CORTICOTHALAMIC INPUT TO THE MOTOR THALAMUS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。运动丘脑中的神经元除了接受基底神经节或小脑的输入外，还接受来自大脑皮层的输入。然而，皮质丘脑传入事件所携带的信号尚不清楚，运动丘脑神经元在不规则和突发放电之间转换的非睡眠相关情况也不清楚。在mptp诱导的半帕金森症后，猴子不能用注射对侧的手臂工作，而且丘脑也显示出更多的爆发，即使动物用同侧的手臂工作。我们已经证明，有两种不同类型的逆行识别皮质丘脑神经元，其中一种与运动相关，具有短的逆行潜伏期，被低刺激强度激活，并且在相对较浅的深度遇到（活跃神经元）。第二种具有较长的反向潜伏期，较高的刺激强度阈值，位于皮层轨道较深的位置，除非被反向激活，否则没有活动。是什么激活了这些“不活跃”的皮质丘脑神经元仍然是一个谜，因为我们无法在睡眠/清醒转换或不同的任务学习状态下激活它们。另一篇论文描述了手臂运动时丘脑皮层神经元的定向调谐曲线，并将其与丘脑刺激正反方向激活的运动皮层神经元的曲线进行了比较。皮质调谐曲线比丘脑皮质调谐曲线窄，这表明皮质连接——局部或更远距离的皮质-皮质连接——使运动皮质细胞的反应场更锐化。两只猴子接受了一项视觉注意力任务的训练，该任务通过改变亮度变化来改变注意力，动物必须在右半脑区或左半脑区检测到亮度变化，才能触发手臂运动。我们已经开始记录一只猴子的丘脑，绘制出运动丘脑，然后研究这些神经元在不同注意力状态下的活动，在MPTP治疗前后。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Neurons in the motor thalamus receive input from the cerebral cortex, in addition to the basal ganglia or the cerebellum. The signals carried by corticothalamic afferents are not well known, however, nor are the non-sleep related conditions in which motor thalamic neurons shift between irregular and burst discharges. After MPTP-induced hemiparkinsonism, monkeys fail to work with the arm contralateral to the injection, and the thalamus also shows more bursts, even when the animal works with the ipsilateral arm. We have shown that there are two different classes of antidromically identified corticothalamic neurons, one of which is active in association with movement, has short antidromic latencies, is activated by low stimulus intensities, and is encountered at relatively more superficial depths (active neurons). The second has long antidromic latencies, higher threshold stimulus intensities, deeper location in cortical tracks, and no activity, except when activated antidromically. What activates these 'inactive' corticothalamic neurons is still a mystery, since we have been unable to activate them during sleep/wake transitions or different task learning states. Another paper describes the directional tuning curve of thalamocortical neurons during arm movements and compares it to the curve for motor cortex neurons activated orthodromically or antidromically by stimulation in the thalamus. Cortical tuning curves are narrower than are thalamocortical ones, suggesting that cortical connections- local or longer distance cortico-cortical- sharpen the response field of motor cortex cells. Two monkeys have been trained on a visual attention task that varies attention by varying the luminance change that animals must detect in the right or left hemifield to trigger an arm movement. We have begun to record from the thalamus of one monkey to map out the motor thalamus and then to study the activity of these neurons during different attention states, pre- and post treatment with MPTP.