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Biomedical subjects

Stuart W G Derbyshire

Publications and source records attributed to Stuart W G Derbyshire.

18 recordsLinked to original sources
PubMed2006

Heightened functional neural activation to psychological stress covaries with exaggerated blood pressure reactivity.

Individuals who show exaggerated blood pressure reactions to psychological stressors are at increased risk for hypertension, atherosclerosis, and stroke. We tested whether individuals who show exaggerated stressor-induced blood pressure reactivity also show heightened stressor-induced neural activation in brain areas involved in controlling the cardiovascular system. In a functional MRI study, 46 postmenopausal women (mean age: 68.04; SD: 1.35 years) performed a standardized Stroop color-word interference task that served as a stressor to increase blood pressure. Across individuals, a larger task-induced rise in blood pressure covaried with heightened and correlated patterns of activation in brain areas implicated previously in stress-related cardiovascular control: the perigenual and posterior cingulate cortex, bilateral prefrontal cortex, anterior insula, and cerebellum. Entered as a set in hierarchical regression analyses, activation values in these brain areas uniquely predicted the magnitude of task-induced changes in systolic (DeltaR(2)=0.54; P<0.001) and diastolic (DeltaR(2)=0.27; P<0.05) blood pressure after statistical control for task accuracy and subjective reports of task stress. Heightened stressor-induced activation of cingulate, prefrontal, insular, and cerebellar brain areas may represent a functional neural phenotype that characterizes individuals who are prone to show exaggerated cardiovascular reactivity.

Aged↗
PubMed2005

Anterior cingulate activity correlates with blood pressure during stress.

The anterior cingulate cortex presumptively regulates blood pressure reactions to behavioral stressors. There is little evidence in humans, however, that stressor-evoked changes in blood pressure correlate with concurrent changes in anterior cingulate activity. Using fMRI, we tested whether changes in mean arterial blood pressure correlate with ongoing changes in blood oxygen level dependent (BOLD) activation in 9 women and 11 men who completed a stressful Stroop color-word interference task. Higher mean arterial pressure during the Stroop task correlated with greater BOLD activation in two regions of the cingulate cortex (perigenual and mid-anterior) and in other networked brain regions, including the insula, thalamus, and periaqueductal gray. These results support the hypothesis that the anterior cingulate cortex regulates blood pressure reactions to behavioral stressors in humans.

Blood Pressure↗
PubMed2004

Cerebral activation during hypnotically induced and imagined pain.

The continuing absence of an identifiable physical cause for disorders such as chronic low back pain, atypical facial pain, or fibromyalgia, is a source of ongoing controversy and frustration among pain physicians and researchers. Aberrant cerebral activity is widely believed to be involved in such disorders, but formal demonstration of the brain independently generating painful experiences is lacking. Here we identify brain areas directly involved in the generation of pain using hypnotic suggestion to create an experience of pain in the absence of any noxious stimulus. In contrast with imagined pain, functional magnetic resonance imaging (fMRI) revealed significant changes during this hypnotically induced (HI) pain experience within the thalamus and anterior cingulate (ACC), insula, prefrontal, and parietal cortices. These findings compare well with the activation patterns during pain from nociceptive sources and provide the first direct experimental evidence in humans linking specific neural activity with the immediate generation of a pain experience.

Adult↗
PubMed2003

Visceral afferent pathways and functional brain imaging.

The application of functional imaging to study painful sensations has generated considerable interest regarding insight into brain dysfunction that may be responsible for functional pain such as that suffered in patients with irritable bowel syndrome (IBS). This review provides a brief introduction to the development of brain science as it relates to pain processing and a snapshot of recent functional imaging results with somatic and visceral pain. Particular emphasis is placed on current hypotheses regarding dysfunction of the brain-gut axis in IBS patients. There are clear and interpretable differences in brain activation following somatic as compared with visceral noxious sensation. Noxious visceral distension, particularly of the lower gastrointestinal tract, activates regions associated with unpleasant affect and autonomic responses. Noxious somatic sensation, in contrast, activates regions associated with cognition and skeletomotor responses. Differences between IBS patients and control subjects, however, were far less clear and interpretable. While this is in part due to the newness of this field, it also reflects weaknesses inherent within the current understanding of IBS. Future use of functional imaging to examine IBS and other functional disorders will be more likely to succeed by describing clear theoretical and clinical endpoints.

Afferent Pathways↗
PubMed2003

Sex-related differences in IBS patients: central processing of visceral stimuli.

