Timora Justin R, Budd Timothy W
Brain Imaging Lab, School of Psychology, University of Newcastle, Ourimbah, NSW, Australia.
Multisens Res. 2018 Jan 1;31(5):391-418. doi: 10.1163/22134808-00002549.
According to the temporal principle of multisensory integration, cross-modal synchronisation of stimulus onset facilitates multisensory integration. This is typically observed as a greater response to multisensory stimulation relative to the sum of the constituent unisensory responses (i.e., superadditivity). The aim of the present study was to examine whether the temporal principle extends to the cross-modal synchrony of amplitude-modulation (AM) rate. It is well established that psychophysical sensitivity to AM stimulation is strongly influenced by AM rate where the optimum rate differs according to sensory modality. This rate-dependent sensitivity is also apparent from EEG steady-state response (SSR) activity, which becomes entrained to the stimulation rate and is thought to reflect neural processing of the temporal characteristics of AM stimulation. In this study we investigated whether cross-modal congruence of AM rate reveals both psychophysical and EEG evidence of enhanced multisensory integration. To achieve this, EEG SSR and psychophysical sensitivity to simultaneous acoustic and/or vibrotactile AM stimuli were measured at cross-modally congruent and incongruent AM rates. While the results provided no evidence of superadditive multisensory SSR activity or psychophysical sensitivity, the complex pattern of results did reveal a consistent correspondence between SSR activity and psychophysical sensitivity to AM stimulation. This indicates that entrained EEG activity may provide a direct measure of cortical activity underlying multisensory integration. Consistent with the temporal principle of multisensory integration, increased vibrotactile SSR responses and psychophysical sensitivity were found for cross-modally congruent relative to incongruent AM rate. However, no corresponding increase in auditory SSR or psychophysical sensitivity was observed for cross-modally congruent AM rates. This complex pattern of results can be understood in terms of the likely influence of the principle of inverse effectiveness where the temporal principle of multisensory integration was only evident in the context of reduced perceptual sensitivity for the vibrotactile but not the auditory modality.
根据多感官整合的时间原则，刺激开始的跨模态同步促进了多感官整合。这通常表现为相对于组成单感官反应的总和，对多感官刺激的反应更大（即超相加性）。本研究的目的是检验时间原则是否扩展到调幅（AM）率的跨模态同步。众所周知，对AM刺激的心理物理敏感性受AM率的强烈影响，其中最佳率因感官模态而异。这种依赖率的敏感性也从脑电图稳态反应（SSR）活动中明显可见，该活动被诱导到刺激率，并被认为反映了AM刺激时间特征的神经处理。在本研究中，我们调查了AM率的跨模态一致性是否揭示了增强多感官整合的心理物理和脑电图证据。为了实现这一点，在跨模态一致和不一致的AM率下测量了对同时出现的听觉和/或振动触觉AM刺激的脑电图SSR和心理物理敏感性。虽然结果没有提供超相加性多感官SSR活动或心理物理敏感性的证据，但复杂的结果模式确实揭示了SSR活动与对AM刺激的心理物理敏感性之间的一致对应关系。这表明，被诱导的脑电图活动可能提供了多感官整合背后皮层活动的直接测量。与多感官整合的时间原则一致，相对于不一致的AM率，发现跨模态一致的振动触觉SSR反应和心理物理敏感性增加。然而，对于跨模态一致的AM率，未观察到听觉SSR或心理物理敏感性相应增加。这种复杂的结果模式可以根据逆有效性原则的可能影响来理解，其中多感官整合的时间原则仅在振动触觉而非听觉模态的感知敏感性降低的背景下才明显。
