Samerphob Nifareeda, Cheaha Dania, Chatpun Surapong, Kumarnsit Ekkasit
Department of Physiology, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand; Brain Signal Research Unit, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
Department of Biology, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand; Brain Signal Research Unit, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
Neurobiol Learn Mem. 2017 Jul;142(Pt B):173-181. doi: 10.1016/j.nlm.2017.05.011. Epub 2017 May 19.
Eating motivation is induced not only by negative energy balance but also food related cues. However, neural processing for acquisition of learned food preference remains to be established. This study aimed to identify hippocampal neural signaling in response to olfactory cue (chocolate scent) after completion of repetitive chocolate sessions. Male Swiss albino mice implanted with intracranial electrode into the hippocampus were used for local field potential (LFP) recording. Animals were given chocolate sessions (a piece of 2g chocolate per each mouse to eat on day 1, 3, 5 and 7). Hippocampal CA1 LFP signals and exploratory behavior of animals receiving chocolate scent were analyzed before and after chocolate sessions. The experiment was performed in a place preference-like apparatus with the zones of normal food pellet and chocolate (both kept in a small perforated cup for smell dispersion) at the opposite ends. Following chocolate sessions, time spent in a chocolate zone and CA1 LFP patterns were analyzed in comparison to control levels. Two-way ANOVA revealed significant increase in time spent seeking for chocolate. Frequency analysis of LFP power spectra revealed significant increases in delta and theta powers. Phase-amplitude analysis showed significant increase in maximal modulation index and decrease in frequency for phase of theta-high gamma coupling. Taken together, neural signaling in the hippocampus was sensitive to chocolate olfactory cue that might underlie learning process in response to repeated chocolate consumptions that primed intense food approaching behavior. Ultimately, these LFP patterns might reflect motivation to eat and predict feeding probability.
进食动机不仅由负能量平衡引发，还受与食物相关的线索影响。然而，习得性食物偏好获取过程中的神经处理机制仍有待确立。本研究旨在确定在重复进行巧克力喂食实验后，海马体对嗅觉线索（巧克力气味）的神经信号反应。将颅内电极植入海马体的雄性瑞士白化小鼠用于记录局部场电位（LFP）。给动物进行巧克力喂食实验（第1、3、5和7天，每只小鼠喂食一块2克的巧克力）。在巧克力喂食实验前后，分析接受巧克力气味刺激的动物的海马CA1区LFP信号和探索行为。实验在一个类似位置偏好的装置中进行，正常食物颗粒区和巧克力区（两者都放在一个有小孔的小杯子里以散发气味）位于相对两端。在巧克力喂食实验后，与对照水平相比，分析动物在巧克力区停留的时间和CA1区LFP模式。双向方差分析显示，寻找巧克力的时间显著增加。LFP功率谱的频率分析显示，δ波和θ波功率显著增加。相位-幅度分析显示，θ波-高γ波耦合的最大调制指数显著增加，相位频率降低。综上所述，海马体中的神经信号对巧克力嗅觉线索敏感，这可能是对重复食用巧克力引发强烈食物趋近行为的学习过程的基础。最终，这些LFP模式可能反映进食动机并预测进食概率。
