Mayrhofer Johannes M, Haiss Florent, Helmchen Fritjof, Weber Bruno
Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland; Neuroscience Center Zurich, CH-8057 Zurich, Switzerland.
Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland; IZKF Aachen, Medical Faculty of the RWTH Aachen University, D-52062 Aachen, Germany; Institute for Neuropathology, RWTH Aachen University, D-52062 Aachen, Germany; Department of Ophthalmology, RWTH Aachen University, D-52062 Aachen, Germany.
Neuroimage. 2015 Jul 15;115:52-63. doi: 10.1016/j.neuroimage.2015.04.045. Epub 2015 Apr 28.
The rodent whisker system is a preferred model for studying plasticity in the somatosensory cortex (barrel cortex). Contrarily, only a small amount of research has been conducted to characterize the stability of neuronal population activity in the barrel cortex. We used the mouse whisker system to address the neuronal basis of stable perception in the somatosensory cortex. Cortical representation of periodic whisker deflections was studied in populations of neurons in supragranular layers over extended time periods (up to 3 months) with long-term two-photon Ca(2+) imaging in anesthetized mice. We found that in most of the neurons (87%), Ca(2+) responses increased sublinearly with increasing number of contralateral whisker deflections. The imaged population of neurons was activated in a stereotypic way over days and for different deflection rates (pulse frequencies). Thus, pulse frequencies are coded by response strength rather than by distinct neuronal sub-populations. A small population of highly responsive neurons (~3%) was sufficient to decode the whisker stimulus. This conserved functional map, led by a small set of highly responsive neurons, might form the foundation of stable sensory percepts.
啮齿动物的触须系统是研究躯体感觉皮层（桶状皮层）可塑性的首选模型。相反，关于桶状皮层中神经元群体活动稳定性的研究却很少。我们利用小鼠触须系统来探究躯体感觉皮层中稳定感知的神经元基础。通过在麻醉小鼠中进行长期双光子Ca(2+)成像，在长达3个月的时间段内，研究了颗粒上层神经元群体对周期性触须偏转的皮层表征。我们发现，在大多数神经元（87%）中，Ca(2+)反应随着对侧触须偏转次数的增加而呈亚线性增加。成像的神经元群体在数天内以及不同的偏转速率（脉冲频率）下均以刻板的方式被激活。因此，脉冲频率是通过反应强度而非不同的神经元亚群进行编码的。一小部分高反应性神经元（约3%）就足以解码触须刺激。这种由一小部分高反应性神经元主导的保守功能图谱可能构成稳定感觉感知的基础。
