NEURAL RESPONSES RELATED TO SMOOTH-PURSUIT EYE-MOVEMENTS AND THEIR CORRESPONDENCE WITH ELECTRICALLY ELICITED SMOOTH EYE-MOVEMENTS IN THE PRIMATE FRONTAL EYE FIELD
NEURAL RESPONSES RELATED TO SMOOTH-PURSUIT EYE-MOVEMENTS AND THEIR CORRESPONDENCE WITH ELECTRICALLY ELICITED SMOOTH EYE-MOVEMENTS IN THE PRIMATE FRONTAL EYE FIELD
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DOI：
10.1152/jn.1994.72.4.1634
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发表时间：
1994-10-01
影响因子：
2.5
通讯作者：
BRUCE, CJ
中科院分区：
文献类型：
--
作者：
GOTTLIEB, JP;MACAVOY, MG;BRUCE, CJ
1.皮质内微刺激的一部分猴子额眼场（FEF）躺在地板和后银行的弓形沟唤起顺利，而不是扫视眼球运动。为了进一步探讨这一地区的参与追求，我们记录从FEF神经元附近的网站，从平滑的眼球运动（SEMs）引起电和研究他们的反应，在平滑的追求和扫视任务。在这份报告中，我们描述了在视觉引导的平滑追踪过程中神经元的反应，并将它们的位置和反应特性与诱发的SEM进行了比较。从三只恒河猴的六个半球的FEF区域记录的193个神经元被归类为“追踪神经元”。这些神经元在对移动视觉刺激的平滑追踪过程中做出反应，但在视觉引导的扫视过程中没有或只有最小的反应。追踪神经元位于弓状基底和后堤的一个小区域，与微刺激诱发SEM的区域重叠，并略超出该区域.所有的追踪神经元都有一个偏好的追踪方向，所有的方向都没有明显的同侧、对侧、向上或向下的偏向。80追求细胞的方向调谐定量测量测试追求在几个方向和拟合的响应高斯函数。调谐指数（高斯拟合的sigma参数）在13度和136度之间变化。中值调谐指数44.5度对应于105度的半高全宽。追求方向的普遍选择性和广泛分布的首选方向表明，追求方向使用FEF中的位置代码类型的表示;然而，大多数神经元的广泛方向调谐表明，追求方向是由在任何给定时间活跃的追求神经元群体中的最佳方向的加权平均值给出的。一般而言，追踪神经元的反应随追踪速度的增加而增加。在13个神经元中，在目标速度的范围内，在其首选方向上进行了2秒的恒速跟踪，追踪速度灵敏度范围为0.24至1.42尖峰.s（-1）.deg（-1）.s（-1），平均灵敏度为0.70。这种关系表明，追求神经元使用速率代码表示追求幅度;这与我们之前的观察结果相似，即在大多数SEM部位，电引起的眼球运动的速度和加速度随着刺激电流而增加。追踪反应开始于目标运动开始后的中位潜伏期103 ms（n = 69）。当相对于平滑追踪的开始计算潜伏期时，大多数（61%）在其首选方向上追踪之前放电，中位相对潜伏期为-19 ms（负意味着放电先于追踪）。因此，显著的FEF活动可能有助于追踪启动的早期阶段，这与先前的观察结果一致，即FEF刺激使SEMs从静止注视中消失。我们记录了追踪反应，随后在113个部位测试了微刺激。其中，电刺激在27个部位产生SEM，在12个部位产生扫视，在其余74个部位没有眼球运动。SEM部位神经元的反应潜伏期与不产生诱发眼动的部位没有差异;然而，相对于对侧偏好方向的神经元，SEM更经常从神经元偏好追踪指向记录半球同侧的部位诱发。诱发SEM的方向与SEM部位记录的神经元的最佳追踪方向相关（r（+）= 0.71）。然而，尽管这种高度显著的整体相关性，但引发的SEM方向与神经元的最佳追踪方向平均相差约40度。这种差异可能反映了追踪神经元的广泛方向性调谐和通常用于获得这些诱发SEM的相对较大的电流（50-100 μ A）。的位置和方向偏好的追求神经元和那些引起的SEMs，以及短lavery的追求反应之间的对应关系，表明FEF追求神经元参与的追求眼球运动的产生和微刺激这个区域elavines SEMs通过激活这些追求神经元，因此他们的预测顺利的追求系统的其他部分。
1. Intracortical microstimulation of a portion of the monkey frontal eye field (FEF) lying in the floor and posterior bank of the arcuate sulcus evokes smooth, rather than saccadic eye movements. To further explore this region's involvement in pursuit, we recorded from FEF neurons in the vicinity of sites from which smooth eye movements (SEMs) were elicited electrically and studied their responses during smooth-pursuit and saccadic tasks. In this report, we describe the neurons' responses during visually guided smooth pursuit and compare their locations and response properties with those of elicited SEMs.2. One hundred and ninety-three neurons, recorded from the FEF region in six hemispheres of three rhesus monkeys, were classified as ''pursuit neurons''. These neurons responded during smooth-pursuit tracking of moving visual stimuli but had no, or only minimal, responses in conjunction with visually guided saccades. Pursuit neurons were located in a small region of the arcuate fundus and posterior bank that overlapped, and extended slightly beyond, the region from which SEMs were elicited with microstimulation.3. All pursuit neurons had a preferred pursuit direction, and all directions were represented with no strong bias toward ipsilateral, contralateral, up, or down. The directional tuning of 80 pursuit cells was measured quantitatively by testing