Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics and Department of Neuroscience, Columbia College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics and Department of Neuroscience, Columbia College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Cell. 2021 Jan 7;184(1):257-271.e16. doi: 10.1016/j.cell.2020.12.014.
Hardwired circuits encoding innate responses have emerged as an essential feature of the mammalian brain. Sweet and bitter evoke opposing predetermined behaviors. Sweet drives appetitive responses and consumption of energy-rich food sources, whereas bitter prevents ingestion of toxic chemicals. Here we identified and characterized the neurons in the brainstem that transmit sweet and bitter signals from the tongue to the cortex. Next we examined how the brain modulates this hardwired circuit to control taste behaviors. We dissect the basis for bitter-evoked suppression of sweet taste and show that the taste cortex and amygdala exert strong positive and negative feedback onto incoming bitter and sweet signals in the brainstem. Finally we demonstrate that blocking the feedback markedly alters responses to ethologically relevant taste stimuli. These results illustrate how hardwired circuits can be finely regulated by top-down control and reveal the neural basis of an indispensable behavioral response for all animals.
先天反应的硬性电路已成为哺乳动物大脑的一个重要特征。甜和苦会引发相反的预定行为。甜能引起食欲反应和对富含能量的食物的摄取，而苦则防止摄入有毒化学品。在这里，我们鉴定并描述了从舌头到大脑皮层传递甜和苦信号的脑干中的神经元。接下来，我们研究了大脑如何调节这个硬性电路来控制味觉行为。我们剖析了苦味抑制甜味的基础，并表明味觉皮层和杏仁核对传入的苦味和甜味信号在脑干中施加强烈的正反馈和负反馈。最后，我们证明阻断反馈会显著改变对与行为相关的味觉刺激的反应。这些结果说明了硬性电路如何可以通过自上而下的控制进行精细调节，并揭示了所有动物必不可少的行为反应的神经基础。
