Regional cerebral blood flow in developmental stutterers

Stuttering is a poorly understood communication disorder with a 1% global prevalence. Recently, there has been a resurgence of interest in a neurogenic origin for the disorder, although no research has established clear neurological differences between "developmental" (stuttering onset in childhood) stutterers and nonstutterers. We have used xenon 133 single-photon emission computed tomography to study regional cerebral blood flow (rCBF) in 20 stutterers. Analysis revealed global, absolute flow reductions. Relative flow asymmetries (left less than right) were identified in three hemispheric regions: anterior cingulate and superior and middle temporal gyri. Milder changes were found in the left inferior frontal gyrus. Stutterers had rCBF values below median for either anterior cingulate or middle temporal gyri. With one exception, severe stutterers had rCBF values below median for the anterior cingulate gyrus. All stutterers with rCBF values above median in the cingulate gyrus had rCBF values below median in the middle temporal gyrus, and severity of their disorder was either mild or moderate. Our findings suggest that stuttering is a neurogenic disorder involving recognized cortical regions of speech-motor control.     

Relative Changes in Regional Cerebral Blood Flow During Spinal Cord Stimulation in Patients with Refractory Angina Pectoris

Spinal cord stimulation applied at thoracic level 1 (T1) has a neurally mediated anti-anginal effect based on anti-ischaemic action in the myocardium. Positron emission tomography was used to study which higher brain centres are influenced by spinal cord stimulation. Nine patients with a spinal cord stimulator for angina pectoris were studied using H₂¹⁵O as a flow tracer. Relative changes in regional cerebral blood flow related to stimulation compared with non-stimulation were assessed and analysed using the method of statistical parametric mapping. Increased regional cerebral blood flow was observed in the left ventrolateral periaqueductal grey, the medial prefrontal cortex [Brodmann area (BA) 9/10], the dorsomedial thalamus bilaterally, the left medial temporal gyrus (BA 21), the left pulvinar of the thalamus, bilaterally in the posterior caudate nucleus, and the posterior cingulate cortex (BA 30). Relative decreases in rCBF were noticed bilaterally in the insular cortex (BA 20/21 and BA 38), the right inferior temporal gyrus (BA 19/37), the right inferior frontal gyrus (BA 45), the left inferior parietal lobulus (BA 40), the medial temporal gyrus (BA 39) and the right anterior cingulate cortex (BA 24). It is concluded that spinal cord stimulation used as an additional treatment for angina applied at TI modulates regional cerebral blood flow in brain areas known to be associated with nociception and in areas associated with cardiovascular control.     

Reduced reward processing in the brains of Parkinsonian patients

Regional cerebral blood flow (rCBF) in healthy controls and non-demented, non-depressed Parkinsonian patients was measured using H2(15)O PET while subjects performed a prelearned pattern recognition task with delayed response. To investigate differences between the two groups in response to reward, the experimental design consisted of three reinforcement conditions: no reinforcement consisting of nonsense feedback, positive symbolic reinforcement and monetary reward. In the controls, monetary reward activated bilaterally the striatum and anterior cingulate gyrus, as well as unilaterally the left cerebellum, midbrain and medial frontal gyrus. Symbolic reinforcement revealed a similar pattern of activation, except that the striatum and left midbrain showed no activation. The Parkinsonian patients responded to monetary reward with increased activation bilaterally in the cerebellum, medial frontal gyrus, and anterior cingulate gyrus as well as unilaterally in the right fusiform gyrus and midbrain and left caudate nucleus and precentral gyrus. Symbolic reinforcement induced significantly increased rCBF in the right cerebellum only. Compared with symbolic reinforcement, monetary reward produced extended activation of temporoparietal association cortex. The pattern observed in the controls demonstrates the role in reward processing of dopaminergic mesolimbic pathways in the healthy human brain, whereas the pattern in the Parkinsonian patients suggests the involvement of compensatory cortical loops in the diseased brain.     

