Data_Sheet_4_Incidental or Intentional? Different Brain Responses to One's Own Action Sounds in Hurdling vs. Tap Dancing.docx

Most human actions produce concomitant sounds. Action sounds can be either part of the action goal (GAS, goal-related action sounds), as for instance in tap dancing, or a mere by-product of the action (BAS, by-product action sounds), as for instance in hurdling. It is currently unclear whether these two types of action sounds—incidental or intentional—differ in their neural representation and whether the impact on the performance evaluation of an action diverges between the two. We here examined whether during the observation of tap dancing compared to hurdling, auditory information is a more important factor for positive action quality ratings. Moreover, we tested whether observation of tap dancing vs. hurdling led to stronger attenuation in primary auditory cortex, and a stronger mismatch signal when sounds do not match our expectations. We recorded individual point-light videos of newly trained participants performing tap dancing and hurdling. In the subsequent functional magnetic resonance imaging (fMRI) session, participants were presented with the videos that displayed their own actions, including corresponding action sounds, and were asked to rate the quality of their performance. Videos were either in their original form or scrambled regarding the visual modality, the auditory modality, or both. As hypothesized, behavioral results showed significantly lower rating scores in the GAS condition compared to the BAS condition when the auditory modality was scrambled. Functional MRI contrasts between BAS and GAS actions revealed higher activation of primary auditory cortex in the BAS condition, speaking in favor of stronger attenuation in GAS, as well as stronger activation of posterior superior temporal gyri and the supplementary motor area in GAS. Results suggest that the processing of self-generated action sounds depends on whether we have the intention to produce a sound with our action or not, and action sounds may be more prone to be used as sensory feedback when they are part of the explicit action goal. Our findings contribute to a better understanding of the function of action sounds for learning and controlling sound-producing actions.

绝大多数人类动作都会伴随产生相应的声音。动作声音可分为两类：一类是与动作目标相关的动作声音（goal-related action sounds, GAS），例如踢踏舞动作；另一类则是动作产生的附带产物（by-product action sounds, BAS），例如跨栏动作。目前尚不明确这两类动作声音——附带性或意向性——在神经表征上是否存在差异，以及二者对动作表现评估的影响是否存在分歧。
本研究旨在探究，相较于跨栏动作，在观察踢踏舞动作时，听觉信息是否对正向动作质量评分具有更重要的影响。此外，我们还测试了：相较于跨栏动作，观察踢踏舞动作是否会引发初级听觉皮层更强的激活衰减，以及当声音与预期不符时是否会产生更强的失匹配信号。
我们录制了新受训参与者完成踢踏舞与跨栏动作的个体点光视频（point-light videos）。在后续的功能磁共振成像（functional magnetic resonance imaging, fMRI）扫描环节中，向参与者展示包含自身动作及对应动作声音的视频，并要求其对动作表现质量进行评分。视频分为四种呈现形式：原始完整形式、仅视觉模态打乱、仅听觉模态打乱，或二者同时打乱。
正如研究假设所示，行为学结果显示：当听觉模态被打乱时，GAS条件下的评分显著低于BAS条件。BAS与GAS动作的功能磁共振成像对比结果表明，BAS条件下初级听觉皮层激活程度更高，这支持了GAS条件下激活衰减更强的推论；同时GAS条件下后颞上回与辅助运动区的激活程度更强。
研究结果表明，对自主产生的动作声音的加工，取决于我们是否意图通过动作产生声音；而当动作声音属于明确的动作目标组成部分时，其更易被用作感官反馈。本研究结果有助于进一步理解动作声音在学习与控制发声动作中的功能。