Activation of the prefrontal cortex to trauma-related stimuli measured by near-infrared spectroscopy in posttraumatic stress disorder due to terrorism

To develop a noninvasive method for psychophysiological assessment of posttraumatic stress disorder (PTSD), 34 victims of the Tokyo Subway Sarin Attack in 1995 including 8 diagnosed as PTSD and 12 controls were examined by a multichannel near-infrared spectroscopy (NIRS) system. Hemodynamic response in the prefrontal cortex was monitored during the presentation of trauma-related and control stimuli by video images. Skin conductance response (SCR) was also examined. Oxygenated hemoglobin significantly increased during the trauma-related image in the victims with or without PTSD. Deoxygenated hemoglobin significantly decreased only in victims with PTSD. No significant alteration was found in controls. Significantly enhanced SCR was also observed in the victims with PTSD during trauma-related stimuli. The findings suggest that measurement of cerebral hemodynamic response by NIRS is useful for psychophysiological assessment of PTSD.     

Synchronous activity of two people's prefrontal cortices during a cooperative task measured by simultaneous near-infrared spectroscopy

The brain activity during cooperation as a form of social process is studied. We investigate the relationship between coinstantaneous brain-activation signals of multiple participants and their cooperative-task performance. A wearable near-infrared spectroscopy (NIRS) system is used for simultaneously measuring the brain activities of two participants. Each pair of participants perform a cooperative task, and their relative changes in cerebral blood are measured with the NIRS system. As for the task, the participants are told to count 10 s in their mind after an auditory cue and press a button. They are also told to adjust the timing of their button presses to make them as synchronized as possible. Certain information, namely, the "intertime interval" between the two button presses of each participant pair and which of the participants was the faster, is fed back to the participants by a beep sound after each trial. When the spatiotemporal covariance between the activation patterns of the prefrontal cortices of each participant is higher, the intertime interval between their button-press times was shorter. This result suggests that the synchronized activation patterns of the two participants' brains are associated with their performance when they interact in a cooperative task.     

A multi-channel near-infrared spectroscopy study of prefrontal cortex activation during working memory task in major depressive disorder

Many neuropsychological studies demonstrate impairment of working memory in patients with major depressive disorder (MDD). However, there are not enough functional neuroimaging studies of MDD patients seeking for the underlying brain activity relevant to working memory function. The objective of this study is to evaluate prefrontal hemodynamic response related to working memory function in patients with MDD. Twenty-four subjects with MDD and 26 age- and gender-matched healthy subjects were recruited for the present study. We measured hemoglobin concentration changes in the prefrontal and superior temporal cortical surface areas during the execution of working memory task (WM; 2-back, letter version) using 52-channel near-infrared spectroscopy (NIRS), which enables real-time monitoring of task-related changes in cerebral blood volumes in the cortical surface areas. MDD patients showed a smaller increase in lateral prefrontal and superior temporal cortex activation during the 2-back task and associated poorer task performance than healthy controls. The results coincided with previous findings in terms of working memory deficits and prefrontal cortex dysfunction in MDD patients, but contradicted with some previous fMRI studies that suggested increased cortical activity during the working memory task in patients with depression. The contradiction may, in part, be explained by a relatively low level of cognitive demand imposed on the subjects in the present study.     

Ventromedial prefrontal cortex connectivity during and after psychological stress in women

