The Experts below are selected from a list of 36516 Experts worldwide ranked by ideXlab platform

Stefan Debener - One of the best experts on this subject based on the ideXlab platform.

  • visual activation of Auditory Cortex reflects maladaptive plasticity in cochlear implant users
    Brain, 2012
    Co-Authors: Pascale Sandmann, Valentine Leslie Marcar, Roberto D Pascualmarqui, Tom Eichele, Norbert Dillier, Martin Meyer, Andrea Kegel, Lutz Jancke, Stefan Debener
    Abstract:

    Cross-modal reorganization in the Auditory Cortex has been reported in deaf individuals. However, it is not well understood whether this compensatory reorganization induced by Auditory deprivation recedes once the sensation of hearing is partially restored through a cochlear implant. The current study used electroencephalography source localization to examine cross-modal reorganization in the Auditory Cortex of post-lingually deafened cochlear implant users. We analysed visual-evoked potentials to parametrically modulated reversing chequerboard images between cochlear implant users ( n  = 11) and normal-hearing listeners ( n  = 11). The results revealed smaller P100 amplitudes and reduced visual Cortex activation in cochlear implant users compared with normal-hearing listeners. At the P100 latency, cochlear implant users also showed activation in the right Auditory Cortex, which was inversely related to speech recognition ability with the cochlear implant. These results confirm a visual take-over in the Auditory Cortex of cochlear implant users. Incomplete reversal of this deafness-induced cortical reorganization might limit clinical benefit from a cochlear implant and help explain the high inter-subject variability in Auditory speech comprehension. * Abbreviation : sLORETA : standardized low-resolution brain electromagnetic tomography VEP : visual-evoked potential

Tom Eichele - One of the best experts on this subject based on the ideXlab platform.

  • visual activation of Auditory Cortex reflects maladaptive plasticity in cochlear implant users
    Brain, 2012
    Co-Authors: Pascale Sandmann, Valentine Leslie Marcar, Roberto D Pascualmarqui, Tom Eichele, Norbert Dillier, Martin Meyer, Andrea Kegel, Lutz Jancke, Stefan Debener
    Abstract:

    Cross-modal reorganization in the Auditory Cortex has been reported in deaf individuals. However, it is not well understood whether this compensatory reorganization induced by Auditory deprivation recedes once the sensation of hearing is partially restored through a cochlear implant. The current study used electroencephalography source localization to examine cross-modal reorganization in the Auditory Cortex of post-lingually deafened cochlear implant users. We analysed visual-evoked potentials to parametrically modulated reversing chequerboard images between cochlear implant users ( n  = 11) and normal-hearing listeners ( n  = 11). The results revealed smaller P100 amplitudes and reduced visual Cortex activation in cochlear implant users compared with normal-hearing listeners. At the P100 latency, cochlear implant users also showed activation in the right Auditory Cortex, which was inversely related to speech recognition ability with the cochlear implant. These results confirm a visual take-over in the Auditory Cortex of cochlear implant users. Incomplete reversal of this deafness-induced cortical reorganization might limit clinical benefit from a cochlear implant and help explain the high inter-subject variability in Auditory speech comprehension. * Abbreviation : sLORETA : standardized low-resolution brain electromagnetic tomography VEP : visual-evoked potential

Stephen G. Lomber - One of the best experts on this subject based on the ideXlab platform.

  • High-field fMRI reveals tonotopically-organized and core Auditory Cortex in the cat.
    Hearing research, 2015
    Co-Authors: Amee J. Hall, Stephen G. Lomber
    Abstract:

    As frequency is one of the most basic elements of sound, it is not surprising that the earliest stages of Auditory cortical processing are tonotopically organized. In cats, there are four known tonotopically organized cortical areas: the anterior (AAF), posterior (PAF), and ventral posterior (VPAF) Auditory fields and primary Auditory Cortex (A1). Electrophysiological and anatomical evidence have suggested that AAF and A1 form core Auditory Cortex. The purpose of this investigation was to determine if high-field functional magnetic resonance imaging (fMRI) could be used to define the borders of all four tonotopically organized areas, identify core Auditory Cortex, and demonstrate tonotopy similar to that found using more invasive techniques. Five adult cats were examined. Eight different pure tones or one broad-band noise (BBN) stimuli were presented in a block paradigm during continuous fMRI scanning. Analysis was performed on each animal individually using conservative familywise error thresholds. Group analysis was performed by extracting data from fMRI analysis software and performing a battery of statistical tests. In Auditory Cortex, a reversal of the tonotopic gradient is known to occur at the borders between tonotopically organized areas. Therefore, high and low tones were used to delineate these borders. Activations in response to BBN as opposed to tonal stimulation demonstrated that core Auditory Cortex consists of both A1 and AAF. Finally, tonotopy was identified in each of the four known tonotopically organized areas. Therefore, we conclude that fMRI is effective at defining all four tonotopically organized cortical areas and delineating core Auditory Cortex.

  • double dissociation of what and where processing in Auditory Cortex
    Nature Neuroscience, 2008
    Co-Authors: Stephen G. Lomber, Shveta Malhotra
    Abstract:

    Studies of cortical connections or neuronal function in different cerebral areas support the hypothesis that parallel cortical processing streams, similar to those identified in visual Cortex, may exist in the Auditory system. However, this model has not yet been behaviorally tested. We used reversible cooling deactivation to investigate whether the individual regions in cat nonprimary Auditory Cortex that are responsible for processing the pattern of an acoustic stimulus or localizing a sound in space could be doubly dissociated in the same animal. We found that bilateral deactivation of the posterior Auditory field resulted in deficits in a sound-localization task, whereas bilateral deactivation of the anterior Auditory field resulted in deficits in a pattern-discrimination task, but not vice versa. These findings support a model of cortical organization that proposes that identifying an acoustic stimulus ('what') and its spatial location ('where') are processed in separate streams in Auditory Cortex.

