Palmer Lucy M, Schulz Jan M, Larkum Matthew E
Physiologisches Institut; Universität Bern; Bern, Switzerland.
Commun Integr Biol. 2013 May 1;6(3):e23545. doi: 10.4161/cib.23545. Epub 2013 May 13.
Processing of sensory information from both sides of the body requires coordination of sensory input between the two hemispheres. This coordination is achieved by transcallosal (interhemispheric) fibers that course though the upper cortical layers. In a recent study by Palmer et al. (2012), we investigated the role of this interhemispheric input on the dendritic and somatic activity of cortical pyramidal neurons. This study showed that interhemispheric input evokes GABAB-mediated inhibition in the distal dendrites of layer 5 pyramidal neurons, decreasing the action potential output when paired with contralateral sensory stimulation. In contrast, layer 2/3 pyramidal neurons were not inhibited by interhemispheric input, possibly due to transcallosal fibers evoking more excitation in these neurons than layer 5 neurons. These results highlight both the precise nature of the microcircuitry of interhemispheric inhibition and how the balance between excitation and inhibition is different in the different layers of the cortex. Identifying the cellular and molecular elements involved in interhemipsheric inhibition is crucial not only for understanding higher brain function and but also dysfunction in the diseased brain.
处理来自身体两侧的感觉信息需要两个半球之间的感觉输入协调。这种协调是通过穿过上层皮质层的胼胝体（半球间）纤维实现的。在Palmer等人（2012年）最近的一项研究中，我们研究了这种半球间输入对皮质锥体神经元树突和体细胞活动的作用。这项研究表明，半球间输入在第5层锥体神经元的远端树突中引发GABAB介导的抑制作用，当与对侧感觉刺激配对时，会减少动作电位输出。相比之下，第2/3层锥体神经元不受半球间输入的抑制，这可能是因为胼胝体纤维在这些神经元中引发的兴奋比第5层神经元更多。这些结果突出了半球间抑制微回路的精确性质，以及皮质不同层中兴奋与抑制之间的平衡是如何不同的。确定参与半球间抑制的细胞和分子成分不仅对于理解高级脑功能至关重要，而且对于理解患病大脑的功能障碍也至关重要。