The ventromedial prefrontal cortex (vmPFC) integrates sensory, affective, memory‐related, and social information from diverse brain systems to coordinate behavioral and peripheral physiological responses according to contextual demands that are appraised as stressful. However, the functionality of the vmPFC during stressful experiences is not fully understood. Among 40 female participants, the present study evaluated (a) functional connectivity of the vmPFC during exposure to and recovery following an acute psychological stressor, (b) associations among vmPFC functional connectivity, heart rate, and subjective reports of stress across individuals, and (c) whether patterns of vmPFC functional connectivity were associated with distributed brain networks. Results showed that psychological stress increased vmPFC functional connectivity with individual brain areas implicated in stressor processing (e.g., insula, amygdala, anterior cingulate cortex) and decreased connectivity with the posterior cingulate cortex and thalamus. There were no statistical differences in vmPFC connectivity to individual brain areas during recovery, as compared with baseline. Spatial similarity analyses revealed stressor‐evoked increased connectivity of the vmPFC with the so‐called dorsal attention, ventral attention, and frontoparietal networks, as well as decreased connectivity with the default mode network. During recovery, vmPFC connectivity increased with the frontoparietal network. Finally, individual differences in heart rate and perceived stress were associated with vmPFC connectivity to the ventral attention, frontoparietal, and default mode networks. Psychological stress appears to alter network‐level functional connectivity of the vmPFC in a manner that further relates to individual differences in stressor‐evoked cardiovascular and affective reactivity.     

Role of the prefrontal cortex in the cognitive control of reaching movements: near-infrared spectroscopy study

To elucidate the role of the prefrontal cortex in cognitive control of reaching movements, by multichannel near-infrared spectroscopy we examine changes in oxygenated hemoglobin (oxy-Hb) as an indicator of changes in regional cerebral blood flow in the bilateral dorsolateral (DLPFC), ventrolateral prefrontal cortex (VLPFC), and frontopolar cortex (FPC) during a reaching task with normal visual feedback (a consistent task) and a reaching task with flipped horizontal visual feedback (an inconsistent task). Subjects first perform 12 trials of the consistent task, and then perform six blocks of the inconsistent task, each of which consists of six trials. During the consistent task, oxy-Hb is increased only in the right VLPFC. During the first block of the inconsistent task, increases in oxy-Hb are observed in the bilateral DLPFC and the right VLPFC, whereas the increased oxy-Hb was gradually reduced as the block proceeded, which was accompanied by an improvement in the task performance. Eventually, there were no differences in the degree of change in oxy-Hb between the consistent and inconsistent tasks in the DLPFC and VLPFC. These findings suggest that the DLPFC is engaged in higher order cognitive control, while the right VLPFC is engaged in both higher and lower order cognitive controls.     

Skin blood flow influences cerebral oxygenation measured by near-infrared spectroscopy during dynamic exercise

Purpose

Near-infrared spectroscopy (NIRS) is widely used to investigate cerebral oxygenation and/or neural activation during physiological conditions such as exercise. However, NIRS-determined cerebral oxygenated hemoglobin (O₂Hb) may not necessarily correspond to intracranial blood flow during dynamic exercise. To determine the selectivity of NIRS to assess cerebral oxygenation and neural activation during exercise, we examined the influence of changes in forehead skin blood flow (SkBF_head) on NIRS signals during dynamic exercise.

Methods

In ten healthy men (age: 20 ± 1 years), middle cerebral artery blood flow velocity (MCA V _mean, via transcranial Doppler ultrasonography), SkBF_head (via laser Doppler flowmetry), and cerebral O₂Hb (via NIRS) were continuously measured. Each subject performed 60 % maximum heart rate moderate-intensity steady-state cycling exercise. To manipulate SkBF_head, facial cooling using a mist of cold water (~4 °C) was applied for 3 min during steady-state cycling.

Results

MCA V _mean significantly increased during exercise and remained unchanged with facial cooling. O₂Hb and SkBF_head were also significantly increased during exercise; however, both of these signals were lowered with facial cooling and returned to pre-cooling values with the removal of facial cooling. The changes in O₂Hb correlated significantly with the relative percent changes in SkBF_head in each individual (r = 0.71–0.99).

Conclusions

These findings suggest that during dynamic exercise NIRS-derived O₂Hb signal can be influenced by thermoregulatory changes in SkBF_head and therefore, may not be completely reflective of cerebral oxygenation or neural activation.     

