CORTICOTHALAMIC INPUT TO THE MOTOR THALAMUS

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。运动丘脑中的神经元除了从基底节或小脑接受输入外，还接受大脑皮层的输入。然而，皮质丘脑传入携带的信号并不是很清楚，也不是与睡眠相关的情况，在这种情况下，运动神经元在不规则和突发性放电之间移动。在MPTP诱导的偏侧帕金森综合症后，猴子无法用注射的对侧手臂工作，丘脑也显示出更多的爆发，即使动物用同侧手臂工作。我们已经证明，有两种不同类型的逆行识别的皮质丘脑神经元，其中一种与运动相关，具有较短的逆行潜伏期，由低刺激强度激活，并在相对较浅的深度遇到(活跃神经元)。第二种刺激具有较长的逆行潜伏期、较高的阈值刺激强度、较深的皮质径路位置以及无活动，除非逆行激活。是什么激活了这些不活跃的皮质丘脑神经元仍然是个谜，因为我们一直无法在睡眠/清醒转换或不同的任务学习状态中激活它们。另一篇文章描述了手臂运动时丘脑皮质神经元的定向调谐曲线，并将其与丘脑刺激正向或反向激活的运动皮质神经元的定向调谐曲线进行了比较。大脑皮质的调谐曲线比丘脑皮质的要窄，这表明皮质连接--局部或更远距离的皮质-皮质--使运动皮质细胞的反应场变得尖锐。两只猴子接受了视觉注意任务的训练，通过改变动物在右半脑或左半脑区域必须检测到的亮度变化来改变注意力，以触发手臂的运动。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状态下的活动，以及MPTP治疗前后的活动。

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.