Sensory input directs spatial and temporal plasticity in primary auditory cortex
Sensory input directs spatial and temporal plasticity in primary auditory cortex
复制标题
DOI：
10.1152/jn.2001.86.1.326
复制
发表时间：
2001-07-01
影响因子：
2.5
通讯作者：
Merzenich, MM
中科院分区：
文献类型：
--
作者：
Kilgard, MP;Pandya, PK;Merzenich, MM
感觉环境的皮层表征不断地被经验所改变。皮层神经元的空间（感受野）和时间响应特性的变化是许多自然学习形式的基础。这些变化的规模和方向似乎是由唤起皮层可塑性的行为任务的特定特征决定的。负责这种差异可塑性的神经机制仍不清楚，部分原因是这些任务之间的重要感觉和认知参数不同。在这份报告中，我们证明了差异的感觉经验指导差异可塑性使用一个单一的范例，消除了任务特定的变量，混淆了以前的研究直接比较。基底前脑（BF）的电激活用于门控皮质可塑性机制。听觉刺激与BF刺激配对系统地变化，以确定几个基本特征的感觉输入直接可塑性在初级听觉皮层（A1）的成年大鼠。分布的皮层反应重建4周后BF声音配对的A1神经元的密集采样。我们以前用这种方法表明，当一个音调与BF激活配对时，皮层地图上对该音调频率的反应区域会特别扩大。在这份报告中，我们表明，感受场的大小是由功能的刺激配对BF激活。具体而言，感受野缩小或扩大作为一个系统的功能，载波频率的变化和配对的声刺激的时间调制率。例如，A1神经元的平均带宽增加（+60%）后配对BF刺激与快速列车的音调和配对后不同频率的未调制的音调下降（-25%）。这些影响是一致的，与以前的报告自然学习诱发的感受野可塑性。最大皮层以下率和最小反应潜伏期也被修改为刺激调制率和载波频率变异性的函数。如果BF刺激与随机载波频率的快速列车配对，则对快速列车的音调的皮层反应几乎加倍，而如果使用单个载波频率，则没有观察到以下速率可塑性。最后，我们观察到显着增加的反应强度和总面积的功能定义的A1后，BF激活配对的某些类别的刺激，而不是其他。这些结果表明，皮层可塑性的时间和感受场的选择性的程度和方向指定的结构和时间表的输入，共同发生与基底前脑激活，并建议皮层可塑性的规则不独立于其他操作的每个元素的刺激功能。
The cortical representation of the sensory environment is continuously modified by experience. Changes in spatial (receptive field) and temporal response properties of cortical neurons underlie many forms of natural learning. The scale and direction of these changes appear to be determined by specific features of the behavioral tasks that evoke cortical plasticity. The neural mechanisms responsible for this differential plasticity remain unclear partly because important sensory and cognitive parameters differ among these tasks. In this report, we demonstrate that differential sensory experience directs differential plasticity using a single paradigm that eliminates the task-specific variables that have confounded direct comparison of previous studies. Electrical activation of the basal forebrain (BF) was used to gate cortical plasticity mechanisms. The auditory stimulus paired with BF stimulation was systematically varied to determine how several basic features of the sensory input direct plasticity in primary auditory cortex (A1) of adult rats. The distributed cortical response was reconstructed from a dense sampling of A1 neurons after 4 wk of BF-sound pairing. We have previously used this method to show that when a tone is paired with BF activation, the region of the cortical map responding to that tone frequency is specifically expanded. In this report, we demonstrate that receptive-field size is determined by features of the stimulus paired with BF activation. Specifically, receptive fields were narrowed or broadened as a systematic function of both carrier-frequency variability and the temporal modulation rate of paired acoustic stimuli. For example, the mean bandwidth of A1 neurons was increased (+60%) after pairing BF stimulation with a rapid train of tones and decreased (-25%) after pairing unmodulated tones of different frequencies. These effects are consistent with previous reports of receptive-field plasticity evoked by natural learning. The maximum cortical following rate and minimum response latency were also modified as a function of stimulus modulation rate and carrier-frequency variability. The cortical response to a rapid train of tones was nearly doubled if BF stimulation was paired with rapid trains of random carrier frequency, while no following rate plasticity was observed if a single carrier frequency was used. Finally, we observed significant increases in response strength and total area of functionally defined A1 following BF activation paired with certain classes of stimuli and not others. These results indicate that the degree and direction of cortical plasticity of temporal and receptive-field selectivity are specified by the structure and schedule of inputs that co-occur with basal forebrain activation and suggest that the rules of cortical plasticity do not operate on each elemental stimulus feature independently of others.