Cortical inactivation by cooling in small animals
Cortical inactivation by cooling in small animals
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DOI：
10.3389/fnsys.2011.00053
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发表时间：
2011-01-01
影响因子：
3
通讯作者：
Palmer, Alan R.
中科院分区：
文献类型：
--
作者：
Ben Coomber;Edwards, Darren;Palmer, Alan R.
通过表面冷却使大脑皮层可逆失活是研究特定区域功能的有力方法。植入的冷却冷冻环已被用于研究单个皮质区域在清醒行为猫的听觉处理中的作用。冷冻环也被用于啮齿类动物的可逆性皮层失活，但最近有一种担忧，即冷冻环也可能直接或通过血液灌注冷却非皮层结构，当血液靠近冷却环时冷却。在这项研究中，我们已经证实，环路可以使大部分听觉皮层失活，而不会导致听觉丘脑或其他皮层下结构的温度显著降低。我们在豚鼠皮层的表面放置了一个冷冻环，将其冷却到2摄氏度，并测量了新皮层表面的热梯度。我们发现，在距离环路约2.5毫米的半径内，电池的温度下降到20-24摄氏度。这种温度下降足以降低大多数皮层细胞的活性，并导致几乎整个听觉区域的失活。当在皮质冷却过程中直接测量丘脑、中脑和中耳的温度时，温度有小幅下降（约4摄氏度），但这不足以直接降低神经活动。为了可视化神经失活的程度，我们测量了静脉注射后铊离子的摄取。这证实了同侧皮层的活动大幅减少，而皮层下结构的活动减少较少。
Reversible inactivation of the cortex by surface cooling is a powerful method for studying the function of a particular area. Implanted cooling cryoloops have been used to study the role of individual cortical areas in auditory processing of awake-behaving cats. Cryoloops have also been used in rodents for reversible inactivation of the cortex, but recently there has been a concern that the cryoloop may also cool non-cortical structures either directly or via the perfusion of blood, cooled as it passed close to the cooling loop. In this study we have confirmed that the loop can inactivate most of the auditory cortex without causing a significant reduction in temperature of the auditory thalamus or other subcortical structures. We placed a cryoloop on the surface of the guinea pig cortex, cooled it to 2 degrees C and measured thermal gradients across the neocortical surface. We found that the temperature dropped to 20-24 degrees C among cells within a radius of about 2.5 mm away from the loop. This temperature drop was sufficient to reduce activity of most cortical cells and led to the inactivation of almost the entire auditory region. When the temperature of thalamus, midbrain, and middle ear were measured directly during cortical cooling, there was a small drop in temperature (about 4 degrees C) but this was not sufficient to directly reduce neural activity. In an effort to visualize the extent of neural inactivation we measured the uptake of thallium ions following an intravenous injection. This confirmed that there was a large reduction of activity across much of the ipsilateral cortex and only a small reduction in subcortical structures.