STIMULUS RATE DEPENDENCE OF REGIONAL CEREBRAL BLOOD-FLOW IN HUMAN STRIATE CORTEX, DEMONSTRATED BY POSITRON EMISSION TOMOGRAPHY
STIMULUS RATE DEPENDENCE OF REGIONAL CEREBRAL BLOOD-FLOW IN HUMAN STRIATE CORTEX, DEMONSTRATED BY POSITRON EMISSION TOMOGRAPHY
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DOI：
10.1152/jn.1984.51.5.1109
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发表时间：
1984-01-01
影响因子：
2.5
通讯作者：
RAICHLE, ME
中科院分区：
文献类型：
--
作者：
FOX, PT;RAICHLE, ME
本文研究了简单感觉刺激的重复频率与人脑局部脑血流量的关系。所有的CBF测量均采用正电子发射断层扫描(PET)，使用静脉注射H_215O作为可扩散的血流示踪剂。使用过氧化氢和正电子发射计算机断层扫描，可以在多种刺激条件下快速连续进行8次脑血流量测量，而无需将受试者从断层扫描中移出，从而将基线脑血流量和头部位置的变化降至最低，因为两次扫描之间的间隔更长。正常志愿者[9]每人接受了一系列8次H_215O脑血流正电子发射计算机断层扫描。最初和最后的扫描是在视力剥夺期间进行的。这6次干预扫描是在视觉激活过程中进行的，按1.0、3.9、7.8、15.5、33.1和61赫兹的重复频率随机给出图案闪光刺激。在每个受试者中，确定了rCBF增加最大的区域。在该区域内，针对每个测试条件确定rCBF，然后将其表示为与初始非刺激扫描值的百分比变化(rCBF%)。利用侧颅X线片的骨性标志、透射式衰减扫描创建的颅骨模板和立体定位图谱，对rCBF反应最大的区域进行解剖定位。在每个受试者中，纹状皮质rCBF%DELTA随刺激率而有系统的变化。在0-7.8赫兹之间，rCBF%Δ与刺激重复率呈线性关系。RCBF反应在7.8赫兹时达到峰值，然后下降。除1.0 Hz外，其余各刺激率的rCBF%DELTA在视觉刺激时均显著大于视觉剥夺时。每个受试者的rCBF反应峰值区域的解剖学定位是沿着距骨裂的枕叶内侧，即初级视觉皮质。因此，刺激率是视皮层rCBF反应的重要决定因素。对选择性激活程序的大脑反应的研究人员应该意识到刺激率对rCBF和其他大脑代谢测量的潜在影响。为了有意义地解释大脑对选择性激活的反应，必须考虑刺激重复率。响应幅度可以通过适当的速率选择来最大化，或者由于选择过高或过低的重复速率而不可检测。当对不同刺激或绩效任务的反应进行比较时，必须控制刺激率，否则对于反应差异是由于比率还是由于正在调查的其他任务变量将存在歧义。
The relationship between the repetition rate of a simple sensory stimulus and regional cerebral blood flow (rCBF) in the human brain was studied. Positron emission tomography (PET), using IV administered H215O as the diffusible blood-flow tracer, was employed for all CBF measurements. The use of H215O with PET allowed 8 CBF measurements to be made in rapid sequence under multiple stimulation conditions without removing the subject from the tomograph, thus minimizing changes in base-line CBF and in head position due to longer intervals between scans. Normal volunteers [9] each underwent a series of 8 H215O PET measurements of CBF. Initial and final scans were made during visual deprivation. The 6 intervening scans were made during visual activation with patterned-flash stimuli given in random order at 1.0-, 3.9-, 7.8-, 15.5-, 33.1- and 61-Hz repetition rates. In each subject the region of greatest rCBF increase was determined. Within this region the rCBF was determined for every test condition and then expressed as the percentage change from the value of the initial unstimulated scan (rCBF%.DELTA.). Anatomical localization of the region of greatest rCBF response was performed employing bony landmarks from a lateral skull radiograph, a template of the cranium created from a transmission attenuation scan and a stereotaxic atlas. In every subject, striate cortex rCBF%.DELTA. varied systematically with stimulus rate. Between 0-7.8 Hz, rCBF%.DELTA. was a linear function of stimulus repetition rate. The rCBF response peaked at 7.8 Hz and then declined. The rCBF%.DELTA. during visual stimulation was significantly greater than that during visual deprivation for every stimulus rate except 1.0 Hz. The anatomical localization of the region of peak rCBF response was determined for every subject to be the mesial occipital lobes along the calcarine fissure, primary visual cortex. Thus the stimulus rate is a significant determinant of rCBF response in the visual cortex. Investigators of brain responses to selective activation procedures should be aware of the potential effects of stimulus rate on rCBF and other measurements of cerebral metabolism. For cerebral responses to selective activation to be meaningfully interpreted, the stimulus repetition rate must be taken into consideration. Response amplitude may be maximized by proper rate selection or be undetectable due to selection of too high or too low a repetition rate. Stimulus rate must be controlled for when responses to unlike stimuli or performance tasks are compared or ambiguities will be present as to whether response differences are due to rate or to other task variables under investigation.