Biomedical subjects

J Suckling

Publications and source records attributed to J Suckling.

At least 19 recordsLinked to original sources

PubMed2006

Local oestrogen for vaginal atrophy in postmenopausal women.

BACKGROUND: Vaginal atrophy is a frequent complaint of postmenopausal women; symptoms include vaginal dryness, itching, discomfort and painful intercourse. Systemic treatment for these symptoms in the form of oral hormone replacement therapy is not always necessary. An alternative choice is oestrogenic preparations administered vaginally (in the form of creams, pessaries, tablets and the oestradiol-releasing ring). OBJECTIVES: The objective of this review was to compare the effectiveness, safety and acceptability of oestrogenic preparations for women who suffer from vaginal atrophy. SEARCH STRATEGY: We searched the Cochrane Menstrual Disorders and Subfertility Group Register of trials (searched January 2006), The Cochrane Library (2006,Issue 2), MEDLINE (1966 to January 2006), EMBASE (1980 to January 2006), Current Contents (1993 to January 2006, Biological Abstracts (1969 to 2006), Social Sciences Index (1980 to January 2006), PsycINFO (1972 to February 2006), CINAHL (1982 to January 2006) and reference list of articles. We also contacted manufacturers and researchers in the field. SELECTION CRITERIA: The inclusion criteria were randomised comparisons of oestrogenic preparations administered intravaginally in postmenopausal women for the treatment of symptoms resulting from vaginal atrophy or vaginitis. DATA COLLECTION AND ANALYSIS: Thirty-seven trials were identified: of these 18 were excluded. Included trials were assessed for quality and two reviewer authors extracted data independently. The ratios for dichotomous outcomes and means for continuous outcomes were calculated. The outcomes analysed were categorised under the headings of: efficacy, safety and acceptability. MAIN RESULTS: Nineteen trials with 4162 women were included in this review. The overall quality of the studies was good, although not all trials measured the same outcomes. All trials measured efficacy, with various outcome measures. When comparing the efficacy of different oestrogenic preparations (in the form of creams, pessaries, tablets and the oestradiol-releasing vaginal ring) in relieving the symptoms of vaginal atrophy, results indicated significant findings favouring the cream, ring, and tablets when compared to placebo and non-hormonal gel. Fourteen trials compared safety. Four looked at hyperplasia, four looked at endometrial overstimulation and seven looked at adverse effects. One trial showed significant adverse effects of the cream (conjugated equine oestrogen) when compared to tablets (oestradiol) which included uterine bleeding, breast pain and perineal pain (1 RCT; OR 0.18, 95% CI 0.07 to 0.50). Two trials showed significant endometrial overstimulation as evaluated by a progestagen challenge test with the cream (conjugated equine oestrogen) group when compared to the ring (OR 0.29, 95% CI 0.11 to 0.78). Although not statistically significant there was a 2% incidence of simple hyperplasia in the ring group when compared to the cream (conjugated equine oestrogen) and 4% incidence of hyperplasia (one simple, one complex) in the cream group (conjugated equine oestrogen) when compared to the tablet (oestradiol). Eleven studies compared acceptability to the participants by comparing: comfort of product use, ease of use, overall product rating, delivery system and satisfaction. Results showed a significant preference for the oestradiol-releasing vaginal ring. AUTHORS' CONCLUSIONS: Creams, pessaries, tablets and the oestradiol vaginal ring appeared to be equally effective for the symptoms of vaginal atrophy. One trial found significant side effects following cream (conjugated equine oestrogen) administration when compared to tablets causing uterine bleeding, breast pain and perineal pain. Another trial found significant endometrial overstimulation following use of the cream (conjugated equine oestrogen) when compared to the ring. As a treatment choice women appeared to favour the oestradiol-releasing vaginal ring for ease of use, comfort of product and overall satisfaction.

