Perceptual and motor processing stages identified in the activity of macaque frontal eye field neurons during visual search
Perceptual and motor processing stages identified in the activity of macaque frontal eye field neurons during visual search
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DOI：
10.1152/jn.1996.76.6.4040
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发表时间：
1996-12-01
影响因子：
2.5
通讯作者：
Schall, JD
中科院分区：
文献类型：
--
作者：
Thompson, KG;Hanes, DP;Schall, JD
1.在人类和猴子的试验中，弹出搜索显示器的出现与眼球运动到显示器的古怪目标之间的延迟是不同的。反应时间的延迟和变化的来源是未知的，但已被归因于尚未明确定义的决策过程。我们记录了神经活动的额叶眼场（FEF），一个地区被认为是发挥核心作用，在生产有目的的眼球运动，猴子（猕猴）执行弹出视觉搜索任务。分析了84个具有视觉诱发活动的神经元。这些神经元中有12个与视觉刺激的呈现相关的阶段性反应。剩下的神经元有更多的紧张性反应，并在扫视过程中持续存在。许多具有更多紧张性反应的神经元类似于视觉运动细胞，因为它们在扫视进入其反应场之前具有增加的活动。采用Poisson峰电位分析法测定FEF神经元的视觉反应潜伏期。平均视觉潜伏期为67 ms（最小= 35 ms，最大= 138 ms）。对单独呈现的目标、同时呈现的目标和同时呈现的目标的视觉反应潜伏期无显著差异。FEF神经元的初始视觉激活不区分目标与弹出视觉搜索刺激阵列的干扰物，但活动演变到区分搜索显示的目标是否在感受野内的状态。我们测试了这样一个假设，即眼跳潜伏期的可变性来源是参与眼跳编程的神经元选择凝视转移的目标所花费的时间。与使用的分析适应信号检测理论，我们确定当单个FEF神经元的活动可以可靠地指示是否存在的目标或干扰在其响应字段。目标辨别的时间将反应时间分为感知阶段和运动阶段，感知阶段发生目标辨别，运动阶段发生眼跳编程和生成。目标辨别的时间最常发生在刺激呈现后120 - 150 ms之间.我们分析了在将试验分为短、中、长扫视潜伏期组后，单细胞活动中目标辨别的时间过程。眼跳潜伏期与知觉阶段的持续时间不相关，但与运动阶段的持续时间相关。这一结果与FEF神经元标记的目标辨别所花费的时间解释了运动启动时间的广泛变化的假设不一致。我们的结论是，在一个简单的视觉搜索任务中观察到的变化性眼跳lasting在很大程度上是由于知觉后运动处理目标歧视。知觉和知觉后加工的特征在FEF中都很明显。在输出阶段的拖延可能会防止刻板行为，这将是不适应不断变化的环境。
1. The latency between the appearance of a popout search display and the eye movement to the oddball target of the display varies from trial to trial in both humans and monkeys. The source of the delay and variability of reaction time is unknown but has been attributed to as yet poorly defined decision processes.2. We recorded neural activity in the frontal eye field (FEF), an area regarded as playing a central role in producing purposeful eye movements, of monkeys (Macaca mulatta) performing a popout visual search task. Eighty-four neurons with visually evoked activity were analyzed. Twelve of these neurons had a phasic response associated with the presentation of the visual stimulus. The remaining neurons had more tonic responses that persisted through the saccade. Many of the neurons with more tonic responses resembled visuomovement cells in that they had activity that increased before a saccade into their response field.3. The visual response latencies of FEF neurons were determined with the use of a Poisson spike train analysis. The mean visual latency was 67 ms (minimum = 35 ms, maximum = 138 ms). The visual response latencies to the target presented alone, to the target presented with distracters, or to the distracters did not differ significantly.4. The initial visual activation of FEF neurons does not discriminate the target from the distracters of a popout visual search stimulus array, but the activity evolves to a state thar discriminates whether the target of the search display is within the receptive field. We tested the hypothesis that the source of variability of saccade latency is the time taken by neurons involved in saccade programming to select the target for the gaze shift.5. With the use of an analysis adapted from signal detection theory, we determined when the activity of single FEF neurons can reliably indicate whether the target or distracters are present within their response fields. The time of target discrimination partitions the reaction time into a perceptual stage in which target discrimination takes place, and a motor stage in which saccade programming and generation take place. The time of target discrimination occurred most often between 120 and 150 ms after stimulus presentation.6. We analyzed the time course of target discrimination in the activity of single cells after separating trials into short, medium, and long saccade latency groups. Saccade latency was not correlated with the duration of the perceptual stage but was correlated with the duration of the motor stage. This result is inconsistent with the hypothesis that the time taken for target discrimination, as indexed by FEF neurons, accounts for the wide variability in the time of movement initiation.7. We conclude that the variability observed in saccade latencies during a simple visual search task is largely due to postperceptual motor processing following target discrimination. Signatures of both perceptual and postperceptual processing are evident in FEF. Procrastination in the output stage may prevent stereotypical behavior that would be maladaptive in a changing environment.