Information Processing Laboratory, Department of Electronics and Electrical Communication Engineering, IIT Kharagpur, Kharagpur 721302, India.
Advanced Technology Development Centre, IIT Kharagpur, Kharagpur 721302, India.
J Neurosci. 2022 Feb 23;42(8):1454-1476. doi: 10.1523/JNEUROSCI.0431-21.2021. Epub 2021 Dec 23.
Sensory experience during a critical period alters sensory cortical responses and organization. We find that the earliest sound-driven activity in the mouse auditory cortex (ACX) starts before ear-canal opening (ECO). The effects of auditory experience before ECO on ACX development are unknown. We find that in mouse ACX subplate neurons (SPNs), crucial in thalamocortical maturation, respond to sounds before ECO showing oddball selectivity. Before ECO, SPNs are more selective to oddball sounds in auditory streams than thalamo-recipient layer 4 (L4) neurons and not after ECO. We hypothesize that SPN's oddball selectivity can direct the development of L4 responses before ECO. Exposing mice, of either sex, before ECO to a rarely occurring tone in a stream of another tone occurring frequently leads to strengthening the adult cortical representation of the rare tone, but not that of the frequent tone. Results of control exposure experiments at multiple developmental windows that also use only a single tone corroborate the observations. We further explain the strengthening of deviant inputs before ECO and not after ECO using a binary network model mimicking the hierarchical structure of subplate and L4 neurons and response properties derived from our data, with synapses following Hebbian spike time-dependent plasticity learning rule. Information-theoretic analysis with sparse coding assumptions also predicts the observations. Thus, relatively salient low probability sounds in the earliest auditory environment cause long-term changes in the ACX. Early auditory experience can change the organization and responses of the auditory cortex in adulthood. However, little is known about how auditory experience at prenatal ages changes neural circuits and response properties. In mice at equivalent early developmental stages, we find that auditory experience of a particular kind, with a less frequently occurring sound in a stream of another sound, alters adult cortical responsiveness, specifically of the less frequent sound. However, at the previously known critical period of development, the opposite is observed, where the more frequent sound's representation is strengthened in the adult compared with the less frequent sound. We thus show that a specific type of auditory environment can influence adult auditory processing at the earliest ages.
在关键期的感觉体验会改变感觉皮层的反应和组织。我们发现，小鼠听觉皮层（ACX）最早的声音驱动活动始于耳道口（ECO）开放之前。ECO 前听觉经验对 ACX 发育的影响尚不清楚。我们发现，在小鼠 ACX 基板神经元（SPN）中，对丘脑皮质成熟至关重要的神经元，在 ECO 之前对声音有反应，表现出异常选择。在 ECO 之前，SPN 对听觉流中异常声音的选择性比丘脑接受层 4（L4）神经元更高，而在 ECO 之后则不是。我们假设 SPN 的异常选择可以指导 ECO 前 L4 反应的发展。在 ECO 之前，无论是雄性还是雌性的小鼠，在听觉流中听到一个很少出现的音调，会导致该罕见音调在成年皮质中的代表性增强，但不增强常见音调的代表性。在多个发育窗口进行的对照暴露实验的结果，这些实验也只使用单一音调，也证实了这一观察结果。我们使用一个模拟基板和 L4 神经元分层结构以及从我们的数据中得出的反应特性的二进制网络模型，进一步解释了 ECO 前而不是 ECO 后偏差输入的增强，该模型的突触遵循赫布型尖峰时间依赖性可塑性学习规则。基于稀疏编码假设的信息论分析也预测了这一观察结果。因此，在最早的听觉环境中，相对突出的低概率声音会导致 ACX 长期变化。早期的听觉经验可以改变成年听觉皮层的组织和反应。然而，关于产前年龄的听觉经验如何改变神经回路和反应特性，我们知之甚少。在处于等效早期发育阶段的小鼠中，我们发现，特定类型的听觉经验，即在另一个声音的流中出现较少的声音，会改变成年皮质的反应性，特别是对较少出现的声音。然而，在以前已知的关键发育时期，观察到的情况正好相反，与较少出现的声音相比，较频繁出现的声音在成年时的表现得到了增强。因此，我们表明，特定类型的听觉环境可以在最早的年龄影响成年听觉处理。
