Bach Eva C, Vaughan John W, Stein Barry E, Rowland Benjamin A
Department Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, United States.
Front Integr Neurosci. 2018 Jan 4;11:40. doi: 10.3389/fnint.2017.00040. eCollection 2017.
Neurons in the superior colliculus (SC) integrate cross-modal inputs to generate responses that are more robust than to either input alone, and are frequently greater than their sum (superadditive enhancement). Previously, the principles of a real-time multisensory transform were identified and used to accurately predict a neuron's responses to combinations of brief flashes and noise bursts. However, environmental stimuli frequently have more complex temporal structures that elicit very different response dynamics than previously examined. The present study tested whether such stimuli (i.e., pulsed) would be treated similarly by the multisensory transform. Pulsing visual and auditory stimuli elicited responses composed of higher discharge rates that had multiple peaks temporally aligned to the stimulus pulses. Combinations pulsed cues elicited multiple peaks of superadditive enhancement within the response window. Measured over the entire response, this resulted in larger enhancements than expected given enhancements elicited by non-pulsed ("sustained") stimuli. However, as with sustained stimuli, the dynamics of multisensory responses to pulsed stimuli were highly related to the temporal dynamics of the unisensory inputs. This suggests that the specific characteristics of the multisensory transform are not determined by the external features of the cross-modal stimulus configuration; rather the temporal structure and alignment of the unisensory inputs is the dominant driving factor in the magnitudes of the multisensory product.
上丘（SC）中的神经元整合跨模态输入，以产生比单独任何一种输入都更强烈的反应，且这种反应通常大于两种输入反应之和（超相加增强）。此前，已确定了实时多感官转换的原理，并用于准确预测神经元对短暂闪光和噪声爆发组合的反应。然而，环境刺激通常具有更复杂的时间结构，会引发与之前研究非常不同的反应动态。本研究测试了这种刺激（即脉冲式）是否会被多感官转换以类似方式处理。脉冲式视觉和听觉刺激引发的反应由更高的放电率组成，这些放电率在时间上有多个峰值与刺激脉冲对齐。组合脉冲线索在反应窗口内引发了多个超相加增强的峰值。在整个反应过程中测量，与非脉冲式（“持续”）刺激引发的增强相比，这导致了更大的增强。然而，与持续刺激一样，对脉冲刺激的多感官反应动态与单感官输入的时间动态高度相关。这表明多感官转换的具体特征不是由跨模态刺激配置的外部特征决定的；相反，单感官输入的时间结构和对齐是多感官乘积大小的主要驱动因素。
