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视觉刺激可提升灵长类动物大脑听觉皮层响应

来源:科学网 2007-02-28 10:07

   

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    经典的神经科学理论认为,各种感官信息是分别在特定区域被处理后才进行整合。但是,德国马普学会生物控制论研究所进行的一项最新研究表明,这些信号的整合可能更早,只有这样,表情和话语、声音和触觉、嗅觉和味觉才能相匹配。  

    由Christoph  Kayser带领的研究小组通过研究短尾猿大脑听觉皮层11个处理不同频率声音的区域,绘制了视觉刺激响应图谱,这为深入了解灵长类动物如何整合感官信息提供了依据,并有望推翻传统的理论。在近期的《神经科学杂志》(Journal  of  Neuroscience)上,研究人员表示,他们发现短尾猿在观看录像的时候,即便声频被关掉,负责处理听力的大脑区域的后部袋状结构也会变得活跃起来。Kayser认为,这种反应是短尾猿集中注意力并有意识地处理刺激的一种表现,可能是用于确定声源的内在机制的一部分。  

    这一结果也支持了此前的一些研究,即人类大脑听觉皮层的后部参与了对文字语言的理解,但以前科学家们一直无法通过功能核磁共振成像(fMRI)来确定这一关系。  

    Kayser和他的同事目前正在试图建立一个更好的人类大脑听觉皮层映射机制。华盛顿乔治敦大学医学中心生理学家和生物物理学家Josef  Rauschecker表示,已经有多项研究表明人类大脑组织与低等灵长类动物类似,尤其在视觉系统方面。  

    对人类听觉皮层处理多种感官信息方式的深入研究有助于科学家认识阅读障碍(Dyslexia)等听觉问题,并进一步采取措施治疗。

英文原文摘要:

Functional Imaging Reveals Visual Modulation of Specific Fields in Auditory Cortex

Christoph Kayser, Christopher I. Petkov, Mark Augath, and Nikos K. Logothetis

Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany

Correspondence should be addressed to Christoph Kayser, Max Planck Institute for Biological Cybernetics, Spemannstrasse 38, 72076 Tübingen, Germany. Email: christoph.kayser@tuebingen.mpg.de

Merging the information from different senses is essential for successful interaction with real-life situations. Indeed, sensory integration can reduce perceptual ambiguity, speed reactions, or change the qualitative sensory experience. It is widely held that integration occurs at later processing stages and mostly in higher association cortices; however, recent studies suggest that sensory convergence can occur in primary sensory cortex. A good model for early convergence proved to be the auditory cortex, which can be modulated by visual and tactile stimulation; however, given the large number and small size of auditory fields, neither human imaging nor microelectrode recordings have systematically identified which fields are susceptible to multisensory influences. To reconcile findings from human imaging with anatomical knowledge from nonhuman primates, we exploited high-resolution imaging (functional magnetic resonance imaging) of the macaque monkey to study the modulation of auditory processing by visual stimulation. Using a functional parcellation of auditory cortex, we localized modulations to individual fields. Our results demonstrate that both primary (core) and nonprimary (belt) auditory fields can be activated by the mere presentation of visual scenes. Audiovisual convergence was restricted to caudal fields [prominently the core field (primary auditory cortex) and belt fields (caudomedial field, caudolateral field, and mediomedial field)] and continued in the auditory parabelt and the superior temporal sulcus. The same fields exhibited enhancement of auditory activation by visual stimulation and showed stronger enhancement for less effective stimuli, two characteristics of sensory integration. Together, these findings reveal multisensory modulation of auditory processing prominently in caudal fields but also at the lowest stages of auditory cortical processing.

Key words: fMRI; macaque monkey; multisensory integration; cross-modal; perception; auditory cortex

更多原文链接:

http://www.jneurosci.org/cgi/content/abstract/27/8/1824

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