Using near-infrared spectroscopy to assess neural activation during object processing in infants

The capacity to represent the world in terms of numerically distinct objects (i.e., object individuation) is a milestone in early cognitive development and forms the foundation for more complex thought and behavior. Over the past 10 to 15 yr, infant researchers have expended a great deal of effort to identify the origins and development of this capacity. In contrast, relatively little is known about the neural mechanisms that underlie the ability to individuate objects, in large part because there are a limited number of noninvasive techniques available to measure brain functioning in human infants. Recent research suggests that near-IR spectroscopy (NIRS), an optical imaging technique that uses relative changes in total hemoglobin concentration and oxygenation as an indicator of neural activation, may be a viable procedure for assessing the relation between object processing and brain function in human infants. We examine the extent to which increased neural activation, as measured by NIRS, could be observed in two neural areas known to be involved in object processing, the primary visual cortex and the inferior temporal cortex, during an object processing task. Infants aged 6.5 months are presented with a visual event in which two featurally distinct objects emerge successively to opposite sides of an occluder and neuroimaging data are collected. As predicted, increased neural activation is observed in both the primary visual and inferior cortex during the visual event, suggesting that these neural areas support object processing in the young infant. The outcome has important implications for research in cognitive development, developmental neuroscience, and optical imaging.     

Multiple-time replicability of near-infrared spectroscopy recording during prefrontal activation task in healthy men

Near-infrared spectroscopy (NIRS) has the potential for clinical application in neuropsychiatry because it enables non-invasive and convenient measurement of hemodynamic response to cognitive activation. Using 24-channel NIRS in 12 healthy men, we examined the replicability of oxy- and deoxy-hemoglobin concentration ([oxyHb], [deoxyHb]) changes in the prefrontal cortex during the category fluency task over four repeated sessions (each 1-week apart). Multiple methods were employed to evaluate the replicability of magnitude, location, and time course of the NIRS signals ([oxyHb], [deoxyHb]). Task performances did not differ significantly across sessions, nor were they significantly correlated with NIRS signals. Repeated measures ANOVA and variance component analysis indicated high replicability of magnitude for both NIRS measures, whereas the effect sizes of between-session differences in [oxyHb] were not negligible. The number and spatial location of significantly activated channels were sufficiently replicable for both measures, except that the across-session overlap of significantly activated channels was weak in [deoxyHb]. The time course of the activation was acceptably replicable in both measures. Taken together, these findings suggest there is considerable replicability of multiple-time measurements of prefrontal hemodynamics during cognitive activation in men. Further studies using different conditions or assessing sensitivity to longitudinal changes following interventions are necessary.     

Intersubject variability of near-infrared spectroscopy signals during sensorimotor cortex activation

We investigate the intersubject signal variability of near-infrared spectroscopy (NIRS), which is commonly used for noninvasive measurement of the product of the optical path length and the concentration change in oxygenated hemoglobin (DeltaC'oxy) and deoxygenated hemoglobin (DeltaC'deoxy) and their sum (DeltaC'total) related to human cortical activation. We do this by measuring sensorimotor cortex activation in 31 healthy adults using 24-measurement-position near-infrared (NIR) topography. A finger-tapping task is used to activate the sensorimotor cortex, and significant changes in the hemisphere contralateral to the tapping hand are assessed as being due to the activation. Of the possible patterns of signal changes, 90% include a positive DeltaC'oxy, 76% included a negative DeltaC'deoxy, and 73% included a positive DeltaC'total. The DeltaC'deoxy and DeltaC'total are less consistent because of a large intersubject variability in DeltaC'deoxy; in some cases there is a positive DeltaC'deoxy. In the cases with no positive DeltaC'oxy in the contralateral hemisphere, there are cases of other possible changes for either or both hemispheres and no cases of no change in any hemoglobin species in either hemisphere. These results suggest that NIR topography is useful for observing brain activity in most cases, although intersubject signal variability still needs to be resolved.     