STN stimulation alters pallidal-frontal coupling during response selection under competition.

To investigate the effects of bilateral subthalamic nucleus (STN) stimulation on patterns of brain activation during random number generation (RNG), a task that requires suppression of habitual counting and response selection under competition. We used H(2)(15)O positron emission tomography to investigate the changes of regional cerebral blood flow (rCBF) induced by bilateral STN stimulation during a RNG task, in six patients with Parkinson's disease. Paced RNG at 1 Hz was compared with a control counting task. Both tasks were performed off medication with deep brain stimulation on and off. Subthalamic nucleus stimulation had a negative effect on performance of fast-paced RNG, leading to reduced randomness and increased habitual counting. Subthalamic nucleus stimulation also induced a reduction of rCBF in the left dorsal frontal gyrus, inferior frontal gyrus, dorsolateral prefrontal cortex, posterior and right anterior cingulate, and an increase of rCBF in the right internal globus pallidum (GPi) during RNG. Stimulation of the STN significantly altered pallidal coupling with frontal and temporal areas compared with when the stimulators were off. In conclusion, during RNG: (i) STN stimulation activates its output neurons to the GPi; (ii) STN stimulation induces increased inhibition of a prefrontal-cingulate network. This is the first direct evidence that STN stimulation significantly alters pallidal coupling with prefrontal, cingulate, and temporal cortices during performance of a task that requires response selection under competition.     

An fMRI investigation of detection of semantic incongruities in autistic spectrum conditions

The aim of this study was to investigate differences in the brain's haemodynamic response to semantically incongruent and congruent sentences in adults with an autistic spectrum condition (ASC) and a typically developing Control group. We used functional magnetic resonance imaging to measure regional variations in neural activity during detection of semantic incongruities within written sentences. Whilst the 12 controls showed a pattern of activity extending from posterior cingulate cortices bilaterally and the left occipitotemporal region to the left superior and inferior temporal lobes, right anterior cingulate and right inferior frontal gyrus, the 12 participants with an ASC presented a more spatially restricted activation pattern, including the left inferior frontal gyrus, left anterior cingulate cortex and right middle frontal gyrus. These results are coherent with the hypothesis that impaired integration of multiple neural networks in people with an ASC is related to previous observations that this group have difficulties in the use of context to predict the final word of sentences.     

SPECT study of visual fixation in schizophrenia and comparison subjects.

BACKGROUND: The consistent association of impaired eye movements and schizophrenia suggests a relationship between the neurobiology of the illness and visual pursuit systems. Visual fixation (VF), an eye "movement" task at zero velocity, is the simplest such abnormality in schizophrenia patients and their relatives. METHODS: We used a VF task for a functional imaging study. Six neuroleptic-free schizophrenia patients and eight gender and mean age matched comparison subjects had SPECT scans with 20 mCi of Tc99-HMPAO, during VF on a simple blue line intersection. MEDX data saved in ANALYZE format for SPM 95 was used to generate paired t-test statistical data for display in Talairach space, with rCBF changes given as Z-scores. RESULTS: Patients, compared to controls, had increased rCBF in both the parahippocampal gyrus (bilaterally) and in the right fusiform gyrus. They had decreased rCBF in the left frontal cortex, including medial and superior frontal gyri and anterior cingulate. Overall, compared to controls, patients had medial temporal lobe hyperperfusion along with left prefrontal hypoperfusion. CONCLUSIONS: These findings are consistent with the hypothesized imbalance between the medial temporal and frontal lobes that is postulated for schizophrenia. It was of interest that the relative rCBF differences between schizophrenia patients and controls in this small sample were observable with this cognitively non-demanding visual fixation task.     

