脑成像介绍(英文版).pptVIP

Brain Imaging 某某某 Brain Imaging Brain imaging involves analyzing activity within the brain while performing various tasks. This allows us to link behavior and brain function to help understand how information is processed. Different types of imaging techniques vary in their temporal (time-based) and spatial (location-based) resolution（时间分辨率和空间分辨率）. Brain imaging is often used in?cognitive neuroscience(认知神经学). 5 Imaging Techniques Tense is said to be a deictic system, since the reference point for the system is usually the act of speaking. Deictic systems are the ways in which a speaker relates references to space and time to the “ here and now” of the utterance. Most grammatical tense systems allow the speaker to describe situations as prior to, concurrent with or following the act of speaking. So in English we have the three tenses: past, future, and present. SPECT ﹠ PET (计算机断层扫描和正电子成像术) SPECT and PET use radioactive isotopes(放射性同位素), which are injected into the subjects bloodstream and taken up by the brain. By observing which areas of the brain take up the radioactive isotope, we can see which areas of the brain are more active than other areas. PET has similar spatial resolution to FMRI, but it has extremely poor temporal resolution. SPECT CT扫描时，一束X射线穿过头部，感光胶片形成图像。这种方法可以产生脑部剖面成像。这种方法只显示脑结构，而非脑功能。 PET EEG（脑电图） EEG measures the electrical fields（电场） generated by large populations of neurons in the cortex（脑皮层） by placing a series of electrodes（电极）on the scalp of the subject. This technique has an extremely high temporal resolution, but a relatively poor spatial resolution. FMRI （功能性磁共振成像） FMRI measures the relative amount of oxygenated blood（含氧血）flowing to different parts of the brain. More oxygenated blood in a particular region is assumed to correlate with an increase in neural activity in that part of the brain. This allows us to localize particular functions within different brain regions. FMRI has moderate spatial and temporal resolut