The role of secondary thalamus in enhancing cortical sensory representations

次级丘脑在增强皮质感觉表征中的作用

基本信息

批准号：
9191868
负责人：
Georgia Marie Pierce
金额：
$ 4.36万
依托单位：
COLUMBIA UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-09-01 至 2018-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9191868
关键词：
Accelerometer Affect Animals Apical Attention Attention deficit hyperactivity disorder Auditory area Automobile Driving Axon Behavior Behavioral Biological Models Brain Calcium Cell Nucleus Cells Cerebral cortex Code Cortical Column Data Dendrites Diagnosis Epilepsy Feedback Functional disorder Goals Head Human Hyperactive behavior Image Impairment Lead Learning Lesion Macaca Medial Mediating Microscopy Modality Mus Neurons Outcome Patients Performance Positioning Attribute Pulvinar structure Rewards Rodent Role Schizophrenia Sensory Sensory Process Shapes Signal Transduction Somatosensory Cortex Stimulus Synapses System Task Performances Testing Thalamic Nuclei Thalamic structure Touch sensation Training Transgenic Organisms Vibrissae Viral Visual area striata base behavioral response design hippocampal pyramidal neuron nervous system disorder optogenetics relating to nervous system research study response sensory cortex sensory stimulus sensory system somatosensory sound two-photon

项目摘要

ABSTRACT Primary sensory cortex, the first point of sensory processing within the cerebral cortex, receives input from both a “primary” and a “secondary” thalamic nucleus. Primary thalamic nuclei relay signals from the external world to primary sensory cortex. In contrast, secondary thalamic nuclei are densely interconnected with many other cortical regions and may therefore be involved in more advanced computations. While the role of primary thalamic nuclei in sensory responses is well understood, secondary nuclei remain under-studied. Lesions in secondary thalamus render subjects unable to notice and choose important objects. These secondary thalamic nuclei may encode representations of behaviorally relevant objects (e.g. those predicting reward outcomes). The goal of this proposal is to determine what information is encoded in the projection from secondary thalamus to primary sensory cortex and how this input influences cortical responses. A well-characterized and genetically tractable model system, the mouse whisker system, will be used. In mice, the posterior medial nucleus (POm, somatosensory secondary thalamus) is in a promising position to influence neural activity in primary somatosensory cortex (S1). POm sends axons to layer 1 of S1, where it contacts S1 neurons at their apical dendrites, computationally powerful segments of cortical neurons. Input to the apical dendrites can strongly potentiate the firing of S1 neurons and has been proposed as a mechanism for feedback from higher cortex to modulate activity in sensory cortex. This thalamic input could increase S1 responses to behaviorally relevant objects. Indeed, many studies have shown that neural responses in primary sensory cortex across sensory systems are enhanced for relevant stimuli, such as attended, rewarded, or punishing stimuli. To test this hypothesis, we will first design a behavior that manipulates the behavioral relevance of objects. Next, the calcium imaging of POm axons within S1 will determine if POm inputs to S1 are biased towards relevant objects. Finally, optogenetic silencing of POm axons during juxtasomal recordings of S1 cells will test whether POm input enhances S1 representations of behaviorally relevant objects. These experiments will elucidate how the projection from secondary thalamus to sensory cortex imparts behavioral meaning to cortical sensory responses.

抽象的初级感觉皮层是大脑皮层内感觉处理的第一个点，接收输入来自“初级”和“次级”丘脑核的信号传递来自丘脑的信号。相比之下，次级丘脑核团与外部世界紧密相连。与许多其他皮质区域一样，因此可能参与更高级的计算。初级丘脑核团在感觉反应中的作用已被充分了解，但次级丘脑核团的研究仍然不足。次级丘脑的损伤使受试者无法注意和选择重要的物体。次级丘脑核可以编码行为相关对象的表示（例如那些预测奖励结果）。该提案的目标是确定在二次投影中编码了哪些信息丘脑到初级感觉皮层以及这种输入如何影响皮层反应。遗传易处理的模型系统，即小鼠胡须系统，将用于小鼠的后内侧。核（POm，体感次级丘脑）在影响神经活动方面处于有利地位初级体感皮层 (S1) 将轴突发送到 S1 的第 1 层，在该层与 S1 神经元接触。顶树突，皮层神经元的计算能力强大的部分可以输入到顶树突。强烈增强 S1 神经元的放电，并已被提议作为来自更高层的反馈机制皮层调节感觉皮层的活动，这种丘脑输入可以增加 S1 对行为的反应。事实上，许多研究表明初级感觉皮层的神经反应跨越。感觉系统针对相关刺激（例如参与、奖励或惩罚刺激）进行增强以进行测试。根据这个假设，我们首先会设计一个行为来操纵对象的行为相关性。 S1 内 POm 轴突的钙成像将确定 S1 的 POm 输入是否偏向相关最后，在 S1 细胞的并列记录期间 POm 轴突的光遗传学沉默将测试是否。 POm 输入增强了行为相关对象的 S1 表示。这些实验将阐明。从次级丘脑到感觉皮层的投射如何赋予皮层感觉行为意义回应。