Administration, Intravaginal↗

PubMed2006

Neuroanatomical correlates of memory deficits in tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is a multisystem syndrome classically associated with the occurrence of focal brain dysplasias. We used structural magnetic resonance imaging to test for neuroradiological abnormalities in TSC (tubers, white matter lesions, and subependymal nodules) and to explore the relationships between these lesions and computational morphometric abnormalities of gray and white matter distribution. We tested memory function in TSC and investigated the relationship between memory function and both morphometric variation and lesion load. Patients demonstrated deficits bilaterally in volume of subcortical gray matter regions including thalamus, basal ganglia, insula, and cerebellum, as well as white matter deficits bilaterally in intrahemispheric tracts. Morphometric deficits could not be explained as local effects of lesions. Patients demonstrated deficits in executive working memory and recall memory, sparing recognition. Structure-function mapping showed long-term and working memory function was positively correlated with gray matter density (in thalamus, caudate nucleus, and frontal cortex) but not with lesion load. The neuroanatomical endophenotype of TSC is more extensive than previously recognized and comprises abnormalities in the distribution of gray and white matter in addition to classical lesions. Normal intelligence quotient patients with TSC show a profile of long-term and working memory impairment that is related to gray matter deficits in thalamus and basal ganglia components of fronto-striatal circuits.

Adult↗

PubMed2006

Variable precision registration via wavelets: optimal spatial scales for inter-subject registration of functional MRI.

The detection of significantly activated brain regions in multi-subject functional magnetic resonance imaging (fMRI) studies almost invariably entails the coregistration of individual subjects' data in a standard space. Here, we investigate how sensitivity to detect loci of generic activation in such studies may be conditioned by the precision of anatomical registration. We describe a novel algorithm, implemented in the wavelet domain, for inhomogeneous deformation of individual images to match a template. The algorithm matches anatomical features in a coarse-to-fine fashion, first minimising a cost function in terms of relatively coarse spatial features and then proceeding iteratively to match the images in terms of progressively more detailed anatomical features. Applying the method to data acquired from two groups of 12 healthy volunteers (with mean age 27 and 70 years, respectively), during performance of a paired associate learning task, we show that geometrical overlap between template and individual images is monotonically improved, compared to an affine transform, by additional inhomogeneous deformations informed by more detailed features. Likewise, sensitivity to detect activated voxels can be substantially improved, by a factor of 4 or more, if wavelet-mediated deformations informed by medium-sized anatomical features are applied in addition to a preliminary affine transform. However, sensitivity to detect activated voxels was reduced by "over-registering" data or matching anatomical features at the finest scales of the wavelet transform. The benefits of variable precision registration are particularly salient for data acquired in older subjects, which showed evidence of greater inter-subject anatomic variability and generally required more extensive local deformation to achieve a satisfactory match to the template image. We conclude that major benefits in sensitivity to detect functional activation in multi-subject fMRI studies can be attained with an inhomogeneous deformation applied over appropriate spatial scales.

Adult↗

PubMed2006

Grey matter correlates of minor physical anomalies in the AeSOP first-episode psychosis study.

BACKGROUND: Minor physical anomalies are more prevalent among people with psychosis. This supports a neurodevelopmental aetiology for psychotic disorders, since these anomalies and the brain are both ectodermally derived. However, little is understood about the brain regions implicated in this association. AIMS: To examine the relationship between minor physical anomalies and grey matter structure in a sample of patients with first-episode psychosis. METHOD: Sixty patients underwent assessment of minor physical anomalies with the Lane scale. High-resolution magnetic resonance images and voxel-based methods of image analysis were used to investigate brain structure in these patients. RESULTS: The total anomalies score was associated with a grey matter reduction in the prefrontal cortex and precuneus and with a grey matter excess in the basal ganglia, thalamus and lingual gyrus. CONCLUSIONS: Minor physical anomalies in a sample of patients with first-episode psychosis are associated with regional grey matter changes. These regional changes may be important in the pathogenesis of psychotic disorder.

Adolescent↗

PubMed2005

Plasma level-dependent effects of methylphenidate on task-related functional magnetic resonance imaging signal changes.