Procedural learning in schizophrenia investigated with functional magnetic resonance imaging

A cerebral basis for the acquisition and retention of procedural knowledge in schizophrenia was examined with 1.5 T functional MRI during an embedded sequence Serial Reaction Time Task (SRTT) in 10 chronic medicated patients and 15 healthy controls. Comparable procedural learning was observed in both groups, suggesting that the impairment reported in previous schizophrenia samples may not be robust. Consistent with previous fMRI reports, procedural learning in the control group was associated with activity in the dorsal striatum, anterior cingulate, parietal cortex and frontal cortex. Greater procedural learning related activity was observed in the control relative to the schizophrenia group in the bilateral frontal, left parietal and bilateral caudate regions. Patients did not activate frontal or parietal areas while responding to the embedded sequence within the SRTT, but greater activation during procedural learning was observed relative to the control sample in the right anterior cingulate, left globus pallidus and the right superior temporal gyrus. Thus, despite comparable instantiation of procedural learning in schizophrenia, the cerebral activation associated with this cognitive skill was abnormal. The paucity of activity in bilateral frontal cortex, left parietal cortex and bilateral caudate nucleus may represent cerebral dysfunction associated with schizophrenia, whereas the hyperactivation of the right superior temporal gyrus, the right anterior cingulate cortex and the left globus pallidus may represent a compensatory cerebral action capable of facilitating near-normal task performance. The results are thus consistent with a neurodevelopmental pathology impinging on fronto-subcortical circuitry.     

A single photon emission computerized tomography (SPECT) study of regional cerebral blood flow in bipolar disorder

Data on functional imaging of bipolar disorder (BD) utilizing single photon emission computerized tomography (SPECT) is limited. This study assessed regional cerebral blood flow (rCBF), using ^99mTc-ECD SPECT, among patients with BD, with mania (N=10) or depression (N=10), compared with 10 patients with unipolar depression and 10 normal controls. Regions of interest were analysed using a semi-automatic brain quantification programme. Compared to controls, patients with mania had significantly reduced perfusion mainly in the left frontal area, also in the left anterior cingulate and parietal cortices; those with bipolar depression had significantly lowered rCBF principally in the anterior temporal regions bilaterally, as well as the left parietal area. Patients with unipolar depression had significantly lowered perfusion than controls in most of the regions examined, chiefly in the anterior temporal and frontal cortices bilaterally; they also had lowered perfusion in the right anterior temporal and frontal areas, as well as the right middle temporal area and the right thalamus, compared to patients with mania. Increased severity of psychotic symptoms was associated with reduced rCBF in patients. These results indicate that altered blood flow in the frontal-subcortical systems characterises patients with BD, as well as those with unipolar depression.     

Regional cerebral blood flow abnormalities in late-life depression:Relation to refractoriness and chronification

Abstract We examined patterns of regional cerebral blood flow (rCBF) abnormalities in 18 patients with major depressive disorder in late life using single photon emission computed tomography (SPECT) and (^99mTc-hexamethyl-propylenamine oxime (^99mTc-HMPAO). Compared with 13 age-matched controls, relative rCBF was significantly decreased bilaterally in the anterior cingulate gyrus, the prefrontal cortex, the temporal cortex, the parietal cortex, the hippocampus and the caudate nucleus. However, it was not correlated with the severity of depression or global cognitive dysfunction. In 10 patients with a prolonged depressive episode or prolonged residual symptoms (the refractory subgroup), robust and extensive decreases in rCBF were found compared with controls and the rCBF decreased significantly in the anterior cingulate gyrus and the prefrontal cortex compared with that in the non-refractory subgroup. In the non-refractory subgroup, rCBF decreased significandy in the caudate nucleus and tended to decrease in the anterior cingulate gyrus compared with controls. These findings indicate that dysfunction of the limbic system, the cerebral association cortex and the caudate nucleus may be implicated in late-life depression and that robust and extensive hypoperfusion, especially in the anterior cingulate and the prefrontal regions, may relate to refractoriness or chronification of depression.     

