Adaptive Rewiring of a Sensory Network through Spike-Timing-Dependent Plasticity

包括人类在内的所有动物的行为都依赖于检测外部感官刺激并做出适当的反应。有各种各样的机制，通过这些机制，感觉系统最大限度地检测对动物很重要的刺激。然而，感官环境是不断变化的。动物如何可靠地探测到与行为相关的感官刺激，同时保持灵活性以适应感官环境的变化？一种可能的机制是突触可塑性，即神经元之间突触连接的强度根据过去的经验进行调整。这个项目的中心假设是，神经网络的内在动力学诱导突触可塑性，从而增加对频繁遇到的刺激的敏感性。突触可塑性在整个大脑中都存在，但直接在活体动物身上进行研究通常具有挑战性。研究人员利用了电鱼独特的实验优势，可以精确地操纵和监测清醒、有行为的动物的感觉神经元的电活动。在社会交际行为的背景下，研究者研究了可塑性如何改变对感觉输入的反应，自然的感觉输入模式是否可以诱导这种可塑性，以及这种可塑性如何影响对刺激的行为检测。这项研究通过阐明感觉系统如何适应不断变化的外部条件具有广泛的意义。此外，在神经科学和行为学方面，电鱼是向公众宣传的绝佳工具。作为外来动物，它们吸引了广泛的观众。该项目包括正在进行的外展和教育活动，向圣路易斯地区的K-12学生讲授假设驱动的科学以及大脑可塑性在感官知觉和行为中的重要性。时间编码与感觉处理、认知和运动控制有关。最近的研究揭示了中枢感觉通路解码时间模式的几种机制。然而，感觉环境是可以改变的。感觉神经科学的一个基本问题是理解中枢回路如何在保持灵活性以适应感觉环境变化的同时，稳健地检测与行为相关的刺激。spike - time -dependent plasticity （STDP）是指突触强度根据突触前和突触后spike的相对时间进行调节，这种可塑性在多种物种的大脑区域中都有发现。然而，它在行为相关刺激处理中的作用仍然存在争议，主要是因为在细胞水平上将突触强度的变化与对行为的影响联系起来本身就很困难。该项目的中心假设是，STDP提供了一种修改网络连接的机制，以使信息处理适应不断变化的感官环境。研究人员通过一种综合的方法来解决这个假设，这种方法利用了电鱼独特的实验优势，其中脉冲的时间模式本身就是行为相关的刺激。结合神经生理学、影像学和行为学，研究人员正在确定STDP如何改变清醒和有行为的动物对感觉输入的反应，感觉输入的自然模式如何引发STDP，以及这些变化如何影响行为刺激检测。该项目包括针对圣路易斯地区K-12学生的推广和教育工作，向他们传授大脑可塑性，以及如何利用科学方法解决大脑如何控制行为的问题。作为拓展的一部分，研究人员领导动手活动，包括对自由行为的鱼进行实验，对参与者进行心理物理实验，以及多媒体演示，以说明大脑的可塑性及其在改变行为方面的作用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Behavior in all animals, including humans, depends on detecting external sensory stimuli and responding appropriately. There are a variety of mechanisms by which sensory systems maximize the detection of stimuli that are important to the animal. However, the sensory environment is constantly changing. How can animals reliably detect behaviorally relevant sensory stimuli while also retaining the flexibility to adapt to changes in the sensory environment? One possible mechanism is synaptic plasticity in which the strengths of the synaptic connections between neurons are adjusted based on past experience. The central hypothesis of this project is that the intrinsic dynamics of neural networks induce synaptic plasticity that results in increased sensitivity to frequently encountered stimuli. Synaptic plasticity is found throughout the brain, but it is generally challenging to study directly in a living animal. The researchers capitalize on the unique experimental advantages of electric fish, in which it is possible to manipulate precisely and monitor the electrical activity of sensory neurons in an awake, behaving animal. In the context of social communication behavior, the researchers study how plasticity alters responses to sensory input, whether natural patterns of sensory input can induce this plasticity, and how this plasticity impacts the behavioral detection of stimuli. This research has broad implications by elucidating how sensory systems adjust to changing external conditions. In addition, electric fish are excellent tools for public outreach in neuroscience and behavior. As exotic animals, they attract a wide audience. The project includes ongoing outreach and education activities to teach K-12 students in the St. Louis region about hypothesis-driven science and the importance of brain plasticity in sensory perception and behavior.Temporal codes have been implicated in sensory processing, cognition, and motor control. Recent studies reveal several mechanisms by which central sensory pathways decode temporal patterns. However, the sensory environment can change. A fundamental problem in sensory neuroscience is understanding how central circuits can robustly detect behaviorally relevant stimuli while retaining the flexibility to adapt to changes in the sensory environment. Spike-timing-dependent plasticity (STDP), in which synaptic strength is adjusted as a function of the relative timing of pre- and postsynaptic spiking, is found in several brain regions across a wide diversity of species. However, its role in the processing of behaviorally relevant stimuli remains controversial, largely because it is inherently difficult to link changes in synaptic strength at the cellular level to effects on behavior. The central hypothesis of this project is that STDP provides a mechanism for modifying network connectivity to adapt information processing to a changing sensory environment. The researchers address this hypothesis by using an integrative approach that capitalizes on the unique experimental advantages of electric fish, in which temporal patterns of spiking are themselves the behaviorally relevant stimulus. Using a combination of neurophysiology, imaging, and behavior, the researchers are determining how STDP alters responses to sensory input in awake and behaving animals, how natural patterns of sensory input can elicit STDP, and how these changes impact behavioral stimulus detection. The project includes outreach and education efforts that target K-12 students in the St. Louis region to teach them about brain plasticity and how the scientific method can be used to address questions about how brains control behavior. As part of the outreach, researchers lead hands-on activities that include experiments with freely behaving fish, psychophysical experiments on participants, and multimedia demonstrations to illustrate brain plasticity and its role in modifying behavior.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.