Evidence for frequency-dependent cortical plasticity in the human brain.
Evidence for frequency-dependent cortical plasticity in the human brain.
复制标题
人脑皮质可塑性与频率相关的证据。
DOI：
10.1073/pnas.1620988114
复制
发表时间：
2017
影响因子：
11.1
通讯作者：
Lea-Carnall CA
中科院分区：
文献类型：
--
作者：
Lea-Carnall CA
频率相关可塑性(FDP)描述了突触对不同频率刺激的适应。它对大脑皮层网络结构和功能的影响尚不清楚。我们使用心理物理学和功能成像(FMRI)测试了皮层“共振”，即感觉皮质反应最大的有利刺激频率，是否影响了FDP对初级躯体感觉皮质的知觉、功能地形图和连接性的影响。我们在体感皮层的共振频率上、上方或下方同时对两个手指进行协同刺激，并测试了协同刺激前后受试者在触觉定位方面的准确性和速度。在共振以上或共振以下分别进行共刺激后，错误更多，反应时间更慢。AT-共振共刺激后的反应时间更快。在功能磁共振成像中，共振上方两个手指的皮质表示更接近共振，这可能是表现较差的原因。共振没有移动数字区域，但增加了它们之间的功能耦合，潜在地解释了反应时间的改善。为了将这些结果与突触可塑性联系起来，我们模拟了一个包含Hebbian学习的振荡器网络。两个相邻的镶嵌在大脑皮层中的贴片，模拟两个数字区域，以不同的频率进行协同刺激。在高于共振频率时，刺激斑块外的网络激活最大，再现了功能磁共振成像所见的数字表征的传播。在AT-共振共刺激后，斑块内的连接强度增加，再现了增加的功能磁共振连接性。我们发现，FDP延伸到大脑皮层水平，并且受到大脑皮层共振的影响。
Frequency-dependent plasticity (FDP) describes adaptation at the synapse in response to stimulation at different frequencies. Its consequence on the structure and function of cortical networks is unknown. We tested whether cortical “resonance,” favorable stimulation frequencies at which the sensory cortices respond maximally, influenced the impact of FDP on perception, functional topography, and connectivity of the primary somatosensory cortex using psychophysics and functional imaging (fMRI). We costimulated two digits on the hand synchronously at, above, or below the resonance frequency of the somatosensory cortex, and tested subjects’ accuracy and speed on tactile localization before and after costimulation. More errors and slower response times followed costimulation at above- or below-resonance, respectively. Response times were faster after at-resonance costimulation. In the fMRI, the cortical representations of the two digits costimulated above-resonance shifted closer, potentially accounting for the poorer performance. Costimulation at-resonance did not shift the digit regions, but increased the functional coupling between them, potentially accounting for the improved response time. To relate these results to synaptic plasticity, we simulated a network of oscillators incorporating Hebbian learning. Two neighboring patches embedded in a cortical sheet, mimicking the two digit regions, were costimulated at different frequencies. Network activation outside the stimulated patches was greatest at above-resonance frequencies, reproducing the spread of digit representations seen with fMRI. Connection strengths within the patches increased following at-resonance costimulation, reproducing the increased fMRI connectivity. We show that FDP extends to the cortical level and is influenced by cortical resonance.