Sharp emergence of feature-selective sustained activity along the dorsal visual pathway.
Sharp emergence of feature-selective sustained activity along the dorsal visual pathway.
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DOI：
10.1038/nn.3785
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发表时间：
2014-09
影响因子：
25
通讯作者：
Martinez-Trujillo JC
中科院分区：
文献类型：
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作者：
Mendoza-Halliday D;Torres S;Martinez-Trujillo JC
在灵长类动物的几个皮层区域已经观察到编码视觉工作记忆表征的持续活动。这种活动是在沿着视觉通路的什么地方出现的，目前还不清楚。在这里，我们表明，在猕猴中，持续的尖峰活动编码记忆的视觉运动方向是不存在的方向选择神经元在早期视觉区中颞叶（MT）。然而，它强烈地存在于紧邻下游的多模态关联区内侧上级颞叶（MST）和外侧前额叶皮层（LPFC）中。这种持续活动沿着背侧通路的急剧出现表明，在编码感觉输入的早期视觉区和编码记忆表征的下游关联区之间存在功能边界。此外，MT中的局部场电位振荡对记忆的方向进行编码，并且在低频下与LPFC尖峰相一致。这表明LPFC持续活动调节MT的突触活动，这是一种假定的自上而下的机制，记忆信号通过这种机制影响早期视皮层的刺激处理。
Sustained activity encoding visual working memory representations has been observed in several cortical areas of primates. Where along the visual pathways this activity emerges remains unknown. Here we show in macaques that sustained spiking activity encoding memorized visual motion directions is absent in direction-selective neurons in early visual area middle temporal (MT). However, it is robustly present immediately downstream, in multimodal association area medial superior temporal (MST), and in the lateral prefrontal cortex (LPFC). This sharp emergence of sustained activity along the dorsal pathway suggests a functional boundary between early visual areas, encoding sensory inputs, and downstream association areas, additionally encoding mnemonic representations. Moreover, local field potential oscillations in MT encoded the memorized directions and, in the low frequencies, were phase-coherent with LPFC spikes. This suggests that LPFC sustained activity modulates synaptic activity in MT, a putative top-down mechanism by which memory signals influence stimulus processing in early visual cortex.