【作者】 李宝林； 黄希庭；

【Author】 Li Baolin;Huang Xiting;Faculty of Psychology, Southwest University;

【机构】 西南大学心理学部；

【摘要】 反复呈现某一特定的时距信息,会改变被试对后续一定范围内的时距信息的知觉。例如,反复向被试呈现一个较长或较短的适应时距,再给被试呈现一个中等的测试时距,相比无适应条件被试会低估或高估中等的测试时距。这种现象被称为时距知觉的适应后效。对于时距知觉适应后效产生的原因,通道模型给出了一种解释。这一模型认为,个体的大脑中存在一些专门加工不同时距信息的神经元。这些神经元都具有各自偏好加工的时距信息,即它们对时距信息的加工具有选择性。因此,某一特定时距信息的重复出现,可以降低特定神经元的反应,进而改变整群神经元的反应模式,最终导致个体对后续时距信息知觉的偏差。虽然通道模型为时距知觉适应后效提供了一种可能的解释,然而目前人们仍不知道导致时距知觉适应后效的神经适应到底发生在大脑的哪个位置。因为,本研究采用长时程的fMRI适应范式探讨了视时距知觉适应后效的神经基础。研究发现视时距知觉适应导致了显著的视时距知觉适应后效,即相比适应不一致时距条件,适应一致时距(500 ms)导致被试高估了较长的测试时距(875 ms)和低估了较短的测试时距(286ms)。此外,研究发现当测试时距和适应时距一致时,左侧前扣带/辅助运动区在加工测试时距时的神经活动显著降低,并且当不要求被试进行外显的时距加工时或者仅当适应刺激和测试刺激的大小一致时,左侧前扣带/辅助运动区的神经活动并不受适应的影响,这说明这一脑区神经活动的降低对外显的时距加工具有特异性。据此,本研究说明在左侧前扣带/辅助运动区存在对时距信息具有选择性加工的神经元,这一脑区的神经适应可能是视时距知觉适应后效产生的神经基础。更多还原

【Abstract】 It has been established that repetitive exposure to a particular duration, the subsequent durations within a certain range appear to be distorted. For example, adaptation to relatively long or short sensory events has been shown to shorten or lengthen the perceived duration of a subsequent medium event. This phenomenon is termed the duration aftereffect, and illustrates how the subsequent perceived duration can be affected by duration adaptation. The channel-based model explains this aftereffect of perceived duration. This model proposes that there are duration-tuned neurons in our brain, each of which responds selectively to a narrow range of the durations centered on its preferred duration. Moreover, the repetitive exposure to a given duration could diminish the responses of the corresponding neurons and alter the relative activation of the population, thereby resulting in duration aftereffect. However, the neural locus of neural adaptation which induced the duration aftereffect is unclear. Therefore, in the present study we investigated the neural basis of visual duration aftereffect using the long-term f MRI adaptation paradigm. The results showed that the visual duration adaptation induced significant visual duration aftereffect. That is, when compared with adaptation to incongruent visual durations, participants overestimated the duration of longer(875 ms) test stimulus and underestimated the duration of shorter(286 ms) test stimulus under adaptation to congruent visual duration(500 ms). Furthermore, the results found that when the adapting duration and the test duration were identical, the left anterior cingulate/supplementary motor area exhibited reduction in neural activity. However, when participants were not asked to explicitly process the duration information, or when only the sizes of adapting and test stimuli were same, the left anterior cingulate/supplementary motor area did not exhibit reduction in neural activity, which suggests the neural adaptation is specific to the explicit timing. These results suggest the left anterior cingulate/supplementary motor area contains duration-tuned neurons and their neural adaptation may be the neural basis of visual duration aftereffect.更多还原