Neuroscience Graduate Program, Oregon Health and Science University, OR, USA.
Oregon Hearing Research Center, Oregon Health and Science University, OR, USA.
Cereb Cortex. 2018 Jan 1;28(1):323-339. doi: 10.1093/cercor/bhx288.
Auditory selective attention is required for parsing crowded acoustic environments, but cortical systems mediating the influence of behavioral state on auditory perception are not well characterized. Previous neurophysiological studies suggest that attention produces a general enhancement of neural responses to important target sounds versus irrelevant distractors. However, behavioral studies suggest that in the presence of masking noise, attention provides a focal suppression of distractors that compete with targets. Here, we compared effects of attention on cortical responses to masking versus non-masking distractors, controlling for effects of listening effort and general task engagement. We recorded single-unit activity from primary auditory cortex (A1) of ferrets during behavior and found that selective attention decreased responses to distractors masking targets in the same spectral band, compared with spectrally distinct distractors. This suppression enhanced neural target detection thresholds, suggesting that limited attention resources serve to focally suppress responses to distractors that interfere with target detection. Changing effort by manipulating target salience consistently modulated spontaneous but not evoked activity. Task engagement and changing effort tended to affect the same neurons, while attention affected an independent population, suggesting that distinct feedback circuits mediate effects of attention and effort in A1.
听觉选择性注意对于解析嘈杂的声学环境是必需的，但介导行为状态对听觉感知影响的皮质系统尚未得到很好的描述。先前的神经生理学研究表明，注意力会对重要目标声音相对于无关干扰的神经反应产生普遍增强。然而，行为研究表明，在掩蔽噪声的存在下，注意力会对与目标竞争的干扰物进行焦点抑制。在这里，我们比较了注意力对掩蔽和非掩蔽干扰物的皮质反应的影响，同时控制了听力努力和一般任务参与的影响。我们在动物行为期间记录了雪貂初级听觉皮层 (A1) 的单个神经元活动，发现与光谱上不同的干扰物相比，选择性注意力降低了对相同光谱带中掩蔽目标的干扰物的反应。这种抑制增强了神经靶检测阈值，表明有限的注意力资源有助于集中抑制干扰目标检测的干扰物的反应。通过操纵目标显著性来改变努力程度，一致地调制自发但不诱发的活动。任务参与度和努力程度往往会影响相同的神经元，而注意力则会影响独立的神经元群体，这表明不同的反馈回路在 A1 中介导注意力和努力的影响。
