Neural Substrates of Learning

人类和动物每天学到的许多东西都是基于两个事件之间的简单联系。人类学会避免使用热炉；门铃响表明有人来访，猫在期待收到食物时学会接近开罐器的声音，这只是几个例子。这些事件通过视觉、听觉、体感、嗅觉和味觉5种主要的特定通路进入神经系统。每一种模式都记录了非常不同的刺激，并有一个独特的神经输入系统。不同模式的学习需要相同数量的神经回路作为输入吗？也许有一些集中的神经回路取决于被处理的全局信息的类型，而不是取决于个体的感觉模式？如果要学习类似的运动反应，可能会使用相同的神经学习回路。简单联想的行为参数，即经典条件反射，即一个刺激预测另一个刺激的出现，已经得到了很好的研究。两种特定类型的经典条件反射——眨眼和恐惧条件反射对音调刺激——的神经基质已经通过损伤、解剖追踪和神经元记录研究从输入到输出得到了验证。眨眼条件反射与肢体屈曲条件反射相似。当使用样本模态的线索时，类似类型的经典条件反射的神经元学习回路有多相似？当使用来自不同模式的线索时，这些不同的输入是否会聚在一个共同的电路上，用于特定运动反应的经典条件反射？本研究的目的有两个方面：首先，通过测量全脑葡萄糖能量代谢来绘制神经基质，对于一个简单的经典条件反射范例，使用常用的纯音刺激进行肢体屈曲。研究结果将与已知的眨眼调节电路进行比较。其次，利用视觉和体感刺激的其他方式的线索绘制这种经典条件反射的神经基质。许多人仅仅通过一种或另一种感官形式的表现来学习有困难。这种类型的研究可能允许识别这些类型的缺陷被修改的特定大脑区域。

Many things that humans and animals learn everyday are predicated on a simple association between two events. Humans learn to avoid hot stoves; a doorbell ringing indicates visitors, and cats learning to approach to the sound of the can opener in the anticipation of receiving food are just a few examples. These events are brought into the neural system by 5 main modality specific pathways, visual, auditory, somatosensory, olfactory and gustatory. Each one of these modalities records very different stimuli and has a unique neural input system. Does learning across different modalities require the same number of neural circuits as types of input? Perhaps there are centrally located neural circuits depending on the type of global information being processed rather than on the individual sensory modality? If similar motor responses were to be learned the same neural learning circuit might be used. The behavioral parameters of simple associative, i.e., classical conditioning, where one stimulus predicts the occurrence of another stimulus, have been well worked out. The neural substrates underlying two specific types of classical conditioning, eyeblink and fear conditioning to tone stimuli, have been verified from input to output with the use of lesion, anatomical tracing and neuronal recording studies. Eyeblink conditioning is similar to limb flexion conditioning. How similar are the neuronal learning circuits for similar types of classical conditioning when using cues from the sample modality? When using cues from different modalities, do these different inputs converge on a common circuit for classical conditioning of a particular motor response? The aim of the proposed research is two-fold: First, map the neural substrates, through measurement of glucose energy metabolism across the whole brain, for a simple classical conditioning paradigm, limb flexion using the commonly used pure tone stimulus. The results will be compared to the known circuitry for eyeblink conditioning. Second, map the neural substrates of this classical conditioned reflex using cues from additional modalities using visual and somatosensory stimuli. Many humans have difficulty learning solely by presentations made in one sensory modality or another. This type of research may allow for the identification of the specific brain regions where these types of deficits are modified.