Department of Biomedical Engineering, Columbia University New York, NY, USA ; Human Research and Engineering Directorate, US Army Research Laboratory Aberdeen, MD, USA.
Front Hum Neurosci. 2013 Mar 18;7:67. doi: 10.3389/fnhum.2013.00067. eCollection 2013.
Important decisions in the heat of battle occur rapidly and a key aptitude of a good combat soldier is the ability to determine whether he is under fire. This rapid decision requires the soldier to make a judgment in a fraction of a second, based on a barrage of multisensory cues coming from multiple modalities. The present study uses an oddball paradigm to examine listener ability to differentiate shooter locations from audio recordings of small arms fire. More importantly, we address the neural correlates involved in this rapid decision process by employing single-trial analysis of electroencephalography (EEG). In particular, we examine small arms expert listeners as they differentiate the sounds of small arms firing events recorded at different observer positions relative to a shooter. Using signal detection theory, we find clear neural signatures related to shooter firing angle by identifying the times of neural discrimination on a trial-to-trial basis. Similar to previous results in oddball experiments, we find common windows relative to the response and the stimulus when neural activity discriminates between target stimuli (forward fire: observer 0° to firing angle) vs. standards (off-axis fire: observer 90° to firing angle). We also find, using windows of maximum discrimination, that auditory target vs. standard discrimination yields neural sources in Brodmann Area 19 (BA 19), i.e., in the visual cortex. In summary, we show that single-trial analysis of EEG yields informative scalp distributions and source current localization of discriminating activity when the small arms experts discriminate between forward and off-axis fire observer positions. Furthermore, this perceptual decision implicates brain regions involved in visual processing, even though the task is purely auditory. Finally, we utilize these techniques to quantify the level of expertise in these subjects for the chosen task, having implications for human performance monitoring in combat.
在激烈的战斗中，重要的决策会迅速做出，而一名优秀战斗士兵的关键能力是能够判断自己是否处于火力之下。这种快速决策要求士兵在一瞬间基于来自多个模态的大量多感觉线索做出判断。本研究使用一种奇特的范式来检查听众区分射击者位置的能力，以及从小武器射击声音记录中获得的音频记录。更重要的是，我们通过使用脑电图（EEG）的单次试验分析来解决这个快速决策过程中涉及的神经相关性。特别是，我们检查了小武器专家听众，因为他们根据相对于射击者的不同观察者位置来区分小武器射击事件的声音。使用信号检测理论，我们通过在试验基础上识别神经区分的时间，找到与射击者射击角度相关的清晰的神经特征。与奇特实验中的先前结果相似，我们发现当神经活动在目标刺激（前火：观察者 0°至射击角度）与标准刺激（偏轴火：观察者 90°至射击角度）之间进行区分时，相对于响应和刺激存在共同的窗口。我们还发现，使用最大区分窗口，听觉目标与标准的区分在 Brodmann 区域 19（BA 19）中产生神经源，即视觉皮层中。总之，当小武器专家区分前火和偏轴火观察者位置时，我们表明 EEG 的单次试验分析可产生有信息量的头皮分布和源电流定位的区分活动。此外，即使任务完全是听觉的，这种感知决策也涉及到参与视觉处理的大脑区域。最后，我们利用这些技术来量化这些主题在所选任务中的专业水平，这对战斗中的人类性能监测具有重要意义。