Abnormal functional connectivity in patients with vascular cognitive impairment, no dementia: a resting-state functional magnetic resonance imaging study

The functional connectivity (FC) method was used to investigate the changes in the resting state of patients with vascular cognitive impairment, no dementia (VCIND). Resting-state functional magnetic resonance images (fMRIs) were acquired from 16 patients with subcortical ischemic vascular disease (SIVD) who fulfilled the criteria for VCIND, as well as 18 age- and sex-matched subjects with SIVD with no cognitive impairment (control group). Posterior cingulate cortex connectivity was gathered by investigating synchronic low-frequency fMRI signal fluctuations with a temporal correlation method. Compared with the control group, the patients showed FC decrease in the left middle temporal gyrus, the left anterior cingulate/left middle frontal gyrus, the right caudate, the right middle frontal gyrus, and the left medial frontal gyrus/paracentral lobule. There were also some regions that showed increased connectivity. These regions included the right inferior temporal gyrus, the left middle temporal gyrus, the left precentral gyrus, and the left superior parietal lobule. Our findings revealed the change in resting-state patterns of neuronal activity in patients with VCIND. This change may be caused by subcortical white matter lesions that destroyed direct and indirect fiber tract connectivity across the cerebral white matter and influenced the cortical FC and hypoperfusion resulted from small vascular disease. The results of the increased connectivity may be evoked by the compensatory recruitment and plasticity mechanism. Our findings suggest that the simplicity and noninvasiveness of this method makes it a potential tool to help thoroughly understand the pathogenesis of VCIND.     

Object identification and lexical/semantic access in children: a functional magnetic resonance imaging study of word-picture matching

Theoretical models for lexical access to visual objects have been based mainly on adult data. To investigate the developmental aspects of object recognition and lexical access in children, a large-scale functional MRI (fMRI) study was performed in 283 normal children ages 5-18 using a word-picture matching paradigm in which children would match an aurally presented noun to one of two pictures (line drawings). Using group Independent Component Analysis (ICA), six task-related components were detected, including (a) the posterior superior temporal gyrus bilaterally; (b) the fusiform, inferior temporal, and middle occipital gyri bilaterally; (c) the dorsal aspect of the inferior frontal gyrus bilaterally, the left precuneus, the left superior/middle temporal gyrus, and the anterior cingulate; (d) the right medial fusiform gyrus; (e) a left-lateralized component including the inferior/middle frontal, middle temporal, medial frontal, and angular gyri, as well as the thalamus and the posterior cingulate; and (f) the ventral/anterior aspect of the inferior frontal gyrus bilaterally. Increased activation associated with age was seen in the components (b) and (d) (ventral visual pathway) for object recognition, and (c) and (f) likely associated with semantic maintenance and response selection. Increased activation associated with task performance was seen in components (b) and (d) (ventral visual pathway) while decreased activation associated with task performance was seen in component (f) (ventral/anterior inferior frontal gyrus). The results corroborate the continued development of the ventral visual pathway throughout the developmental period.     

Cortical reorganization for response regulation with unilateral thalamic stroke detected by functional MRI

To understand neural reorganization of response regulation after stroke, a 54-year-old woman with a chronic left thalamic stroke performed a task requiring decisions about the directionality of an arrow during cerebral functional magnetic resonance imaging. Her performance was compared to 13 matched healthy control subjects. Her behavioral responses were slower but as accurate. Bilateral frontal activations were observed in the right medial frontal gyrus (BA 9), left superior frontal gyrus (BA 45), and left frontal rectus gyrus (BA 11). Activation in the right medial frontal gyrus, along with activity in close proximity to the anterior cingulate cortex, was observed, which may reflect reorganization of activity after the loss of function of the anterior cingulate cortex.     