RATIONALE: Methylphenidate (MPH) is a dopamine and noradrenaline enhancing drug used to treat attentional deficits. Understanding of its cognition-enhancing effects and the neurobiological mechanisms involved, especially in elderly people, is currently incomplete. OBJECTIVES: The aim of this study was to investigate the relationship between MPH plasma levels and brain activation during visuospatial attention and movement preparation. METHODS: Twelve healthy elderly volunteers were scanned twice using functional magnetic resonance imaging (fMRI) after oral administration of MPH 20 mg or placebo in a within-subject design. The cognitive paradigm was a four-choice reaction time task presented at two levels of difficulty (with and without spatial cue). Plasma MPH levels were measured at six time points between 30 and 205 min after dosing. FMRI data were analysed using a linear model to estimate physiological response to the task and nonparametric permutation tests for inference. RESULTS: Lateral premotor and medial posterior parietal cortical activation was increased by MPH, on average, over both levels of task difficulty. There was considerable intersubject variability in the pharmacokinetics of MPH. Greater area under the plasma concentration-time curve was positively correlated with strength of activation in motor and premotor cortex, temporoparietal cortex and caudate nucleus during the difficult version of the task. CONCLUSION: This is the first pharmacokinetic/pharmacodynamic study to find an association between plasma levels of MPH and its modulatory effects on brain activation measured using fMRI. The results suggest that catecholaminergic mechanisms may be important in brain adaptivity to task difficulty and in task-specific recruitment of spatial attention systems.

Aged↗

PubMed2005

Reduced volume of parietal and frontal association areas in patients with schizophrenia characterized by passivity delusions.

BACKGROUND: In patients with schizophrenia, passivity delusions are characterized by a difficulty in determining the agency of purposive actions. Neuropsychological and functional neuroimaging data suggest that passivity delusions are associated with dysfunction of the parietal lobe association cortex. METHOD: Cortical volume calculated from magnetic resonance imaging data in a group of 12 patients with schizophrenia characterized by motor passivity delusions was compared statistically with the cortical volume of 11 patients without passivity delusions. RESULTS: Reduced cortical volume was observed in parietal and frontal association cortices in the passivity group. CONCLUSIONS: These data provide direct evidence for the involvement of the parietal lobe in the pathophysiology of passivity delusions in schizophrenia.

Adult↗

PubMed2004

Ketamine disrupts frontal and hippocampal contribution to encoding and retrieval of episodic memory: an fMRI study.

The N-methyl-D-aspartate (NMDA) receptor antagonist ketamine produces episodic memory deficits. We used functional magnetic resonance imaging to characterize the effects of ketamine on frontal and hippocampal responses to memory encoding and retrieval in healthy volunteers using a double-blind, placebo-controlled, randomized, within-subjects comparison of two doses of intravenous ketamine. Dissociation of the effects of ketamine on encoding and retrieval processes was achieved using two study-test cycles: in the first, items were encoded prior to drug infusion and retrieval tested, during scanning, on drug; in the second, encoding was scanned on drug, and retrieval tested once ketamine plasma levels had declined. We additionally determined the interaction of ketamine with the depth of processing that occurred at encoding. A number of effects upon task-dependent activations were seen. Overall, our results suggest that left frontal activation is augmented by ketamine when elaborative semantic processing is required at encoding. In addition, successful encoding on ketamine is supplemented by additional non-verbal processing that is incidental to task demands. The effects of ketamine at retrieval are consistent with impaired access to accompanying contextual features of studied items. Our findings show that, even when overt behaviour is unimpaired, ketamine has an impact upon the recruitment of key regions in episodic memory task performance.

Adolescent↗

PubMed2004

The FLUSH trial--flushing with lipiodol for unexplained (and endometriosis-related) subfertility by hysterosalpingography: a randomized trial.

BACKGROUND: To assess the effectiveness of flushing with the oil-soluble contrast medium lipiodol in women with unexplained infertility. METHODS: An open randomized controlled trial design in a single centre secondary and tertiary level infertility service setting. A total of 158 women with unexplained infertility were stratified into two populations: 96 women without confirmed endometriosis and 62 women with endometriosis who had normal Fallopian tubes and ovaries. Randomization was computer-generated, with allocation concealment by opaque sequentially numbered envelopes. Lipiodol flushing was tested versus no intervention. The main outcome measures were clinical pregnancy (assessed at 6 months following randomization) and live birth. RESULTS: Lipiodol flushing resulted in a significant increase in pregnancy [48.0 versus 10.8%, relative risk (RR) 4.44, 95% confidence interval (CI) 1.61-12.21] and live birth (40.0 versus 10.8%, RR 3.70, 95% CI 1.30-10.50) rates versus no intervention for women with endometriosis, although there was no significant difference in pregnancy (33.3 versus 20.8%, RR 1.60, 95% CI 0.81-3.16) or live birth (27.1 versus 14.6%, RR 1.86, 95% CI 0.81-4.25) rates for women with unexplained infertility without confirmed endometriosis. CONCLUSIONS: Lipiodol flushing is an effective treatment for couples with unexplained infertility (based on meta-analysis data), but is particularly effective for women with endometriosis who have normal Fallopian tubes and ovaries.

