Functionally Distinct Gamma Range Activity Revealed by Stimulus Tuning in Human Visual Cortex
Functionally Distinct Gamma Range Activity Revealed by Stimulus Tuning in Human Visual Cortex
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DOI：
10.1016/j.cub.2019.08.004
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发表时间：
2019-10-21
期刊：
影响因子：
9.2
通讯作者：
Foster, Brett L.
中科院分区：
文献类型：
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作者：
Bartoli, Eleonora;Bosking, William;Foster, Brett L.
长期以来，新皮质伽玛活动一直被假设为同步大脑区域以支持更广泛的视觉感知和认知的机制。虽然早期研究集中在窄带伽马振荡（类似于 20-60 Hz），但最近的工作强调了更宽带的“高伽马”响应（类似于 70-150+ Hz）。这些响应通常在概念上或分析上被视为伽马活动的同义标记。使用来自人类视觉皮层的高密度颅内记录，我们通过显示窄带和宽带伽马的不同光谱、时间和功能特性来挑战这一观点。在四个实验中，窄带伽马对光栅和长波长颜色有很强的选择性，显示出延迟的响应开始、持续的时间分布和对比度相关的峰值频率。此外，诱导的窄带伽马振荡在刺激重复中缺乏相位一致性，并显示出高度的焦点间同步。相反，宽带伽马对所有呈现的刺激都被一致地观察到，显示出快速响应开始、瞬态时间分布和不变的光谱特性。与宽带高伽玛不同，视觉窄带伽玛振荡的发生似乎取决于与感受野相交的特定结构和色彩刺激属性，这些发现对新皮质伽玛范围活动的研究、分析和功能解释具有重要意义。
Neocortical gamma activity has long been hypothesized as a mechanismfor synchronizing brain regions to support visual perception and cognition more broadly. Although early studies focused on narrowband gamma oscillations (similar to 20-60 Hz), recent work has emphasized a more broadband "high-gamma'' response (similar to 70-150+ Hz). These responses are often conceptually or analytically treated as synonymous markers of gamma activity. Using high-density intracranial recordings from the human visual cortex, we challenge this view by showing distinct spectral, temporal, and functional properties of narrow and broadband gamma. Across four experiments, narrowband gamma was strongly selective for gratings and long-wavelength colors, displaying a delayed response onset, sustained temporal profile, and contrast-dependent peak frequency. In addition, induced narrowband gamma oscillations lacked phase consistency across stimulus repetitions and displayed highly focal inter-site synchronization. In contrast, broadband gamma was consistently observed for all presented stimuli, displaying a rapid response onset, transient temporal profile, and invariant spectral properties. We exploited stimulus tuning to highlight the functional dissociation of these distinct signals, reconciling prior inconsistencies across species and stimuli regarding the ubiquity of visual gamma oscillations during natural vision. The occurrence of visual narrowband gamma oscillations, unlike broadband high gamma, appears contingent on specific structural and chromatic stimulus attributes intersecting with the receptive field. Together, these findings have important implications for the study, analysis, and functional interpretation of neocortical gamma-range activity.