Acupuncture at the Taixi （KI3） acupoint activates cerebral neurons in elderly patients with mild cognitive impairment

Our previous ifndings have demonstrated that acupuncture at the Taixi （KI3） acupoint in healthy youths can activate neurons in cognitive-related cerebral cortex. Here, we investigated whether acupuncture at this acupoint in elderly patients with mild cognitive impairment can also activate neurons in these regions. Resting state and task-related functional magnetic resonance imaging showed that the pinprick senstation of acupuncture at the Taixi acupoint differed signiifcantly between elderly patients with mild cognitive impairment and healthy elderly controls. Results showed that 20 brain regions were activated in both groups of participants, including the bi-lateral anterior cingulate gyrus （Brodmann areas [BA] 32, 24）, left medial frontal cortex （BA 9, 10, 11）, left cuneus （BA 19）, left middle frontal gyrus （BA 11）, left lingual gyrus （BA 18）, right medial frontal gyrus （BA 11）, bilateral inferior frontal gyrus （BA 47）, left superior frontal gyrus （BA11）, right cuneus （BA 19, 18）, right superior temporal gyrus （BA 38）, left subcallosal gyrus （BA 47）, bilateral precuneus （BA 19）, right medial frontal gyrus （BA 10）, right superior frontal （BA 11）, left cingulate gyrus （BA 32）, left precentral gyrus （BA 6）, and right fusiform gyrus （BA 19）. These results suggest that acupuncture at the Taixi acupoint in elderly patients with mild cogni-tive impairment can also activate some brain regions.     

Recovery from wernicke's aphasia: A positron emission tomographic study

Changes in the organization of the brain after recovery from aphasia were investigated by measuring increases in regional cerebral blood flow (rCBF) during repetition of pseudowords and during verb generation. Six right-handed patients who had recovered from Wernicke's aphasia caused by an infarction destroying the left posterior perisylvian language zone were compared with 6 healthy, right-handed volunteers. In the control subjects, strong rCBF increases were found in the left hemisphere in the posterior part of the superior and middle temporal gyrus (Wernicke's area), and during the generation task in lateral prefrontal cortex (LPFC) and in inferior frontal gyrus (Broca's area). There were some weak right hemisphere increases in superior temporal gyrus and inferior premotor cortex. In the patients, rCBF increases were preserved in the frontal areas. There was clear right hemisphere activation in superior temporal gyrus and inferior premotor and lateral prefrontal cortices, homotopic to the left hemisphere language zones. Increased left frontal and right perisylvian activity in patients with persisting destruction of Wernicke's area emphasizes redistribution of activity within the framework of a preexisting, parallel processing and bilateral network as the central mechanism in functional reorganization of the language system after stroke.     

PET study of the human foveal fixation system.

Positron emission tomography (PET) was used to investigate the functional anatomy of the foveal fixation system in 10 subjects scanned under three different conditions: at rest (REST), during the fixation of a central point (FIX), and while fixating the same foveal target during the presentation of peripheral visual distractors (DIS). Compared with the REST condition, both FIX and DIS tasks activated a common set of cortical areas. First, in addition to the involvement of the occipital visual cortex, both the frontal eye field (FEF) and the intraparietal sulcus (IPS) were bilaterally activated. Right frontal activation was also found in the dorsolateral prefrontal cortex, the inferior part of the precentral gyrus, and the inferior frontal gyrus. These results suggest that both FEF and IPS may constitute the main cortical regions subserving bilaterally the foveal fixation system in humans. The remaining right frontal activations may be considered as part of the anterior attentional network, supporting a role for the right frontal lobe in the allocation of the attentional mechanisms. Compared with the FIX condition, the DIS task also revealed the perceptual and cognitive processes related to the presence of peripheral visual distractors during foveal fixation. In addition to a bilateral activation of the V5/MT motion-sensitive area, a right FEF-IPS network was activated which may correspond to the engagement of the visuospatial attention. Finally, normalized regional cerebral blood flow (NrCBF) decreases were also observed during both DIS and FIX condition performance. Such NrCBF decreases were centered in the superior and middle temporal gyri, the prefrontal cortex, and the precuneus and the posterior retrosplenial part of the cingulate gyrus.     

