Role of Rhythmic Oscillations in Neuronal Plasticity

在这些群体中，胆碱能神经元被认为是振荡活动的关键调节剂。在过去，胆碱能神经元的功能作用已经通过免疫毒素消除这些神经元来研究，然而，这种神经元的不可逆消除带来了不可逆的变化，损害了行为实验的解释。为了直接测试振荡在学习、记忆和情绪中的作用，我们将通过调节破伤风毒素轻链的表达，可逆地灭活小鼠大脑中的胆碱能神经元。这种毒素不杀死神经元，但通过切断突触短缩蛋白来阻止神经递质的分泌，而突触短缩蛋白是突触囊泡对接所必需的。一旦毒素的表达被关闭，神经元就会恢复它们的功能。我们将利用系统的可逆性来测试节律振荡在记忆形成、巩固和检索的不同阶段的作用。罗格斯大学的Buzsaki博士将进行神经元活动的体内记录和分析。

Among these groups, cholinergic neurons are considered the key modulators of the oscillatory activities. In the past, the functional role of cholinergic neurons has been studied by the elimination of these neurons with immunotoxins, however this irreversible elimination of neurons brings about irreversible changes compromising interpretation of behavioral experiments. To directly test the role of oscillations in learning, memory and mood, we will reversibly inactivate cholinergic neurons in the mouse brain using regulated expression of the light chain of tetanus toxin. This toxin does not kill neurons, but prevent secretion of neurotransmitter by cleaving synaptobrevin, which is required for the docking of synaptic vesicles. Once the expression of the toxin is turned off, neurons should recover their functions. We will test the role of rhythmic oscillations at different stages of memory formation, consolidation and retrieval taking advantage of the reversibility of the system. In vivo recording and analysis of neuronal activity will be performed by Dr. Buzsaki at Rutgers University. We have completed the design of the scheme for reversible genetic inactivation of cholinergic neurons. The scheme includes generation of 2 lines of genetically modified mice. The first line will express tetracycline transactivator in the cholinergic neurons. It will be produced by targeting cholinergic locus with the construct harboring a gene for tetracycline transactivator. The second line will carry modified inactive tetanus toxin, which could only be activated only in the brain following a withdrawal of doxycycline from mouse diet. During the past fiscal year, we have completed a generation of mice with the tetracyclin transactivator gene expressed from the cholinergic locus promoter. Specifically, as the last step, we have successfully excised a selectable marker used during targeting of the locus. We were continuing work on making a targeting construct containing the tetanus toxin gene.