BACKGROUND & AIMS: Women have a higher prevalence of irritable bowel syndrome (IBS) and possible differences in response to treatment, suggesting sex-related differences in underlying pathophysiology. The aim of this study was to determine possible sex-related differences in brain responses to a visceral and a psychological stressor in IBS. METHODS: Regional cerebral blood flow measurements using H(2)(15)O positron emission tomography were compared across 23 female and 19 male nonconstipated patients with IBS during a visceral stimulus (moderate rectal inflation) and a psychological stimulus (anticipation of a visceral stimulus). RESULTS: In response to the visceral stimulus, women showed greater activation in the ventromedial prefrontal cortex, right anterior cingulate cortex, and left amygdala, whereas men showed greater activation of the right dorsolateral prefrontal cortex, insula, and dorsal pons/periaqueductal gray. Similar differences were observed during the anticipation condition. Men also reported higher arousal and lower fatigue. CONCLUSIONS: Male and female patients with IBS differ in activation of brain networks concerned with cognitive, autonomic, and antinociceptive responses to delivered and anticipated aversive visceral stimuli.

Adult↗
PubMed2003

Caudal cingulate cortex involvement in pain processing: an inter-individual laser evoked potential source localisation study using realistic head models.

Electrophysiological studies have revealed a source of laser pain evoked potentials (LEPs) in cingulate cortex. However, few studies have used realistically shaped head models in the source analysis, which account for individual differences in anatomy and allow detailed anatomical localisation of sources. The aim of the current study was to accurately localise the cingulate source of LEPs in a group of healthy volunteers, using realistic head models, and to assess the inter-individual variability in anatomical location. LEPs, elicited by painful CO(2) laser stimulation of the right forearm, were recorded from 62 electrodes in five healthy subjects. Dipole source localisation (CURRY 4.0) was performed on the most prominent (P2) peak of each LEP data set, using head models derived from each subject's structural magnetic resonance image (MRI).For all subjects, the P2 LEP peak was best explained by a dipole whose origin was in cingulate cortex (mean residual variance was 3.9+/-2.4 %). For four out of five subjects, it was located at the border of the caudal division of left anterior cingulate cortex (area 24/32') with left posterior cingulate cortex (area 23/31). For the fifth subject the dipole was centred in right posterior cingulate cortex (area 31). This study demonstrates that the location of the cingulate source of LEPs is highly consistent across subjects, when analysed in this way, and supports the involvement of caudal cingulate regions in pain processing.

Adult↗
PubMed2003

Structural and functional dichotomy of human midcingulate cortex.

Anterior cingulate cortex is comprised of perigenual and midcingulate regions based on cytology, imaging and connections. Its anterior (aMCC) and posterior (pMCC) parts and transition to posterior area 23 were evaluated in six human cingulate gyri with Nissl staining and immunoreactions for neuron-specific nuclear binding protein and intermediate neurofilament proteins (NFP), and their pain and emotion functions evaluated in standard coordinates. Morphological differences included a poorly differentiated layer III with few NFP-expressing neurons in aMCC and a very dense layer Va with small and large pyramids intermingled in pMCC. The density of NFP-positive, layer Vb neurons was higher in pMCC than in aMCC. The junction of pMCC with area 23 had a dysgranular area 23d with clumps of layer IV neurons and a very dense layer Va. Each case was co-registered to standard coordinates and the regional borders identified and measured. Although both regions had overall equivalent activations during noxious cutaneous thermal stimulation, the posterior two-thirds of pMCC was relatively inactive. About 60% of fear-induced activity was in aMCC, sadness and happiness activated perigenual cortex, and neither were activated with non-emotion tasks. Thus, pain activity is coupled to fear in aMCC, while other MCC processing is not related to affect. Beyond midcingulate duality, this is the first report of a very dense layer Va for areas p24' and 23 and the features of transitional area 23d. The MCC dichotomy suggests that two circuits differentially regulate the two cingulate motor areas, and involvement of aMCC in pain and fear make it selectively vulnerable to chronic pain and stress syndromes.

Adult↗
PubMed2003

A systematic review of neuroimaging data during visceral stimulation.

