美国科学家近日研究发现，大脑处理声音信号的区域同时也能处理视觉信号，并且这两种信号的同时处理时间要比之前认为的早得多。这一发现有助于科学家深入理解大脑接收和汇总大量外部刺激的工作方式。相关论文近期在线发表于美国《国家科学院院刊》（PNAS）上。
之前脑科学家一般认为，人体的5种感觉（视觉、听觉、嗅觉、触觉和味觉）由各自单独的、位于大脑中的通讯区域所支配。这些区域分别处理这些信号，并将处理后的信号传输给大脑皮层进行汇总。
在最新的研究中，美国杜克大学的神经生物学家Jennifer Groh和同事以猴子为实验对象，重点研究了下丘（inferior colliculus），它是信号从耳向大脑皮层传输的最初几个停靠站之一。研究人员发现，下丘上64%的神经元不仅能运输听觉信号，也能运输视觉信号。这意味着，听觉信息和视觉信息很早就在一起进行了加工，之后才将组合信息传到了大脑皮层。
Groh说，这应该就是口技能够行得通的原因。观众还没有有意识地考虑时，口技表演者的声音和木偶嘴巴的运动之间的联系就已经在他们脑中形成了。
Groh还表示，人类大脑的下丘与猴子的相似，随着新技术的涌现，比如能够实时成像的功能核磁共振成像（fMRI）技术，我们将能够在人类身上进行类似的研究。Groh目前正和研究小组进行新的实验，以确定是否某种感觉影响了机体对另一种感觉的感知。（科学网 杰克·梅/编译）
原始出处:
Published online before print October 31, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0706249104
OPEN ACCESS ARTICLE
Visual- and saccade-related signals in the primate inferior colliculus
Kristin Kelly Porter*, Ryan R. Metzger, and Jennifer M. Groh
Center for Cognitive Neuroscience, Department of Psychology and Neuroscience and Department of Neurobiology, Duke University, Durham, NC 27708
Edited by Eric I. Knudsen, Stanford University School of Medicine, Stanford, CA, and approved August 23, 2007 (received for review July 3, 2007)
Abstract
The inferior colliculus (IC) is normally thought of as a predominantly auditory structure because of its early position in the ascending auditory pathway just before the auditory thalamus. Here, we show that a majority of IC neurons (64% of 180 neurons) in awake monkeys carry visual- and/or saccade-related signals in addition to their auditory responses (P < 0.05). The response patterns involve primarily excitatory visual responses, but also increased activity time-locked to the saccade, slow rises in activity time-locked to the onset of the visual stimulus, and inhibitory responses. The presence of these visual-related signals suggests that the IC plays a role in integrating visual and auditory information. More broadly, our results show that interactions between sensory pathways can occur at very early points in sensory processing streams, which implies that multisensory integration may be a low-level rather than an exclusively high-level process.
auditory | monkey | multisensory | vision | cross-modal