Adult↗

PubMed2004

Hormone replacement therapy in postmenopausal women: endometrial hyperplasia and irregular bleeding.

BACKGROUND: The decline in circulating oestrogen around the time of the menopause often induces unacceptable symptoms that affect the health and well being of women. Hormone replacement therapy (both unopposed oestrogen and oestrogen and progestogen combinations) is an effective treatment for these symptoms. In women with an intact uterus, unopposed oestrogen may induce endometrial stimulation and increase the risk of endometrial hyperplasia and carcinoma. The addition of progestogen reduces this risk but may cause unacceptable symptoms, bleeding and spotting which can affect adherence to therapy. OBJECTIVES: The objective of this review is to assess which hormone replacement therapy regimens provide effective protection against the development of endometrial hyperplasia and/or carcinoma with a low rate of abnormal vaginal bleeding. SEARCH STRATEGY: We searched the Cochrane Menstrual Disorders and Subfertility Group trials register (searched January 2003), The Cochrane Library (Issue 2, 2003), MEDLINE (1966 to January 2003), EMBASE (1980 to January 2003), Current Contents (1993 to January 2003), Biological Abstracts (1969 to 2002), Social Sciences Index (1980 to January 2003), PsycINFO (1972 to February 2003) and CINAHL (1982 to January 2003). The search strategy was developed by the Cochrane Menstrual Disorder and Subfertility Group. Attempts were also made to identify trials from citation lists of review articles and drug companies were contacted for unpublished data. In most cases, the corresponding author of each included trial was contacted for additional information. SELECTION CRITERIA: The inclusion criteria were randomised comparisons of unopposed oestrogen therapy, combined continuous oestrogen-progestogen therapy and sequential oestrogen-progestogen therapy with each other and placebo administered over a minimum treatment period of six months. Trials had to assess which regimen was the most protective against the development of endometrial hyperplasia/carcinoma and/or caused the lowest rate of irregular bleeding. DATA COLLECTION AND ANALYSIS: Sixty RCTs were identified. Of these 23 were excluded and seven remain awaiting assessment. The reviewers assessed the thirty included studies for quality, extracted the data independently and odds ratios for dichotomous outcomes were estimated. Outcomes analysed included frequency of endometrial hyperplasia or carcinoma, frequency of irregular bleeding and unscheduled biopsies or dilation and curettage, and adherence to therapy. MAIN RESULTS: Unopposed moderate or high dose oestrogen therapy when compared to placebo was associated with a significant increase in rates of endometrial hyperplasia with increasing rates at longer duration of treatment and follow up. Odds ratios ranged from (1 RCT; OR 5.4, 95% CI 1.4 to 20.9) for 6 months of treatment to (4 RCTs; OR 9.6, 95% CI 5.9 to 15.5) for 24 months treatment and (1 RCT; OR 15.0, 95% CI 9.3 to 27.5) for 36 months of treatment with moderate dose oestrogen (in the PEPI trial, 62% of those who took moderate dose oestrogen had some form of hyperplasia at 36 months compared to 2% of those who took placebo). Irregular bleeding and non adherence to treatment were also significantly more likely under these unopposed oestrogen regimens that increased bleeding with higher dose therapy. Although not statistically significant, there was a 3% incidence (2 RCTs) of hyperplasia in women who took low dose oestrogen compared to no incidence of hyperplasia in the placebo group. The addition of progestogens, either in continuous combined or sequential regimens, helped to reduce the risk of endometrial hyperplasia and improved adherence to therapy. At longer duration of treatment, continuous therapy was more effective than sequential therapy in reducing the risk of endometrial hyperplasia. There was evidence of a higher incidence of hyperplasia under long cycle sequential therapy (progestogen given every three months) compared to monthly sequential therapy (progestogen given every month). No increase in endometrial cancer was seen in any of t in any of the treatment groups during the duration (maximum of six years) of these trials. During the first year of therapy irregular bleeding and spotting was more likely in continuous combined therapy than sequential therapy. However, during the second year of therapy bleeding and spotting was more likely under sequential regimens. REVIEWERS' CONCLUSIONS: There is strong and consistent evidence in this review that unopposed oestrogen therapy, at moderate and high doses, is associated with increased rates of endometrial hyperplasia, irregular bleeding and consequent non adherence to therapy. The addition of oral progestogens administered either sequentially or continuously is associated with reduced rates of hyperplasia and improved adherence to therapy. Irregular bleeding is less likely under sequential than continuous therapy during the first year of therapy but there is a suggestion that continuous therapy over long duration is more protective than sequential therapy in the prevention of endometrial hyperplasia. Hyperplasia is more likely when progestogen is given every three months in a sequential regimen compared to a monthly progestogen sequential regimen.