OBJECTIVE: The application of functional imaging to study visceral sensation has generated considerable interest regarding insight into the function of the brain-gut axis, but also some contradictory and confusing results that require appraisal. METHODS: Published studies of visceral sensation were grouped according to stimulus region and study population. The results of each study were tabulated and the center of reported activations plotted onto the lateral and medial surface of a representative brain. RESULTS: Esophageal distension predominantly activated primary sensory and motor cortices and the midsection of the medial surface. Lower GI distension predominantly activated bilateral prefrontal and orbitofrontal cortices and more anterior and ventral regions of the medial surface. CONCLUSIONS: Activation sites are reasonably well clustered within stimulus modality, implying consistent brain response to visceral sensation. The differences in reported activation during esophageal and lower GI sensation imply altered motor, autonomic, and affect response during distension at opposite ends of the GI tract that may be explored in future studies.

Brain↗
PubMed2002

Functional imaging of pain perception.

The application of functional imaging techniques has revolutionized the field of human pain physiology and has elaborated the understanding of mechanisms involved in pain processing at the cortical and subcortical levels. With these insights, new therapeutic interventions are being developed in the treatment of acute and chronic pain conditions.

Acute Disease↗
PubMed2002

Measuring our natural painkiller.

Studies of the brain during noxious experience converge on the anterior cingulate cortex as a key region in the processing of pain. A recent exciting study extends this understanding to include the anterior cingulate as a center for endogenous opioid activation specific to negative pain affect.

Brain Mapping↗
PubMed2002

Gender differences in patterns of cerebral activation during equal experience of painful laser stimulation.

A previous functional imaging study demonstrated greater female response in the anterior insula and thalamus and left prefrontal activation in men and right prefrontal activation in women during equal heat intensity but unequal pain experience. For the current study, subjective intensities of noxious heat delivered to the back of the right hand were equalized across subjects, and regional cerebral blood flow was recorded by using positron emission tomography. The female subjects required less laser energy before reporting pain, but the difference was not significant. Correlation of regional cerebral blood flow with subjective pain experience in the whole group showed significant bilateral responses in the parietal, lateral premotor, prefrontal, secondary somatosensory, anterior cingulate and insula cortices, as well as the thalamus. There was significantly greater activation in the left, contralateral, prefrontal, primary and secondary somatosensory, parietal, and insula cortices in the male subjects compared with the female subjects and greater response in the perigenual cingulate cortex in the female subjects. Our study is the first to associate consistent pain experience with gender differences in central response. These differences may relate to differential processing of acute pain with implications for clinical disorders that show a female dominance. The subtle behavioral differences and inconsistent findings across studies, however, suggest the need for caution and further experimentation before speculating further.

Journal Article↗
PubMed1997

Pain processing during three levels of noxious stimulation produces differential patterns of central activity.

Previous functional imaging studies have demonstrated a number of discrete brain structures that increase activity with noxious stimulation. Of the commonly identified central structures, only the anterior cingulate cortex shows a consistent response during the experience of pain. The insula and thalamus demonstrate reasonable consistency while all other regions, including the lentiform nucleus, somatosensory cortex and prefrontal cortex, are active in no more than half the current studies. The reason for such discrepancy is likely to be due in part to methodological variability and in part to individual variability. One aspect of the methodology which is likely to contribute is the stimulus intensity. Studies vary considerably regarding the intensity of the noxious and non-noxious stimuli delivered. This is likely to produce varying activation of central structures coding for the intensity, affective and cognitive components of pain. Using twelve healthy volunteers and positron emission tomography (PET), the regional cerebral blood flow (rCBF) responses to four intensities of stimulation were recorded. The stimulation was delivered by a CO2 laser and was described subjectively as either warm (not painful), pain threshold just painful), mildly painful or moderately painful. The following group subtractions were made to examine the changing cerebral responses as the stimulus intensity increased: (1) just painful - warm; (2) mild pain - warm; and (3) moderate pain - warm. In addition, rCBF changes were correlated with the subjective stimulus ratings. The results for comparison '1' indicated activity in the contralateral prefrontal (area 10/46/44), bilateral inferior parietal (area 40) and ipsilateral premotor cortices (area 6), possibly reflecting initial orientation and plans for movement. The latter comparisons and correlation analysis indicated a wide range of active regions including bilateral prefrontal, inferior parietal and premotor cortices and thalamic responses, contralateral hippocampus, insula and primary somatosensory cortex and ipsilateral perigenual cingulate cortex (area 24) and medial frontal cortex (area 32). Decreased rCBF was observed in the amygdala region. These responses were interpreted with respect to their contribution to the multidimensional aspects of pain including fear avoidance, affect, sensation and motivation or motor initiation. It is suggested that future studies examine the precise roles of each particular region during the central processing of pain.

Adult↗