一种用于fMRI的嗅觉刺激装置优化与验证

为搭建可用于磁共振环境下的自动控制嗅觉刺激器，本文根据刺激装置搭建的通用要求和实验室已有装置的性能提出了改进需求和系统整体设计方案．刺激装置分为控制系统与气体输送系统两部分．控制系统的软件部分基于LabVIEW平台编程，采用了虚拟仪器方案，提供可输入刺激序列的人机界面，并根据不同的刺激需求来控制电磁阀动作，以切换不同气路．气体输送系统由4条可变支路和1条恒流支路组成，其中的3条可变气路由洁净空气分别通过装有不同气味液体的洗气瓶来产生3种刺激气味．系统搭建完成后，使用霍尼韦尔AWM43600空气流量传感器测量了系统气体流量波动率为0.3%，同时测得不同刺激气路切换时的切换响应时间为1.07 s．最后使用该刺激装置对8名被试进行嗅觉刺激的同时进行功能磁共振成像（fMRI）实验，实验采用了乙醇、吡啶和乙酸异戊酯3种刺激气味，fMRI图像结果显示被试的嗅觉受到刺激后，丘脑、杏仁核、梨状皮质、眶额皮层等嗅觉相关脑区激活．以上实验表明，本文搭建的指标可量化的刺激器更能满足嗅觉fMRI实验的要求．

Optimization and Evaluation of an Olfactory Stimulator for fMRI Studies

An automatically-controlled olfactometer that can be used in the magnetic resonance imaging environment was designed and built in this study. The overall system design was in accordance with the general requirements of stimulator and aimed to show improvement over an existing olfactometer in the laboratory. The device included two parts: the control system and the gas transportation system. The control system used LabVIEW platform-based software and adopted a virtual apparatus scheme. It was capable of providing man-machine interaction controlling stimulus sequence and gas paths according to the applications. The gas delivery system consisted of 4 variable gas paths and 1 constant gas path, through which clean air was transmitted to three gas-washing bottles filled with liquids having different odors. The fluctuation of gas flow measured by a Honeywell AWM43600 airflow sensor was within 0.3%, and the switching response time between different branches was about 1.07 s. Founctional magnetic resonance imaging (fMRI) experiments on olfaction were performed on 8 subjects with the stimulation device, providing odors of ethanol, pyridine and isoamyl acetate. The fMRI results demonstrated thalamus, amygdala, piriform cortex, orbital frontal cortex activations upon olfactory stimulation. It was concluded that the olfactometer built can deliver quantitative olfactory stimulus and meet the requirements for olfactory fMRI experiments.