Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, United States.
MRC Centre for Neurodevelopmental Disorders (CNDD), King's College London, London, United Kingdom.
Front Neural Circuits. 2022 Jan 31;15:815554. doi: 10.3389/fncir.2021.815554. eCollection 2021.
Stimulus-selective response plasticity (SRP) is a robust and lasting modification of primary visual cortex (V1) that occurs in response to exposure to novel visual stimuli. It is readily observed as a pronounced increase in the magnitude of visual evoked potentials (VEPs) recorded in response to phase-reversing grating stimuli in neocortical layer 4. The expression of SRP at the individual neuron level is equally robust, but the qualities vary depending on the neuronal type and how activity is measured. This form of plasticity is highly selective for stimulus features such as stimulus orientation, spatial frequency, and contrast. Several key insights into the significance and underlying mechanisms of SRP have recently been made. First, it occurs concomitantly and shares core mechanisms with behavioral habituation, indicating that SRP reflects the formation of long-term familiarity that can support recognition of innocuous stimuli. Second, SRP does not manifest within a recording session but only emerges after an off-line period of several hours that includes sleep. Third, SRP requires not only canonical molecular mechanisms of Hebbian synaptic plasticity within V1, but also the opposing engagement of two key subclasses of cortical inhibitory neuron: the parvalbumin- and somatostatin-expressing GABAergic interneurons. Fourth, pronounced shifts in the power of cortical oscillations from high frequency (gamma) to low frequency (alpha/beta) oscillations provide respective readouts of the engagement of these inhibitory neuronal subtypes following familiarization. In this article we will discuss the implications of these findings and the outstanding questions that remain to gain a deeper understanding of this striking form of experience-dependent plasticity.
刺激选择响应可塑性（SRP）是初级视觉皮层（V1）对新视觉刺激产生的一种强大而持久的修饰，表现为在对新皮质层 4 中相位反转光栅刺激的视觉诱发电位（VEP）记录中，响应幅度明显增加。在个体神经元水平上，SRP 的表达同样强大，但由于神经元类型和活动测量方式的不同，其性质也有所不同。这种形式的可塑性对刺激特征（如刺激方向、空间频率和对比度）具有高度选择性。最近，人们对 SRP 的意义和潜在机制有了一些关键的认识。首先，它与行为习惯化同时发生，并且共享核心机制，表明 SRP 反映了长期熟悉度的形成，这可以支持对无害刺激的识别。其次，SRP 不会在记录过程中表现出来，而是只在离线数小时的睡眠期间后才出现。第三，SRP 不仅需要 V1 内的Hebbian 突触可塑性的典型分子机制，还需要两种关键的皮质抑制性神经元亚类的拮抗作用：表达 parvalbumin 和 somatostatin 的 GABA 能中间神经元。第四，皮质振荡的功率从高频（伽马）到低频（α/β）的显著变化为熟悉化后这两种抑制性神经元亚型的参与提供了相应的读数。在本文中，我们将讨论这些发现的意义以及仍然存在的问题，以深入了解这种引人注目的经验依赖性可塑性。
