OPERANTLY CONDITIONED PATTERNS OF PRECENTRAL UNIT-ACTIVITY AND CORRELATED RESPONSES IN ADJACENT CELLS AND CONTRALATERAL MUSCLES
OPERANTLY CONDITIONED PATTERNS OF PRECENTRAL UNIT-ACTIVITY AND CORRELATED RESPONSES IN ADJACENT CELLS AND CONTRALATERAL MUSCLES
复制标题
DOI：
10.1152/jn.1973.36.2.179
复制
发表时间：
1973-01-01
影响因子：
2.5
通讯作者：
BAKER, MA
中科院分区：
文献类型：
--
作者：
FETZ, EE;BAKER, MA
方法选用体重3~5 kg的猕猴(Macaca Mulatta)。在录音和训练过程中，猴子坐在灵长类束缚椅上，这样可以相对自由地移动胳膊和腿。细胞外单位记录用Isoel 31绝缘的钨微电极进行。电极用遥控液压微驱动器(Trent Wells)固定在不锈钢骨固定适配器上，永久植入中央前臂或腿皮质。适配器用一层薄薄的硅橡胶(道康宁)密封，以保护硬脑膜并延缓感染。早期的适配器允许探索直径为5毫米的皮质圆形区域；随后的适配器允许在直径为ZO毫米的圆圈内进行记录。在后者中，硅橡胶膜被固定在一个螺纹状的中心环中，可以被移除以治疗任何感染或允许手术移除硬膜外疤痕组织。组织学证实记录部位在中央前回的第4区，在4只猴子身上，将肌电(EMG)电极长期植入皮质记录部位对侧的踝关节和膝关节的屈伸肌中，每组电极由一对尼龙绝缘的绞合不锈钢丝组成(Bergen Wire Rope Co.，Lodi，NJ。)在顶端裸露，并缝合到肌肉中，顶端间隔5-20毫米。电线的两端连接到一个粘在头骨上的皮下连接器。四只猴子将双极刺激电极长期植入锥体束(PT)；在条件反射方面，PT和非PT中央前单位之间没有一致的差异。在这些实验中，我们倾向于对具有较大动作电位和一定程度波动的“自发”活动的单位进行抽样。较大的单元在相对不受限制的肢体运动中提供了更长的稳定性。为了确保在整个过程中只监测到一个相同的单元，我们在从波形上升沿触发的示波束上显示其动作电位，扫描设置得足够快，以在整个屏幕上显示整个动作电位。在这些条件下，可以根据动作电位的不同时间进程很容易地区分两个或更多个单元。为了进一步确保训练过程只涉及一个单元，我们在磁带记录器的第二个通道上记录了从该单元触发的I毫秒电压脉冲。为了验证这些脉冲在整个过程中只与一个单元相关联，我们倒放磁带，并检查从I毫秒电压脉冲的前沿触发的示波器扫描上的数据通道。这产生了触发每个脉冲的整个动作电位的时间反转显示；其中脉冲与多于一个动作电位波形相关联的任何记录都被丢弃。
METHODSSix monkeys (Macaca mulatta) weighing 3-5 kg were used. During recording and training sessions monkeys sat in primate restraint chairs which allow relatively free movement of arms and legs. Extracellular unit recordings were made with tungsten microelectrodes insulated with Isonel 31. Electrodes were advanced with a remotely controlled hydraulic microdrive (Trent Wells) fastened to a stainless steel bonefixed adapter permanently implanted over precentral arm or leg cortex. The adapter was sealed with a thin sheet of Silastic rubber (Dow Corning) to protect dura and retard infections. Early adapters allowed exploration of a circular region of cortex 5 mm in diameter; subsequent adapters allowed recording within a ZO-mm-diameter circle. In the latter the Silastic membrane was held in a threaded center ring, which could be removed to treat any infection or permit surgical removal of extradural scar tissue. Recording sites were histologically confirmed to be in area 4 of the precentral gyrus, In four monkeys electromyographic(EMG) electrodes were chronically implanted in flexors and extensors of the ankle and knee contralateral to the cortical recording site, Each electrode set consisted of a pair of nylon-insulated stranded stainless steel wires (Bergen Wire Rope Co., Lodi, NJ.) bared at the tip and sutured into the muscles with tip separations of 5-20 mm. The ends of the wires led subcutaneously to a connector cemented to the skull. Four monkeys had a bipolar stimulating electrode chronically implanted in the pyramidal tract (PT); no consistent difference was found between PT and non-PT precentral units with respect to conditionability. In these experiments we tended to sample units with large action potentials and some degree of fluctuating “spontaneous” activity. The larger units provided prolonged stability during relatively unrestricted limb movements. To assure that only one and the same unit was monitored throughout the session we displayed its action potentials on an oscilloscope beam triggered from the rising edge of the waveform, with the sweep set fast enough to display the entire action potential over the whole screen.Under these conditions two or more units could be readily distinguished on the basis of differing time courses of their action potentials. To further assure that a training session involved only one cell, we recorded I-msec voltage pulses triggered from the unit on a second channel of the magnetic tape recorder. To verify that these pulses were associated with only one unit throughout the session, we played the tape backward and examined the data channel on an oscilloscope sweep triggered from the leading edge of the I-msec voltage pulses. This produced a time-reversed display of the entire action potential which had triggered each pulse; any records in which the pulses were associated with more than one action potential waveform were discarded.