Visual Processing in Deaf Signers: Psychophysics and Brain Imaging Studies

在美国国家科学基金会的支持下，Dobkins博士及其同事将进行一项为期三年的研究，以调查早发性感觉剥夺的感知和神经后果。对聋人的研究，他们从出生起就被剥夺了自由，他们依赖视觉语言（即，美国手语（American Sign Language，ASL）为交流提供了一个独特的机会来研究如何以及在何种程度上改变了其余感官（特别是视觉）的感觉处理作为改变感官体验的结果。长期以来，人们一直认为（主要是通过轶事证据）聋人“看”得更好（盲人“听”得更好）。然而，由于听力研究人员和聋人受试者（他们说不同的语言，是不同文化的一部分）之间的沟通困难，令人惊讶的是，对聋人的视觉处理知之甚少。 为了研究这个问题，我们使用心理物理学技术（即，要求受试者报告在视频监视器上呈现给他们的刺激，例如，“刺激政策是上调还是下调？“）和脑成像技术（定位和测量视觉刺激引起的神经活动），以表征聋人和听力受试者之间视觉处理的差异。在我们之前的NSF研究中，我们专注于视觉运动处理，认为运动可能对聋人受试者特别重要，因为1）ASL理解严重依赖于手的运动，2）在没有听觉线索的情况下，聋人受试者可能依赖于他们周围的运动来帮助他们定位进入视野的物体。这些研究的结果揭示了一个强大的右视野/左半球的优势，聋人手语运动处理，这可能是占提出的知觉过程所需的理解语言（在ASL的情况下运动处理）得到招聘的左，语言占主导地位的半球。在目前的建议中，我们通过测试聋人和听力受试者的运动处理以及视觉的其他两个领域，即颜色和形状处理来扩展这些发现。此外，作为我们以前的注意力研究的延伸，我们将调查是否注意资源聋人和听力受试者之间的差异，特别是在周边视野。最后，结合这些视觉研究，我们将进行语言学研究，检查语言在个体受试者中向左半球偏侧化的程度。这将使我们能够进一步调查聋人的视觉和语言经验之间的联系。 这项活动的智力价值包括提高我们对大脑中正在发育的感觉区域如何根据改变的感觉输入进行自我重组的认识，这应该对大脑发育的一般原则产生影响。从临床的角度来看，这些结果可能是有用的，在设计补偿方案，为delicorily-deprived的人，谁可以训练利用这些方面的感觉处理，最适应于改变感觉输入。此外，随着人工耳蜗植入频率的增加，我们的研究结果可能有助于为聋人设计这些假体设备的特殊功能。 这些项目的广泛影响包括一个强有力的外联部分;就其性质而言，它们包括代表性不足的群体（即，人，作为主体。他们还吸引聋人在我们的实验室接受研究人员的培训。最后，除了通过会议和期刊出版物接触到广泛的受众（包括心理物理学，神经科学，发展和语言学领域的研究人员）外，这些项目的结果还通过PI的课程教学，如“感觉和感知”和“生理心理学”，带给加州大学圣地亚哥分校的本科生和研究生。

With National Science Foundation support, Dr. Dobkins and colleagues will conduct a three-year study to investigate the perceptual and neural consequences of early-onset sensory deprivation. The study of deaf individuals, who have been auditorily deprived since birth and who rely upon a visual language (i.e., American Sign Language, ASL) for communication, affords a unique opportunity to investigate how and the degree to which sensory processing within the remaining senses (specifically vision) is modified as a result of altered sensory experience. It has long been thought (mostly through anecdotal evidence) that the deaf "see" better (and that the blind "hear" better). However, owing to the difficult nature of communication between hearing researchers and deaf subjects (who speak different languages and are part of different cultures), surprisingly little is known about visual processing in the deaf. To investigate this issue, we use both psychophysical techniques (i.e., asking subjects to report about stimuli presented to them on a video monitor, e.g., "did the stimulus move up or down?") and brain imaging techniques (which localize and measure neural activity elicited by visual stimuli) to characterize differences in visual processing between deaf and hearing subjects. In our prior NSF studies, we focused on visual motion processing, with the notion that motion may be particularly important to deaf subjects, since 1) ASL comprehension relies heavily on the motion of the hands and 2) in the absence of auditory cues, deaf subjects may rely on motion in their periphery to help orient them to objects entering their visual field. The results of these studies revealed a robust right visual field / left hemisphere dominance for motion processing in deaf signers, which can potentially be accounted for by proposing that perceptual processes required for the comprehension of language (motion processing in the case of ASL) get recruited by the left, language-dominant hemisphere. In the current proposal, we expand on these findings by testing deaf and hearing subjects on motion processing, as well as two other domains of vision, namely color and form processing. In addition, as an extension of our previous attentional studies, we will investigate whether attentional resources differ between deaf and hearing subjects, particularly in the peripheral visual fields. Finally, in combination with these visual studies, we will conduct linguistic studies that examine the degree to which language is lateralized to the left hemisphere within individual subjects. This will allow us to investigate further the proposed link between the deaf's visual and linguistic experience. The intellectual merits of this proposed activity include advancing our knowledge of how developing sensory areas of the brain reorganize themselves in response to altered sensory input, which should have implications for principles of brain development in general. From the clinical standpoint, the results may be useful in designing compensatory programs for auditorily-deprived persons, who could be trained to exploit those aspects of sensory processing that are most adaptive in response to altered sensory input. Moreover, with the frequency of cochlear implants on the rise, our findings may be helpful in designing special features for these prosthetic devices in deaf individuals. The broader impacts of these projects include a strong outreach component; by their very nature, they include people from an underrepresented group (i.e., deaf people) as subjects. They also attract deaf people to be trained as researchers in our laboratory. Finally, in addition to reaching a broad audience (including researchers in the fields of psychophysics, neuroscience, development and linguistics) through conferences and journal publications, the results of these projects are brought to both undergraduate and graduate students at UC San Diego through the PI's teaching of courses such as "Sensation and Perception" and "Physiological Psychology".