大鼠前扣帶皮質迴的疼痛同理心相關神經元

Abstract

大鼠能夠理解他同伴的情緒嗎? 目前，已經被證實小鼠對疼痛的反應會受到社會性活動的調控，而且這可能和同理心有關。所以我們利用電生理記錄的方式，想測試在大鼠的前扣帶皮質中有沒有同理心相關的神經元。我們使用16頻道微電極記錄前扣帶皮質的神經訊號。實驗過程中，我們把兩隻大鼠(示範鼠、觀察鼠)放在中間有隔板的兩個27公分x 21公分x 35公分的透明壓克力箱中。接著使用雷射熱刺激示範鼠的前腳，並記錄觀察大鼠的行為和神經訊號的反應。結果發現，當示範鼠接受雷射熱刺激時，觀察大鼠會有更多嗅、探索對方的籠子以及顫慄不動的行為。而且有12% 到20% 的前扣帶皮質神經元會對示範鼠被雷射熱刺激有反應。這些因同伴被雷射熱刺激而有反應的神經元反應時間會比當自己被雷射熱刺激的反應時間緩慢。除此之外，當觀察鼠自己有被雷射熱刺激的經驗後，再看同伴鼠被刺激時，其前扣帶皮質神經元的反應會比沒有經驗的時候更快更強。我們的結果顯示在大鼠的前扣帶皮質中可能存在同理心相關神經元。

Social modulation of pain response has been demonstrated in mice. Do rats have feelings for their conspecies? In the present study we tested whether empathy-related neuron could be found in the anterior cingulate cortex (ACC) of the rat. Sixteen-channel microwire electrodes were implanted in the ACC of rats under pentobarbital anesthesia. After full recovery, the implanted rat (observer) was placed next to a demonstrator rat in a 27 cm x 21 cm x 35 cm chamber divided into two equal compartments by a transparent and perforated plexiglass divider. A noxious infrared CO2 laser beam was directed to the forepaw of the demonstrator from under the chamber. The unit activities and behavior responses of the observer were recorded. We found that when the demonstrator was under noxious radiant heat stimulation, more freezing, sniffing and social investigation behaviors of the observer occurred and 12-20 % ACC neurons of the observer responded. The latency of the ACC response of seeing another rat in pain is slower (500-1500 ms) than that of being hit itself (200-400 ms). In addition, when the test trials were repeated after the observer had the noxious experience itself, the responses of seeing their conspecific under laser heat stimulation became faster and stronger. When visual cue was blocked by an opaque divider, the empathy-related social behavior and ACC neuron decreased significantly. Our results demonstrated that behaviors and some of the ACC neurons had empathy-related properties