Information in Limited-Capacity Neural Codes

描述（由申请人提供）：许多事情同时发生——总是有大量的刺激要被感知，项目要被记住，和行动方案要被计划。大量关于注意力的研究探索了我们有限的大脑是如何屏蔽这种冲击的。这个问题的另一面是，尽管处理能力有限，但有时必须保留有关多个刺激的信息。这一建议探讨了能够同时保存多个听觉信息项目的潜在大脑机制。我们试图了解不同类型的神经编码是如何完成这一壮举的。我们专注于声音定位，这对于交流和避免复杂场景中的危险至关重要。多种声音的定位涉及大脑听觉区域的两种代码：一种是水平声音位置的发射率代码，它叠加在声音频率的地图上。然而，定位的放电率编码的一个关键限制是，由于神经元不能同时以一个以上的放电率放电，因此多个项目的表征似乎是不可能的。因此，我们将研究两种可能性：代码保留多个项目

DESCRIPTION (provided by applicant): Many things happen at once - there are always abundant stimuli to be perceived, items to be remembered, and courses of action to be planned. Considerable research on attention has explored how our limited-capacity brains screen out the onslaught. The flip side of this problem is that sometimes information about multiple stimuli must be preserved despite limitations in processing capacity. This proposal explores potential brain mechanisms capable of preserving multiple auditory items of information simultaneously. We seek to understand how different types of neural codes accomplish this feat. We focus on sound location, which is critical for communicating and avoiding hazards in complex scenes. Localizing multiple sounds involves two types of codes in auditory brain areas: a firing-rate code for horizontal sound location which is superimposed on a map for sound frequency. A critical limitation of the firing- rate code for location, however, is that the representation of multiple iems would appear to be impossible because neurons cannot discharge at more than one firing rate at a time. We will therefore investigate two possibilities: that the code preserves multiple items via segregation into different hills of activity as afforded by the associated frequency map (aim 1), and that the code preserves multiple items by some form of switching behavior, in which individual neurons encode only one stimulus at a time but multiple sounds are represented at the population level and/or across time (aim 2). These experiments will be carried out in the inferior colliculus (IC), an essential processing stage of the auditory pathway: nearly all information reaching higher auditory areas must pass through this structure. Thus, what the IC can encode places boundary conditions on the information that is available to subsequent stages of processing. We will conduct single and multiple electrode recordings of spiking and local field potential activity during performance of a task involving eye movements to multiple sounds. These experiments will yield important insights into many aspects of normal perception and cognition as well as related disorders. The ability to keep multiple items in mind is central t communication, working memory, attention, and sensory-motor skills, and it may be adversely affected in disorders such as attention-deficit disorder, autism, central auditory processing disorder, and age- related hearing loss.