Endometrial Hyperplasia↗

PubMed2004

A double-blind randomised controlled trial of laparoscopic uterine nerve ablation for women with chronic pelvic pain.

OBJECTIVE: To determine the effectiveness of laparoscopic uterine nerve ablation (LUNA) for chronic pelvic pain in women with endometriosis and women with no laparoscopic evidence of endometriosis. DESIGN: A prospective double-blind randomised controlled trial (RCT). SETTING: Single-centre, secondary-level gynaecology outpatient service and tertiary-level pelvic pain and endometriosis outpatient service in Auckland, New Zealand. POPULATION: One hundred and twenty-three women undergoing laparoscopy for investigation and management of chronic pelvic pain, 56 with no laparoscopic evidence of endometriosis and 67 with endometriosis. METHODS: Women were randomised from the two populations, firstly those with no evidence of endometriosis and secondly those undergoing laparoscopic surgical treatment for endometriosis, to receive LUNA or no LUNA. Participant and assessor blinding was employed. Follow up for pain outcomes was undertaken at 24 hours, 3 months and 12 months. MAIN OUTCOME MEASURES: Changes in non-menstrual pelvic pain, dysmenorrhoea, deep dyspareunia and dyschezia were assessed primarily by whether there was a decrease in visual analogue score for these types of pain of 50% or more from baseline and additionally whether there was a significantly different change in median visual analogue score. The numbers requiring further surgery or starting a new medical treatment for pelvic pain and complications were also measured. RESULTS: There was a significant reduction in dysmenorrhoea at 12 month follow up in women with chronic pelvic pain in the absence of endometriosis who underwent LUNA (median change in visual analogue scale (VAS) from baseline -4.8 versus-0.8 (P= 0.039), 42.1%versus 14.3% experiencing a successful treatment defined as a 50% or greater reduction in visual analogue pain scale for dysmenorrhoea (P= 0.045). There was no significant difference in non-menstrual pelvic pain, deep dyspareunia or dyschezia in women with no endometriosis undergoing LUNA versus no LUNA. The addition of LUNA to laparoscopic surgical treatment of endometriosis was not associated with a significant difference in any pain outcomes. CONCLUSIONS: LUNA is effective for dysmenorrhoea in the absence of endometriosis, although there is no evidence of effectiveness of LUNA for non-dysmenorrhoeic chronic pelvic pain or for any type of chronic pelvic pain related to endometriosis.

Adolescent↗

PubMed2003

Dopaminergic drug effects on physiological connectivity in a human cortico-striato-thalamic system.

Cortico-striato-thalamic (CST) systems are anatomical substrates for many motor and executive functions and are implicated in diverse neuropsychiatric disorders. Electrophysiological studies in rats, monkeys and patients with Parkinson's disease have shown that power and coherence of low frequency oscillations in CST systems can be profoundly modulated by dopaminergic drugs. We combined functional MRI with correlational and path analyses to investigate functional and effective connectivity, respectively, of a prefronto-striato-thalamic system activated by object location learning in healthy elderly human subjects (n = 23; mean age = 72 years). Participants were scanned in a repeated measures, randomized, placebo-controlled design to measure modulation of physiological connectivity between CST regions following treatment with drugs which served both to decrease (sulpiride) and increase (methylphenidate) dopaminergic transmission, as well as non-dopaminergic treatments (diazepam and scopolamine) to examine non-specific effects. Functional connectivity of caudate nucleus was modulated specifically by dopaminergic drugs, with opposing effects of sulpiride and methylphenidate. The more salient effect of sulpiride was to increase functional connectivity between caudate and both thalamus and ventral midbrain. A path diagram based on prior knowledge of unidirectional anatomical projections between CST components was fitted satisfactorily to the observed inter-regional covariance matrix. The effect of sulpiride was defined more specifically in the context of this model as increased strength of effective connection from ventral midbrain to caudate nucleus. In short, we have demonstrated enhanced functional and effective connectivity of human caudate nucleus following sulpiride treatment, which is compatible both with the anatomy of ascending dopaminergic projections and with electrophysiological studies indicating abnormal coherent oscillations of CST neurons in parkinsonian states.

