Institute of Psychology, Osnabrück University, Seminarstraße 20, 49074, Osnabrück, Germany.
DRK-Norddeutsches Epilepsiezentrum für Kinder und Jugendliche, Henry-Dunant-Str. 6-10, 24223, Schwentinental, Germany.
Exp Brain Res. 2020 Jun;238(6):1399-1410. doi: 10.1007/s00221-020-05819-6. Epub 2020 May 3.
Gist perception refers to perceiving the substance or general meaning of a scene. To investigate its neuronal mechanisms, we used the steady-state visually evoked potential (SSVEP) method-an evoked oscillatory cortical response at the same frequency as a visual stimulus flickered at this frequency. Two neighboring stimuli were flickered at different frequencies f and f, for example, a drawing of a sun on the left side of the screen flickering at 8.6 Hz and the drawing of a parasol on the right side of the screen flickering at 12 Hz. SSVEPs enabled us to separate the responses to the two distinct stimuli by extracting oscillatory brain responses at f and f. Additionally, it allowed to investigate intermodulation frequencies, that is, the brain's response at a linear combination of f and f (here at f + f = 20.6 Hz) as an indicator of processing shared aspects of the input, that is, gist perception (here: a beach scene). We recorded high-density EEG of 18 participants. Results revealed clear and separable neuronal oscillations at f and f. Additionally, occipital electrodes showed increased amplitudes at the intermodulation frequency in related as compared to unrelated pairs. The increase in intermodulation frequency was associated with bilateral temporal and parietal lobe activation, probably reflecting the interaction of local object representations as a basis for activating the gist network. The study demonstrates that SSVEPs are an excellent method to unravel mechanisms underlying the processing within multi-stimulus displays in the context of gist perception.
大意感知是指感知场景的实质或大意。为了研究其神经机制，我们使用了稳态视觉诱发电位（SSVEP）方法——在与视觉刺激以相同频率闪烁的刺激下，大脑皮层会产生一种振荡反应。例如，在屏幕的左侧闪烁频率为 8.6Hz 的太阳图案，在屏幕的右侧闪烁频率为 12Hz 的遮阳伞图案。SSVEP 可以通过提取频率为 f 和 f 的振荡脑响应来分离对两个不同刺激的响应。此外，它还可以研究互调频率，即大脑对 f 和 f 的线性组合（此处为 f + f = 20.6Hz）的响应，作为处理输入共享方面的指标，即大意感知（此处为：海滩场景）。我们记录了 18 名参与者的高密度 EEG。结果表明，在 f 和 f 处存在明显且可分离的神经元振荡。此外，与不相关的对相比，相关对的枕叶电极在互调频率处显示出更高的振幅。互调频率的增加与双侧颞叶和顶叶的激活有关，可能反映了局部对象表示的相互作用，作为激活大意网络的基础。该研究表明，SSVEP 是一种极好的方法，可以在大意感知的背景下揭示多刺激显示中处理机制的奥秘。
