Short-term plasticity of the retinogeniculate synapse

描述(申请人提供)：来自感觉输入的信息在传递到大脑皮层之前汇聚在丘脑。丘脑在这些信息的处理和选通中起着重要的作用。例如，根据人是醒着还是睡着，丘脑传递给大脑皮层的信息的性质不同。因此，丘脑必须能够在毫秒级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神经元的相互作用。这一建议解决了这样的假设，即突触可塑性机制对丘脑传入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觉丘脑之间的联系，视丘脑是视网膜生成的突触。视觉系统是研究最多的信息处理系统之一，输入的视觉信息编码在视网膜神经节细胞的放电模式中，已经得到了很好的表征。然而，对于将这一信息从视网膜神经节细胞传递到外侧膝状体背核(DLGN)的丘脑皮质神经元的重要突触过程，我们知之甚少。为了确定在视网膜起源突触传递信息的重要机制，将使用电生理和光学技术的组合。将监测突触前视网膜输入的特征和突触后丘脑中继神经元的反应。短期突触可塑性的机制将通过检测对视网膜纤维刺激和模拟视网膜神经节细胞活动的刺激模式的突触反应来识别和表征。此外，还将评估脑干输入的神经递质投射和内在抑制连接对视黄素原性突触的调节。最后，将检验这些突触可塑性机制对突触后丘脑中继神经元放电模式的影响。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贡献的理解。

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.