Aged↗

PubMed2003

Local oestrogen for vaginal atrophy in postmenopausal women.

BACKGROUND: Vaginal atrophy is a frequent complaint of postmenopausal women; symptoms include vaginal dryness, itching, discomfort and painful intercourse. Systemic treatment for these symptoms in the form of oral hormone replacement therapy is not always necessary. An alternative choice is oestrogenic preparations administered vaginally (in the form of creams, pessaries, tablets and the estradiol releasing ring). OBJECTIVES: The objective of this review is to compare the effectiveness, safety and acceptability of oestrogenic preparations for women who suffer from vaginal atrophy. SEARCH STRATEGY: We searched the Cochrane Menstrual Disorders and Subfertility Group register of trials (searched January 2003), The Cochrane Library (Issue 2, 2003), MEDLINE (1966-January 2003), EMBASE (1980-January 2003), Current Contents (1993-January 2003), Biological Abstracts (1969-2002), Social Sciences Index (1980-January 2003), PsycINFO (1972-February 2003), CINAHL (1982-January 2003) and reference list of articles. We also contacted manufacturers and researchers in the field. SELECTION CRITERIA: The inclusion criteria were randomised comparisons of oestrogenic preparations administered intravaginally in postmenopausal women for the treatment of symptoms resulting from vaginal atrophy or vaginitis. DATA COLLECTION AND ANALYSIS: Twenty nine trials were identified, of these 13 were excluded. Trials were assessed for quality and two reviewers extracted data independently. Ratios for dichotomous and means for continuous outcomes were estimated. Outcomes analysed were included under the headings of efficacy, safety and acceptability. MAIN RESULTS: Sixteen trials with 2129 women were included in this review. The overall quality of the studies was good, although not all trials measured the same outcomes. All trials measured efficacy with various outcome measures. When comparing efficacy of oestrogenic preparations (in the form of creams, pessaries, tablets and the estradiol releasing vaginal ring) with each other in relieving the symptoms of vaginal atrophy, results indicated significant differences favouring the cream, ring, and tablets when compared to placebo and non-hormonal gel. Fourteen trials compared safety. Four looked at hyperplasia, four looked at endometrial overstimulation and six looked at adverse effects. One trial showed significant adverse effects of cream (conjugated equine oestrogen) when compared to tablets (estradiol) which included uterine bleeding, breast pain and perineal pain (1 RCT; OR 0.18, 95% CI 0.07 to 0.50). Two trials showed significant endometrial overstimulation as evaluated by progestagen challenge test in the cream (conjugated equine oestrogen) group when compared to the ring (OR 0.29, 95% CI 0.11 to 0.78). Although not statistically significant there was a 2% incidence of simple hyperplasia in the ring group when compared to cream (conjugated equine oestrogen) and 4% incidence of hyperplasia (one simple, one complex) in the cream group (conjugated equine oestrogen) when compared to the tablet (estradiol). Nine studies compared acceptability to the participants by comparing comfort of product, ease of use, overall product rating, delivery system and satisfaction. Results showed a significant preference for the estradiol releasing vaginal ring. REVIEWER'S CONCLUSIONS: Creams, pessaries, tablets and the estradiol vaginal ring appeared to be equally effective for the symptoms of vaginal atrophy. One trial found significant side effects noted following cream (conjugated equine oestrogen) administration when compared to tablets causing uterine bleeding, breast pain and perineal pain. Another trial found significant endometrial overstimulation following cream (conjugated equine oestrogen) when compared to the ring. As a treatment choice women appeared to favour the estradiol releasing vaginal ring for ease of use, comfort of product and overall satisfaction.

