvements in auditory Temporal Order judgment (TOJ) during the course of the first vs. latter half of the experiment. Training-induced changes in brain activity were first evident 43–76 ms post stimulus onset and followed from topographic, rather than pure strength, AEP modulations. Improvements in auditory TOJ accuracy thus followed from changes in the configuration of the underlying brain networks during the initial stages of sensory processing. Source estimations revealed an increase in the lateralization of initially bilateral posterior sylvian region (PSR) responses at the beginning of the experiment to left-hemisphere dominance at its end. Further supporting the critical role of left and right PSR in auditory TOJ proficiency, as the experiment progressed, responses in the left and right PSR went from being correlated to un-correlated. These collective findings provide insights on the neurophysiologic mechanism and plasticity of Temporal processing of sounds and are consistent with models based on spike timing dependent plasticity.
Fosco Bernasconi - One of the best experts on this subject based on the ideXlab platform.
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pre stimulus beta oscillations within left posterior sylvian regions impact auditory Temporal Order judgment accuracy
International Journal of Psychophysiology, 2011Co-Authors: Fosco Bernasconi, Micah M Murray, Aurelie L Manuel, Lucas SpiererAbstract:Both neural and behavioral responses to stimuli are influenced by the state of the brain immediately preceding their presentation, notably by pre-stimulus oscillatory activity. Using frequency analysis of high-density electroencephalogram coupled with source estimations, the present study investigated the role of pre-stimulus oscillatory activity in auditory spatial Temporal Order judgments (TOJ). Oscillations within the beta range (i.e. 18-23 Hz) were significantly stronger before accurate than inaccurate TOJ trials. Distributed source estimations identified bilateral posterior sylvian regions as the principal contributors to pre-stimulus beta oscillations. Activity within the left posterior sylvian region was significantly stronger before accurate than inaccurate TOJ trials. We discuss our results in terms of a modulation of sensory gating mechanisms mediated by beta activity.
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interhemispheric coupling between the posterior sylvian regions impacts successful auditory Temporal Order judgment
Neuropsychologia, 2010Co-Authors: Fosco Bernasconi, Jeremy Grivel, Micah M Murray, Lucas SpiererAbstract:Abstract Accurate perception of the Temporal Order of sensory events is a prerequisite in numerous functions ranging from language comprehension to motor coordination. We investigated the spatio-Temporal brain dynamics of auditory Temporal Order judgment (aTOJ) using electrical neuroimaging analyses of auditory evoked potentials (AEPs) recorded while participants completed a near-threshold task requiring spatial discrimination of left–right and right–left sound sequences. AEPs to sound pairs modulated topographically as a function of aTOJ accuracy over the 39–77 ms post-stimulus period, indicating the engagement of distinct configurations of brain networks during early auditory processing stages. Source estimations revealed that accurate and inaccurate performance were linked to bilateral posterior sylvian regions activity (PSR). However, activity within left, but not right, PSR predicted behavioral performance suggesting that left PSR activity during early encoding phases of pairs of auditory spatial stimuli appears critical for the perception of their Order of occurrence. Correlation analyses of source estimations further revealed that activity between left and right PSR was significantly correlated in the inaccurate but not accurate condition, indicating that aTOJ accuracy depends on the functional decoupling between homotopic PSR areas. These results support a model of Temporal Order processing wherein behaviorally relevant Temporal information – i.e. a Temporal ‘stamp’ – is extracted within the early stages of cortical processes within left PSR but critically modulated by inputs from right PSR. We discuss our results with regard to current models of Temporal of Temporal Order processing, namely gating and latency mechanisms.
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plastic brain mechanisms for attaining auditory Temporal Order judgment proficiency
NeuroImage, 2010Co-Authors: Fosco Bernasconi, Jeremy Grivel, Micah M Murray, Lucas SpiererAbstract:Abstract Accurate perception of the Order of occurrence of sensory information is critical for the building up of coherent representations of the external world from ongoing flows of sensory inputs. While some psychophysical evidence reports that performance on Temporal perception can improve, the underlying neural mechanisms remain unresolved. Using electrical neuroimaging analyses of auditory evoked potentials (AEPs), we identified the brain dynamics and mechanism supporting improvements in auditory Temporal Order judgment (TOJ) during the course of the first vs. latter half of the experiment. Training-induced changes in brain activity were first evident 43–76 ms post stimulus onset and followed from topographic, rather than pure strength, AEP modulations. Improvements in auditory TOJ accuracy thus followed from changes in the configuration of the underlying brain networks during the initial stages of sensory processing. Source estimations revealed an increase in the lateralization of initially bilateral posterior sylvian region (PSR) responses at the beginning of the experiment to left-hemisphere dominance at its end. Further supporting the critical role of left and right PSR in auditory TOJ proficiency, as the experiment progressed, responses in the left and right PSR went from being correlated to un-correlated. These collective findings provide insights on the neurophysiologic mechanism and plasticity of Temporal processing of sounds and are consistent with models based on spike timing dependent plasticity.
