Ranaweera Ruwan D, Kwon Minseok, Hu Shuowen, Tamer Gregory G, Luh Wen-Ming, Talavage Thomas M
Department of Electrical & Electronic Engineering, University of Peradeniya, Peradeniya, Sri Lanka; School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA.
School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA.
Hear Res. 2016 Jan;331:57-68. doi: 10.1016/j.heares.2015.09.017. Epub 2015 Oct 28.
This study investigated the hemisphere-specific effects of the temporal pattern of imaging related acoustic noise on auditory cortex activation. Hemodynamic responses (HDRs) to five temporal patterns of imaging noise corresponding to noise generated by unique combinations of imaging volume and effective repetition time (TR), were obtained using a stroboscopic event-related paradigm with extra-long (≥27.5 s) TR to minimize inter-acquisition effects. In addition to confirmation that fMRI responses in auditory cortex do not behave in a linear manner, temporal patterns of imaging noise were found to modulate both the shape and spatial extent of hemodynamic responses, with classically non-auditory areas exhibiting responses to longer duration noise conditions. Hemispheric analysis revealed the right primary auditory cortex to be more sensitive than the left to the presence of imaging related acoustic noise. Right primary auditory cortex responses were significantly larger during all the conditions. This asymmetry of response to imaging related acoustic noise could lead to different baseline activation levels during acquisition schemes using short TR, inducing an observed asymmetry in the responses to an intended acoustic stimulus through limitations of dynamic range, rather than due to differences in neuronal processing of the stimulus. These results emphasize the importance of accounting for the temporal pattern of the acoustic noise when comparing findings across different fMRI studies, especially those involving acoustic stimulation.
本研究调查了成像相关声学噪声的时间模式对听觉皮层激活的半球特异性影响。使用频闪事件相关范式和超长（≥27.5秒）的重复时间（TR）来最小化采集间效应，获得了对与成像体积和有效重复时间（TR）的独特组合产生的噪声相对应的五种成像噪声时间模式的血流动力学反应（HDR）。除了确认听觉皮层中的功能磁共振成像反应并非呈线性表现外，还发现成像噪声的时间模式可调节血流动力学反应的形状和空间范围，经典的非听觉区域对持续时间更长的噪声条件表现出反应。半球分析显示，右侧初级听觉皮层比左侧对成像相关声学噪声的存在更敏感。在所有条件下，右侧初级听觉皮层的反应都明显更大。对成像相关声学噪声的这种反应不对称可能导致在使用短TR的采集方案期间出现不同的基线激活水平，通过动态范围的限制，在对预期声学刺激的反应中产生观察到的不对称，而不是由于刺激的神经元处理存在差异。这些结果强调了在比较不同功能磁共振成像研究的结果时，尤其是那些涉及声学刺激的研究，考虑声学噪声时间模式的重要性。