Administration, Intravaginal↗

PubMed2003

GABAergic inhibitory mechanisms for repetition-adaptivity in large-scale brain systems.

Molecular mechanisms for systems level adaptivity of brain activation are largely unknown but a key role for active inhibition by gamma-aminobutyric acid (GABA) is plausible. We used functional magnetic resonance imaging to contrast the modulatory effects on brain adaptivity to task repetition and task difficulty of two GABAergic drugs, lorazepam and flumazenil. In a working memory paradigm, occipitotemporal regions clearly demonstrated attenuation of activation as a function of within-session task repetition or practice in data acquired following placebo, but this spatiotemporal pattern of repetition adaptivity was abolished by both lorazepam and flumazenil. However, in other brain systems flumazenil enhanced repetition adaptivity compared to placebo: in frontal cortex, flumzenil induced attenuation of signal related to task repetition and in hippocampus it exaggerated normal enhancement of signal with repetition. In contrast, there were no significant effects of either flumazenil or lorazepam on areas of frontal cortex which normally demonstrated significant neurocognitive load response or adaptivity to task difficulty. We argue that repetition adaptivity of large-scale brain systems is regulated by GABAergic inhibitory mechanisms and that expression of repetition adaptivity in a given brain system may show an "inverted-U" form of relationship with pharmacologically manipulable levels of GABAergic inhibitory tone.

Adult↗

PubMed2003

The functional neuroanatomy of schizophrenic subsyndromes.

BACKGROUND: There is considerable variability between patients in their expression of the diverse range of symptoms encompassed by the syndrome of schizophrenia, which may modulate functional activation to cognitive processing. METHOD: Here we investigate associations between schizophrenic subsyndrome scores, identified by factor analysis, and experimentally controlled brain activation. Five factors were defined by rotated principal components analysis of PANSS rating scale measurements in 100 patients with schizophrenia. A subsample of 30 patients and a group of 27 comparison subjects were studied using functional magnetic resonance imaging (fMRI) during the performance of two periodically designed cognitive activation experiments: verbal working memory and psychomotor sequencing. RESULTS: Factor analysis replicated the five dimensions consistently reported. Within the patient group. power of activation by working memory was negatively associated with global symptom severity in left lingual and temporo-parietal cortices; negatively associated with positive subsyndrome scores in left inferior frontal and superior temporal cortices and basal ganglia; and positively associated with negative subsyndrome scores in lateral and medial premotor cortex. No relationship was observed between subsyndrome scores and functional activation during the motor task. Between-group comparisons demonstrated reduced power of response to the working memory task by patients in bilateral dorsolateral prefrontal and left pre- and post-central cortices. CONCLUSIONS: In this study we observed task-specific modulation of functional response associated with symptom expression in schizophrenia. Our findings are compatible with previous empirical findings and theoretical conceptualization of human brain function, in terms of capacity constraints on activation in the face of competing demands from pathological and task-related cognitive activity.

Adult↗

PubMed2003

Cerebral tissue alterations and daily life stress experience in psychosis.

OBJECTIVE: To examine whether the total volumes of cerebrospinal fluid (CSF), cerebral grey matter and white matter were correlated with the experience of environmental stress in daily life situations. METHOD: Twenty-seven patients with psychosis underwent magnetic resonance imaging scanning and a random time-sampling self-assessment technique (Experience Sampling Method) to determine subjective daily life stress experiences. Total cerebral tissue volumes were derived from an automated segmentation procedure. RESULTS: CSF volume was positively associated with daily life event-related stress (beta=0.016, P=0.002), while the association with total white matter was negative (beta=-0.013, P=0.005). The effects were independent of each other and of total cerebral volume and other confounders. No large or significant association was found with grey matter volume. CONCLUSION: Subjective stress experience in daily life is associated with increased CSF and reduced white matter volumes in patients with psychosis, suggesting functional significance of these cerebral measures.

Adolescent↗

PubMed2002

Effects of verbal working memory load on corticocortical connectivity modeled by path analysis of functional magnetic resonance imaging data.