Effect of worry on regional cerebral blood flow in nonanxious subjects

Several studies suggest that cognitive tasks attenuate activation of the limbic system by emotional stimuli. We investigated the possibility that worry would similarly inhibit the limbic system by examining its effects on regional cerebral blood flow (rCBF). Ten nonanxious volunteers underwent four scans within one session, using positron emission tomography (PET) with H₂¹⁵O as tracer. The first two scans recorded emotionally neutral thinking induced after listening to tapes describing neutral statements. Preceding the third and fourth scans, subjects listened to the self-recorded tape describing their individual worries, were instructed to continue to worry, and were scanned 5 min later. Subjects rated themselves as more anxious during the worry scans but showed no significant heart interbeat or skin conductance changes. During worry, rCBF increases were found bilaterally in the medial fronto-orbital gyri and the right thalamus; rCBF decreases were found bilaterally in the hippocampi and amygdalae, in the right insula, the left and right inferior, middle and superior temporal gyri and the occipito-temporal gyri, the right inferior occipital gyrus and the left supramarginal gyrus. Activity of the left orbito-frontal gyrus was negatively correlated with activity of the amygdalae. The results support the hypothesis that worry-induced prefrontal activity suppresses affect-related subcortical regions.     

Neural networks for internal reading and visual imagery of reading: a PET study

Regional cerebral blood flow (rCBF) measurements with positron emission tomography (PET) were made on 10 volunteers in rest condition as well as while the subjects, with closed eyes, (i) internally listed the letters of the alphabet and cited the first verse of the Hungarian national anthem, (ii) visualised the capital letters of the alphabet, and (iii) visualised the capital letters of the first verse of the Hungarian national anthem. Significant changes in rCBF indicated various networks of cortical neuronal populations active during the tasks. Internal listing, as compared to the rest condition, activated the left precentral gyrus. Visualising the letters of the alphabet, when compared to the rest condition, activated a cortical network comprising fields along the banks of the left and right intraparietal sulci, the left medial frontal, precentral and occipital sulci, and the right superior frontal gyrus. Visualising the letters of the anthem, when compared to the rest condition, activated a cortical network comprising fields along the banks of the left and right intraparietal sulci, the left medial and inferior frontal gyri, and the right anterior cingulate gyrus. Contrasting the two visualisation tasks revealed task specific activation in the left lateral occipital gyrus (alphabet vs. anthem visualisation) and in the left anterior cingulate gyrus (anthem vs. alphabet visualisation). The data indicate that visual imagery of letters of the alphabet or a text engages a widespread network of cortical fields in the visual association cortices and the frontal cortex, without the engagement of the primary (V1) and secondary (V2) visual cortical areas. This finding supports the hypothesis that neuronal populations engaged by visual imagery and visual perception only partially overlap. The networks, activated in the visualisation tasks, have a core which is identical in the different visualisation tasks. The core network is complemented in a task-specific manner by the recruitment of additional cortical neuronal populations.     

Changes in regional cerebral blood flow by therapeutic vagus nerve stimulation in depression: an exploratory approach

Abnormalities in regional cerebral blood flow (rCBF) have been reported to characterize depressive episodes; they are at least partly reversed by antidepressant treatment. Treatment-specific as well as response-related changes in rCBF have been reported. We explored the changes in rCBF induced by vagus nerve stimulation (VNS), a recently proposed antidepressant strategy, by application of single photon emission-computed tomography with (99m)Tc-hexamethyl-propylene amine oxime in otherwise treatment-refractory patients. Both region-of-interest (ROI) and statistical parametric mapping (SPM) analytic approaches were used. Decreases of rCBF in the amygdala, left hippocampus, left subgenual cingulate cortex, left and right ventral anterior cingulum, right thalamus and brain stem were observed; the only increase of rCBF was found by SPM analysis in the middle frontal gyrus. This pattern shares features with changes of rCBF previously associated with the administration of selective serotonin reuptake inhibitors. Similarities to other brain-stimulation strategies in antidepressant treatment were less pronounced.     