pursuit in several directions and fitting the responses to a Gaussian function. Tuning indices (the sigma parameter of the Gaussian fit) varied between 13 degrees and 136 degrees. The median tuning index, 44.5 degrees, corresponds to a full width at half maximum of 105 degrees. The ubiquity of selectivity for pursuit direction and the wide distribution of preferred directions indicates that pursuit direction uses a place-code type of representation in FEF; however, the broad directional tuning of most neurons suggests that pursuit direction is given by a weighted average of optimal directions across the population of pursuit neurons active at any given time.4. In general, the responses of pursuit neurons increased with pursuit velocity. Of 13 neurons formally tested with 2 s of constant-velocity tracking in their preferred direction across a range of target speeds, pursuit velocity sensitivity ranged from 0.24 to 1.42 spikes.s(-1).deg(-1).s(-1), with an average sensitivity of 0.70. This relationship suggests that pursuit neurons represent pursuit magnitude using a rate code; this parallels our previous observation that at most SEM sites, the velocity and acceleration of the electrically elicited eye movements increased as a function of the stimulation current.5. Pursuit responses began at a median latency of 103 ms (n = 69) after target motion began. When latencies were computed relative to the initiation of smooth pursuit, the majority (61%) discharged before pursuit in their preferred direction and the median relative latency was -19 ms (with negative meaning that the discharge preceded pursuit). Thus significant FEF activity could contribute to the early stages of pursuit initiation, consistent with the previous observation that FEF stimulation elicits SEMs from stationary fixation.6. We recorded pursuit responses and subsequently tested microstimulation at 113 sites. Of these, the electrical stimulation yielded SEMs at 27, saccades at 12, and no eye movements at the remaining 74 sites. The response latencies of neurons at SEM sites did not differ from those at sites yielding no elicited eye movements; however, SEMs were elicited more often from sites where neurons preferred pursuit directed ipsilateral to the recording hemisphere, relative to those with contralateral preferred directions.7. The direction of elicited SEMs were correlated with the best tracking direction of neurons recorded at the SEM site (r(+) = 0.71). Despite this highly significant overall correlation, however, elicited SEM direction varied by similar to 40 degrees, on average, from the best pursuit direction of the neuron. This discrepancy may reflect the broad directional tuning of pursuit neurons and the relatively large currents, 50-100 mu A, that were often used to obtain these elicited SEMs.8. The correspondence between the location and direction preferences of pursuit neurons and those of elicited SEMs, as well as the short latencies of the pursuit responses, suggest that FEF pursuit neurons participate in the generation of pursuit eye movements and that microstimulation of this region elicits SEMs by activating these pursuit neurons, and hence their projections to other parts of the smooth pursuit system.