  • sound localization deficits during reversible deactivation of primary Auditory Cortex and or the dorsal zone
    Journal of Neurophysiology, 2008
    Co-Authors: Shveta Malhotra, Stephen G. Lomber, Christopher G Stecker, John C Middlebrooks
    Abstract:

    We examined the contributions of primary Auditory Cortex (A1) and the dorsal zone of Auditory Cortex (DZ) to sound localization behavior during separate and combined unilateral and bilateral deacti...

Nikos K. Logothetis - One of the best experts on this subject based on the ideXlab platform.

  • multisensory integration of dynamic faces and voices in rhesus monkey Auditory Cortex
    The Journal of Neuroscience, 2005
    Co-Authors: Asif A Ghazanfar, Joost X Maier, Kari L Hoffman, Nikos K. Logothetis
    Abstract:

    In the social world, multiple sensory channels are used concurrently to facilitate communication. Among human and nonhuman primates, faces and voices are the primary means of transmitting social signals ([Adolphs, 2003][1]; [Ghazanfar and Santos, 2004][2]). Primates recognize the correspondence between species-specific facial and vocal expressions ([Massaro, 1998][3]; [Ghazanfar and Logothetis, 2003][4]; [Izumi and Kojima, 2004][5]), and these visual and Auditory channels can be integrated into unified percepts to enhance detection and discrimination. Where and how such communication signals are integrated at the neural level are poorly understood. In particular, it is unclear what role “unimodal” sensory areas, such as the Auditory Cortex, may play. We recorded local field potential activity, the signal that best correlates with human imaging and event-related potential signals, in both the core and lateral belt regions of the Auditory Cortex in awake behaving rhesus monkeys while they viewed vocalizing conspecifics. We demonstrate unequivocally that the primate Auditory Cortex integrates facial and vocal signals through enhancement and suppression of field potentials in both the core and lateral belt regions. The majority of these multisensory responses were specific to face/voice integration, and the lateral belt region shows a greater frequency of multisensory integration than the core region. These multisensory processes in the Auditory Cortex likely occur via reciprocal interactions with the superior temporal sulcus. [1]: #ref-2 [2]: #ref-20 [3]: #ref-31 [4]: #ref-19 [5]: #ref-26

  • multisensory integration of dynamic faces and voices in rhesus monkey Auditory Cortex
    The Journal of Neuroscience, 2005
    Co-Authors: Asif A Ghazanfar, Joost X Maier, Kari L Hoffman, Nikos K. Logothetis
    Abstract:

    In the social world, multiple sensory channels are used concurrently to facilitate communication. Among human and nonhuman primates, faces and voices are the primary means of transmitting social signals (Adolphs, 2003; Ghazanfar and Santos, 2004). Primates recognize the correspondence between species-specific facial and vocal expressions (Massaro, 1998; Ghazanfar and Logothetis, 2003; Izumi and Kojima, 2004), and these visual and Auditory channels can be integrated into unified percepts to enhance detection and discrimination. Where and how such communication signals are integrated at the neural level are poorly understood. In particular, it is unclear what role "unimodal" sensory areas, such as the Auditory Cortex, may play. We recorded local field potential activity, the signal that best correlates with human imaging and event-related potential signals, in both the core and lateral belt regions of the Auditory Cortex in awake behaving rhesus monkeys while they viewed vocalizing conspecifics. We demonstrate unequivocally that the primate Auditory Cortex integrates facial and vocal signals through enhancement and suppression of field potentials in both the core and lateral belt regions. The majority of these multisensory responses were specific to face/voice integration, and the lateral belt region shows a greater frequency of multisensory integration than the core region. These multisensory processes in the Auditory Cortex likely occur via reciprocal interactions with the superior temporal sulcus.

Pascale Sandmann - One of the best experts on this subject based on the ideXlab platform.

  • visual activation of Auditory Cortex reflects maladaptive plasticity in cochlear implant users
    Brain, 2012
    Co-Authors: Pascale Sandmann, Valentine Leslie Marcar, Roberto D Pascualmarqui, Tom Eichele, Norbert Dillier, Martin Meyer, Andrea Kegel, Lutz Jancke, Stefan Debener
    Abstract:

    Cross-modal reorganization in the Auditory Cortex has been reported in deaf individuals. However, it is not well understood whether this compensatory reorganization induced by Auditory deprivation recedes once the sensation of hearing is partially restored through a cochlear implant. The current study used electroencephalography source localization to examine cross-modal reorganization in the Auditory Cortex of post-lingually deafened cochlear implant users. We analysed visual-evoked potentials to parametrically modulated reversing chequerboard images between cochlear implant users ( n  = 11) and normal-hearing listeners ( n  = 11). The results revealed smaller P100 amplitudes and reduced visual Cortex activation in cochlear implant users compared with normal-hearing listeners. At the P100 latency, cochlear implant users also showed activation in the right Auditory Cortex, which was inversely related to speech recognition ability with the cochlear implant. These results confirm a visual take-over in the Auditory Cortex of cochlear implant users. Incomplete reversal of this deafness-induced cortical reorganization might limit clinical benefit from a cochlear implant and help explain the high inter-subject variability in Auditory speech comprehension. * Abbreviation : sLORETA : standardized low-resolution brain electromagnetic tomography VEP : visual-evoked potential