前额叶皮层和纹状体的局域场电位的功率编码奖励信息

Reward information encoded by power of local field potentials in the primate prefrontal cortex and striatum

前额叶皮层和纹状体是大脑内两个重要的区域,研究表明它们都参与了许多高级认知过程,如学习记忆、奖励信息处理、行为决策等。单细胞电生理记录实验已显示前额叶皮层和纹状体的神经元能够编码奖励信息,但不清楚这两个区域的局域场电位(local field potential,LFP)是否也能编码奖励信息。为研究这个问题,当猴子在进行一个奖励预测实验时,用多通道电极同时记录了前额叶皮层和纹状体的LFP。采用短时傅里叶变换,将记录的LFP转换为时、频域上的信号,比较不同奖励条件(大容量水奖励和小容量水奖励)下功率值的分布。结果显示前额叶皮层和纹状体的LFP的功率能够区分不同的奖励条件,并且小容量水奖励条件下的功率值大于大容量水奖励条件下的功率值;进一步研究显示LFP在β频段(14~30 Hz)能更好地编码奖励信息。以上结果表明前额叶皮层和纹状体的LFP能够有效地编码奖励信息,有助于进一步理解LFP在处理奖励信息过程中的作用。

Prefrontal cortex and striatum are two major areas in the brain. Some research reports suggest that both areas are involved in many advanced cognitive processes, such as learning and memory, reward processing, and behavioral decision. Single-unit recording experiments have found that neurons in the prefrontal cortex and striatum can represent reward information, but it remains elusive whether and how local field potentials （LFPs） in the two areas encode reward information. To investigate these issues, we recorded LFPs simultaneously in the prefrontal cortex and striatum of two monkeys by performing a reward prediction task （a large amount reward vs a small amount reward）. Recorded LFP signals were transformed from the time domain to the time and frequency domain using the method of short-time Fourier transform （STFT）. We calculated the power in each frequency and time, and examined whether they were different in the two reward conditions. The results showed that power of LFPs in both the prefrontal cortex and striatum distinguished one reward condition from the other one. And the power in small reward trials was greater than that in large reward trials. Furthermore, it was found that the LFPs better encoded reward information in the beta band （14-30 Hz） rather than other frequency bands. Our results suggest that the LFPs in the prefrontal cortex and striatum effectively represent reward information, which would help to further understand functional roles of LFPs in reward processing.