Short-term plasticity of the retinogeniculate synapse

描述（由申请人提供）：来自感觉输入的信息在传递到大脑皮层之前在丘脑中会聚。丘脑在这些信息的处理和门控中起着重要的作用。例如，视丘传递给皮层的信息的性质取决于一个人是醒着还是睡着。因此，丘脑必须能够在毫秒的时间尺度上快速调节感觉信息。许多机制被认为有助于这一动态过程，从分子水平上发生的变化到网络水平上的神经元相互作用。这一提议提出了一个假说，即突触可塑性机制对丘脑中传入的感觉信息的处理有重要贡献。为了验证这一假设，我们将检查视网膜和视丘脑之间的联系，视网膜神经突触。视觉系统是信息处理的最佳研究系统之一，并且输入的视觉信息编码在视网膜神经节细胞的放电模式中，已经被很好地表征。然而，很少有人知道的突触过程中重要的中继信息从视网膜神经节细胞的丘脑皮质神经元的背外侧膝状体核（dLGN）。为了确定在视网膜神经突触的信息中继的重要机制，电生理学和光学技术的组合将被使用。将监测突触前视网膜输入的特性和突触后丘脑中继神经元的响应。短期突触可塑性的基础机制将通过检查对视网膜纤维刺激的突触反应和模拟视网膜神经节细胞活动的刺激模式来确定和表征。此外，将评价脑干输入和内在抑制连接的神经递质投射对视网膜膝状体突触的调制。最后，这些突触可塑性机制的影响将被检查突触后丘脑中继神经元的放电模式。这些研究将加深我们对突触机制在中枢神经系统信息处理中的作用的理解。

DESCRIPTION (provided by applicant): Information from sensory inputs converges in the thalamus before passing on to the cerebral cortex. The thalamus plays an important role in the processing and gating of this information. For example, the nature of the information that the thalamus relays to the cortex differs depending on whether one is awake or asleep. Thus the thalamus must be capable of rapidly modulating sensory information on a time scale of milliseconds. Many mechanisms are thought to contribute to this dynamic process, ranging from changes that occur at the molecular level to interactions of neurons at the network level. This proposal addresses the hypothesis that mechanisms of synaptic plasticity contribute significantly to the processing of incoming sensory information in the thalamus. To test this hypothesis, we will examine the connection between the retina and visual thalamus, the retinogeniculate synapse. The visual system is one of the best-studied systems for information processing, and the incoming visual information, encoded in the firing patterns of retinal ganglion cells, has been well characterized. Little, however, is known of the synaptic processes important in relaying this information from the retinal ganglion cells to thalamocortical neurons of the dorsal lateral geniculate nucleus (dLGN). In order to identify mechanisms important to the relay of information at the retinogeniculate synapse, a combination of electrophysiological and optical techniques will be used. Both the characteristics of the presynaptic retinal input and the response of postsynaptic thalamic relay neurons will be monitored. Mechanisms that underlie short-term synaptic plasticity will be identified and characterized by examining the synaptic response to pairs of retinal fiber stimuli and stimulation patterns that mimic retinal ganglion cell activity. In addition, the modulation of the retinogeniculate synapse by neurotransmitter projections from brainstem inputs and intrinsic inhibitory connection will be evaluated. Finally, the effects of these synaptic mechanisms of plasticity will be examined on the firing patterns of postsynaptic thalamic relay neurons. These studies will enhance our understanding of the contributions of synaptic mechanisms to information processing in the central nervous system.