Functional near-infrared spectroscopy reveals heterogeneous patterns of language lateralization over frontopolar cortex

Functional near-infrared spectroscopy (fNIRS), a non-invasive neuroimaging optical technique which measures the cortical concentration changes in oxygenated and deoxygenated hemoglobin (O(2)Hb and HHb, respectively), has been extensively utilized in language studies. Most of these studies investigated the ventrolateral/dorsolateral cortex responses, while few language studies on the frontopolar cortex are reported. The aim of this study was to investigate by fNIRS the frontopolar cortex response to a letter verbal fluency task (VFT) in single healthy subjects to better understand the symmetry/asymmetry of language processing. The O(2)Hb and HHb changes were measured on 33 University students by a 8-channel fNIRS system. A significant increase in O(2)Hb (p<0.001), accompanied by a smaller significant decrease in HHb (p<0.001), was observed in each measurement point. However, the laterality index of 21 out of the 33 subjects evidenced a hemispheric dominance (right 9, left 12). Although these results have confirmed a bilateral activation over the frontopolar cortex upon VFT, no clear pattern of lateralization was found. Considering the importance of establishing a response pattern related to cognitive functions in clinical populations, the fNIRS investigation of the frontopolar cortex (and other areas involved in language) in single subject and the use of the laterality index are recommended.     

Functional near-infrared spectroscopy study on primary motor and sensory cortex response to clenching

The purpose of this study was to elucidate the influence of clenching and clenching intensity on oxygenated hemoglobin (OxyHb) levels in regional cerebral blood flow as an indicator of brain activity in the primary motor and sensory cortices. Functional near-infrared spectroscopy (fNIRS) was used to minimize the effect of clenching-associated muscle activity in eight healthy subjects. Subjects were required to clench at 20%, 50% and 80% of maximum clenching force. To minimize the effect of temporal muscle activity on the working side of the jaw, the fNIRS probes were positioned contralaterally, in the left temporal region. Activation of the primary motor and sensory cortices with clenching was noted in all subjects, irrespective of intensity of clenching. A significant increase was observed in OxyHb in the primary motor cortex between at 80% and both 20% and 50% clenching intensity. In the primary sensory cortex, OxyHb showed a significant increase between all levels of clenching intensity. The results suggest that clenching elicits activation of both the primary motor and sensory cortices, and that intensity of clenching influences activation levels in the brain.     

Activation of the visual cortex imaged by 24-channel near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) is a noninvasive technique for continuous monitoring of the amounts of total hemoglobin (total-Hb), oxygenated hemoglobin, (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb). The purpose of the present study was to demonstrate the utility of NIRS in functional imaging of the human visual cortex. A new NIRS imaging system enabled measurements from 24 scalp locations covering a 9 cm sq area. Topographic images were obtained from interpolations of the concentration changes between measurement points. Five healthy subjects between 25 and 49 years of age were investigated. After a resting baseline period of 50 s, the subjects were exposed to a visual stimulus for 20 s, followed by a 50 s resting period in a dimly lit, sound attenuating room. The visual stimulus was a circular, black and white, alternating checkerboard. In four of five subjects the visual cortex was the most activated area during visual stimulation. This is the first reported use of a NIRS-imaging system for assessing hemodynamic changes in the human visual cortex. The typical hemodynamic changes expected were observed; the total-Hb and oxy-Hb increased just after the start of stimulation and plateaued after 10 s of the stimulation period.     

Functional connectivity of disparity-tuned neurons in the visual cortex

Different mechanisms have been proposed concerning how disparity-tuned neurons might be connected to produce the signals for depth perception. Here we present neurophysiological evidence providing insight on this issue. We have recorded simultaneously from pairs of disparity-tuned neurons in the cat's striate cortex. The purpose was to determine the relationships between disparity tuning and functional connectivity revealed through neural cross-correlograms. Monosynaptic connections tend to be stronger between pairs of cells with similar disparity tuning. Pairs of complex cells tend to have either similar tuning or nearly opposite tuning with an absence of quadrature relations. Pairs with at least one simple cell do have some nearly quadrature relationships when they are recorded from the same electrode. Coarse-to-fine connections (i.e., the presynaptic cell has lower disparity frequency and larger disparity range) tend to be stronger but less frequent than those of a fine-to-coarse nature. Our results are consistent with a system that produces weighted averaging across cells that are tuned to similar disparities but different disparity scales to reduce false matches.     

