视觉系统有节奏地运行,通过及时协调的感知和注意过程,涉及alpha范围(7-13Hz)中的共存模式,在~10Hz,和θ(3-6Hz)范围,分别。在这里,我们旨在消除任务需求中的变化是否存在歧义,在注意力需求和目标呈现方面,可能会影响行为视觉表现中感知或注意成分的出现,还揭示了两个大脑半球的采样机制可能存在的差异。为了这个目标,视觉空间性能在两个版本的视觉检测任务中被密集采样,其中目标呈现的一侧是固定的(任务1),参与者监测一个单一的半球,或者在试验中随机变化,参与者同时监测两个半球(任务2)。通过光谱分解对性能进行了分析,揭示行为振荡模式。对于任务1,当注意力资源只集中在一个半球时,结果显示了一个振荡模式,波动幅度在10赫兹和6-9赫兹,对于左侧和右侧偏场的刺激,分别,可能代表在左半球和右半球内具有不同效率的感知采样机制。对于任务2,当注意力资源同时部署到两个半场时,对于向左和向右呈现的刺激,都出现了5赫兹的节奏,反映了一个注意的抽样过程,同样由两个半球支撑。总的来说,结果表明,不同的感知和注意采样机制在不同的振荡频率下起作用,其患病率和半球偏侧化取决于任务要求。
The visual system operates rhythmically, through timely coordinated perceptual and attentional processes, involving coexisting patterns in the alpha range (7-13 Hz) at ∼10 Hz, and theta (3-6 Hz) range, respectively. Here we aimed to disambiguate whether variations in task requirements, in terms of attentional demand and side of target presentation, might influence the occurrence of either perceptual or attentional components in behavioral visual performance, also uncovering possible differences in the sampling mechanisms of the two cerebral hemispheres. To this aim, visuospatial performance was densely sampled in two versions of a visual detection task where the side of target presentation was fixed (Task 1), with participants monitoring one single hemifield, or randomly varying across trials, with participants monitoring both hemifields simultaneously (Task 2). Performance was analyzed through spectral decomposition, to reveal behavioral oscillatory patterns. For Task 1, when attentional resources where focused on one hemifield only, the results revealed an oscillatory pattern fluctuating at ∼10 Hz and ∼6-9 Hz, for stimuli presented to the left and the right hemifield, respectively, possibly representing a perceptual sampling mechanism with different efficiency within the left and the right hemispheres. For Task 2, when attentional resources were simultaneously deployed to the two hemifields, a ∼5 Hz rhythm emerged both for stimuli presented to the left and the right, reflecting an attentional sampling process, equally supported by the two hemispheres. Overall, the results suggest that distinct perceptual and attentional sampling mechanisms operate at different oscillatory frequencies and their prevalence and hemispheric lateralization depends on task requirements.