PET脑成像观察电针天枢穴治疗腹泻型肠易激综合征：脑内脏感觉中心的变化

题目：电针天枢穴治疗腹泻型肠易激综合征的PET脑成像研究 目的：运用脑功能成像正电子发射扫描技术（PET）,观察D-IBS患者在直肠扩张刺激下脑内脏感觉中心的功能变化,以及电针天枢穴对内脏感觉中心的影响,并初步探讨天枢穴治疗肠易激综合征的神经生物学机制。 方法：6例D-IBS患者（4例男性,2例女性）,其中4例行静息状态、直肠气囊扩张、直肠气囊扩张加电针天枢穴三状态下18F-FDG PET脑显像,2例行直肠气囊扩张、直肠气囊扩张加电针天枢穴两状态下18F-FDG PET脑显像,应用统计参数图（SPM）软件对患者静息状态和正常人静息状态、自身直肠气囊扩张前后、电针天枢穴前后脑PET图像进行配对t检验,分析比较脑局部葡萄糖代谢的差异,P值设为0.001。 结果：① 与正常人对照,D-IBS患者存在双侧颞上回、右枕中回、右额上回、双侧额中回等脑区的葡萄糖代谢增强,但内脏感觉中心并没有增强的表现;② 直肠气囊扩张前后对照,直肠疼痛刺激能使额前皮质、左侧扣带回、中央前后回、颞回等脑区的葡萄糖代谢增强,出现了内脏感觉中心如扣带前回等的激活;③ 电针天枢穴前后对照,电针天枢穴能使左侧扣带回、右侧脑岛、右侧海马旁回、楔前叶、右侧尾状核等脑区葡萄糖代谢降低,内脏感觉中心区域葡萄糖代谢明显降低。 结论：① IBS患者存在内脏敏感性异常,尤其是中枢内脏感觉网络的扣带前回、额前皮质等敏感性有升高的趋势。这可能是临床IBS腹痛、腹胀或腹部不适、腹泻等症状发生的重要的病理生理基础;② 电针天枢穴可以降低扣带回等内脏感觉中心的葡萄糖代谢率,该作用可能是电针天枢穴有效缓解IBS腹痛、腹泻等症状的神经生物学机制。电针天枢穴能削弱内脏高敏感性的原理,可能存在两条途径：一、在脊髓层面抑制内脏疼痛信息的上传;二、在丘脑层面通过整合内脏疼痛信息,抑制内脏感觉信息的上传。     

Effect of worry on regional cerebral blood flow in nonanxious subjects

Several studies suggest that cognitive tasks attenuate activation of the limbic system by emotional stimuli. We investigated the possibility that worry would similarly inhibit the limbic system by examining its effects on regional cerebral blood flow (rCBF). Ten nonanxious volunteers underwent four scans within one session, using positron emission tomography (PET) with H(2)(15)O as tracer. The first two scans recorded emotionally neutral thinking induced after listening to tapes describing neutral statements. Preceding the third and fourth scans, subjects listened to the self-recorded tape describing their individual worries, were instructed to continue to worry, and were scanned 5 min later. Subjects rated themselves as more anxious during the worry scans but showed no significant heart interbeat or skin conductance changes. During worry, rCBF increases were found bilaterally in the medial fronto-orbital gyri and the right thalamus; rCBF decreases were found bilaterally in the hippocampi and amygdalae, in the right insula, the left and right inferior, middle and superior temporal gyri and the occipito-temporal gyri, the right inferior occipital gyrus and the left supramarginal gyrus. Activity of the left orbito-frontal gyrus was negatively correlated with activity of the amygdalae. The results support the hypothesis that worry-induced prefrontal activity suppresses affect-related subcortical regions.