大脑前额叶多通道近红外光谱信号数据的分类鉴别

背景：精神分裂症主要是通过症候学的方法进行诊断,近年来通过神经影像技术与模式识别的结合对精神分裂症患者与正常人进行鉴别的研究已经引起人们的兴趣。 目的：利用模式识别的方法对精神分裂症患者和正常人的大脑前额叶多通道近红外光谱信号数据进行分类鉴别,验证其可行性。 方法：使用言语流畅性测验作为激活任务,采集精神分裂症患者和正常人的大脑前额叶的近红外光谱信号数据。对采集数据进行预处理后计算各通道均值作为特征,计算接收者操作特征的曲线下方面积对通道特征进行分类性能排序,使用支持向量机按性能排序的特征组合做分类,然后用留一验证法计算分类性能指标,验证分类能力。 结果与结论：研究发现特征性能排序前8位的特征组合的准确度最高达到95.24%,并且这8个通道都位于右侧前额叶。推断右侧前额叶区域可能是影响精神分裂症患者的主要脑区,因此根据结果可以推断出近红外光谱数据通过与模式识别方法的结合可以成为辅助诊断精神分裂症病患者的一种手段。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

Functional columns in the primate prefrontal cortex revealed by optical imaging in vitro

Although the functional column has been implicated in the dorsolateral prefrontal cortex (DLPFC) of primates, its dynamics and even existence are still uncertain. We performed optical recording with a voltage-sensitive dye (RH482) in brain slices obtained from the principal sulcal region (area 46) of macaque monkeys. Columnar activity was evoked by electrical stimulation of the middle layer (lower layer III or layer IV); this activity consisted of two components: probably action potentials and excitatory postsynaptic potentials. The width of the columnar activity was saturated when the current intensity of stimulation exceeded a certain level, that is, approximately 900 microm at the peak with this intensity. The stimulation of different sites within the same slice activated different columnar activities with only slight overlaps. Furthermore, similar columnar activity appeared when a different site within the area with columnar activity was stimulated. These findings suggest that the primate DLPFC consists of functional columns formed by excitatory synaptic connections.     

Ontogeny of Rat Recognition Memory measured by the novel object recognition task

Detection of novelty is an essential component of recognition memory, which develops throughout cerebral maturation. To better understand the developmental aspects of this memory system, the novel object recognition task (NOR) was used with the immature rat and ontogenically profiled. It was hypothesized that object recognition would vary across development and be inferior to adult performance. The NOR design was made age‐appropriate by downsizing the testing objects and arena. Weanling (P20–23), juvenile (P29–40), and adult (P50+) rats were tested after 0.25, 1, 24, and 48 hr delays. Weanlings exhibited novel object recognition at 0.25 and 1 hr, while older animals showed a preference for the novel object out to 24 hr. These findings are consistent with previous research performed in humans and monkeys, as well as to studies using the NOR after medial temporal lobe damage in adult rats. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 672–678, 2009     

活体磁共振波谱定量检测前额皮层γ-氨基丁酸的方法和临床意义

正磁共振波谱(magnetic resonance spectroscopy,MRS)及相关的磁共振波谱成像(magnetic resonance spectroscopy imaging,MRSI)广泛用于非侵入性评价临床和临床前研究的脑物质代谢。氢质子磁共振波谱(1H-MRS)是一种可无创地测量脑内神经化学物质的技术。1H-MRS已被应用于精神类疾病患者的活体病理生理研究。其中前额皮层(prefrontal cortex,PFC)在精神类疾病中起到重要作用。抑制性神经递质氨基丁酸(γ-aminobutyric acid,GABA)是中枢神经系统中最重要的神经递质,对机体的功能具有重要的调节作用。定量检测精神疾病患者PFC中的GABA水平,有望阐明此类疾病的病理生理及发病机制。本文从人类PFC的解剖功能以及