Neuronal mechanisms of sensory binding

感觉结合的神经机制

• 批准号: RGPIN-2015-05065
• 负责人: Ross, Bernhard
• 金额: $ 2.4万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=684878
• 关键词: Neuronal; mechanisms; sensory; binding

When the electroencephalogram (EEG) has been discovered, one early observations was that the brain activity follows rhythmic changes, termed oscillations. Slow and fast oscillations, occur whether we are awake or in sleep, our eyes are open or closed, or whether we are moving or at rest. Recently, it has been found that brain oscillations are important for neural communication between distant brain areas.***We recorded fast gamma oscillations (40 Hz) with magnetoencephalography (MEG) in human volunteers, who were listening to 40-Hz amplitude modulated sound. 40-Hz oscillations informed us about hearing and how auditory perception is organized in the brain, such as when we localize a sound in space or understand speech in noise. Previous animal research helped us interpreting our MEG results and to develop a model of central auditory processing. However, the previous studies were rather different from our MEG work and did not completely explain the neural mechanisms underlying the non-invasively recorded MEG. Therefore, in the current project we will perform a set of studies that will help us interpreting MEG and EEG findings. ***First, we will test our hypothesis, that one role of fast oscillations is, to determine at which exact time point a neuron fires. This is an important mechanism, because the brain oscillations would determine which neurons are firing at the same time and thus would be connected and work together. We will record neural firing with electrodes in the auditory cortex in chinchilla while stimulating with 40-Hz sound. ***Second, we will measure the concentration of the neurotransmitter GABA using magnetic resonance spectroscopy and compare the GABA level with the amplitude of gamma oscillations recorded in MEG. The results will inform us about how the gamma oscillations are generated, specifically how inhibitory interneurons in the cortex are involved in generating gamma oscillations.***Third, we will investigate how 40-Hz oscillations influence auditory perception. We will perform a gap detection task while listening to 40-Hz AM sounds and test our hypothesis, that gap detection will be better at a certain phase of the 40-Hz sound than on others, according to the hypothesis, that gamma oscillations determine the time point of neural firing. Moreover we will present parts of speech stimuli separately to the left and right ear and test, whether common 40-Hz modulation helps to fuse the parts into understandable speech.***We will use the results of this research for interpreting our MEG findings about changes in auditory processing in elderly people and their problem of understanding speech in noise. Moreover, it has been found that gamma oscillations are different in brain conditions and disorders such as in autism and in schizophrenia. If we know more about the mechanisms and functional meaning of gamma oscillations, we can use EEG or MEG recording of gamma oscillations as sensitive diagnostic tool. **

当脑电图 (EEG) 被发现时，一项早期观察发现大脑活动遵循节律变化，称为振荡。无论我们是醒着还是在睡觉，我们的眼睛是睁着还是闭着，无论我们是在移动还是在休息，都会发生缓慢和快速的振荡。最近，人们发现大脑振荡对于遥远大脑区域之间的神经通讯非常重要。***我们用脑磁图 (MEG) 记录了人类志愿者的快速伽马振荡 (40 Hz)，这些志愿者正在聆听 40 Hz 调幅声音。 40 赫兹的振荡让我们了解听觉以及大脑中听觉感知的组织方式，例如我们何时定位空间中的声音或理解噪音中的语音。之前的动物研究帮助我们解释了脑磁图结果并开发了中枢听觉处理模型。然而，之前的研究与我们的脑磁图工作有很大不同，并没有完全解释非侵入性记录脑磁图背后的神经机制。因此，在当前的项目中，我们将进行一系列研究，帮助我们解释脑磁图和脑电图结果。 ***首先，我们将测试我们的假设，即快速振荡的一个作用是确定神经元在哪个确切时间点放电。这是一个重要的机制，因为大脑振荡将决定哪些神经元同时放电，从而相互连接并一起工作。我们将在用 40 Hz 的声音刺激时，用龙猫听觉皮层的电极记录神经放电。 ***其次，我们将使用磁共振波谱测量神经递质 GABA 的浓度，并将 GABA 水平与 MEG 中记录的伽马振荡振幅进行比较。结果将告诉我们伽马振荡是如何产生的，特别是皮层中的抑制性中间神经元如何参与产生伽马振荡。***第三，我们将研究 40 Hz 振荡如何影响听觉感知。我们将在收听 40 Hz AM 声音时执行间隙检测任务，并测试我们的假设，即间隙检测在 40 Hz 声音的某个相位会比其他相位更好，根据假设，伽马振荡决定神经放电的时间点。此外，我们将分别向左耳和右耳呈现部分语音刺激，并测试常见的 40 Hz 调制是否有助于将这些部分融合成可理解的语音。***我们将利用这项研究的结果来解释我们关于老年人听觉处理变化以及他们在噪声中理解语音问题的 MEG 研究结果。此外，人们还发现，伽马振荡在大脑状况和疾病（例如自闭症和精神分裂症）中是不同的。如果我们更多地了解伽马振荡的机制和功能意义，我们可以使用伽马振荡的脑电图或脑磁图记录作为敏感的诊断工具。 **