Pilato Stephen A, O'Connell Flynn P, Victor Jonathan D, Di Lorenzo Patricia M
Department of Psychology, Binghamton University, Binghamton, NY, United States.
Weill Cornell Medical College, Feil Family Brain and Mind Research Institute, New York, NY, United States.
Front Integr Neurosci. 2024 Jul 16;18:1430950. doi: 10.3389/fnint.2024.1430950. eCollection 2024.
As the intermediate nucleus in the brainstem receiving information from the tongue and transmitting information upstream, the rostral portion of the nucleus tractus solitarius (rNTS) is most often described as a "taste relay". Although recent evidence implicates the caudal NTS in a broad neural circuit involved in regulating ingestion, there is little information about how cells in the rNTS respond when an animal is eating solid food.
Single cells in the rNTS were recorded in awake, unrestrained rats as they explored and ate solid foods (Eating paradigm) chosen to correspond to the basic taste qualities: milk chocolate for sweet, salted peanuts for salty, Granny Smith apples for sour and broccoli for bitter. A subset of cells was also recorded as the animal licked exemplars of the five basic taste qualities: sucrose, NaCl, citric acid, quinine and MSG (Lick paradigm).
Most cells were excited by exploration of a food-filled well, sometimes responding prior to contact with the food. In contrast, cells that were excited by food well exploration became significantly less active while the animal was eating the food. Most cells were broadly tuned across foods, and those cells that were recorded in both the Lick and Eating paradigms showed little correspondence in their tuning across paradigms.
The preponderance of robust responses to the appetitive versus the consummatory phase of ingestion suggests that multimodal convergence onto cells in the rNTS may be used in decision making about ingestion.
作为脑干中接收来自舌头的信息并向上游传递信息的中间核，孤束核吻侧部（rNTS）通常被描述为一个“味觉中继站”。尽管最近的证据表明尾侧孤束核参与了一个广泛的调节摄食的神经回路，但关于rNTS中的细胞在动物进食固体食物时如何反应的信息却很少。
在清醒、不受束缚的大鼠探索和进食对应基本味觉特性的固体食物（进食模式）时，记录rNTS中的单细胞活动。这些固体食物分别为：牛奶巧克力代表甜味、咸花生代表咸味、澳洲青苹代表酸味、西兰花代表苦味。还记录了动物舔舐五种基本味觉特性的样品（舔舐模式）时一部分细胞的活动，这五种基本味觉特性分别为蔗糖、氯化钠、柠檬酸、奎宁和味精。
大多数细胞在探索装有食物的凹槽时被激活，有时在接触食物之前就有反应。相比之下，在探索食物凹槽时被激活的细胞在动物进食时活动显著减少。大多数细胞对不同食物的反应具有广泛的调谐性，并且在舔舐模式和进食模式中都被记录的那些细胞在两种模式下的调谐反应几乎没有对应关系。
对摄食的欲求阶段与完成阶段的强烈反应占主导地位，这表明rNTS中细胞的多模式汇聚可能用于关于摄食的决策。
