The role of the thalamus in human olfactory processing

描述(申请人提供)：一般来说，对感觉刺激的有意识知觉依赖于通向新皮质的途径，在除嗅觉之外的所有形式中，这需要穿过丘脑。仔细的解剖学研究发现，在嗅觉中，嗅觉皮质和前额叶皮质之间的通路大多是直接的，只有一小部分纤维流向丘脑内侧。嗅觉系统结构组织的这种根本差异表明丘脑在嗅觉处理中扮演着不同的角色。这项提议的目标是阐明这一角色。在目标1中，我将使用功能磁共振成像来表征丘脑活动的有意调节的性质。通过系统地改变对不同气味的注意力，我将检验这样一个假设，即气味质量的分布代码在丘脑内侧背核是注意力依赖的，而在初级嗅觉皮质是不依赖注意力的。在目标2中，我将使用fMRI来使用层次聚类分析和一般线性模型方法进行数据分析，我将能够区分参与基本感觉处理的嗅觉大脑区域，以及气味价格决定和质量识别过程中的信息积累和识别时刻。在目标3中，我将使用功能磁共振成像来询问在嗅觉决策过程中，背内侧丘脑是否整合了来自多个通道的信息。在扫描过程中，受试者将闻到单独呈现或与其他方式的刺激配对的气味，使我们能够测试丘脑内侧背侧的多模式嗅觉反应曲线。 与公共健康相关：了解嗅觉系统的功能组织有许多潜在的健康益处。首先，嗅觉结构与大脑区域重叠，这些区域受到许多常见疾病的影响，包括阿尔采默氏症、癫痫、帕金森氏症和精神分裂症。内侧丘脑是这项提案的主要焦点，与上述所有疾病都有关联。增加对内侧丘脑在嗅觉处理中的作用的了解将增加我们对影响它的疾病的了解。

DESCRIPTION (provided by applicant): In general, conscious perception of sensory stimuli depends on a pathway to neocortex, and in all modalities except for olfaction, this requires going through the thalamus. Careful anatomical studies have found that in olfaction, the pathway between olfactory cortex and prefrontal cortex is mostly direct, with only a small contingent of fibers going to mediodorsal thalamus. This fundamental difference in the structural organization of the olfactory system indicates a qualitatively different role for the thalamus in olfactory processing. The goal of this proposal is to elucidate that role. In Aim 1, I will use fMRI to characterize the nature of intentional modulation of activity in the thalamus. By systematically altering attention to different odors, I will test the hypothesis that distributed codes of odor quality are attention dependent in the mediodorsal nucleus of the thalamus, while they are attention independent in primary olfactory cortex. In Aim 2, I will use fMRI to Using hierarchical cluster analysis and a general linear model approach to data analysis, I will be able to distinguish between olfactory brain regions that are involved in basic sensory processing, accumulation of information and moment of recognition during odor valence decisions and quality recognition. In Aim 3, I will use fMRI to ask whether the mediodorsal thalamus integrates information from multiple modalities during olfactory decisions. During scanning, subjects will smell odors that are either presented alone or paired with stimuli from other modalities, enabling us to test for multimodal olfactory response profiles in the mediodorsal thalamus. PUBLIC HEALTH RELEVANCE: Understanding the functional organization of the olfactory system has numerous potential health benefits. For one, olfactory structures overlap with brain areas that are affected by many common diseases including Alzeimer's disease, epilepsy, Parkinson's disease and schizophrenia. The mediodorsal thalamus, which is the main focus of this proposal, has been implicated in all of the aforementioned diseases. Increased knowledge of the role of the mediodorsal thalamus in olfactory processing will increase our knowledge of the diseases that affect it.