We investigated the hypothesis that there are load-related changes in the integrated function of frontoparietal working memory networks. Functional magnetic resonance imaging time-series data from 10 healthy volunteers performing a graded n-back verbal working memory task were modeled using path analysis. Seven generically activated regions were included in the model: left/right middle frontal gyri (L/R MFG), left/right inferior frontal gyri (L/R IFG), left/right posterior parietal cortex (L/R PPC), and supplementary motor area (SMA). The model provided a good fit to the 1-back (chi(2) = 7.04, df = 8, P = 0.53) and 2-back conditions (chi(2) = 9.35, df = 8, P = 0.31) but not for the 3-back condition (chi(2) = 20.60, df = 8, P = 0.008). Model parameter estimates were compared overall among conditions: there was a significant difference overall between 1-back and 2-back conditions (chi(2)(diff) = 74.77, df = 20, P < 0.001) and also between 2-back and 3-back conditions (chi(2)(diff) = 96.28, df = 20, P < 0.001). Path coefficients between LIFG and LPPC were significantly different from zero in both 1-back and 2-back conditions; in the 2-back condition, additional paths from LIFG to LPPC via SMA and to RMFG from LMFG and LPPC were also nonzero. This study demonstrated a significant change in functional integration of a neurocognitive network for working memory as a correlate of increased load. Enhanced inferior frontoparietal and prefrontoprefrontal connectivity was observed as a correlate of increasing memory load, which may reflect greater demand for maintenance and executive processes, respectively.

Adult↗

PubMed2001

Depersonalization disorder: thinking without feeling.

Patients with depersonalization disorder (DP) experience a detachment from their own senses and surrounding events, as if they were outside observers. A particularly common symptom is emotional detachment from the surroundings. Using functional magnetic resonance imaging (fMRI), we compared neural responses to emotionally salient stimuli in DP patients, and in psychiatric and healthy control subjects. Six patients with DP, 10 with obsessive-compulsive disorder (OCD), and six volunteers were scanned whilst viewing standardized pictures of aversive and neutral scenes, matched for visual complexity. Pictures were then rated for emotional content. Both control groups rated aversive pictures as much more emotive, and demonstrated in response to these scenes significantly greater activation in regions important for disgust perception, the insula and occipito-temporal cortex, than DP patients (covarying for age, years of education and total extent of brain activation). In DP patients, aversive scenes activated the right ventral prefrontal cortex. The insula was activated only by neutral scenes in this group. Our findings indicate that a core phenomenon of depersonalization--absent subjective experience of emotion--is associated with reduced neural responses in emotion-sensitive regions, and increased responses in regions associated with emotion regulation.

Adult↗

PubMed2001

Volumetric analysis reveals corticospinal tract degeneration and extramotor involvement in ALS.

BACKGROUND: Pathologic changes in the motor cortex and corticospinal tracts in ALS may be reflected by abnormal signal intensities on conventional MRI. The sensitivity of these changes in detecting underlying pathology remains unclear. METHOD: The authors used automated image analysis to quantify volumes of cerebral gray and white matter in 16 patients with ALS (eight limb onset, eight bulbar onset) and eight normal controls. Previously they had demonstrated a reduction in N-acetyl aspartate/creatine + phosphocreatine (NAA/[Cr + PCr]) measured by (1)H-MRS in the subcortical white matter in the motor cortex region in the patients with bulbar-onset ALS. To determine whether this resulted from axonal degeneration, they also compared gray and white matter volumes in the patients with limb- and bulbar-onset ALS. RESULTS: There were no differences in the total brain volumes of gray or white matter for the three subject groups (p > 0.23). Comparison of the total ALS group and controls revealed localized deficits in gray matter volume centered on Brodmann areas 8, 9, and 10 bilaterally. Comparison of the patients with limb- and bulbar-onset ALS revealed deficits in the white matter volume in the bulbar-onset group, extending bilaterally from the precentral gyrus into the internal capsule and brainstem, consistent with the course of the corticospinal tract. There was no loss in gray matter volume in the precentral gyri. CONCLUSIONS: The loss of gray matter in the frontal regions (total ALS group) provides further support that ALS is a multisystem disorder. In addition, there is in vivo evidence of axonal degeneration in the subcortical white matter in the motor region in patients with bulbar-onset ALS. This is consistent with a "dying back" process affecting cortical motoneurons in bulbar-onset ALS.

Adult↗