Cardin Jessica A, Schmidt Marc F
Department of Biology and Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Neurophysiol. 2003 Nov;90(5):2884-99. doi: 10.1152/jn.00391.2003. Epub 2003 Jul 23.
We used auditory responsiveness in the avian song system to investigate the complex relationship between behavioral state and sensory processing in a high-order sensorimotor brain area. We present evidence from recordings in awake, anesthetized, and sleeping male zebra finches (Taeniopygia guttata) that auditory responsiveness in nucleus HVc is profoundly affected by changes in behavioral state. In anesthetized and sleeping birds, auditory responses were characterized by an increase in firing rate that was selective for the bird's own song (BOS) and highly stable over time. In contrast, HVc responses during wakefulness were extremely variable and transitioned between undetectable and robust levels over short intervals. Surprisingly, auditory responses in awake birds were not selective for the BOS stimulus. The variability of HVc auditory responses in awake birds suggests that, as in mammals, wakefulness is not a uniform behavioral state. Rather, auditory responsiveness likely is continually influenced by variables such as arousal state. We therefore developed several experimental paradigms in which we could manipulate arousal levels during auditory stimulus presentation. In all cases, arousal suppressed HVc auditory responses. This effect was specific to the song system, as auditory responses in Field L, a primary auditory area that is a source of auditory input to HVc, were unaffected. While arousal acts as a negative regulator of HVc auditory responsiveness, the presence and variability of the responses observed in awake, alert birds suggests that other mechanisms, such as attention, may enhance auditory responsiveness. The interplay between behavioral state and sensory processing may regulate song system responsiveness according to the bird's behavioral and social context.
我们利用鸟类鸣叫系统中的听觉反应性，来研究高阶感觉运动脑区中行为状态与感觉处理之间的复杂关系。我们提供了来自清醒、麻醉和睡眠状态下雄性斑胸草雀（Taeniopygia guttata）记录的证据，表明HVC核中的听觉反应性受到行为状态变化的深刻影响。在麻醉和睡眠的鸟类中，听觉反应的特征是放电率增加，这种增加对鸟类自身的歌声（BOS）具有选择性，并且随时间高度稳定。相比之下，清醒时HVC的反应极具变异性，在短时间内会在不可检测和强烈反应水平之间转换。令人惊讶的是，清醒鸟类的听觉反应对BOS刺激没有选择性。清醒鸟类中HVC听觉反应的变异性表明，与哺乳动物一样，清醒并非一种统一的行为状态。相反，听觉反应性可能持续受到诸如觉醒状态等变量的影响。因此，我们开发了几种实验范式，在其中可以在听觉刺激呈现期间操纵觉醒水平。在所有情况下，觉醒都会抑制HVC的听觉反应。这种效应是鸣唱系统特有的，因为L区（作为HVC听觉输入来源的初级听觉区域）的听觉反应不受影响。虽然觉醒作为HVC听觉反应性的负调节因子，但在清醒、警觉的鸟类中观察到的反应的存在和变异性表明，其他机制（如注意力）可能会增强听觉反应性。行为状态与感觉处理之间的相互作用可能根据鸟类的行为和社会背景来调节鸣唱系统的反应性。
