| 中文题名： | 利用两步眼跳任务探索空间记忆的跨眼跳更新策略 |
| 姓名： | |
| 保密级别： | 公开 |
| 论文语种： | 中文 |
| 学科代码： | 04020002 |
| 学科专业： | |
| 学生类型： | 硕士 |
| 学位： | 理学硕士 |
| 学位类型： | |
| 学位年度： | 2022 |
| 校区： | |
| 学院： | |
| 第一导师姓名： | |
| 第一导师单位： | |
| 提交日期： | 2022-06-21 |
| 答辩日期： | 2022-06-07 |
| 外文题名： | MECHANISM OF SPATIAL MEMORY UPDATING ACROSS SACCADE IN DOUBLE-STEP SACCADE TASK |
| 中文关键词： | |
| 中文摘要： |
认知神经科学中的一个重要问题便是理解大脑是如何将输入的视觉信息进
行编码并指导准确的空间定位行为的。外界的视觉信息首先进入眼球的视网膜，
而清晰的视觉主要来自视网膜的中央凹，中央凹由紧密排列的视锥细胞所编码，
此时的视觉信息是以网膜中心坐标系编码的，视觉信息在视觉皮层一层层向上传
导的过程中也大致遵循了这种视网膜中心坐标系的结构。但考虑到眼球会以每秒
2 到 3 次的频率进行眼跳，该网膜中心坐标系的原点会随着眼球运动发生相应的
位移，要整合多次眼动前后的视觉信息形成稳定的空间表征，就需要关于眼位置
变化的信息。目前已经经过实验证明的可以提供眼位置的信号有眼本体感受信号
和动作副本信号，这两种信号作为对视觉信号的补充，被统称作网膜外信号。现
有研究认为两种信号在时程上具有不同的特点，但都可以与来自视网膜的视觉信
息结合，以帮助灵长类大脑进行空间定位和产生准确的眼动或躯体运动。
本文主要通过两步眼跳任务来理解视觉空间信息如何随快速的眼跳更新并
指导完成准确的空间定位行为。在传统的两步眼跳任务基础上，我们还引入了改
进的两步眼跳任务，利用巩膜线圈记录猕猴完成任务时的眼位置信号，探索不同
呈现形式下的两步眼跳任务中，猕猴所采用的策略。而猕猴所采用的策略除了反
映在初次眼跳反应时与眼跳间隔期的相关关系外，还反映在两步眼跳落点间的相
关性。本实验结果表明由传统的两步眼跳任务转向改进的两步眼跳任务时，猕猴
所采用的策略也从并行编码为主转为序列编码为主，对于序列编码策略，已有的
研究认为该策略需要来自动作副本的信号来提供即时的眼位置信息。我们认为目
前较多已有的采用传统两步眼跳任务进行的研究未能对大脑能采用的策略进行
有效控制，被试或猕猴在传统的了两步眼跳任务中所展示的行为结果并不能完全
从空间信息更新能力是否完好角度来解释。
本论文还尝试进行了对猕猴顶叶皮层 LIP 神经元的胞外电生理记录，目前有
记录发现 LIP 神经元的感受野不仅可以对传统的视觉刺激做出反应，也可以对出
现在感受野内的记忆踪迹产生发放活动，而这种发放活动表明 LIP 作为视觉信息
处理的高级皮层，能够通过某种神经运算，获得第二步眼跳靶点随眼跳更新后的
空间位置，此类神经元的发现能够支持感受野重构假说。
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| 外文摘要： |
A major question in cognitive neuroscience research is how the brain encode the
visual information coming from our eyes and use these information to facilitate spatial
localization. Visual information first entered the center of retina called fovea, where
densely packed cone cells could be found, these cells then coded the incoming visual
information in a retinotopic map. This retinotopic representation is present even in
brain areas that are high on visual processing hierarchy. However, with our eyes
constantly moving, making fast ballistic eye movement called saccades, maintaining a
coherent spatial representation requires the combination of visual information from
multiple saccades and fixations, this process requires information regarding eye
position changes. Researchers have been able to demonstrate two signals that can
fulfill this need. One is oculomotor proprioceptive signal and the other is corollary
discharge, despite following different time course and being transmitted in different
neuronal circuits, plenty of studies have demonstrated they play a vital role in creating
a stable visual perception, sometimes refered as extraretinal signals, the two signals
were actively engaged in the spatial localization and motor behaviors.
In order to understand the details about how visual information is updated across
saccades, we gathered and analysed eye-trace data from two monkeys using
traditional double-step task and a modified double-step saccade task. Specifically, we
are interested in the strategy the primate brain adopt to solve this task, besides the
critical evidence coming from reaction time measurements, we also tried to analyse
whether the variability coming from first saccade is inherited or compensated in the
4second saccade. Our results suggest when performing modified double-step saccade
task, less correlation is found for saccade endpoint variability, we believe this is the
result of using serial processing strategy and corrollary discharge information with
short delay is crucial in this strategy. We believe by taking a closer look at the strategy
the primate brain adopts could help to explain some of the ambiguity in the existing
literature using double-step saccade task.
We also recorded single-unit LIP neuronal activity while monkeys were
performing memory-guided saccade and the modified double-step saccade task, we
observed neurons that are active during the delay period in memory-guided saccade
and activity related to the memory trace of visual targets in the modified double-step
saccade task, we believe memory remapping mechanism may be a manifestation of
LIP neurons implement computation that update the spatial location of memory
targets, and these findings could further support the remapping hypothesis of visual
stability
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| 参考文献总数： | 66 |
| 开放日期： | 2023-06-21 |
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